B
Bo the symbol used for the static main magnetic field, in magnetic resonance imaging, which is orientated along the x axis and measured in Tesla.
B1 the symbol used for radiofrequency magnetic field, in a magnetic resonance imaging system, and measured in Tesla.
Babinski’s reflex or sign movement of the great toe upwards (dorsiflexion) instead of downwards (plantar flexion) on stroking the sole of the foot. It is indicative of disease or injury to upper motor neurons. Babies exhibit dorsiflexion, but after learning to walk they show the normal plantar flexion response.
bacillaemia the presence of bacilli in the blood.
bacille Calmette–Guörin a form of tubercle bacilli; it has lost its power to cause tuberculosis, but retains its antigenic function; it is the base of a vaccine used for immunization against tuberculosis. Also used in urology for the treatment of high-risk superficial bladder cancer.
bacillus colloquial term for any rod-shaped microorganism.
Bacillus a type of bacteria consisting of aerobic, Gram-positive, rod-shaped cells that produce endospores. The majority have flagella and are motile. The spores are common in soil and dust.
Bacillus anthracis bacteria which cause anthrax in humans and domestic animals.
Bacillus cereus bacteria which produce exotoxins and cause food poisoning. It can occur after eating cooked food, for example, rice, that has been stored prior to reheating.
back pointer used in radiotherapy to indicate the central exit point of the radiation. See also front pointer.
back projection mathematical basis for tomographic imaging. In CT scanning in order to overcome the blurring inherent in this method a filtered back projection is used, resulting in a sharper image.
back scatter radiation that having passed through the object hits a surface, for example the couch, and is reflected back onto the original object.
bacteraemia the presence of bacteria in the blood.
bacteria microscopic unicellular organisms widely distributed in the environment. Pathogens may be virulent and always cause infection, whereas others, known as opportunists, usually only cause infection when the host defences are impaired, such as during cancer chemotherapy. Non-pathogenic bacteria may become pathogenic if they move from their normal site, for example, intestinal bacteria causing a wound infection. Bacteria are classified and identified by features that include: shape and staining characteristics with Gram stain (positive or negative). Bacteria may be: (a) round (cocci), paired (diplococci), in bunches (staphylococci) or in chains (streptococci); (b) rod-shaped (bacilli); or (c) curved or spiral (vibrios, spirilla and spirochaetes).
bacterial associated with bacteria.
bactericidal describes agents that kill bacteria, for example, some antibiotics.
bactericidin antibody that kills bacteria.
bacteriologist an expert in bacteriology.
bacteriology the scientific study of bacteria.
bacteriolysin a specific antibody formed in the blood that causes bacteria to break up.
bacteriolysis the disintegration and dissolution of bacteria.
bacteriophage a virus parasitic on bacteria. Some of these are used in phage-typing staphylococci, etc.
bacteriostatic describes an agent that inhibits bacterial growth, for example, some antibiotics.
bacteriuria the presence of bacteria in the urine (100000 or more pathogenic microorganisms per millilitre). Acute cystitis may be preceded by, and active pyelonephritis may be associated with, asymptomatic bacteriuria.
Bainbridge reflex stretch receptors in the heart (right atrium) can increase heart rate through sympathetic stimulation when venous return increases.
Baker’s cyst a cyst that forms at the back of the knee. Often associated with rheumatoid arthritis and may appear only when the leg is straightened.
balance of probabilities the standard of proof required in civil proceedings.
balanitis inflammation of the glans penis.
balanitis xerotica obliterans (BXO) inflammatory condition involving the glans and prepuce.
balanoposthitis inflammation of the glans penis and prepuce.
balanus the glans of the penis or clitoris.
ball and socket joint a type of synovial joint with a wide range of movement, for example shoulder joint.
ball catcher’s projection an anteroposterior oblique projection of both hands.
bandage material applied to a wound or used to bind an injured part of the body. May be used to: (a) retain a dressing or splint; (b) support, compress, immobilize; (c) prevent or correct deformity. Available in strips or circular form in a range of different materials and applying varying levels of pressure. compression bandages are widely used in the management of venous leg ulceration.
bandwidth the difference between the maximum and minimum frequency in a system. A range of frequencies in magnetic resonance. See also receiver bandwidth, transmitter bandwidth.
Bankart’s operation for recurrent dislocation of the shoulder joint: the defect of the glenoid cavity of the scapula is repaired.
barbiturates a group of sedative/hypnotic drugs. They are associated with serious problems of dependence and tolerance, and sudden withdrawal may cause a serious withdrawal syndrome that includes anxiety, convulsions and even death. They have been replaced by safer drugs and their use is limited to anaesthesia and sometimes for epilepsy.
barbotage a method of extending the spread of spinal anaesthesia whereby local anaesthetic is directly mixed with aspirated cerebrospinal fluid and reinjected into the subarachnoid space.
bar chart a graph displaying the data in columns, which are separate from each other.
barium enema a radiographic examination of the large bowel using barium sulphate as the contrast agent. Barium sulphate liquid, followed by a quantity of air, is introduced into the large bowel by means of a rectal tube, during fluoroscopy. It is used for diagnostic purposes, for example, for colon cancers, in conjunction with endoscopy. See also barium sulphate, colonoscopy.
barium meal (barium swallow) a radiographic examination of the upper gastrointestinal tract (oesophagus and stomach) and the small intestine with follow-through radiographs, using barium sulphate as the contrast agent. The barium sulphate suspension is swallowed and radiographs are taken of the gastrointestinal tract. Pre-examination fasting is required and medicines, for example, some antacids, that may interfere with the examination should be stopped. Further fasting may be required until follow-through radiographs are completed.
barium sulphate a heavy insoluble powder used, in an aqueous suspension, as a contrast agent in radiographic visualization of the alimentary tract by either being introduced orally, via the rectum or via a colostomy.
Barlow’s test a manoeuvre designed to test for congenitally dislocatable hips in the neonate. Often used in association with the Ortolani test. See also developmental dysplasia of the hip.
barn a unit of measure used in atomic physics to measure cross sections which equal 10−28 m2. See also scattered cross-section.
baroreceptors sensory nerve endings which respond to pressure changes. They are present in the cardiac atria, aortic arch, venae cavae, carotid sinus and the internal ear.
Barrett’s oesophagus benign, ulcer-like lesions in columnar epithelium of the lower oesophagus often resulting from chronic irritation by the acid from gastric reflux. Predisposes to oesophageal cancer.
barrier nursing a method of preventing the spread of infection from an infectious individual to other people. It is achieved by isolation techniques.
Bartholin’s glands (greater vestibular glands) two small glands situated at each side of the external orifice of the vagina. Their ducts open into the vestibule. They produce lubricating mucus that facilitates coitus.
bartholinitis inflammation of Bartholin’s (greater vestibular) glands.
Barton’s fracture a break in the distal articular surface of the radius which may be associated with dorsal dislocation of the carpus on the radius.
basal cell carcinoma a tumour of the basal aspect of the epidermis which accounts for 80% of all skin tumours.
basal dose rate used in brachytherapy and is the average of all dose rates calculated at the minimum dose point in the central transverse plane of a brachytherapy dose distribution. Used in the Paris system of dosimetry.
basal ganglia structures in the peripheral nervous system. See also basal nuclei.
basal metabolic rate (BMR) the energy consumed at complete rest for essential physiological functions. It is influenced by nutritional status, age, gender, physiological status, disease, certain drugs and ambient temperature. It is determined by measuring the oxygen consumption when the energy output has been reduced to a basal minimum, that is the person is fasting and is physically and mentally at rest, and is expressed per kilogram body weight. In clinical practice it is usually estimated by prediction equations and used to estimate energy requirements.
basal metabolism the minimum energy expended in the maintenance of essential physiological processes such as respiration.
basal nuclei a collection of interconnected structures (grey cells) deep within the cerebral hemispheres concerned with cognition, and modifying and coordinating voluntary muscle movement. Their proper functioning requires the release of the neurotransmitter dopamine. Sometimes erroneously referred to as ganglia, which more properly describes structures in the peripheral nervous system. Site of degeneration in Parkinson’s disease. See also dopamine.
base the lowest part such as the lung. The major part of a compound. An alkali. A supporting medium for other layers of either a film or intensifying screens. See also blue-based films, clear-based films.
basement membrane a thin layer beneath the epithelium of mucous surfaces.
BASIC (Beginners All-purpose Symbolic Instruction Code) a high level language for computers and almost universally used for home computers.
basic fog the recorded density of a radiographic film base plus the recorded density of chemical blackening on an unexposed part of a film.
basic life support (BLS) a term that describes the application of artificial respiration (usually by mouth-to-mouth breathing) and external cardiac massage to save life without the use of artificial aids or equipment.
basilic vein on the inner side of the arm.
basophil a cell which has an affinity for basic dyes. A polymorphonuclear granulocyte (white blood cell) which takes up a particular dye: it is phagocytic and has granules containing heparin and histamine.
basophilia increase in the number of basophils in the blood. Basophilic staining of red blood cells.
Batchelor plaster a type of double abduction plaster, with the legs encased from groins to ankles, in full abduction and medial rotation. The feet are then attached to a wooden pole or ‘broomstick’. Alternative to frog plaster, but the hips are free. See also developmental dysplasia of the hip.
battery legal term. An unlawful touching. Constitutes a trespass against the person. See also assault.
Battle’s sign bruising over the mastoid process indicative of a skull fracture.
baud the unit for measuring the rate at which data are transmitted or received.
BCG (bacille Calmette–Guörin) an attenuated form of tubercle bacilli: it has lost its power to cause tuberculosis, but retains its antigenic function; it is the base of a vaccine used for immunization against tuberculosis. Also used in urology for the treatment of high-risk superficial bladder cancer.
beam metal pole attached to a hospital bed to facilitate the use of traction. For example, a Thomas’ splint can be slung up, with pulleys and weights attached, to allow movement and provide counterbalance to the weight of the splint and leg.
beam direction device pointers, light sources or laser beams used to indicate the beam direction, the centre of the beam and the source skin distance.
beam direction shell a device worn by the patient to enable accurate and reproducible treatment localization, patient positioning, patient contour, beam exit and entry points and a base for additional build-up material. Produced using either clear Perspex or a thermoplastic material.
beam’s eye view when an observer looks directly at the planning target volume from the position of the central ray from the X-ray tube, this gives the extent of the beam coverage.
beam hardening when the total intensity of the X-ray beam is reduced by the addition of filters, as the reduction is much greater at lower energies. An increase in the average energy of an X-ray spectrum caused by greater absorption of the low-energy component by filtration.
beam hardening filters addition of pieces of metal to improve the relative penetration of the X-ray beam, they are not effective at megavoltages. See also compound filters.
beam intensity modulation linear accelerator beam intensity is varied during treatment by altering the collimation leaves to create a better dose distribution over the field.
beam profile the dose of the X-ray beam including any scattered radiation which is added to the primary beam as it passes through the patient. The variation of dose along a line at right angles to the central axis of a radiation beam.
beam quality is the penetrating ability of primary radiation and is influenced by: the accelerating voltage (kVp) across the tube, the voltage waveform, the target material, the inherent filtration and the additional filtration.
beam width the width of an ultrasound beam at a given depth in the patient.
beat pulsation of the blood in the heart and blood vessels. dropped beat refers to the loss of an occasional ventricular beat as occurs in extrasystoles. premature beat an extrasystole.
Beau’s lines transverse ridges or grooves which reflect a temporary retardation of the normal nail growth following a debilitating illness. They first appear towards the proximal nail fold and move towards the free edge as the nail grows. The distance the groove has moved indicates quite accurately the length of time since the illness or trauma (nail growth being about 1 mm per week).
becquerel (Bq) the derived SI unit (International System of Units) for radioactivity. Equals the amount of a radioactive substance undergoing one nuclear disintegration per second. Has replaced the curie.
bed cradle a frame placed over a patient’s body to relieve the weight of bedding over the injured part of the body.
bed elevator a wedge used to raise either end of a bed, for example, to aid breathing or to treat shock.
bedpan a shallow vessel used for defecation or urination by patients who are confined to bed.
bedsore obsolete term for decubitus ulcer or pressure sore. A breakdown of the skin due to pressure or immobility; usual sites are buttocks, heels, elbows, shoulders.
Beer Lambert Law the greater the distance a ray of light travels in a coloured medium the more it is absorbed.
Behöet syndrome a form of systemic vasculitis. There is stomatitis, genital ulceration and uveitis. There may also be skin nodules, thrombophlebitis and arthritis of one or more of the large joints. Gastrointestinal and neurological complications may occur. The syndrome is associated with the presence of a certain human leukocyte antigen (HLA). Treatment is with non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroids and immunosuppressant drugs.
bejel a non-venereal form of syphilis mainly affecting children in the Middle East and sub-Saharan Africa. The causative organism is Treponema pallidum. It usually starts in the mouth and affects mucosae, skin and bones.
Bell’s palsy usually non-permanent facial hemiparesis due to idiopathic (cause unknown) lesion of the seventh (facial) cranial nerve.
Bence Jones protein protein that is excreted in the urine of some patients with multiple myeloma; composed of fragments of immunoglobulin molecules.
benchmarking part of quality assurance. Involves the identification of examples of best practice from others engaged in similar practice. From this, best practice benchmark scores in agreed areas of care are identified, against which individual units can compare their own performance.
bends (caisson disease) results from sudden reduction in atmospheric pressure, as experienced by divers on return to surface, aircrew ascending to great heights. Caused by bubbles of nitrogen which are released from solution in the blood; symptoms vary according to the site of these. The condition is largely preventable by proper and gradual decompression technique. See also decompression illness.
benign benign, simple or innocent tumours are encapsulated, do not infiltrate adjacent tissue and are unlikely to recur if removed. They are non-malignant (of a growth), non-invasive (no capacity to metastasize), non-cancerous (of a growth). Describes a condition or illness which is not serious and does not usually have harmful consequences.
benign hypotonia describes infants who are initially floppy but otherwise healthy. Improvement occurs and the infant regains normal tone and motor development.
benign intracranial hypertension (BIH) a condition in which there is raised intracranial pressure with papilloedema and which can lead to the loss of vision, typically in young, obese women. Often associated with thrombosis in the sagittal sinus.
benign myalgic encephalomyelitis (BME) a flu-like illness with varied symptoms including dizziness, muscle fatigue and spasm, headaches and other neurological pain. A high percentage of BME sufferers have a higher level of coxsackie B antibodies in their blood than the rest of the population.
benign tumour a localized growth which is not malignant and does not metastasize but may be dangerous by virtue of its position.
Bennett’s fracture fracture/dislocation of proximal end of first metacarpal involving the first carpo-metacarpal joint.
benzene a colourless inflammable liquid obtained from coal tar. Extensively used as a solvent. Continued occupational exposure to it results in aplastic anaemia and, rarely, leukaemia.
benzodiazepines a group of anxiolytic/hypnotic drugs. Dependence and withdrawal problems may occur. They may be misused.
benzotriazole a radiographic developer restrainer.
beri-beri a deficiency disease caused by lack of vitamin B1 (thiamin). It occurs mainly in those countries where the staple diet is polished rice. Beri-beri is usually described as either ‘wet’ (cardiac) or ‘dry’ (neurological) depending on the symptoms. The symptoms are pain from neuritis, paralysis, muscular wasting, progressive oedema, mental deterioration and, finally, heart failure.
berylliosis an industrial disease: there is impaired lung function because of interstitial fibrosis from inhalation of beryllium. Corticosteroids are used in treatment.
beta decay the process of ejecting a beta particle from the nucleus of an atom; if the particle is negative (negatron) the atomic number will increase by one, if the particle is positive (positron) the atomic number will decrease by one.
beta particle a mass, equal to that of an electron, which is ejected from the nucleus of an atom and has either a positive or a negative charge.
biaxial joint a joint that allows movement round two axes for example, flexion, extension, abduction and adduction.
bibliographical databases details of papers, etc., but sometimes abstracts and full articles, are available electronically via CD-ROM or the internet, for example, Medline.
bicellular composed of two cells.
biceps two-headed muscle of the upper arm.
biconcave concave or hollow on both surfaces.
biconvex convex on both surfaces.
bicornate having two horns; generally applied to a double uterus or a single uterus possessing two horns.
bicuspid having two cusps or points. bicuspid teeth the premolars. bicuspid valve the mitral valve between the left atrium and ventricle of the heart.
bifid divided into two parts. Cleft or forked.
bifurcation division into two branches.
bilateral associated with both sides.
bile a bitter, alkaline, viscid, greenish-yellow fluid secreted by the liver and stored in the gallbladder. 500–1000mL is produced each day. It contains water, mucin, lecithin, cholesterol, bile salts, bile acids, the pigments bilirubin and biliverdin and substances for excretion. Bile is needed for the absorption of fat-soluble vitamins, stimulates peristalsis and deodorizes faeces.
bile acids organic acids; cholic and chenodeoxycholic, present in bile.
bile ducts the hepatic and cystic, which join to form the common bile duct that empties into the duodenum.
bile pigments made up of bilirubin and biliverdin, produced by haemolysis in the spleen. Normally these colour the faeces only but in jaundice the skin and urine may also become coloured. See also bilirubin, biliverdin.
bile salts emulsifying agents, sodium glycocholate and taurocholate. Conju-gated bile acids (with taurine and glycine) form these sodium salts.
biliary colic pain in the right upper quadrant of abdomen, due to obstruction of the gallbladder or common bile duct, usually by a stone; it may last several hours and is usually steady, which differentiates it from other forms of colic. Vomiting may occur.
biliary fistula an abnormal track conveying bile to the surface or to some other organ.
bilious a word usually used to signify vomit containing bile. A non-medical term, usually meaning ‘suffering from indigestion’.
bilirubin a red pigment derived mostly from haemoglobin during red blood cell breakdown. Unconjugated fat-soluble bilirubin, which gives an indirect reaction with Van den Bergh’s test, is potentially toxic to metabolically active tissues, particularly the basal nuclei of the immature brain. Unconjugated bile is transported to the blood attached to albumen to make it less likely to enter and damage brain cells. In the liver the enzyme glucuronyl transferase conjugates fat-soluble bilirubin with glucuronic acid to make it water-soluble, in which state it is relatively non-toxic (reacts directly with Van den Bergh’s test) and can be excreted in the bile. See also haemolytic disease of the newborn, jaundice.
bilirubinaemia the presence of bilirubin in the blood. Sometimes used (incorrectly) for an excess of bilirubin in the blood.
bilirubinuria the presence of the bile pigment bilirubin in the urine.
biliverdin the green pigment formed by oxidation of bilirubin.
bilobular having two little lobes or lobules.
binary a system of counting to base two, i.e. generating figures with only 1 or 0.
binary fission a method of reproduction common among the bacteria and protozoa. The cell divides into two equal ‘daughter’ cells.
binder an agent used to suspend the phosphors in the phosphor layer of an intensifying screen, acetate acrylate is often used and contains a dye to control screen speed and unsharpness.
binocular vision the focusing of both eyes on one object at the same time, in such a way that only one image of the object is seen.
binovular derived from two separate ova. Binovular twins may be of different sexes.
bioavailability the amount of a drug (or nutrient) that enters the circulation in the active form. It is dependent on the route of administration and the degree to which the drug is metabolized before it reaches the bloodstream. Drugs administered intravenously will have 100% bioavailability, whereas those given orally may not be fully absorbed and are subject to first-pass metabolism in the liver. Some drugs are totally metabolized in the liver, so other routes of administration must be used such as sublingually.
biochemistry the chemistry of life and organic molecules.
bioethics the application of ethical principles to biological problems.
biofeedback presentation of immediate visual or auditory information about usually unconscious body functions such as blood pressure, heart rate and muscle tension. Either by trial and error or by operant conditioning a person can learn to repeat behaviour which results in a satisfactory level of body functions.
biofilm collection of microorganisms and their products that stick to a surface, for example, a urinary catheter.
bioflavonoids a large group of coloured substances that occur naturally in many vegetables and fruit (for example, tomatoes, broccoli, cherries, plums, etc.). Bioflavonoids are also present in tea and wine. Many are antibacterial and some may offer protection against heart disease and cancer.
biohazard anything that presents a hazard to life. Some specimens for the pathological laboratory are so labelled.
biological effect when a body is irradiated changes can occur which can include, skin reddening, loss of hair, radiation-induced cancers, genetic changes, changes in blood count and, if sufficiently high radiation dose is received to the whole body, death.
biological engineering designing microelectronic or mechanical equipment for external use by patients: for attachment to patients, or placement inside patients.
biological half-life the time taken for the concentration of a certain chemical in an organ to be reduced to half its original concentration.
biological response modifier (BRM) cancer treatment that manipulates the patient’s immune response in order to destroy cancer cells. They include colony stimulating factors, interleukins and interferons.
biologically effective dose a comparison between the total radiation dose given during a fractionated treatment and a single dose of the same quantity of radiation. A quantity used in the radiobiology of radiotherapy to compare the effects of different fractionation schedules. The total dose given in very small fractions required to produce a particular effect.
biology the science of life, concerned with the structure, function and organization of all living organisms.
biophysical profile used in the third trimester to assess fetal well being using measurable parameters of: fetal breathing, fetal movement, fetal tone, amniotic fluid volume and heart rate.
biopsy removal of tissue to provide a sample for microscopic examination to establish a precise diagnosis.
biopsy forceps long, metal forceps with a scissor action of the end blade, used for taking tissue samples from narrow passages.
biorhythm the cyclical patterns of biological functions unique to each person, for example, sleep–wake cycles, body temperature, etc.
biosensors non-invasive devices that measure the result of biological processes, for example, skin temperature or blood oxygen saturation.
biotechnology the use of biology in the scientific study of technology and vice versa.
biparietal diameter the transverse distance between the two parietal bones of the skull. A measurement used in ultrasound imaging to assess the gestational age of a fetus in the second and third trimesters.
biparous producing two offspring at one birth.
biphasic positive airways pressure (BIPAP) mode of ventilatory (respiratory) support in which the airway pressure alternates between two levels. The higher pressure ventilates the patient or provides pressure support, while the lower pressure acts as positive end expiratory pressure/continuous positive airway pressure. Can be delivered non-invasively (without intubation) by mask to patients with chronic lung disease or as an aid to weaning from ventilatory support.
bisexual having some of the physical genital characteristics of both sexes; a hermaphrodite. When there is gonadal tissue of both sexes in the same person that person is a true hermaphrodite. Describes a person who is sexually attracted to both men and women.
bisphosphonates drugs that reduce bone turnover. Used in the management of bone diseases and the hypercalcaemia associated with cancer.
bit the smallest unit of data in a computer, a contraction of BInary digiT.
bite block a dental impression suspended from a gantry which the patient bites to enable accurate head position to be maintained during treatment.
bivalve having two blades such as in the vaginal speculum. In orthopaedics, the division of a plaster of Paris splint into two portions – an anterior and posterior half.
bivariate statistics descriptive statistics that compare the relationship between two variables, such as correlations. Can be used to decide whether multivariate statistics are needed.
black body a body which will absorb 100% of all radiations falling on it.
bladder a membranous sac containing fluid or gas. A hollow organ for receiving fluid. See also gallbladder, urinary bladder.
bladder outflow obstruction pathophysiological obstruction to the lower urinary tract commonly due to benign prostatic hyperplasia in older males.
Blalock–Taussig procedure a temporary measure to improve pulmonary blood flow in congenital heart abnormalities, such as tetralogy of Fallot. A shunt is constructed by anastomosing the subclavian artery to the pulmonary artery to divert blood from the systemic circulation to the lungs.
blastocyst (blastula) stage in early embryonic development that follows the morula, which becomes cystic and enfolds. Comprises a fluid-filled cavity and inner cell mass surrounded by trophoblast cells.
blastoderm a cell layer of the blastocyst. Eventually becomes the three primary germ layers, ectoderm, endoderm and mesoderm, from which the embryo will form.
blastomycosis granulomatous condition caused by Blastomyces dermatitidis; infection starts in the lungs and lymph nodes. May affect the skin, viscera, bones and joints.
‘bleeding time’ the time required for the spontaneous arrest of bleeding from a skin puncture: under controlled conditions this forms a clinical test.
blind loop syndrome a condition resulting from sluggish movement of faeces (stasis) in the small intestine leading to bacterial growth, thus producing diarrhoea and malabsorption (for example, due to surgical anastomosis or dysmotility).
blind spot the spot at which the optic nerve leaves the retina. Without any cones or rods it is insensitive to light.
blink mode the comparison of two images in quick succession to identify minute changes between the images.
blood the red viscid fluid filling the heart and blood vessels. It consists of a colourless fluid, plasma, in which are suspended the red blood cells (erythrocytes), the white cells (leucocytes), and the platelets (thrombocytes). The plasma contains a great many substances in solution including factors which enable the blood to clot.
blood-borne viruses (BBV) viruses transmitted via blood to cause infection. Include: HIV and several hepatitis viruses.
blood–brain barrier (BBB) the protective arrangement that prevents many substances crossing from the blood to the brain. It consists of capillary endothelial cells and astrocytes that ensure that the capillary wall is relatively impermeable. The barrier allows the passage of nutrients and metabolic waste. However, some drugs, alcohol and other toxic substances, for example, lead in young children, can pass from the blood through this barrier to the cerebrospinal fluid.
blood count calculation of the number of red or white cells per cubic millimetre of blood, using a haemocytometer. See also differential blood count.
blood culture a sample of venous blood is incubated in a suitable medium at an optimum temperature, so that any microorganisms can multiply and so be isolated and identified microscopically. See also septicaemia.
blood gases (arterial blood gases) measurement of the oxygen (PaO2), carbon dioxide (PaCO2) and acid–base (pH or hydrogen ion concentration) content of the arterial blood.
blood plasma the fluid part of blood.
blood pressure the pressure exerted by the blood on the blood vessel walls. Usually refers to the pressure within the arteries, which may be measured in millimetres of mercury (mmHg) using a sphygmomanometer. The arterial blood pressure fluctuates with each heart beat, having a maximum value (the systolic pressure) which is related to the ejection of blood from the heart into the arteries and a minimum value (diastolic pressure) when the aortic and pulmonary valves are closed and the heart is relaxed. Usually values for both systolic and diastolic pressures are recorded (for example, 120/70). See also hypertension, hypotension.
blood sugar the amount of glucose in the blood; varies within the normal range. It is regulated by hormones, for example, insulin. See also hyperglycaemia, hypoglycaemia.
blood transfusion the intravenous replacement of lost or destroyed blood by compatible citrated human blood.
blood urea the amount of urea (the end product of protein metabolism) in the blood; varies within the normal range. This is virtually unaffected by the amount of protein in the diet when the kidneys, which are the main organs of urea excretion, are functioning normally. When they are diseased the blood urea quickly rises.
blood volume the amount of blood circulating in the body. In an adult male equal to 5.5 litres.
blow-out fracture fracture of the orbital wall due to blunt trauma.
‘blue baby’ cyanotic appearance at birth, often attributed to congenital cyanotic heart defects.
blue-based films have a blue dye in the base and produce a slightly higher visual contrast.
B-mode brightness modulation in ultrasound techniques. When the ultrasound reflections are recorded as dots of varying brightness on an oscilloscope, which is converted into a grey scale picture by a scan converter and a two-dimensional image is formed showing a section through the organ being examined.
Bobath concept the concept of treatment of abnormal muscle tone and movement disorder, seen in children with cerebral palsy and adults after a stroke, and now widely applied to similar dysfunction caused by multiple sclerosis and other neurological conditions.
body mass index (BMI) used as an index of adiposity. It is calculated by dividing an individual’s weight (kg) by their height (m) squared. Separate charts are available for adults and children, adult charts should not be used for children. The WHO (1998) classification for BMI is: less than 18.5 underweight, 18.6–24.9 normal weight, 25–29.9 pre-obese, 30–34.9 obese class 1, 35–39.9 obese class 2 and greater than 40 obese class 3.
body temperature the balance between heat produced and heat lost in the body. It is maintained around 37öC throughout the 24 hours but varies between 0.5 and 1.0öC during that period. Most heat is produced by metabolism, voluntary and involuntary muscular activities, and heat loss occurs through convection, conduction and evaporation of sweat; small amounts are lost during expiration, urination and defaecation. See also core body temperature, shell body temperature.
Bohler’s angle two lines drawn on a lateral radiograph of a calcaneum. Line one is from the posterior aspect of the calcaneum to its highest midpoint. The second line is from the highest midpoint to the highest anterior point. The normal angle is 25–40ö, any other angle indicating an injury to the calcaneum.
boil (furuncle) an acute inflammatory condition, surrounding a hair follicle; often caused by Staphylococcus aureus. Usually attended by suppuration; it has one opening for drainage in contrast to a carbuncle.
Bolam test the test laid down in the case of Bolam versus Friern HMC on the standard of care expected of a professional in cases of alleged negligence.
bolus a chewed lump of food ready to be swallowed. A large dose of medication, contrast agent or radioactive isotope injected all at once intravenously to raise the blood concentration rapidly. A tissue equivalent material used in radiotherapy when irradiating irregular body shapes, to attenuate the primary beam and absorb scattered radiation to maintain accurate treatment dosage or to increase the dose to the skin when high-energy photon beams are used.
bone connective tissue in which salts, such as calcium carbonate and calcium phosphate, are deposited in an organic matrix to make it hard and dense. Bone tissue is of two types, hard dense compact bone and spongy cancellous bone. The separate bones make up the skeleton.
bone death occurs when there is a loss of blood supply to the bone, can happen following a fracture.
bone density a description of bone mass. It is decreased in osteoporosis. See also peak bone density.
bone graft the transplantation of a piece of bone from one part of the body to another, or from one person to another. Used to repair bone defects or to supply osteogenic tissue.
bone marrow the substance contained within bone cavities. At birth the cavities are filled with blood-forming red marrow but later in life, deposition of fat in the long bones converts the red into yellow bone marrow.
bone marrow biopsy (sampling) an investigation of blood cell production whereby a sample of marrow is obtained by aspiration or trephine. Usually the site used is the iliac crest or sometimes the sternum.
bone marrow transplantation (BMT, stem cell transplant) the infusion of bone marrow into a patient’s vein. The bone marrow may be obtained either on an earlier occasion from the patient (autologous transplantation) or from a suitable donor (allogeneic transplantation). Usually follows myeloablative doses of chemotherapy or radiotherapy as therapy for (most commonly) haematological cancers although also used therapeutically and experimentally for some solid tumours.
booting Bps bits per second, the rate information is transferred between computers. Starting up a computer by loading it with its starting instructions.
borborygmi rumbling noises caused by the movement of gas in the intestines.
botulism an intoxication with the preformed exotoxin of Clostridium botulinum. Vomiting, respiratory, ocular and pharyngeal paralysis occur within 24–72 hours of eating food contaminated with the spores, which require anaerobic conditions to produce the toxin. Associated with home preserving of vegetables and meat and improperly treated tinned food.
bounce the automatic return of email.
bovine relating to the cow or ox.
bovine spongiform encephalopathy (BSE) a fatal, infective (prion) neurological disease of cattle. See also Creutzfeldt–Jakob disease.
bovine tuberculosis is endemic in cattle and transmitted to humans by drinking infected milk. Pasteurization of milk and monitoring of dairy herds are the mainstays of disease control. M. avium intracellulare (MAI) is an atypical mycobacterium which may infect severely immunocompromised individuals (such as those with advanced AIDS). Tuberculosis causes systemic effects such as pyrexia, night sweats and weight loss, plus those dependent upon the site, for example, cough in lung disease, haematuria in renal TB.
Bowen’s disease a form of carcinoma in situ, which may progress to invasive malignancy, characterized by red-brown scaly or crusted lesions that resemble a patch of psoriasis or dermatitis.
box technique in radiotherapy when two intersecting parallel pairs produce a uniform distribution of dose over the centrally placed volume enclosed by all four fields.
Boyle’s anaesthetic machine apparatus for delivering anaesthetic agents mixed with oxygen and nitrous oxide or air.
Bps (Bits per second) the rate information is transferred between computers.
brachial associated with the arm. Applied to vessels in this region (brachial artery, brachial vein) and a nerve plexus at the root of the neck.
brachialis a muscle of the upper arm.
brachiocephalic associated with the arm and head.
brachiocephalic (innominate) artery large artery branching from the aortic arch which forms the right common carotid and right subclavian arteries.
brachiocephalic (innominate) veins two large veins derived from the internal jugular and subclavian veins. Convey blood to the heart via the superior vena cava.
brachioradialis a muscle of the forearm.
brachium the arm (especially from shoulder to elbow), or any arm-like appendage.
brachydactyly short phalanges.
brachytherapy when a sealed radioactive source is placed in a body cavity, or inserted into tissue to deliver a large radiation dose to a tumour with a smaller dose to the surrounding tissue. The technique may be used to treat cancers of the anus, breast, cervix, lung, oesophagus and the tongue.
brachymesophalangy short middle phalanges.
Bradford frame a stretcher type of bed used for: (a) immobilizing the spine; (b) resting trunk and back muscles; (c) preventing deformity. It is a tubular steel frame fitted with two canvas slings allowing a 100–150mm gap to facilitate personal care.
bradycardia slow rate of heart contraction, resulting in a pulse rate less than 60 beats per minute. Can occur during sleep/old age/hypothermia or as a result of treatment with certain drugs.
bradykinesia abnormally slow or retarded movement associated with difficulty initiating and then stopping a movement; typically seen in Parkinson’s disease.
bradypnoea an abnormally low rate of breathing.
brain (encephalon) the largest part of the central nervous system: it is contained in the cranial cavity and is surrounded by three membranes called meninges. It comprises the cerebral hemispheres, brainstem (midbrain, pons varolii and medulla oblongata) and the cerebellum. The brainstem connects the cerebral hemispheres to the cerebellum and the spinal cord. The cerebrospinal fluid inside the brain is contained in the ventricles, and outside in the subarachnoid space acts as a shock absorber to the delicate nerve tissue.
brain death a situation where the brainstem is fatally and irreversibly damaged. The brainstem is responsible for maintaining vital functions including breathing. Strict criteria must be met before the patient is declared dead. These include testing certain reflexes, for example, gag and pupillary, and the absence of factors that could depress brainstem activity. Suitable patients may become organ donors if this coincides with the wishes of the family and those of the patient if known.
branchial relating to the gills. Embryonic clefts or fissures either side of the neck from which the nose, ears and mouth will eventually develop.
branchial cyst a cyst in the neck resulting from a developmental abnormality of the branchial clefts.
Braun’s frame a metal frame, bandaged for use, and equally useful for drying a lower leg plaster and for applying skeletal traction (Steinmann’s pin or Kirschner wire inserted through the calcaneus) to a fractured tibia, after reduction.
breast the anterior upper part of the thorax. The mammary gland.
breast board an immobilization device used to aid and maintain patient positioning during treatment. The patient’s shoulders may be raised while providing arm support and/or handgrips.
breast care nurse specialized nurse who provides counselling and support to patients with breast cancer including advice on prostheses available to patients who have had a mastectomy.
breast jig a support which raises the patient’s shoulders and provides arm support and/or handgrip to enable the patient to maintain the position during radiotherapy treatment.
breech/birth presentation refers to the position of a baby in the uterus such that the buttocks would be born first: the normal position is head first.
bregma the anterior fontanelle.
Bremsstrahlung radiation electromagnetic radiation produced by the rapid deceleration of an electron during a close approach to the atomic nucleus, e.g. the X-ray quanta produced when electrons from the filament of the X-ray tube interact with the nuclei of the target.
bridge in dentistry, restoration to replace one or more teeth using artificial crowns connected to natural teeth.
British sign language (BSL) a type of sign language (signing) used in the UK.
broadband a transmission technique which uses a number of frequencies to allow a number of computer and/or telephone messages to be sent together.
broad focus the selection of a large filament to enable a larger area of the anode to be bombarded with electrons.
broad ligaments lateral ligaments; double fold of parietal peritoneum which hangs over the uterus and outstretched uterine (fallopian) tubes, forming a lateral partition across the pelvic cavity.
Broca’s area the motor speech area, situated in the dominant cerebral hemisphere (usually the left). Injury to this centre can result in an inability to speak.
Brodie’s abscess chronic abscess in bone.
bronchi the two tubes into which the trachea divides at its lower end.
bronchial associated with the bronchi.
bronchial alveolar lavage (BAL) irrigation of the lungs with small volumes of saline which are then aspirated and examined for infection; occasionally large volume lavage may be therapeutic.
bronchial cancer see non-small cell carcinoma, oat cell carcinoma.
bronchial tree network of bronchi as they subdivide within the lungs.
bronchiectasis abnormal dilatation of the bronchi which, when localized, is usually the result of pneumonia or lobar collapse in childhood, but when generalized is due to some inherent disorder of the bronchial mucous membrane as in cystic fibrosis. Characterized by recurrent respiratory infections with profuse purulent sputum and digital clubbing. Eventually leads to respiratory failure. Treatment is with appropriate antibiotics and regular physiotherapy to optimize sputum clearance.
bronchiole one of the minute subdivisions of the bronchi which terminate in the alveoli (air sacs) of the lungs.
bronchiolitis inflammation of the bronchioles, usually due to viral infection in children in the first year of life.
bronchiolitis obliterans syndrome (BOS) progressive scarring and loss of function seen in the lungs, in part as a result of chronic rejection of a transplanted lung over time.
bronchitis inflammation of the bronchi. acute bronchitis as an isolated incident is usually a primary viral infection occurring in children as a complication of the common cold, influenza, whooping cough, measles or rubella. Secondary infection occurs with bacteria, commonly Streptococcus pneumoniae or Haemophilus influenzae. acute bronchitis in adults is usually an acute exacerbation of chronic bronchitis precipitated by a viral infection but sometimes by a sudden increase in atmospheric pollution. chronic bronchitis is defined as a cough productive of sputum for at least 3 consecutive months in 2 consecutive years. The bronchial mucus-secreting glands are hypertrophied with an increase in goblet cells and loss of ciliated cells due to irritation from tobacco smoke, or atmospheric pollutants. See also chronic obstructive pulmonary disease (COPD), pulmonary emphysema.
bronchoconstrictor any agent which constricts the bronchi.
bronchodilator any agent which dilates the bronchi.
bronchogenic arising from one of the bronchi.
bronchography radiological demonstration of the bronchial tree following the introduction of contrast agent via the trachea.
bronchomycosis general term describing a variety of fungal infections of the bronchi and lungs, for example, pulmonary candidiasis.
bronchophony abnormal transmission of voice sounds heard over consolidated lung or over a thin layer of pleural fluid.
bronchopleural fistula pathological communication between the pleural cavity and one of the bronchi.
bronchopneumonia describes a type of pneumonia in which areas of consolidation are distributed widely around bronchi and not in a lobar pattern. Generally affects patients at the extremes of age, those who are debilitated or secondary to existing condition.
bronchopulmonary associated with the bronchi and the lungs.
bronchorrhoea an excessive discharge of mucus from the bronchial mucosa.
bronchoscope an endoscope used for examining and taking biopsies from the interior of the bronchi. Also used for removal of inhaled foreign bodies. Bronchoscopes are either flexible fibreoptic instruments or rigid tubes.
bronchoscopy visual examination of the tracheobronchial tree using a bronchoscope.
bronchospasm sudden constriction of the bronchial tubes due to contraction of involuntary smooth muscle in their walls.
bronchostenosis narrowing of one of the bronchi.
bronchotracheal associated with the bronchi and trachea.
bronchus one of the two tubes into which the trachea divides at its lower end.
Brook airway used in expired air ventilation to avoid direct contact with the patient.
brought in dead (BID) describes a situation where the person has died prior to arriving at the hospital.
brow the forehead; the region above the supraorbital ridge.
Brown-Söquard syndrome the compression of the spinal cord, usually by a tumour, resulting in a loss of pain and temperature sensation on the opposite side of the body from the compression.
brucellosis a disease contracted by drinking contaminated milk which may affect the spine with the appearance of osteomyelitis.
Brudzinski’s sign immediate flexion of knees and hips on raising head from pillow. Seen in meningitis.
bruise (contusion, ecchymosis) a discoloration of the skin due to an extravasation of blood into the underlying tissues; there is no break of the skin.
Bruton’s agammaglobulinaemia a congenital condition in boys, in which B lymphocytes are absent but cellular immunity remains intact. See also dysgammaglobulinaemia.
bruxism abnormal grinding of teeth, often producing wearing down (attrition) of the surface.
Bryant’s ‘gallows’ traction skin traction applied to the lower limbs; the legs are then suspended vertically (from an overhead beam), so that the buttocks are lifted just clear of the bed. Used for fractures of the femur in children up to 4 years. Now largely replaced with hoop traction.
bubo enlargement of lymph nodes, especially in the groin. A feature of chancroid, lymphogranuloma venereum and bubonic plague.
buccal relating to the cheek or mouth.
bucket handle tear a description given to a type of tear of the meniscus of the knee joint that extends along the length of the meniscus.
bucky a device for holding a cassette beneath an X-ray table which contains a grid which moves during the radiographic exposure.
Buerger’s disease (thromboangiitis obliterans) a chronic obliterative vascular disease of peripheral vessels that results in ischaemia, intermittent limping (claudication), skin changes and gangrene. The incidence is associated with the presence of HLA-A9 and HLA-B5. It affects young and middle-aged men. Buerger’s exercises were designed to treat this condition. The legs are placed alternately in elevation and dependence to assist perfusion of the extremities with blood.
buffer substances that limit pH change by their ability to accept or donate hydrogen ions as appropriate. Radiographic film processing, in developer boric acid and sodium hydroxide are used to absorb the products of development and therefore maintain the pH of the solution. In biological systems they limit pH changes that would inhibit cell functioning. The important buffer systems in the body include: bicarbonate (hydrogen carbonate) system, hydrogen phosphates and proteins, for example, haemoglobin. Any agent that reduces shock or jarring due to contact. In computing an area which stores information at one rate and releases it at a slower rate to another device.
bug a problem in the computer or (usually) in the program.
bulbar associated with the medulla oblongata. bulbar palsy or paralysis paralysis which involves the labioglossopharyngeal (lips, tongue and pharynx) region and results from degeneration of the motor nuclei in the medulla oblongata. There are problems with swallowing and speech. Individuals are at risk of inhaling fluids and food, with the development of pneumonia.
bulbourethral (Cowper’s) glands two mucus-secreting glands which open into the bulb of the male urethra. Their secretion is part of seminal fluid.
bulimia abnormal increase in the sensation of hunger.
bulimia nervosa a pattern of binge eating occurring in response to stress.
Burkitt’s lymphoma a lymphosarcoma, usually of the jaw, predominantly occurring in African children living in low-lying moist areas.
burn tissue damage (necrosis) due to chemicals, moist heat, dry heat, electricity, flame, friction or radiation; classified as partial or full thickness according to the depth of skin destroyed: the latter usually requiring skin graft(s). Analgesia and the prevention of shock, infection and malnutrition are important aspects of treatment.
burr an attachment for a surgical drill which is used for cutting into tooth or bone.
bursa a fibrous sac lined with synovial membrane and containing a small quantity of synovial fluid. Bursae are found between (a) tendon and bone, (b) skin and bone, (c) muscle and muscle. Their function is to facilitate movement by reducing friction between these surfaces.
bursitis inflammation of a bursa. olecranon bursitis inflammation of the bursa over the point of the elbow. prepatellar bursitis (housemaid’s knee) a fluid-filled swelling of the bursa in front of the kneecap (patella). It is frequently associated with excessive kneeling. A blow can result in bleeding into the bursa and there can be infection with pyogenic pathogens. retrocalcaneal bursitis inflammation of an anatomical bursa located between the posterior angle of the calcaneus and the Achilles tendon near to its insertion. There is a fluctuant soft tissue swelling both sides of the tendon.
bus a semi-standard connector to the computer through which all data are passed to an external device.
buttock one of the two projections posterior to the hip joints. Formed mainly of the gluteal muscles.
byssinosis a form of pneumoconiosis caused by inhalation of cotton or linen dust.
byte the number of bits which are needed to form a single character, usually 8. See also bit.
