Circulatory system of the blood Health Dictionary

Circulatory System Of The Blood: From 1 Different Sources


The course of the circulation is as follows: the veins pour their blood, coming from the head, trunk, limbs and abdominal organs, into the right atrium of the HEART. This contracts and drives the blood into the right ventricle, which then forces the blood into the LUNGS by way of the pulmonary artery. Here it is contained in thin-walled capillaries, over which the air plays freely, and through which gases pass readily out and in. The blood gives o? carbon dioxide (CO2) and takes up oxygen (see RESPIRATION), and passes on by the pulmonary veins to the left atrium of the heart. The left atrium expels it into the left ventricle, which forces it on into the aorta, by which it is distributed all over the body. Passing through capillaries in the various tissues, it enters venules, then veins, which ultimately unite into two great veins, the superior and the inferior vena cava, these emptying into the right atrium. This complete circle is accomplished by any particular drop of blood in about half a minute.

In one part of the body there is a further complication. The veins coming from the bowels, charged with food material and other products, split up, and their blood undergoes a second capillary circulation through the liver. Here it is relieved of some food material and puri?ed, and then passes into the inferior vena cava, and so to the right atrium. This is known as the portal circulation.

The circle is maintained always in one direction by four valves, situated one at the outlet from each cavity of the heart.

The blood in the arteries going to the body generally is bright red, that in the veins dull red in colour, owing to the former being charged with oxygen and the latter with carbon dioxide (see RESPIRATION). For the same reason the blood in the pulmonary artery is dark, that in the pulmonary veins is bright. There is no direct communication between the right and left sides of the heart, the blood passing from the right ventricle to the left atrium through the lungs.

In the embryo, before birth, the course of circulation is somewhat di?erent, owing to the fact that no nourishment comes from the bowels nor air into the lungs. Accordingly, two large arteries pass out of the navel, and convey blood to be changed by contact with maternal blood (see PLACENTA), while a large vein brings this blood back again. There are also communications between the right and left atria, and between pulmonary artery and aorta. The latter is known as the ductus arteriosus. At birth all these extra vessels and connections close and rapidly shrivel up.

Health Source: Medical Dictionary
Author: Health Dictionary

Central Nervous System

A collective term for the brain, spinal cord, their nerves, and the sensory end organs. More broadly, this can even include the neurotransmitting hormones instigated by the CNS that control the chemical nervous system, the endocrine glands.... central nervous system

Blood Pressure

Blood pressure is that pressure which must be applied to an artery in order to stop the pulse beyond the point of pressure. It may be roughly estimated by feeling the pulse at the wrist, or accurately measured using a SPHYGMOMANOMETER. It is dependent on the pumping force of the heart, together with the volume of blood, and on the elasticity of the blood vessels.

The blood pressure is biphasic, being greatest (systolic pressure) at each heartbeat and falling (diastolic pressure) between beats. The average systolic pressure is around 100 mm Hg in children and 120 mm Hg in young adults, generally rising with age as the arteries get thicker and harder. Diastolic pressure in a healthy young adult is about 80 mm Hg, and a rise in diastolic pressure is often a surer indicator of HYPERTENSION than is a rise in systolic pressure; the latter is more sensitive to changes of body position and emotional mood. Hypertension has various causes, the most important of which are kidney disease (see KIDNEYS, DISEASES OF), genetic predisposition and, to some extent, mental stress. Systolic pressure may well be over 200 mm Hg. Abnormal hypertension is often accompanied by arterial disease (see ARTERIES, DISEASES OF) with an increased risk of STROKE, heart attack and heart failure (see HEART, DISEASES OF). Various ANTIHYPERTENSIVE DRUGS are available; these should be carefully evaluated, considering the patient’s full clinical history, before use.

HYPOTENSION may result from super?cial vasodilation (for example, after a bath, in fevers or as a side-e?ect of medication, particularly that prescribed for high blood pressure) and occur in weakening diseases or heart failure. The blood pressure generally falls on standing, leading to temporary postural hypotension – a particular danger in elderly people.... blood pressure

Immune System

See IMMUNITY.

Age Disease and mode of administration

3 days BCG (Bacille Calmette-Guerin) by injection if tuberculosis in family in past 6 months.

2 months Poliomyelitis (oral); adsorbed diphtheria, whooping-cough (pertussis)1 and tetanus2 (triple vaccine given by injection); HiB injection.3

3 months Poliomyelitis (oral); diphtheria, whooping-cough (pertussis)1 and tetanus2 (triple vaccine given by injection); HiB injection.3

4 months Poliomyelitis (oral); diphtheria, whooping-cough (pertussis)1 and tetanus2 (triple vaccine given by injection); HiB injection.3

12–18 months Measles, mumps, and rubella (German measles)4 (given together live by injection).

(SCHOOL ENTRY)

4–5 years Poliomyelitis (oral); adsorbed diphtheria and tetanus (given together by injection); give MMR vaccine if not already given at 12–18 months.

10–14 females Rubella (by injection) if they have missed MMR.

10–14 BCG (Bacille Calmette-Guerin) by injection to tuberculin-negative children to prevent tuberculosis.

15–18 Poliomyelitis single booster dose (oral); tetanus (by injection).

1 Pertussis may be excluded in certain susceptible individuals.

2 Known as DPT or triple vaccine.

3 Haemophilus in?uenzae immunisation (type B) is being introduced to be given at same time, but di?erent limb.

4 Known as MMR vaccine. (Some parents are asking to have their infants immunised with single-constituent vaccines because of controversy over possible side-effects – yet to be con?rmed scienti?cally – of the combined MMR vaccine.)

Recommended immunisation schedules in the United Kingdom... immune system

Limbic System

A functional, not physical, system in the brain, generally considered to mediate emotions with metabolism.... limbic system

Nervous System

This extensive, complex and ?nely tuned network of billions of specialised cells called neurones (see NEURON(E)) is responsible for maintaining the body’s contacts with and responses to the outside world. The network also provides internal communication links – in concert with HORMONES, the body’s chemical messengers – between the body’s diverse organs and tissues, and, importantly, the BRAIN stores relevant information as memory. Each neurone has a ?lamentous process of varying length called an AXON along which passes messages in the form of electrochemically generated impulses. Axons are bundled together to form nerves (see NERVE).

The nervous system can be likened to a computer. The central processing unit – which receives, processes and stores information and initiates instructions for bodily activities – is called the central nervous system: this is made up of the brain and SPINAL CORD. The peripheral nervous system – synonymous with the cables that transmit information to and from a computer’s processing unit – has two parts: sensory and motor. The former collects information from the body’s many sense organs. These respond to touch, temperature, pain, position, smells, sounds and visual images and the information is signalled to the brain via the sensory nerves. When information has been processed centrally, the brain and spinal cord send instructions for action via motor nerves to the ‘voluntary’ muscles controlling movements and speech, to the ‘involuntary’ muscles that operate the internal organs such as the heart and intestines, and to the various glands, including the sweat glands in the skin. (Details of the 12 pairs of cranial nerves and the 31 pairs of nerves emanating from the spinal cord are given in respective texts on brain and spinal cord.)

Functional divisions of nervous system As well as the nervous system’s anatomical divisions, the system is divided functionally, into autonomic and somatic parts. The autonomic nervous system, which is split into sympathetic and parasympathetic divisions, deals with the automatic or unconscious control of internal bodily activities such as heartbeat, muscular status of blood vessels, digestion and glandular functions. The somatic system is responsible for the skeletal (voluntary) muscles (see MUSCLE) which carry out intended movements initiated by the brain – for example, the activation of limbs, tongue, vocal cords (speech), anal muscles (defaecation), urethral sphincters (urination) or vaginal muscles (childbirth). In addition, many survival responses – the most powerfully instinctive animal drives, which range from avoiding danger and pain to shivering when cold or sweating when hot – are initiated unconsciously and automatically by the nervous system using the appropriate neural pathways to achieve the particular survival reaction required.

The complex functions of the nervous system include the ability to experience emotions, such as excitement and pleasure, anxiety and frustration, and to undertake intellectual activities. For these experiences an individual can utilise many built-in neurological programmes and he or she can enhance performance through learning – a vital human function that depends on MEMORY, a three stage-process in the brain of registration, storage and recall. The various anatomical and functional divisions of the nervous system that have been unravelled as science has strived to explain how it works may seem confusing. In practical terms, the nervous system works mainly by using automatic or relex reactions (see REFLEX ACTION) to various stimuli (described above), supplemented by voluntary actions triggered by the activity of the conscious (higher) areas of the brain. Some higher functions crucial to human activity – for example, visual perception, thought, memory and speech – are complex and subtle, and the mechanisms are not yet fully understood. But all these complex activities rest on the foundation of relatively simple electrochemical transmissions of impulses through the massive network of billions of specialised cells, the neurones.... nervous system

Respiratory System

All the organs and tissues associated with the act of RESPIRATION or breathing. The term includes the nasal cavity (see NOSE) and PHARYNX, along with the LARYNX, TRACHEA, bronchi (see BRONCHUS), BRONCHIOLES and LUNGS. The DIAPHRAGM and other muscles, such as those between the RIBS, are also part of the respiratory system which is responsible for oxygenating the blood and removing carbon dioxide from it.... respiratory system

Autonomic Nervous System

Part of the nervous system which regulates the bodily functions that are not under conscious control: these include the heartbeat, intestinal movements, salivation, sweating, etc. The autonomic nervous system consists of two main divisions – the SYMPATHETIC NERVOUS SYSTEM and the PARASYMPATHETIC NERVOUS SYSTEM. The smooth muscles, heart and most glands are connected to nerve ?bres from both systems and their proper functioning depends on the balance between these two. (See also NERVES; NERVOUS SYSTEM.)... autonomic nervous system

Blood

Blood consists of cellular components suspended in plasma. It circulates through the blood vessels, carrying oxygen and nutrients to the organs and removing carbon dioxide and other waste products for excretion. In addition, it is the vehicle by which hormones and other humoral transmitters reach their sites of action.

Composition The cellular components are red cells or corpuscles (ERYTHROCYTES), white cells (LEUCOCYTES and lymphocytes – see LYMPHOCYTE), and platelets.

The red cells are biconcave discs with a diameter of 7.5µm. They contain haemoglobin

– an iron-containing porphyrin compound, which takes up oxygen in the lungs and releases it to the tissue.

The white cells are of various types, named according to their appearance. They can leave the circulation to wander through the tissues. They are involved in combating infection, wound healing, and rejection of foreign bodies. Pus consists of the bodies of dead white cells.

Platelets are the smallest cellular components and play an important role in blood clotting (see COAGULATION).

Erythrocytes are produced by the bone marrow in adults and have a life span of about 120 days. White cells are produced by the bone

marrow and lymphoid tissue. Plasma consists of water, ELECTROLYTES and plasma proteins; it comprises 48–58 per cent of blood volume. Plasma proteins are produced mainly by the liver and by certain types of white cells. Blood volume and electrolyte composition are closely regulated by complex mechanisms involving the KIDNEYS, ADRENAL GLANDS and HYPOTHALAMUS.... blood

Blood Clot

A blood clot arises when blood comes into contact with a foreign surface – for example, damaged blood vessels – or when tissue factors are released from damaged tissue. An initial plug of PLATELETS is converted to a de?nitive clot by the deposition of FIBRIN, which is formed by the clotting cascade and erythrocytes. (See COAGULATION.)... blood clot

Blood Count

The number of each of the cellular components per litre of blood. It may be calculated using a microscope or by an automated process.... blood count

Blood Transfusion

See TRANSFUSION – Transfusion of blood.... blood transfusion

Blood-poisoning

See SEPTICAEMIA.... blood-poisoning

Extrapyramidal System

This is a complex part of the nervous system, extending from the cortex to the medulla in the BRAIN, from which emerge descending spinal pathways which in?uence voluntary motor activity throughout the body. Although the normal functions of the system are poorly understood, there are characteristic signs of an extrapyramidal LESION. These include disturbance of voluntary movements, notably slowness and ‘poverty’ of movement; disturbance of muscular tone, which may be increased or decreased; and involuntary movements, such as a tremor, irregular jerking movements, or slow writhing movements.

Diseases There are several diseases that result from lesions to the extrapyramidal system, of which the most common is PARKINSONISM. Others include WILSON’S DISEASE, KERNICTERUS, CHOREA and ATHETOSIS.... extrapyramidal system

Peripheral Nervous System

See NERVOUS SYSTEM.... peripheral nervous system

Sympathetic Nervous System

Part of the AUTONOMIC NERVOUS SYSTEM. It consists of scattered collections of grey matter known as ganglia, united by an irregular network of nerve-?bres; those portions where the ganglia are placed most closely and where the network of ?bres is especially dense being known as plexuses. The chief part of the sympathetic system consists of two ganglionated cords that run through the neck, chest, and abdomen, lying close in front of the spine. In conjunction with the other part of the autonomic nervous system – the parasympathetic – this part controls many of the body’s involuntary activities involving glands, organs and other tissues. (For further details, see NERVOUS SYSTEM.)... sympathetic nervous system

System

A network of interdependent components that work together to attain the goals of the complex whole.... system

Lymphatic System

Lymph is the same fluid which oozes from a cut when bleeding stops. It surrounds every living cell. Lymph conveys to the blood the final products of digestion of food. It also receives from the blood waste products of metabolism. This is a two-way traffic.

Lymph fluid, loaded with waste, excess protein, etc, is sucked into the lymph tubes to be filtered by the spleen and the lymph nodes. The tubes are filled with countless one-way valves referred to collectively as the lymphatic pump, which propels the flow of lymph forwards. Lymph ultimately is collected in the main thoracic duct rising upwards in front of the spine to enter the bloodstream at the base of the neck.

A number of disorders may arise when the fluid becomes over-burdened by toxaemia, poor drainage and enlarged nodes (glands). Such un-eliminated wastes form cellulite – unwanted tissue formation and swelling. Thus, the soil may be prepared for various chronic illnesses from glandular disorders to arthritis. If the lymph is circulating freely it is almost impossible to become sick.

This system is capable of ingesting foreign particles and building up an immunity against future infection. Some herbal Lymphatics are also antimicrobials, natural alternatives to conventional antibiotics.

Treatment. Clivers is particularly relative to glandular swellings of neck and axillae.

For active inflammation: Echinacea, Goldenseal, Ginseng (Panax).

Alternatives. Teas: Clivers, Red Clover, Agnus Castus herb, Bladderwrack, Violet leaves, Marigold petals.

Decoctions: Blue Flag, Echinacea, Fenugreek seeds, Saw Palmetto.

Tablets/capsules. Agnus Castus, Echinacea, Bladderwrack, Red Clover, Thuja, Poke root, Fenugreek. Formula No 1. Echinacea 2; Clivers 1; Burdock 1; Poke root half. Dose: Liquid Extracts: one 5ml teaspoon. Tinctures: two 5ml teaspoons. Powders: 500mg (two 00 capsules or one-third teaspoon). Thrice daily.

Formula No 2. Equal parts: Blue Flag root, Poke root, Senna. Dose: as above.

Topical. Poultices: Slippery Elm, Fenugreek seeds, Marshmallow. Horsechestnut (Aesculus) ointment. ... lymphatic system

Abo Blood Groups

See BLOOD GROUPS.... abo blood groups

Blood Bank

A department in which blood products are prepared, stored, and tested prior to transfusion into patients.... blood bank

Blood Brain Barrier

A functional, semi-permeable membrane separating the brain and cerebrospinal ?uid from the blood. It allows small and lipid-soluble molecules to pass freely but is impermeable to large or ionised molecules and cells.... blood brain barrier

Blood Corpuscle

See ERYTHROCYTES and LEUCOCYTES.... blood corpuscle

Blood Donor

An individual who donates his or her own blood for use in patients of compatible blood group who require transfusion.... blood donor

Blood Test

Removal of venous, capillary or arterial blood for haematological, microbiological or biochemical laboratory investigations.... blood test

Blood Vessel

Tube through which blood is conducted from or to the heart. Blood from the heart is conducted via arteries and arterioles through capillaries and back to the heart via venules and then veins. (See ARTERIES and VEINS.)... blood vessel

Blood Gases

Speci?cally, this describes the measurement of the tensions of oxygen and carbon dioxide in blood. However, it is commonly used to describe the analysis of a sample of heparinised arterial blood for measurement of oxygen, carbon dioxide, oxygen saturation, pH, bicarbonate, and base excess (the amount of acid required to return a unit volume of the blood to normal pH). These values are vital in monitoring the severity of illness in patients receiving intensive care or who have severe respiratory illness, as they provide a guide to the e?ectiveness of oxygen transport between the outside air and the body tissues. Thus they are both a guide to whether the patient is being optimally ventilated, and also a general guide to the severity of their illness.... blood gases

Blood Groups

People are divided into four main groups in respect of a certain reaction of the blood. This depends upon the capacity of the serum of one person’s blood to cause the red cells of another’s to stick together (agglutinate). The reaction depends on antigens (see ANTIGEN), known as agglutinogens, in the erythrocytes and on ANTIBODIES, known as agglutinins, in the serum. There are two of each, the agglutinogens being known as A and B. A person’s erythrocytes may have (1) no agglutinogens, (2) agglutinogen A, (3) agglutinogen B, (4) agglutinogens A and B: these are the four groups. Since the identi?cation of the ABO and Rhesus factors (see below), around 400 other antigens have been discovered, but they cause few problems over transfusions.

In blood transfusion, the person giving and the person receiving the blood must belong to the same blood group, or a dangerous reaction will take place from the agglutination that occurs when blood of a di?erent group is present. One exception is that group O Rhesus-negative blood can be used in an emergency for anybody.

Agglutinogens Agglutinins Frequency
in the in the in Great
Group erythrocytes plasma Britain
AB A and B None 2 per cent
A A Anti-B 46 per cent
B B Anti-A 8 per cent
O Neither Anti-A and 44 per cent
A nor B Anti-B

Rhesus factor In addition to the A and B agglutinogens (or antigens), there is another one known as the Rhesus (or Rh) factor – so named because there is a similar antigen in the red blood corpuscles of the Rhesus monkey. About 84 per cent of the population have this Rh factor in their blood and are therefore known as ‘Rh-positive’. The remaining 16 per cent who do not possess the factor are known as ‘Rh-negative’.

The practical importance of the Rh factor is that, unlike the A and B agglutinogens, there are no naturally occurring Rh antibodies. However, such antibodies may develop in a Rh-negative person if the Rh antigen is introduced into his or her circulation. This can occur (a) if a Rh-negative person is given a transfusion of Rh-positive blood, and (b) if a Rh-negative mother married to a Rh-positive husband becomes pregnant and the fetus is Rh-positive. If the latter happens, the mother develops Rh antibodies which can pass into the fetal circulation, where they react with the baby’s Rh antigen and cause HAEMOLYTIC DISEASE of the fetus and newborn. This means that, untreated, the child may be stillborn or become jaundiced shortly after birth.

As about one in six expectant mothers is Rh-negative, a blood-group examination is now considered an essential part of the antenatal examination of a pregnant woman. All such Rh-negative expectant mothers are now given a ‘Rhesus card’ showing that they belong to the rhesus-negative blood group. This card should always be carried with them. Rh-positive blood should never be transfused to a Rh-negative girl or woman.... blood groups

Cardiovascular System

This refers to the whole circulatory system: the heart, the systemic circulation (the arteries and veins of the body) and the pulmonary circulation (the arteries and veins of the lungs). Blood circulates throughout the cardiovascular system bringing oxygen and nutrients to the tissues and removing carbon dioxide and other waste products.... cardiovascular system

Blood Root

Sanguinaria canadensis. N.O. Papaveraceae.

Habitat: Widely distributed throughout North America.

Features ? Root reddish-brown, wrinkled lengthwise, about half-inch thick. Fracture short. Section whitish, with many small, red resin cells which sometimes suffuse the whole. Heavy odour, bitter and harsh to the taste.

Part used ? Root.

Action: Stimulant, tonic, expectorant.

Pulmonary complaints and bronchitis. Should be administered in whooping-cough and croup until emesis occurs. The powdered root is used as a snuff in nasal catarrh, and externally in ringworm and other skin eruptions. The American Thomsonians use it in the treatment of adenoids. Dose, 10 to 20 grains of the powdered root.... blood root

Fetal Blood Sampling

A procedure performed during a mother’s labour in which a blood sample is taken from a vein in the scalp of the FETUS. This enables tests to be performed that indicate whether the fetus is, for example, suffering from a shortage of oxygen (HYPOXIA). If so, the obstetrician will usually accelerate the baby’s birth.... fetal blood sampling

Hla System

The major histocompatibility complex, or human leucocyte antigen (HLA) region, consists of genetically determined antigens, situated on chromosome 6. Found in most tissues, though to a di?ering extent, the four gene loci are known as A, B, C, D, while the individual alleles at each locus are numbered 1, 2, 3, etc. The number of possible combinations is thus enormous, and the chance of two unrelated people being identical for HLA is very low.

HLA incompatibility causes the immune response, or rejection reaction, that occurs with unmatched tissue grafts. Strong associations between HLA and susceptibility to certain diseases – notably the AUTOIMMUNE DISORDERS such as rheumatoid arthritis, insulin-dependent diabetes, and thyrotoxicosis – have been described. Certain HLA antigens occur together more frequently than would be expected by chance (linkage disequilibrium), and may have a protective e?ect, conferring resistance to a disease. (See IMMUNITY.)... hla system

Portal System

A vein or collection of veins which ?nish at both ends in a bed of capillary blood vessels. An important example is the hepatic portal system, comprising the portal vein and its tributaries. Blood from the stomach, pancreas, spleen and intestines drains into the veins that join up to comprise the portal vein into the liver, where it branches into sinusoids.... portal system

Red Blood Cell

See ERYTHROCYTES; BLOOD.... red blood cell

Parasympathetic Nervous System

That part of the AUTONOMIC NERVOUS SYSTEM which is connected with the BRAIN and SPINAL CORD through certain nerve centres in the midbrain, medulla, and lower end of the cord. The nerves from these centres are carried in the third, seventh, ninth and tenth cranial nerves and the second, third and fourth sacral nerves. The action of the parasympathetic system is usually antagonistic to that of the sympathetic system. Thus it inhibits the action of the HEART and augments the action of the INTESTINE; whereas the sympathetic augments the action of the heart and inhibits that of the intestine. (See diagram of sympathetic and parasympathetic nervous systems under NERVOUS SYSTEM.)... parasympathetic nervous system

Reproductive System

A collective term for all the organs involved in sexual reproduction. In the female these are the OVARIES, FALLOPIAN TUBES, UTERUS, VAGINA and VULVA. In the male these are the testes (see TESTICLE), VAS DEFERENS, SEMINAL VESICLES, URETHRA and PENIS.... reproductive system

White Blood Cell

See LEUCOCYTES.... white blood cell

Blood Sugar

See blood glucose.... blood sugar

Blood Clotting

The process of blood solidification. Clotting is important in stemming bleeding from damaged blood vessels. However, unwanted blood clotting can occur inside major blood vessels and cause a myocardial infarction (heart attack) or stroke (see thrombosis).

When a blood vessel is damaged, it constricts immediately to reduce blood flow to the area. The damage sets off a series of chemical reactions that lead to the formation of a clot to seal the injury. First, platelets around the injury site are activated, becoming sticky and adhering to the blood-vessel wall. Then, the activated platelets release chemicals, which, in turn, activate blood clotting factors. These factors, together with vitamin K, act on fibrinogen and convert it to fibrin. Strands of fibrin form a meshwork, which traps red blood cells to form a clot.

There are several anticlotting mechanisms to prevent the formation of unwanted clots. These include prostacyclin (a prostaglandin), which prevents platelet aggregation, and plasmin, which breaks down fibrin (see fibrinolysis). Blood flow washes away active coagulation factors; and the liver deactivates excess coagulation factors.

Defects in blood clotting may result in bleeding disorders.

Excessive clotting (thrombosis) may be due to an inherited increase or defect in a coagulation factor (see factor V), the use of oral contraceptives, a decrease in the level of enzymes that inhibit coagulation, or sluggish blood flow through a particular area.

Treatment is usually with anticoagulant drugs such as heparin or warfarin.... blood clotting

Circulatory System

The heart and blood vessels, which together maintain a continuous flow of blood throughout the body. The system provides tissues with oxygen and nutrients, and carries away waste products. The circulatory system consists of 2 main parts: the systemic circulation, which supplies blood to the whole body apart from the lungs; and the pulmonary circulation to the lungs. Within the systemic circulation, there is a bypass (the portal circulation), which carries nutrient-rich blood from the stomach, intestine, and other digestive organs to the liver for processing, storage, or re-entry into general circulation.

In the systemic circulation, oxygen-rich blood from the pulmonary circulation is pumped under high pressure from the left ventricle of the heart into the aorta, from where it travels through arteries and smaller arterioles to all parts of the body. Within body tissues, the arterioles branch into networks of fine blood vessels called capillaries. Oxygen and other nutrients pass from the blood through the capillaries’ thin walls into body tissues; carbon dioxide and other wastes pass in the opposite direction. Deoxygenated blood is returned to the heart via venules, veins, and the venae cavae.

Venous blood returns to the right atrium of the heart to enter the pulmonary circulation. It is pumped from the right ventricle through the pulmonary artery

to the lungs, where carbon dioxide is exchanged for oxygen. The reoxygenated blood then returns through the pulmonary veins to the heart and re-enters the systemic circulation.... circulatory system

All Payer System

A system in which prices for health services and payment methods are the same, regardless of who is paying. For instance, in an all payer system, federal or state government, a private insurer, a self-insured employer plan, an individual, or any other payer could pay the same rates. The uniform fee bars health care providers from shifting costs from one payer to another. See “cost shifting”.... all payer system

Alternative Medical System

A complete system of theory and practices that has evolved independently of, and often prior to, the conventional biological approach. Many are traditional systems of medicine that are practised by individual cultures throughout the world. Traditional Oriental medicine and Ayurveda, India’s traditional system of medicine, are two examples.... alternative medical system

Appointment Scheduling System

A system for planning of appointments between resources such as clinicians and facilities and patients. It is used in order to minimize waiting times, prioritize appointments and optimize the utilization of resources.... appointment scheduling system

Assessment System

A structured process developed to ensure that assessment is relevant, consistent, fair and valid. The system requires rules of operation, a regular review process and competent assessors.... assessment system

Autologous Blood Transfusion

See TRANSFUSION – Transfusion of blood.... autologous blood transfusion

Blood-letting

See VENESECTION.... blood-letting

Blood, Diseases Of

See ANAEMIA; LEUKAEMIA; LYMPHOMA; MYELOMATOSIS; THROMBOSIS.... blood, diseases of

Bloodroot

Love, Protection, Purification... bloodroot

Buffering System

The several blood factors that enable the acid waste products of metabolism to be carried in the alkaline blood without disrupting its chemistry. These include carbolic acid, carbonates, phosphates, electrolytes, blood proteins, and erythrocyte membranes.... buffering system

Clinical Information System

An information system that collects, stores and transmits information that is used to support clinical applications (e.g. transmission of laboratory test results, radiology results, prescription drug orders). Electronic medical records are one method by which clinical information systems can be created.... clinical information system

Cleavers Tea - Best Tonic For The Lymphatic System Available In Nature

Cleavers tea has been used for centuries, even in ancient Greece. It is considered probably the best tonic for the lymphatic system available. Discover all of its benefits and learn how to make the most of this type of tea. Description of Cleavers tea Cleavers is an annual green plant that grows mostly in Britain, North America and Eurasia regions. The green to white flowers look like small balls and they are very sticky, similar to the leaves. Scientifically named gallium aparine, cleavers is also called bedstraw, barweed, catchweed, grip grass. The entire cleavers plant is used in herbal medicine and is harvested just before it blooms in early summer. The active constituents of cleavers tea are chlorophyll, citric acide, rubichloric acid, galiosin and tannins. To benefit the most from these constituents, you can consume cleavers, usually found in the form of tea, extracts, capsule, or fresh for many cooking recipes. The roasted seeds are used as a coffee substitute and the young leaves can be eaten like spinach. Cleavers tea has a slightly bitter taste and no odor. Cleavers tea brew For a tasty Cleavers tea, take 2 to 3 teaspoons of the dried above-ground parts of the plant and infuse them in a 250 mg cup of hot water for 10 or 15 minutes. You may add sugar or honey to improve its taste and drink up to three times per day. Cleavers tea  Benefits Cleavers tea is a strong detoxifying for the lymphatic system. It is diuretic, thus treating most of urinary tract infections. It cleans the blood, the liver and kidneys. The tea can be used together with Uva Ursi or Echinacea for best results. Applied topically, Cleavers tea helps in the treatment of many skin conditions like acne, eczema, psoriasis, dandruff, itchy scalp, sunburns or even wounds. Cleavers tea can be used as a facial tonner because it helps clear the complexion. Cleavers tea Side effects Cleavers tea has no known side effects. Though it is widely safe, children, pregnant or nursing women should drink it with precaution. Cleavers tea can surely be included in a healthy lifestyle. As long as you don’t exaggerate with it, you can enjoy the benefits of this tea and even use the plant to prepare many tasty recipes and salads.... cleavers tea - best tonic for the lymphatic system available in nature

Complement System

This is part of the body’s defence mechanism that comprises a series of 20 serum peptides (see PEPTIDE). These are sequentially activated to produce three signi?cant effects: ?rstly, the release of small peptides which provoke in?ammation and attract phagocytes (see PHAGOCYTE); secondly, the deposition of a substance (component C3b) on the membranes of invading bacteria or viruses, attracting phagocytes to destroy the microbes; thirdly, the activation of substances that damage cell membranes – called lytic components – which hasten the destruction of ‘foreign’ cells. (See IMMUNOLOGY.)... complement system

Comprehensive Health System

A health system that includes all the elements required to meet all the health needs of the population.... comprehensive health system

Decision Support System

See “decision analysis”.... decision support system

Defective Blood Formation

This is the main cause of anaemia in infections. The micro-organism responsible for the infection has a deleterious e?ect upon the blood-forming organs, just as it does upon other parts of the body.

Toxins. In conditions such as chronic glomerulonephritis (see KIDNEYS, DISEASES OF) and URAEMIA there is a severe anaemia due to the e?ect of the disease upon blood formation.

Drugs. Certain drugs, such as aspirin and the non-steroidal anti-in?ammatory drugs, may cause occult gastrointestinal bleeding.... defective blood formation

Dragons Blood

Love, Protection, Exorcism, Potency... dragons blood

Health Care Delivery System

See “health system”.... health care delivery system

Health Information System

The generation and the use of appropriate health information to support decision-making, health care delivery and management of health services at national and subnational level.... health information system

Health System

The people, institutions and resources, arranged together in accordance with established policies, to improve the health of the population they serve, while responding to people’s legitimate expectations and protecting them against the cost of ill-health through a variety of activities, the primary intent of which is to improve health. Health systems fulfil three main functions: health care delivery, fair treatment of all, and meeting non-health expectations of the population. These functions are performed in the pursuit of three goals: health, responsiveness and fair financing. A health system is usually organized at various levels, starting at the community level or the primary level of health care and proceeding through the intermediate (district, regional or provincial) to the central level.... health system

Health System Infrastructure

Services, facilities, institutions, personnel or establishments, organizations and those operating them for the delivery of a variety of health programmes.... health system infrastructure

Integrated Delivery System / Integrated Services Network (isn)

A network of organizations, usually including hospitals and medical practitioner groups, that provides or arranges to provide a coordinated continuum of services to a defined population and is held both clinically and financially accountable for the outcomes in the populations served.... integrated delivery system / integrated services network (isn)

Management Information System

A system of databases designed to process and exchange information to support decision-making as well as implementation, monitoring and evaluation of programmes, activities and projects. See also “health information system”.... management information system

National Blood Authority

This body manages regional TRANSFUSION centres. Among its aims are the maintenance and promotion of blood and blood products based on a system of voluntary donors; implementing a cost-e?ective national strategy for ensuring adequate supplies of blood and its products to meet national needs; and ensuring high standards of safety and quality.... national blood authority

Loss Of Blood

As a result of trauma. This is perhaps the simplest example of all, when, as a result of an accident involving a large artery, there is severe haemorrhage.

Menstruation. The regular monthly loss of blood which women sustain as a result of menstruation always puts a strain on the blood-forming organs. If this loss is excessive, then over a period of time it may lead to quite severe anaemia.

Childbirth. A considerable amount of blood is always lost at childbirth; if this is severe, or if the woman was anaemic during pregnancy, a severe degree of anaemia may develop.

Bleeding from the gastrointestinal tract. The best example here is anaemia due to ‘bleeding piles’ (see HAEMORRHOIDS). Such bleeding, even though slight, is a common cause of anaemia in both men and women if maintained over a long period of time. The haemorrhage may be more acute and occur from a DUODENAL ULCER or gastric ulcer (see STOMACH, DISEASES OF), when it is known as haematemesis.

Certain blood diseases, such as PURPURA and HAEMOPHILIA, which are characterised by bleeding.... loss of blood

Nervous System, Disorders Of

The following conditions are discussed under their individual headings: APHASIA; BRAIN, DISEASES OF; CATALEPSY; CHOREA; CRAMP; EPILEPSY; HYSTERIA; LEARNING DISABILITY; MEMORY; MENTAL ILLNESS; MULTIPLE SCLEROSIS (MS); NERVES, INJURIES TO; NEURALGIA; NEURITIS; PARALYSIS; PSYCHOSOMATIC DISEASES; SPINE AND SPINAL CORD, DISEASES AND INJURIES OF; STROKE; TABES.... nervous system, disorders of

Organized Delivery System

See “integrated delivery system”.... organized delivery system

Pluralistic System

A system that is based on incorporating divergent provider modalities (e.g. public, private, non-profit, etc.).... pluralistic system

Prospective Payment System

A system whereby reimbursement rates are set for a given period of time prior to the circumstances giving rise to actual reimbursement claims.... prospective payment system

Peripheral-blood Stem-cell Transplants

These have almost completely replaced BONE MARROW TRANSPLANT, used to treat malignancies such as LEUKAEMIA and LYMPHOMA for the past 20 years. The high doses of CHEMOTHERAPY or RADIOTHERAPY used to treat these diseases destroy the bone marrow which contains stem cells from which all the blood cells derive. In 1989 stem cells were found in the blood during recovery from chemotherapy. By giving growth factors (cytokines), the number of stem cells in the blood increased for about three to four days. In a peripheral-blood stem-cell transplant, these cells can be separated from the peripheral blood, without a general anaesthetic. The cells taken by either method are then frozen and returned intravenously after the chemotherapy or radiotherapy is completed. Once transplanted, the stem cells usually take less than three weeks to repopulate the blood, compared to a month or more for a bone marrow transplant. This means that there is less risk of infection or bleeding during the recovery from the transplant. The whole procedure has a mortality risk of less than 5 per cent – half the risk of a bone marrow transplant.... peripheral-blood stem-cell transplants

Picture Archiving And Communications System (pacs)

The use of digital imaging systems to replace conventional X-ray pictures and other imaging techniques. Though expensive to operate, digital imaging and storage systems o?er promising possibilities for transmission of clinical images within and between hospitals and community health-care units, providing fast access and remote working that will bene?t patients and health-care sta? alike. When security and con?dentiality are assured, images could be transferred via the Internet and teleradiology. In future, hospitals might be able to eliminate the costly physical transfer and storage of X-ray ?lms. The integration of PACS with hospital information systems in the NHS will (hopefully) facilitate the introduction of electronic radiology.... picture archiving and communications system (pacs)

Reticulo-endothelial System

This consists of highly specialised cells scattered throughout the body, but found mainly in the SPLEEN, BONE MARROW, LIVER, and LYMPH nodes or glands. Their main function is the ingestion of red blood cells and the conversion of HAEMOGLOBIN to BILIRUBIN. They are also able to ingest bacteria and foreign colloidal particles.... reticulo-endothelial system

Coughing Of Blood

See: BLEEDING (haemoptysis). ... coughing of blood

Glentona Herbal Blood Purifier

Popular blood tonic of the 1930s, 1940s and 1950s. Ingredients: Liquid Extract Liquorice 5 per cent, Infusion Gentian Co Conc 10 per cent, Infusion Senna Conc 5 per cent. And 25 per cent alcoholic extractive from Burdock 5 per cent, Red Clover 5 per cent, Queen’s root 2.5 per cent, Yellow Dock root 1.25 per cent, Poke root 2.5 per cent, Sarsaparilla 2.5 per cent. (Carter Bros) ... glentona herbal blood purifier

Blood-clotting Tests

Tests to screen for and diagnose bleeding disorders, usually resulting from deficiencies or abnormalities of blood coagulation factors or of platelets (see blood clotting). Tests are also used to monitor treatment with anticoagulant drugs.... blood-clotting tests

Blood Culture

See culture.... blood culture

Blood Glucose

The level of glucose in the blood. Abnormally high blood glucose (sometimes called sugar) levels are an indication of diabetes mellitus. (See also hyperglycaemia; hypoglycaemia.)... blood glucose

Tea For Blood Pressure

As a natural beverage, a cup of tea brings you many health benefits. One of them is related to blood pressure. Based on the type of tea you drink, it can help lower your blood pressure. Find out more about teas for blood pressure! Problems with blood pressure Blood pressure represents the pressure made by the circulating blood on the walls of the blood vessels. However, problems appear in the case of hypertension and hypotension. Hypertension is a medical condition caused by a high blood pressure, while hypotension is caused by a low blood pressure. Both can be treated with one of the various types of tea for blood pressure. Tea for high blood pressure If you’ve got problems with hypertension (high blood pressure), hibiscus tea can help, as it is known to lower blood pressure. You can also pick one of these herbal teas: chrysanthemum tea, flax tea, periwinkle tea, red root tea, self-heal tea, white peony root tea, valerian tea, or wild cherry bark tea. You can also drink hyssop tea, barberry tea, and rosemary tea, regardless of the blood pressure problem. These three teas will help regulate your blood pressure and reduce the risk of getting either high or low blood pressure problems. Tea for low blood pressure In the case of hypotension (low blood pressure), some of the teas you can try include lovage tea, ephedra tea, wu yi tea, cat’s claw tea, vervain tea, or wheatgrass tea. Black tea can help too, though you have to be careful with it as it has a high content of caffeine. Forbidden teas for blood pressure problems There are several teas which you should avoid drinking, no matter if you’ve got problems with high blood pressure or low blood pressure. The list of teas you shouldn’t drink includes arnica tea, black cohosh tea, gentian tea, juniper tea, lobelia tea, red ginseng tea, sage tea, stone root tea, and yohimbe tea. Also, generally it isn’t recommended to drink tea that lowers blood pressure if you’ve got hypotension, or tea that leads to high blood pressure if you’ve got hypertension. Whether you’ve got problems with high blood pressure or low blood pressure, try a more natural treatment: choose one of the many teas for blood pressure!... tea for blood pressure

Blood Purifiers

Alteratives. The blood is a fluid from which every variety of cell and tissue derives its special form of food for the repair of constant wastage resulting from functions they perform. When the blood becomes vitiated from lack of exercise, too little oxygen, debilitating personal habits and sophisticated foodstuffs the whole body suffers. The vital fluid then needs to be cleansed of its impurities. Nature’s blood purifiers are unique in the world of medicine, restoring biochemical balance and promoting healthy elimination.

Blood tonic. Decoction, tablets, tinctures or fluid extracts:– Echinacea 3; Burdock 2; Goldenseal 1. See also: ALTERATIVES. ... blood purifiers

Circulatory Disorders

Poor circulation may be due to a number of disorders including varicose veins, high or low blood pressure, arterio-sclerosis, thrombosis, phlebitis, chilblains, anaemia, weak heart. A common cause is auto-toxaemia, calling for blood tonics and agents to assist elimination of wastes and poisons via the kidneys, skin and bowels.

Other causes requiring specific treatment are: thickening and narrowing of blood vessels, diabetes, Buerger’s disease, Raynaud’s disease (spasm of the arterioles and veins), arteritis. See appropriate entries.

As a protection against these diseases Garlic becomes increasingly popular. Control of blood fats through diet and exercise necessary.

Alternatives. Cayenne, Ginger, Hawthorn berries, Horseradish, Mustard, Prickly Ash bark, Buckwheat, Dandelion, Lime flowers, Mistletoe, Rosemary, Yarrow, Ginkgo.

Tea: Lime flowers, Hawthorn berries, Yarrow. Equal parts. Mix. Ginger, quarter part (or pinch of Red Pepper). Mix. 1-2 teaspoons to each cup water. Bring to boil. Remove vessel when boiling point is reached. Dose: 1 cup 2-3 times daily.

Tablets or capsules: Prickly Ash, Hawthorn, Mistletoe, Ginkgo.

Formula. Hawthorn 2; Yarrow 2; Prickly Ash 1; Ginger quarter. Dose: Powders: 500mg (two 00 capsules or one-third teaspoon). Liquid extracts: 1 teaspoon. Tinctures 2 teaspoons 2-3 times daily.

Practitioner. Liquid extracts: Hawthorn 2; Lily of the Valley 2; Prickly Ash 1; Tincture Capsicum (one- tenth part). Dose: 30-60 drops in water or honey, 2-3 times daily.

Diet and Supplements. See: DIET – HEART AND CIRCULATION. ... circulatory disorders

Blood Smear

See blood film.... blood smear

Blood Transfusion, Autologous

The use of a person’s own blood, donated earlier, for blood transfusion. Autologous transfusion eliminates the slight but serious risk of contracting a serious infectious illness from contaminated blood. There is no risk of a transfusion reaction occurring as a result of incompatibility between donor and recipient blood. Up to 3.5 litres of blood can be removed and stored in several sessions at least 4 days apart and up to 3 days before planned surgery. Blood may be salvaged during surgery, filtered and returned to the circulation, reducing the need for transfusion of donated blood.... blood transfusion, autologous

Blood Vessels

A general term given to arteries, veins, and capillaries (see circulatory system).... blood vessels

Coagulation, Blood

The main mechanism by which blood clots are formed, involving a complex series of reactions in the blood plasma (see blood clotting).... coagulation, blood

Endocrine System

The collection of glands around the body that produce hormones.

These glands include the thyroid gland, pancreas, testes, ovaries, and adrenal glands.

Their hormones are responsible for numerous bodily processes, including growth, metabolism, sexual development and function, and response to stress.

Any increase or decrease in the production of a specific hormone interferes with the process it controls.

To prevent under- or overproduction, hormone secretion from many endocrine glands is regulated by the pituitary gland, which is in turn influenced by the hypothalamus in the brain according to a feedback mechanism.... endocrine system

Tea For Immune System

Your immune system consists of a series of antibodies and other microorganisms whose main purpose is to defend your system against external attacks. When we have a cold or flu, the main thing that keeps us alive is this line of defense that keeps all bacteria, infections and microbes away from us. Unfortunately, our immune system is not strong enough to fight all causes, so we need to enhance its power by taking a treatment. How a Tea for Immune System Works A Tea for Immune System must contain enough active constituents to fight a wide range of diseases. First of all, it must contain minerals, manganese, magnesium, iron, volatile oils, acids, tannins, nutrients and enzymes. These teas can be taken as cures for a short amount of time (1 or 2 weeks) to enhance your body strength, so you mustn’t exaggerate when taking it. Efficient Tea for Immune System A Tea for Immune System must contain a lot of active constituents and it must be very effective. If you don’t know which teas to choose from, here’s a list to guide you on: - Garlic Tea – can be found almost anywhere on the globe and it has a wide range of uses, from cuisine to pharmaceutical purposes. Also a great cure for diarrhea, this Tea for Immune System has a rather unpleasant taste and smell. Feel free to add honey, lemon, ginger or mint in order to make it more adequate. - Green Tea – probably the most important tea in the world, Green Tea contains all the ingredients necessary to promote a healthy life, full of great benefits. However, don’t take it in case you suffer from menstrual and menopausal pains in order to avoid stomach and uterus irritations. - Yerba Mate Tea – the South American tea has a series of health advantages and it’s been named by the scientific society “the new green tea”. Drink it from a traditional bombilla or straight from a normal glass, but make sure you know which the risks are and that you’re taking this treatment under supervision. - Ginseng Tea – this wonderful Chinese Tea is used as a main ingredient in the Asian cuisine, but also as a great adjuvant in cases of nausea, vomiting and auto-immune deficiencies. However, make sure that you’re using the right amount of herbs when preparing this decoction in order to avoid developing a acid foods and drinks intolerance! Tea for Immune System Side Effects When taken properly, these teas are generally safe. However, drinking more tea than it’s recommended may lead to constipation, upset stomach or even death. Talk to your doctor before starting any kind of herbal treatment and find out which are the risks. Don’t take a treatment based on a Tea for Immune System if you’re pregnant, breastfeeding, on anti coagulants, blood thinners or preparing for a surgery. Also, children must be kept away from these teas since there’s no study to prove how safe it is for them. When in doubt, always ask your doctor. If he says there’s nothing that could interfere with your treatment, choose a tea that fits you best and enjoy its health benefits!... tea for immune system

Faeces, Blood In The

See faeces, abnormal; rectal bleeding.... faeces, blood in the

Occult Blood, Faecal

The presence in the faeces of blood that cannot be seen by the naked eye, but can be detected by chemical tests. Such tests are widely used in screening for cancer of the colon (see colon, cancer of). Faecal occult blood may also be a sign of a gastrointestinal disorder such as oesophagitis, gastritis, or stomach cancer; cancer of the intestine (see intestine, cancer of); rectal cancer (see rectum, cancer of); diverticular disease; polyps in the colon; ulcerative colitis; or irritation of the stomach or intestine by drugs such as aspirin. (See also rectal bleeding.)... occult blood, faecal

Semen, Blood In The

A usually harmless condition in which a small amount of blood is present in the semen.

Occasionally, there is an underlying cause (such as an infection or, very rarely, cancer) that requires treatment.

Blood in the semen may also occur after a prostate biopsy.... semen, blood in the

Urinary System

See urinary tract.... urinary system

Abo System

see blood group.... abo system

Apache Scoring System

acute physiological and chronic health evaluation: a tool used to assess the severity of illness in a critically ill patient and to estimate mortality. The assessment uses information from 12 physiological measurements, including temperature, blood pressure, arterial pH, and certain blood results.... apache scoring system

Tea For Nervous System

The nervous system is responsible for almost any reaction that comes from your body. From eyes to muscles and even hair, your body is a very complex electric system directed by your brain. Most of the problems that a person has in a lifetime are related to a nervous system failure. In order to treat this kind of problems or prevent them from happening, you may want to try a tea instead of all those traditional pills. How a Tea for Nervous System Works A Tea for Nervous System is indeed helpful if it contains an important amount of nutrients, enzymes, tannins, volatile oils and minerals (sodium, iron, magnesium and manganese). You may want to avoid a tea that has an elevated acids level since it may cause you even more damages. A Tea for Nervous System will make your body send all the active constituents to the affected areas and heal the damaged tissue. Efficient Tea for Nervous System In order to work properly, a Tea for Nervous System must show results in a short time period and be one hundred percent safe (you don’t want any more complications than you already have). However, before starting any kind of herbal treatment, remember to take the indicated dose and never surpass it in order to avoid other health problems. If you don’t know which teas could be helpful for you, here’s a list for guidance: - Oolong Tea – contains half the amount of caffeine that other teas have so it’s best for your health to give it a try every once in a while. This Tea for Nervous System will also strengthen your entire organism and rejuvenate the aspect of your skin. However, don’t drink more than 2 cups per day. - Green Tea – as the scientists have proved, this decoction contains all the ingredients necessary to sustain life, so it’s good for a number of other health complaints, such as infertility, headaches, nausea, loss of appetite, anemia and asthenia. Just make sure you avoid it at all costs in case you’re experiencing some menstrual or menopausal symptoms (it may cause uterine contractions and internal bleedings). - Black Tea – some say that it does more damages than good for your nervous system and some others think that this tea is worth a try. Having an elevated level of caffeine, this tea is highly addictive. In right amount, it can treat infertility, erectile dysfunctions, sore throats and colds. However, ask an herbalist before starting a treatment based on this Tea for Nervous System in order to find out which are the risks. Tea for Nervous System Side Effects When taken according to specifications, these teas are generally safe. However, exceeding the number of cups recommended per day may lead to other health complaints, such as nausea, diarrhea, uterine contractions, internal bleedings and headaches. If you’ve tried one of these teas and something doesn’t feel quite right, talk to your doctor as soon as possible! Don’t take a Tea for Nervous System if you’re pregnant, breastfeeding, on blood thinners or anticoagulants. The same advice if you’re preparing for a surgery (some of the active compounds in these teas may interfere with your anesthetic and cause death). But if you have the green light from your doctor, choose a tea that fits best your requirements and enjoy its wonderful health benefits!... tea for nervous system

Biliary System

The organs and ducts by which bile is formed, concentrated, and carried from the liver to the duodenum (the first part of the small intestine). Bile is secreted by the liver cells and collected by a network of bile ducts that carry the bile out of the liver by way of the hepatic duct. A channel called the cystic duct branches off the hepatic duct and leads to the gallbladder where bile is concentrated and stored. Beyond this junction, the hepatic duct becomes the common bile duct and opens into the duodenum at a controlled orifice called the ampulla of Vater. The presence of fat in the duodenum after a meal causes secretion of a hormone, which opens the ampulla of Vater and makes the gallbladder contract, squeezing stored bile into the duodenum.

The main disorders affecting the biliary system are gallstones, congenital biliary atresia and bile duct obstruction.

(See also gallbladder, disorders of.)... biliary system

Blood Cells

Cells, also called blood corpuscles, present in blood for most or part of their lifespan. They include red blood cells, which make up about 45 per cent by volume of normal blood, white blood cells, and platelets. Blood cells are made in the bone marrow by a series of divisions from stem cells.

Red blood cells (also known as RBCs, red blood corpuscles, or erythrocytes) transport oxygen from the lungs to the tissues (see respiration). Each is packed with haemoglobin, enzymes, minerals, and sugars. Abnormalities can occur in the rate at which RBCs are either produced or destroyed, in their numbers, and in their shape, size, and haemoglobin content, causing forms of

anaemia and polycythaemia (see blood, disorders of).

White blood cells (also called WBCs, white blood corpuscles, or leukocytes) protect the body against infection and fight infection when it occurs. The 3 main types of are granulocytes (also called polymorphonuclear leukocytes), monocytes, and lymphocytes. Granulocytes are further classified as neutrophils, eosinophils, or basophils, and each type of granulocyte has a role in either fighting infection or in inflammatory or allergic reactions. Monocytes and lymphocytes also play an important part in the immune system. Lymphocytes are usually formed in the lymph nodes. One type, a T-lymphocyte, is responsible for the delayed hypersensitivity reactions

White (see allergy) and Red blood blood cell is also involved in cell (neutrophil) protection against cancer. T-lymphocytes manufacture chemicals, known as lymphokines, which affect the function of other cells. In addition, the T-cells moderate the activity of B-lymphocytes, which form the antibodies that can prevent a second attack of certain infectious diseases. Platelets (also known as thrombocytes), are the smallest blood cells and are important in blood clotting.

The numbers, shapes, and appearance of the various types of blood cell are of great value in the diagnosis of disease (see blood count; blood film).... blood cells

Blood Cell

(blood corpuscle) any of the cells that are present in the blood in health or disease. The cells may be subclassified into three major categories, namely red cells (*erythrocytes); white cells (*leucocytes), which include granulocytes, lymphocytes, and monocytes; and *platelets (see illustration). The blood cells account for approximately 40% of the total volume of the blood in health; red cells comprise the vast majority.... blood cell

Blood, Disorders Of

Disorders resulting from abnormalities in any of the components of blood or from infection. Disorders include types of anaemia, polycythaemia, bleeding disorders, and unwanted clot formation (thrombosis), hypoalbuminaemia (albumin deficiency) and agammaglobulinaemia (deficiency of gamma-globulin). Blood disorders such as sickle cell anaemia, thalassaemia, and haemophilia are inherited. Bone marrow cancers that affect production of blood components include leukaemia, polycythaemia vera, and multiple myeloma. Blood poisoning is usually due to septicaemia or a toxin such as carbon monoxide. Some drugs can cause blood abnormalities as a side effect. (See also anaemia, haemolytic; anaemia, iron-deficiency; anaemia, megaloblastic; malaria; hyperbilirubinaemia.)... blood, disorders of

Blood Donation

The process of giving blood for use in blood transfusion.

Donated blood is tested for a range of infectious agents such as hepatitis B and hepatitis C and antibodies to HIV. After being classified into blood groups, the blood is stored in a blood bank, either whole or separated into its different components (see blood products). Apheresis is a type of blood donation in which only a specific blood component, such as plasma, platelets, or white cells, is withdrawn from the donor. blood film A test that involves smearing a drop of blood on to a glass slide for examination under a microscope. The blood film is stained with dyes to make the blood cells show up clearly.

The test allows the shape and appearance of blood cells to be checked for any abnormality, such as the sickleshaped red blood cells characteristic of sickle cell anaemia.

The relative proportions of the different types of white blood cells can also be counted.

This examination, called a differential white cell count, may be helpful in diagnosing infection or leukaemia.

Blood films are also used in diagnosing infections, such as malaria, in which the parasites can be seen inside the red blood cells.

Blood films are usually carried out together with a full blood count.... blood donation

Blood Products

Donated blood that is separated into its various components: red cells, white cells, platelets, and plasma (see blood donation). Each blood product has a specific lifespan and use in blood transfusion. Packed red cells (blood with most of the plasma removed) are used to treat patients with some forms of chronic anaemia and babies with haemolytic disease of the newborn. Washed red cells (with white blood cells and/or plasma proteins removed) are used when a person needs repeated transfusions because there is less risk of an allergy to any of the blood components developing.

Platelets may be given in transfusions for people with blood-clotting disorders. Patients who have life-threatening infections may be treated with granulocytes, a type of white blood cell. Fresh frozen plasma is used to correct many types of bleeding disorder because it contains all the clotting factors. Albumin, prepared from the plasma of whole blood, is used mainly to treat shock resulting from severe blood loss until compatible whole blood becomes available. Purified albumin preparations are used to treat nephrotic syndrome and chronic liver disease.

Concentrates of blood clotting factors and are used in the treatment of haemophilia and Christmas disease.

Immunoglobulins (also called antibodies), which are extracted from blood plasma, can be given by injection (see immunoglobulin injection) to protect people who are unable to produce their own antibodies or have already been exposed to an infectious agent, or to provide short-term protection against hepatitis A.

Immunoglobulins are given in large doses to treat certain autoimmune disorders.... blood products

Donor’s Blood Group

Blood group of people donor can receive blood from... donor’s blood group

Blood Plasma See Plasma.

... blood plasma see plasma.

Blood Serum

see serum.... blood serum

Early Warning System

(EWS) a system to detect deteriorating patients on the ward. Certain physical parameters are accorded scores: the higher the scores for individual patients, the greater the deterioration in their condition. Parameters scored include blood pressure, respiratory rate, pulse rate, blood oxygen saturation, and level of consciousness. Adjustments can be made for increased age.... early warning system

Faecal Occult Blood Test

(FOBT) a noninvasive test used to identify microscopic blood (see occult) in faeces. It is widely used as a screening test for colorectal cancer.... faecal occult blood test

Blood Tests

Analysis of a sample of blood to give information on its cells and proteins and any of the chemicals, antigens, antibodies, and gases that it carries. Such tests can be used to check on the health of major organs, as well as on respiratory function, hormonal balance, the immune system, and metabolism. Blood tests may look at numbers, shape, size, and appearance of blood cells and assess the function of clotting factors. The most important tests are blood count and blood group tests if transfusion is needed. Biochemical tests measure chemicals in the blood (see acid–base balance; kidney function tests; liver function tests). Microbiological tests (see immunoassay) look for microorganisms that are in the blood, as

in septicaemia. Microbiology also looks for antibodies in the blood, which may confirm immunity to an infection. blood transfusion The infusion of large volumes of blood or blood products directly into the bloodstream to remedy severe blood loss or to correct chronic anaemia. In an exchange transfusion, nearly all of the recipient’s blood is replaced by donor blood. Before a transfusion, a sample of the recipient’s blood is taken to identify the blood groups, and it is matched with suitable donor blood. The donor blood is transfused into an arm vein through a plastic cannula. Usually, each unit (about 500 ml) of blood is given over 1–4 hours; in an emergency, 500 ml may be given in a couple of minutes. The blood pressure, temperature, and pulse are monitored during the procedure.

If mismatched blood is accidentally introduced into the circulation, antibodies in the recipient’s blood may cause donor cells to burst, leading to shock or kidney failure. Less severe reactions can produce fever, chills, or a rash. Reactions can also occur as a result of an allergy to transfused blood components. All

blood used for transfusion is carefully screened for a number of infectious agents, including HIV (the AIDS virus) and hepatitis B and hepatitis C.

In elderly or severely anaemic patients, transfusion can overload the circulation, leading to heart failure.

In patients with chronic anaemia who need regular transfusion over many years, excess iron may accumulate (haemosiderosis) and damage organs such as the heart, liver, and pancreas.

Treatment with desferrioxamine to remove excess iron may be needed.... blood tests

Coughing Up Blood

A symptom, medically known as haemoptysis, that is caused by rupture of a blood vessel in the air-ways, lungs, nose, or throat. The coughed-up blood may appear as brightred or rusty-brown streaks, clots in the sputum, a pinkish froth, or, more rarely, blood alone. In all cases, medical assessment is needed. Many disorders can cause haemoptysis. The most common are infections, such as pneumonia or bronchitis; and congestion in and rupture of blood vessels in the lungs due to heart failure, mitral stenosis, or pulmonary embolism. A cancerous tumour can also produce haemoptysis by eroding the wall of a blood vessel.

Investigations into coughing up blood include chest X-ray, and, in some cases, bronchoscopy. In about a 3rd of cases, no underlying cause is found. Treatment depends on the cause.... coughing up blood

Four-layer System

a continuous compression bandage consisting of four layers that are applied and left in situ for up to seven days to treat venous leg ulcers, increasing the chance of healing by up to 30%. Thorough assessment of the patient’s status must be undertaken before the application.... four-layer system

Haversian System

one of the cylindrical units of which compact *bone is made. A Haversian canal forms a central tube, around which are alternate layers of bone matrix (lamellae) and lacunae containing bone cells. The lacunae are linked by minute channels (canaliculi).... haversian system

Heel-prick Blood Test

see Guthrie test.... heel-prick blood test

House–brackmann Facial Nerve Grading System

(House–Brackmann score, House–Brackmann scale, House–Brackmann facial weakness scale) a six-point grading system for patients with *Bell’s palsy or other forms of facial nerve palsy. Grade I is normal function; grade VI is a total palsy. [J. W. House and D. E. Brackmann (21st century), US otorhinolarygologists]... house–brackmann facial nerve grading system

Human Leucocyte Antigen System

see HLA system.... human leucocyte antigen system

Induction Loop System

(loop system) a device for helping people with some types of *hearing aid or *cochlear implant to hear more effectively in certain situations. Electrical signals from a television, sound system, or microphone are passed through an amplifier to a wire that is positioned in a loop encompassing the desired listening area. This creates an electromagnetic field that can be picked up by a coil within the hearing aid or cochlear implant. Induction loops are installed in such places as public buildings, lecture theatres, classrooms, and churches. See also assistive listening device.... induction loop system

Digestive System

The group of organs responsible for digestion. It consists of the digestive tract (also known as the alimentary tract or canal) and various associated organs. The digestive tract consists of the mouth, pharynx, oesophagus, stomach, intestines, and the anus. The intestines are the small intestine (comprising the duodenum, jejunum, and ileum) and the large intestine (comprising the caecum, colon, and rectum). The associated organs, such as the salivary glands, liver, and pancreas, secrete digestive juices that break down food as it goes through the tract.

Food and the products of digestion are moved from the throat to the rectum by peristalsis (waves of muscular contractions of the intestinal wall).

Food is broken down into simpler substances before being absorbed into the bloodstream.Physical breakdown is performed by the teeth, which cut and chew, and the stomach, which churns the food. The chemical breakdown of food is performed by the action of enzymes, acids, and salts.

Carbohydrates are broken down into simple sugars. Proteins are broken down into polypeptides, peptides, and amino acids. Fats are broken down into glycerol, glycerides, and fatty acids.

In the mouth, saliva lubricates food and contains enzymes that begin to break down carbohydrates. The tongue moulds food into balls (called boli) for easy swallowing. The food then passes into the pharynx. From here, it is pushed into the oesophagus and squeezed down into the stomach, where it is mixed with hydrochloric acid and pepsin. Produced by the stomach lining, these substances help break down proteins. When the food has been converted to a semi-liquid consistency, it passes into the duodenum where bile salts and acids (produced by the liver) help to break down fats. Digestive juices released by the pancreas into the duodenum contain enzymes that further break down food. Breakdown ends in the small intestine, carried out by enzymes produced by glands in the intestinal lining. Nutrients are absorbed in the small intestine. The residue enters the large intestine, where water is absorbed. Undigested matter is expelled via the rectum and anus as faeces.... digestive system

Muscular System

The muscles of the body that are attached to the skeleton. These muscles are responsible for voluntary movement, and also support and stabilize the skeleton. In most cases, a muscle attaches to a bone (usually by means of a tendon) and crosses over a joint to attach to another bone. Muscles can produce movement by contracting and shortening to pull on the bone to which they are attached. They can only pull, not push, and are therefore arranged so that the pull of one muscle or group of muscles is opposed to another, enabling a movement to be reversed. Although most actions of the skeletal muscles are under conscious control, reflex movements of certain muscles occur in response to stimuli.

There are more than 600 muscles in the body, classified according to the type of movement they produce.

An extensor opens out a joint, a flexor closes it; an adductor draws a part of the body inwards, an abductor moves it outwards; a levator raises it, a depressor lowers it; and constrictor or sphincter muscles surround and close orifices.... muscular system

Reproductive System, Female

The female organs involved in ovulation, sexual intercourse, nourishing a fertilized ovum until it has developed into a full-grown fetus, and childbirth. With the exception of the vulva, which protects the opening of the vagina, these organs lie within the pelvic cavity.

Ova (eggs) are released at monthly intervals from the 2 ovaries, which also secrete oestrogen hormone; and progesterone hormones that control the reproductive cycle. The ova travel through the fallopian tubes to the uterus. Fertilization takes place if a sperm released into the vagina during sexual intercourse travels through the cervix and uterus to penetrate an ovum while it is in the fallopian tube.... reproductive system, female

Reproductive System, Male

The male organs involved in the production of sperm and in sexual intercourse. Sperm and male sex hormones (androgen hormones) are produced in the testes, which are suspended in the scrotum. From each testis, sperm pass into an epididymis, where they mature and are stored. Shortly before ejaculation, sperm are propelled into a duct called the vas deferens, which carries the sperm to the seminal vesicles behind the bladder. These 2 sacs produce seminal fluid, which is added to the sperm to produce semen.

Semen travels along 2 ducts to the urethra.

The ducts pass through the prostate gland, which produces secretions that are added to the semen.

At orgasm, semen is ejaculated from the urethra through the erect penis, which is placed in the woman’s vagina during sexual intercourse.... reproductive system, male

Injury Scoring System

(injury severity scale, ISS) a system used, particularly in *triage, for grading the severity of an injury. See also abbreviated injury scale.... injury scoring system

Intrauterine System

see IUS.... intrauterine system

Loop System

see induction loop system.... loop system

Multiple System Atrophy

(MSA) a condition that results from degeneration of cells in the *basal ganglia (resulting in *parkinsonism), the *cerebellum (resulting in *ataxia), the *pyramidal system, and the *autonomic nervous system (resulting in symptoms of autonomic failure, such as postural hypotension).... multiple system atrophy

Neuroendocrine System

the system of dual control of certain activities of the body by means of both nerves and circulating hormones. The functioning of the autonomic nervous system is particularly closely linked to that of the pituitary and adrenal glands. The system can give rise to neuroendocrine tumours (NETs), which have special structural features and often produce active hormones. See also neurohormone; neurosecretion.... neuroendocrine system

Nhs Blood And Transplant

(NHSBT) a *special health authority established in 2005 to provide a safe and reliable supply of blood, organs, stem cell services, and diagnostics to hospitals. NHSBT also provides specialist therapeutic apheresis services, which remove or replace a single component of blood (e.g. malignant white cells or low-density lipoprotein), at six sites in England.

NHS Blood and Transplant website... nhs blood and transplant

Vomiting Blood

A symptom of bleeding from within the digestive tract. Vomiting blood may be caused by a tear in the lower oesophagus (see Mallory–Weiss syndrome), bleeding from oesophageal varices, erosive gastritis, peptic ulcer, or, rarely, stomach cancer. Blood can also be vomited if it is swallowed during a nosebleed. Vomited blood may be dark red, brown, black, or may resemble coffee grounds. Vomiting of blood is often accompanied by the passing of black, tarry faeces.

The cause of vomiting blood is investigated by endoscopy of the oesophagus and stomach, or by barium X-ray examinations. If blood loss is severe, blood transfusion, and possibly surgery to stop the bleeding, may be required.... vomiting blood

Blood Coagulation

(blood clotting) the process whereby blood is converted from a liquid to a solid state. The process may be initiated by contact of blood with a foreign surface (intrinsic system) or with damaged tissue (extrinsic system). These systems involve the interaction of a variety of substances (*coagulation factors) and lead to the production of the enzyme thrombin, which converts the soluble blood protein *fibrinogen to the insoluble protein *fibrin, forming the blood clot. Finally, fibrin is broken down by the action of *plasmin. Anticoagulants and tissue plasminogen activators act by inhibiting or activating various pathways in this cascade (see illustration). Blood coagulation is an essential mechanism for the arrest of bleeding (*haemostasis). See also platelet activation.... blood coagulation

Blood Group

any one of the many types into which a person’s blood may be classified, based on the presence or absence of certain inherited antigens on the surface of the red blood cells. Blood of one group contains antibodies in the serum that react against the cells of other groups.

There are more than 30 blood group systems, one of the most important of which is the ABO system. This system is based on the presence or absence of antigens A and B: blood of groups A and B contains antigens A and B, respectively; group AB contains both antigens and group O neither. Blood of group A contains antibodies to antigen B; group B blood contains anti-A antibodies or *isoagglutinins; group AB has neither antibody and group O has both. A person whose blood contains either (or both) of these antibodies cannot receive a transfusion of blood containing the corresponding antigens. The table illustrates which blood groups can be used in transfusion for each of the four groups.

Blood group... blood group

Complaints System

a process that enables patients to voice concerns about the standard of care they receive. In the UK, any complaints should be raised as soon as possible, in the first instance locally with the NHS provider involved. Various statutory and voluntary advice and advocacy services are available to assist in this. If a patient is not satisfied with the outcome of local resolution, the matter can be referred to the *Parliamentary and Health Service Ombudsman. Legal action cannot usually proceed at the same time and only a small proportion of complaints proceed to law. Disciplinary procedures are separate from the complaints procedure although complaints may prompt or inform disciplinary action.... complaints system

Picture Archiving And Communication System

see PACS.... picture archiving and communication system

Pyramidal System

a collection of nerve fibres in the central nervous system that extend from the *motor cortex in the brain to the spinal cord and are responsible for initiating movement. In the medulla oblongata the fibres form a *pyramid (hence the name), within which they cross from one side of the brain to the opposite side of the spinal cord; this is called the decussation of the pyramids. Damage to the pyramidal system manifests in a specific pattern of weakness in the face, arms, and legs, abnormally brisk reflexes, and an extensor *plantar reflex (Babinski response).... pyramidal system

Radiology Information System

(RIS) a computer database used to keep details of all the patients attending a clinical radiology department. It records patient demographics, imaging procedures done, medications given and dosage, person performing the imaging, and time and place of examination. Radiologist reports interpreting the images will also feature here. The RIS is vital to the functioning of a picture archiving and communications system (see PACS) and the electronic medical record system.... radiology information system

Reticular Activating System

the system of nerve pathways in the brain concerned with the level of consciousness – from the states of sleep, drowsiness, and relaxation to full alertness and attention. The system integrates information from all of the senses and from the cerebrum and cerebellum and determines the overall activity of the brain and the autonomic nervous system and patterns of behaviour during waking and sleeping.... reticular activating system

Reticuloendothelial System

(RES) a community of cells – *phagocytes – spread throughout the body. It includes *macrophages and *monocytes. The RES is concerned with defence against microbial infection and with the removal of worn-out blood cells from the bloodstream. See also spleen.... reticuloendothelial system

Scoring System

any of various methods in which the application of an agreed numerical scale is used as a means of estimating the degree of a clinical situation, e.g. the severity of an injury, the degree of patient recovery, or the extent of malignancy. Examples include the *Glasgow Coma Scale (or scoring system) and the *injury scoring system.... scoring system

Single-payer System

a type of health-care system in which there is only one purchaser of health-care services, usually the government. The NHS is a single-payer system.... single-payer system

Umbilical Cord Blood Banked Stem Cells

haemopoietic *stem cells collected from umbilical cord blood donated at birth, which can be stored indefinitely and used if a sibling or any other blood-compatible baby develops an illness (such as leukaemia) that could only be treated by cord-blood stem-cell transplantation. This facility is now available in the UK and the USA.... umbilical cord blood banked stem cells

Vascular System

see cardiovascular system.... vascular system

Vestibular System

those parts of the body involved in balance. The peripheral vestibular system, or *vestibular apparatus, is in the inner ear. The central vestibular system comprises those parts of the brain that are involved in balance. The central vestibular system receives other inputs as well as from the ear, in particular inputs from the eyes and proprioceptors.... vestibular system



Recent Searches