Definitions and descriptions

Definitions and descriptions

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There are currently 89 terms in this directory beginning with the letter E.
Ear (EER)
The organ that contains the sensory receptors for hearing and equilibrium; consists of the outer ear, middle ear, and inner ear.
Eccrine gland (EK-rin)
The type of sweat gland (exocrine) that produces watery sweat; important in maintenance of normal body temperature.
Echinococcosis
It is a canine tape worm Echinococcus granulosus which is transmitted by dogs, sheeps and horses. Human infestation is through contamination of food or water causing visceral cysts (Hydatid Cyst Disease) particularly in the liver and lungs and is usually asymptomatic in susceptible host.
Eclampsia
Eclampsia is a condition peculiar to pregnancy and post-partum periods, characterized by elevated BP and tonic-clonic convulsions which are not caused by epilepsy, severe malaria, meningitis, hypoglycemia or other causes of convulsions. It is common in preterm. Eclampsia may occur without prior elevation of BP.
Ectoderm (EK-toh-derm)
The outer primary germ layer of cells of an embryo; gives rise to the epidermis and nervous system.
Ectoparasite (EK-toh-PAR-uh-sight)
A parasite that lives on the surface of the body.
Ectopic focus (ek-TOP-ik FOH-kus)
The initiation of a heartbeat by part of the myocardium other than the sinoatrial node.
Ectopic pregnancy
Ectopic pregnancy (EP) is defined as a pregnancy in which the implantation of the embryo occurs outside the uterine cavity, most frequently in one of the two Fallopian tubes or, more rarely, in the abdominal cavity.
Ectopic pregnancy (ek-TOP-ik PREG-nun-see)
Implantation of a fertilized ovum outside the uterus; usually occurs in the fallopian tube but may be in the ovary or abdominal cavity; often results in death of the embryo because a functional placenta cannot be formed in these abnormal sites.
Eczema (EK-zuh-mah)
An inflammatory condition of the skin that may include the formation of vesicles or pustules.
Edema (uh-DEE-muh)
An abnormal accumulation of tissue fluid; may be localized or systemic.
Edentulousness
It is the partial or full loss of natural teeth and subsequent resorption of the alveolar bone.
Effector (e-FEK-tur)
An organ such as a muscle or gland that produces a characteristic response after receiving a stimulus.
Efferent (EFF-er-rent)
To carry away from a center or main part.
Efferent arteriole (EFF-er-ent ar-TIR-ee-ohl)
The arteriole that takes blood from a glomerulus to the peritubular capillaries that surround the renal tubule.
Ejaculation (ee-JAK-yoo-LAY-shun)
The ejection of semen from the male urethra.
Ejaculatory duct (ee-JAK-yoo-la-TOR-ee DUKT)
The duct formed by the union of the ductus deferens and the duct of the seminal vesicle; carries sperm to the urethra.
Ejection fraction (ee-JEK-shun FRAK-shun)
The percent of blood in a ventricle that is pumped during systole; a measure of the strength of the heart.
Elastin (eh-LAS-tin)
A protein that is found in the form of elastic fibers in several types of connective tissue
Electrocardiogram (ECG or EKG) (ee-LEK-troh-KARdee-oh-GRAM)
A recording of the electrical changes that accompany the cardiac cycle.
Electrolytes (ee-LEK-troh-lites)
Substances that, in solution, dissociate into their component ions; include acids, bases, and salts.
Electron (e-LEK-trahn)
A subatomic particle that has a negative electrical charge; found orbiting the nucleus of an atom.
Element (EL-uh-ment)
A substance that consists of only one type of atom; 92 elements occur in nature.
Embolism (EM-boh-lizm)
Obstruction of a blood vessel by a blood clot or foreign substance that has traveled to and lodged in that vessel.
Embryo (EM-bree-oh)
The developing human individual from the time of implantation until the eighth week of gestation.
Emphysema (EM-fi-SEE-mah)
The deterioration of alveoli and loss of elasticity of the lungs; normal exhalation and gas exchange are impaired.
Emulsify (e-MULL-si-fye)
To physically break up fats into smaller fat globules; the function of bile salts in bile
Enamel (en-AM-uhl)
The hard substance that covers the crowns of teeth and forms the chewing surface.
Encapsulated nerve ending (en-KAP-sul-LAY-ted NERV END-ing)
A sensory nerve ending enclosed in a specialized cellular structure; the cutaneous receptors for touch and pressure.
Endemic (en-DEM-ik)
A disease that occurs continuously or expectedly in a given population.
Endemic occurrence
Regular and continuing occurrence of infectious diseases in populations with no time limit
Endocardium (EN-doh-KAR-dee-um)
The simple squamous epithelial tissue that lines the chambers of the heart and covers the valves.
Endocrine gland (EN-doh-krin)
A ductless gland that secretes its product (hormone) directly into the blood.
Endocrine system (EN-doh-krin SIS-tem)
The organ system that consists of the endocrine glands that secrete hormones into the blood.
Endocytosis (EN-doh-sigh-TOH-sis)
The process by which a cell takes in particulate matter or a fluid, such as phagocytosis of bacteria by WBCs; the cell membrane conforms to the material taken in and forms an intracellular vesicle or vacuole.
Endoderm (EN-doh-derm)
The inner primary germ layer of cells of an embryo; gives rise to respiratory organs and the lining of the digestive tract
Endogenous (en-DOJ-en-us)
Coming from or produced within the body.
Endogenous infection
Infection arising from the colonizing flora
Endogenous infection (en-DOJ-en-us)
An infection caused by a person’s own normal flora that have been introduced into an abnormal body site.
Endolymph (EN-doh-limf)
The fluid in the membranous labyrinth of the inner ear.
Endometrium (EN-doh-MEE-tree-um)
The vascular lining of the uterus that forms the maternal portion of the placenta.
Endophthalmitis
It is an infection of the ocular cavity. It is an ophthalmic emergency that can cause blindness that may occur secondary to bacteraemia (endogenous infection) or following penetrating eye injury of surgery.
Endoplasmic reticulum (ER) (EN-doh-PLAZ-mik re-TIK-yoo-lum)
A cell organelle found in the cytoplasm; a network of membranous channels that transport materials within the cell and synthesize lipids.
Endothelium (EN-doh-THEE-lee-um)
The simple squamous epithelial lining of arteries and veins, continuing as the walls of capillaries.
Endotoxin (EN-doh-TAHK-sin)
The toxic portion of the cell walls of gram-negative bacteria; causes fever and shock.
Endotoxin shock (EN-doh-TAHK-sin SHAHK)
A state of circulatory shock caused by infection with gram-negative bacteria.
Energy levels (EN-er-jee LEV-els)
The position of electrons within an atom (Syn.—orbitals or shells).
Enteric nervous system (en-TER-ik)
The nerve fibers and plexuses of the alimentary tube; regulate secretions and contractions, able to function independently of the CNS
Enteroendocrine cell (EN-ter-oh-EN-doh-krin SELL)
A cell of the alimentary tube that secretes hormones
Enzyme (EN-zime)
A protein that affects the speed of a chemical reaction. Also called an organic catalyst
Eosinophil (EE-oh-SIN-oh-fill)
A type of white blood cell (granular); active in allergic reactions and parasitic infections
Epicardium (EP-ee-KAR-dee-um)
The serous membrane on the surface of the myocardium (Syn.—visceral pericardium)
Epidemic (EP-i-DEM-ik)
A disease that affects many people in a given population in a given time with more than the usual or expected number of cases.
Epidemic occurrence
Significantly increased occurrence of an infectious disease within given localities and time periods
Epidemiology (EP-i-DEE-mee-AH-luh-jee)
The study of the spread of disease and the factors that determine disease frequency and distribution
Epidermis (EP-i-DER-miss)
The outer layer of the skin, made of stratified squamous epithelium
Epididymis (EP-i-DID-i-mis) (Pl.—epididymides)
The tubular organ coiled on the posterior side of a testis; sperm mature here and are carried to the ductus deferens
Epiglottis (EP-i-GLAH-tis)
The uppermost cartilage of the larynx; covers the larynx during swallowing
Epinephrine (EP-i-NEFF-rin)
A hormone secreted by the adrenal medulla that stimulates many responses to enable the body to react to a stressful situation (Syn.—adrenaline)
Epiphyseal disc (e-PIFF-i-se-al DISK)
A plate of cartilage at the junction of an epiphysis with the diaphysis of a long bone; the site of growth of a long bone.
Epiphysis (e-PIFF-i-sis)
The end of a long bone.
Epithelial tissue (EP-i-THEE-lee-uhl TISH-yoo)
The tissue found on external and internal body surfaces and that forms glands.
Equilibrium (E-kwe-LIB-ree-um)
1. A state of balance.

2. The ability to remain upright and be aware of the position of the body.
Eruption of teeth
Eruption of deciduous/primary teeth usually starts at five months of age. Symptoms associated with it like fever and diarrhea are normal and self limiting unless any other causes can be established.

"Nylon teeth" is a myth/belief existing in some traditions. These are conditions associated with the eruption of deciduous/primary teeth.
Erysipelas
Erysipelas is an acute superficial dermal infection commonly caused by Streptococci
Erythema (ER-i-THEE-mah)
Redness of the skin
Erythroblastosis fetalis (e-RITH-roh-blass-TOH-sis fee-TAL-is)
Hemolytic anemia of the newborn, characterized by anemia and jaundice; the result of an Rh incompatibility of fetal blood and maternal blood; also called Rh disease of the newborn.
Erythrocyte (e-RITH-roh-sight)
Red blood cell
Erythropoietin (e-RITH-roh-POY-e-tin)
A hormone secreted by the kidneys in a state of hypoxia; stimulates the red bone marrow to increase the rate of red blood cell production
Esophagus (e-SOF-uh-guss)
The organ of the alimentary tube that is a passageway for food from the pharynx to the stomach.
Essential amino acids (e-SEN-shul ah-MEE-noh ASSids)
The amino acids that cannot be synthesized by the liver and must be obtained from proteins in the diet.
Essential fatty acids (e-SEN-shul FA-tee ASS-ids)
The fatty acids that cannot be synthesized by the body and must be obtained from fats in the diet.
Estrogen (ES-troh-jen)
The sex hormone secreted by a developing ovarian follicle; contributes to the growth of the female reproductive organs and the secondary sex characteristics.
Ethmoid bone (ETH-moyd)
An irregular cranial bone that forms the upper part of the nasal cavities and a small part of the lower anterior braincase.
Exocrine gland (EK-so-krin)
A gland that secretes its product into a duct to be taken to a cavity or surface.
Exocytosis (EKS-oh-sigh-TOH-sis)
The process by which material is ejected or secreted from a cell; characteristic of the Golgi apparatus, in which membrane-bound vesicles fuse with the cell membrane and release their contents.
Exogenous infection
Infection arising from invasion of host by microorganisms from sources external to it
Exotoxins.
Pathogenic bacteria can produce a variety of toxins that are either the only pathogenic factor (e.g., in diphtheria, cholera, and tetanus) or at least a major factor in the unfolding of the disease. One aspect the classification and nomenclature of these toxins must reflect is the type of cell affected: cytotoxins produce toxic effects in many different host cells; neurotoxins affect the neurons; enterotoxins affect enterocytes.
Expiration (EK-spi-RAY-shun)
Exhalation; the output of air from the lungs.
Expiratory reserve (ek-SPYR-ah-tor-ee ree-ZERV)
The volume of air beyond tidal volume that can be exhaled with the most forceful exhalation; average: 1000–1500 mL.
Extension (eks-TEN-shun)
To increase the angle of a joint.
External (eks-TER-nuhl)
On the outside; toward the surface
External anal sphincter (eks-TER-nuhl AY-nuhl SFINKter)
The circular skeletal muscle that surrounds the internal anal sphincter and provides voluntary control of defecation.
External auditory meatus (eks-TER-nuhl AW-di-TORee me-AY-tuss)
The ear canal; the portion of the outer ear that is a tunnel in the temporal bone between the auricle and the eardrum.
External respiration (eks-TER-nuhl RES-pi-RAY-shun)
The exchange of gases between the air in the alveoli and the blood in the pulmonary capillaries.
External urethral sphincter (eks-TER-nuhl yoo-REEthruhl SFINK-ter)
The skeletal muscle of the pelvic floor encircling the urethra; provides voluntary control of urination.
Extracellular fluid (EKS-trah-SELL-yoo-ler FLOO-id)
The water found outside cells; includes plasma, tissue fluid, lymph, and other fluids.
Extrinsic factor (eks-TRIN-sik FAK-ter)
Vitamin B12, obtained from food and necessary for DNA synthesis, especially by stem cells in the red bone marrow.
Extrinsic muscles (eks-TRIN-sik)
The six muscles that move the eyeball.
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