Definitions and descriptions

Definitions and descriptions

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There are currently 54 terms in this directory beginning with the letter B.
B cell (B SELL)
A subgroup of lymphocytes, including memory B cells and plasma cells, both of which are involved in adaptive immune responses
Bacillus (buh-SILL-us) (Pl.—bacilli)
A rod-shaped bacterium
Bacteremia (bak-tah-REE-mee-ah)
The presence of bacteria in the blood, which is normally sterile
Bacteria (bak-TEER-ee-yuh) (Sing.— bacterium)
The simple unicellular microorganisms of the class Schizo-mycetes; may be free living, saprophytic, or parasitic
Bactericide (bak-TEER-i-sigh’d)
A chemical that kills bacteria
Bacteriostatic (bak-TEE-ree-oh-STAT-ik)
Capable of inhibiting the reproduction of bacteria
Bacteruria (BAK-tur-YOO-ree-ah)
The presence of large numbers of bacteria in urine
Ball-and-socket joint (BAWL and SOK-et)
A diarthrosis that permits movement in all planes
Band cell (BAND SELL)
An immature neutrophil with a nucleus that has not yet segmented
Barrett Esophagus
This is a condition in which the squamous epithelium of the esophagus is replaced by metaplastic columnar epithe­lium containing goblet and columnar cells (specialized intestinal metaplasia). Present in up to 15% of patients with chronic reflux, Barrett esophagus is believed to arise from chronic reflux-induced injury to the esophageal squamous epithelium; however, it is also increased in patients with truncal obesity independent of GERD. Barrett esophagus is suspected at endoscopy from the presence of orange, gas­tric type epithelium that extends upward more than 1 cm from the gastroesophageal junction into the distal tubular esophagus in a tongue-like or circumferential fashion.
Bartholin’s glands (BAR-toh-linz)
The small glands in the wall of the vagina; secrete mucus into the vagina and vestibule (Syn.—vestibular glands)
Basal ganglia (BAY-zuhl GANG-lee-ah)
Masses of gray matter within the white matter of the cerebral hemispheres; concerned with subconscious aspects of skeletal muscle activity, such as accessory movements
Basal metabolic rate (BAY-zuhl met-ah-BAHL-ik RAYT)
The energy required to maintain the functioning of the body in a resting condition
Base (BAYS)
A hydrogen ion (H +) acceptor, or hydroxyl ion (OH -) donor; when in solution, has a pH greater than 7
Basilar layer (bah-SILL-ar LAY-er)
The permanent vascular layer of the endometrium that is not lost in menstruation; regenerates the functional layer during each menstrual cycle
Basophil (BAY-so-fill)
A type of white blood cell (granular); contains heparin and histamine
Benign (bee-NINE)
Not malignant
Benign Prostatic Hyperplasia (BPH)
Benign prostatic hyperplasia is a noncancerous (benign) growth of the prostate gland.
Beta cells (BAY-tah SELLS)
The cells of the islets of Langerhans of the pancreas that secrete the hormone insulin
Beta-oxidation (BAY-tah-AHK-si-DAY-shun)
The process by which the long carbon chain of a fatty acid molecule is broken down into two-carbon acetyl groups to be used in cell respiration; takes place in the liver
Bile (BYL)
The secretion of the liver that is stored in the gallbladder and passes to the duodenum; contains bile salts to emulsify fats; is the fluid in which bilirubin and excess cholesterol are excreted
Bile salts (BYL SAWLTS)
The active component of bile that emulsifies fats in the digestive process
Bilirubin (BILL-ee-roo-bin)
The bile pigment produced from the heme portion of the hemoglobin of old red blood cells; excreted by the liver in bile
Binary fission (BYE-na-ree FISH-en)
The asexual reproductive process in which one cell divides into two identical new cells
Binocular vision (bye-NOK-yoo-lur VI-zhun)
Normal vision involving the use of both eyes; the ability of the brain to create one image from the slightly different images received from each eye
Biopsy (BYE-op-see)
Removal of a small piece of living tissue for microscopic examination; a diagnostic procedure
Birth canal (BERTH ka-NAL)
The vagina during delivery of an infant
Blastocyst (BLAS-toh-sist)
The early stage of embryonic development that follows the morula; consists of the outer trophoblast and the internal inner cell mass and blastocele (cavity)
Blister (BLISS-ter)
A collection of fluid below or within the epidermis
Blood (BLUHD)
The fluid that circulates in the heart and blood vessels; consists of blood cells and plasma
Blood pressure (BLUHD PRE-shure)
The force exerted by the blood against the walls of the blood vessels; measured in mmHg
Blood–brain barrier (BLUHD BRAYN)
The barrier between the circulating blood and brain tissue, formed by astrocytes and brain capillaries; prevents harmful sub- stances in the blood from damaging brain neurons
Body (BAH-dee)

  1. The physical human being as a whole.

  2. The supporting part of a vertebra.

  3. The central portion of the sternum.

  4. Any of a number of small structures, such as the cell body of a neuron or the sensory carotid body

Body-mass index (BAH-dee mass IN-deks)
A measure of leanness using height and weight
Bond (BAHND)
An attraction or force that holds atoms together in the formation of molecules
Bone (BOWNE)

  1. A connective tissue made of osteocytes in a calcified matrix.

  2. An organ that is an individual part of the skeleton

Botulism (BOTT-yoo-lizm)
A disease, characterized by muscle paralysis, caused by the bacterium Clostridium botulinum
Bowman’s capsule (BOW-manz KAP-suhl)
The expanded end of the renal tubule that encloses a glomerulus; receives filtrate from the glomerulus
Bradycardia (BRAY-dee-KAR-dee-yah)
An abnormally slow heart rate; less than 60 beats per minute
Brain (BRAYN)
The part of the central nervous system within the skull; regulates the activity of the rest of the nervous system
Brain Abscess
Brain abscess is a focal collection of pus/necrotic tissue with the brain paranchyma, which can arise as a compication of a variety of infections, trauma or surgery. The manifestations of brain abscess depends on the site, size and the immune status of the patient.
Brain stem (BRAYN STEM)
The portion of the brain that consists of the medulla, pons, and midbrain
Broad spectrum (BRAWD SPEK-trum)
An antibiotic that is effective against a wide variety of bacteria
Bronchial tree (BRONG-kee-uhl TREE)
The entire system of air passageways formed by the branching of the bronchial tubes within the lungs; the smallest bronchioles terminate in clusters of alveoli
Bronchiectasis is usually established clinically on the basis of chronic daily cough with viscid sputum production, and radiographically by the presence of bronchial wall thickening and luminal dilation on chest x-rays.
Bronchioles (BRONG-kee-ohls)
The smallest of the air passageways within the lungs
Brush border (BRUSH BORE-der)
The collective name for the microvilli of the absorptive cells of the mucosa of the small intestine
Bubonic plague
Bubonic Plague is the most common, caused by the bite of an infected flea. Y.pestis, enters at the bite and travels through the lymphatic system to the nearest lymph node, replicates itself and causes the lymph node to be inflamed, tense and painful, turning into open sores with pus.
Buffer system (BUFF-er SIS-tem)
A pair of chemicals that prevents significant changes in the pH of a body fluid
Bulbourethral glands (BUHL-boh-yoo-REE-thruhl)
The glands on either side of the prostate gland that open into the urethra; secrete an alkaline fluid that becomes part of semen (Syn.—Cowper’s glands)
Bundle of His (BUN-duhl of HISS)
The third part of the cardiac conduction pathway, located in the upper interventricular septum (Syn.—atrioventricular bundle)
Burn (BERN)
Damage caused by heat, flames, chemicals, or electricity, especially to the skin; classified as first degree (minor), second degree (blisters), or third degree (extensive damage)
Bursa (BURR-sah)
A sac of synovial fluid that decreases friction between a tendon and a bone
Bursitis (burr-SIGH-tiss)
Inflammation of a bursa
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