E-rosette is a technique used to identify cell surface receptors. Signal cells, carrying a receptor-binding substance on its surface, are mixed with receptor-bearing cells. When the receptor-bearing cells bind to the signal cells, they form "rosettes."
Eccentric refers to a muscle movement causing a lengthening of the muscle; movement of a muscle away from the body.
Electrocardiogram (ECG or EKG) is the graphic record of the heart's electrical currents obtained with the electrocardiograph, an instrument designed for recording the electrical currents that traverse the heart and initiate its contraction.
An echinocyte is a red blood cell that has changed from the normal, biconcave disc shape to a sphere with short, sharply pointed projections. Aging of blood in circulation, in a tube or on a slide is the most common cause of the discocyte to echinocyte transformation.
An echocardiogram is an instrument that uses ultrasound (sound waves at extremely high frequencies) to produce images of the heart and major blood vessels non-invasively (without breaking the skin).
Echocardiographic refers to the echocardiograph, an instrument that uses ultrasound to produce images of the heart and major blood vessels.
The term ecological relates to the total complex of interrelationships among living organisms, encompassing the relations of organisms to each other, to the environment, and to the entire energy balance within a given ecosystem.
Ecology is the branch of biology concerned with studying the interrelationships of living organisms, specifically their relationships to each other and to the environment.
Ectopic means "out of place" and is said of an organ which is not in its proper position, or of a pregnancy occurring elsewhere than in the cavity of the uterus. In cardiography, it denotes a heart beat that has its origin in some abnormal focus other than the sinoatrial node (the area of the heart where heart beats normally originate).
An edema (or dropsy) is an excessive accumulation of fluid in the body tissues. The resultant swelling may be local, associated with an injury or inflammation, or general, as occurs in heart or kidney failure.
Effective renal plasma flow (ERPF)
Effective renal plasma flow (ERPF) is often also referred to as plasma clearance, and refers to the ability of the kidneys to clean or clear the plasma of unwanted substances. It is a rate, usually expressed in milliliters of cleared substances per minute (ml/min).
An effector is a cell or organ that produces a physiological response when stimulated by a nerve impulse. Examples of effectors include muscles and glands.
Efferent means conducting (fluid or a nerve impulse) outward from a given organ or part thereof, e.g. the efferent connections of a group of nerve cells, efferent blood vessels, or the excretory duct of an organ.
Efficacy is the power or capacity to produce a desired effect; effectiveness.
Effluent refers to something that flows out or forth.
Egocentric means to place extreme concentration or attention on one's self. Egocentric motor strategies are those in which the subject concentrates on a body frame of reference rather than on the external world.
Ejection time is the period during which, in the heart, ventricular pressures push the heart valves open and the blood in the ventricles is forced into the aorta, the main artery leading from the heart.
The elbow extensor is the muscle (called the triceps brachii) that extends the elbow joint.
The elbow flexor is the muscle (called the biceps brachii) which acts to flex the elbow.
An electro-oculograph is an instrument which records eye movements by measuring small electrical charges with tiny electrodes attached to the skin at the inner and outer corners of the eye.
Electro-oculography (EOG) is the method of placing electrodes on the skin around the eye to record eye movements. The electrodes measure the small changes in the electrical potentials in the skin as the eyeball moves.
Electro-osmosis is the diffusion of a substance through a membrane in an electrical field.
Electrocardiogram (ECG or EKG)
An electrocardiogram (ECG or EKG) is the graphic record of the heart's electrical currents obtained with the electrocardiograph, an instrument designed for recording the electrical currents that traverse the heart and initiate its contraction.
An electrocardiograph is an instrument used to record the potential of electrical currents that traverse the heart and initiate its contraction.
Electrocardiographic refers to an electrocardiogram (ECG or EKG). An ECG is the graphic record of the heart's electrical currents obtained with the electrocardiograph, an instrument designed for recording the electrical currents that traverse the heart and initiate its contraction.
An electrode is a small device (a solid electric conductor) that is attached to the body and through which the microscopic electric current generated by the human body enters and can be recorded or measured.
An electroencephalogram is a device which records the electrical activity from different parts of the brain and converts it into a tracing called an electroencephalogram or EEG. The machine that records this activity is known as an encephalograph. The pattern of the EEG reflects the state of the patient's brain and the level of consciousness in a characteristic manner. A recording of the electrical impulses of the brain can be used to diagnose certain diseases (such as epilepsy), furnish information regarding sleep and wakefulness, and confirm brain death.
Electrofusion is the process of fusing two separate cells by applying an electric current. For example, plant cell protoplasts of two different species of sunflowers were fused during the D-2 Space Shuttle mission by the application of electric pulses of short duration and high intensity. As the cells came in contact with each other, their walls combined. They formed one larger cell, a hybrid, with new characteristics distinct from the two original parent cells.
Electrogenesis refers to the creation of electrical energy.
Electrolysis is the decomposition of a salt or other chemical compound by means of an electric current.
An electrolyte is an element or compound that, when dissolved or melted in water or other solvent, dissociates into ions and is able to conduct electric current. Electrolytes differ in their concentrations in blood plasma, interstitial fluid, and cell fluid and affect the movement of substances between those compartments. Proper quantities of principal electrolytes and balance among them are critical to normal metabolism and function.
An electromyogram (EMG) is an instrument that records electrical currents generated in an active muscle.
Electromyographic refers to an electromyogram (EMG), which is an instrument that records electrical currents generated in an active muscle.
Electromyography is the recording of electrical currents generated in an active muscle using an instrument called an electromyogram (EMG). EMG recordings can be used to ascertain causes of muscular weakness, paralysis, involuntary twitching, and abnormal levels of muscle enzymes; EMGs can also be used as part of biofeedback studies.
Electron microscopy is inspection with an electron microscope. An electron microscope utilizes streams of electrons deflected from their course by an electrostatic or electromagnetic field for magnification of objects. The final image is viewed on a fluorescent screen or recorded on a photographic plate. Because of greater resolving power, images may be magnified up to 40,000 diameters, more than any other type of microscope.
An electronystagmograph is an electronic device used to collect data on the nystagmic properties of eye movement by detecting and recording the nerve signals that cause such movements.
Electrophoresis is the technique of separating electrically charged particles, particularly proteins, in a solution by passing an electric current through the solution. The rate of movement of the different components depends upon their charge, so that they gradually separate into bands. Electrophoresis is widely used in the analysis of body chemicals, such as the analysis of the different proteins in blood serum.
Elodea is any of a small American genus of submerged aquatic monocotyledonous herbs.
An embryo is an animal at the early stage of development, before birth.
An embryo sac is a large cell that develops in the ovule of flowering plants. It contains the egg cell which, when fertilized, becomes an embryo, and then, eventually, a seed.
Embryological refers to an embryo, an animal at the early stage of development before birth.
Embryonate means containing an embryo.
Embryonic refers to an embryo, an animal at the early stage of development before birth.
An electromyogram (EMG) is an instrument that records electrical currents generated in an active muscle.
Emphysema is a pulmonary disorder involving over-distention and destruction of the air spaces in the lungs.
End Diastolic Cardiac Volume
End diastolic cardiac volume is the volume measured in each ventricle during diastole (period of the heart's relaxation) which normally increases to about 130 ml.
End Systolic Cardiac Volume
End systolic cardiac volume is the volume measured in the ventricles during systole (period of the heart's contraction) which normally decreases to about 60 ml.
End tidal carbon dioxide
End tidal carbon dioxide is the concentration of carbon dioxide in exhaled breath at the end of each expiration.
Endemic, in relation to a microorganism or disease, means indigenous to a geographical area or population.
Endocrine pertains to a gland that secretes hormones directly into the blood stream.
The endocrine glands manufacture one or more hormones and secrete them directly into the bloodstream. Endocrine glands include the pituitary, thyroid, parathyroid, adrenal, ovary, testis, placenta and part of the pancreas.
The endocrine secretions are hormones secreted directly into the bloodstream and not through a duct to the exterior.
The endocrine system refers to all of the body's hormone-secreting glands. This system works in conjunction with the nervous system to control the production of hormones and their release into the circulatory system.
Endocrinology is the study of the structure and functions of the endocrine glands and the diagnosis and treatment of disorders of the endocrine system.
The endosteal surface is the inside surface of bones which border the bone marrow cavity.
Enema is the injection of a liquid into the rectum through the anus for cleansing, as a laxative, or for other therapeutic purposes.
Energy metabolism refers to the transformation of chemical energy from food to mechanical energy or heat.
Engorgement means distention or vascular congestion of body tissues.
Enteric means relating to the intestine.
Enteric cytopathogenic human orphan (ECHO) virus
The enteric cytopathogenic human orphan (ECHO) virus is an enterovirus isolated from man that belongs to the family Picornaviridae. While there are several inapparent infections, certain of the several serotypes are associated with fever and aseptic meningitis, and some appear to cause mild respiratory disease.
Enteritis is the inflammation of the intestine, especially of the small intestine.
Enterococcus faecalis is a species of non-motile bacteria having gram-positive spherical cells, occurring in chain-like groups. They are commonly found in the intestinal tract of humans.
Environmental monitoring is the quantification and tracking of physical, chemical, biological and radiological factors in a defined environment, such as the interior of a spacecraft.
An enzyme is usually a protein that, in small amounts, speeds up the rate of a biological reaction without itself being used up in the reaction (i.e., it acts as a catalyst). For example, enzymes present in the digestive juices of the stomach break down food into simpler compounds to be absorbed into the body.
Enzyme histochemistry is the study of the chemistry of enzymes.
Enzyme Linked Immunosorbent Assay
Enzyme Linked Immunosorbent Assay (ELISA) is used for diagnosis of specific infectious diseases. An enzyme is used as the indicator system; when the enzyme and the antigen-antibody complex bind, a color indicator or other easily recognizable sign occurs.
EOG, or Electro-oculography, is a test in which electrodes placed on the skin adjacent to the outside corner of the eyes measure electrical changes between the front and back of the eyeball as the eyes move.
An eosinophil is a variety of white blood cell distinguished by the presence in its cytoplasm of a multi-lobed nucleus and acid vacuoles. Its function is poorly understood, but it is known to be capable of ingesting foreign particles, is present in large numbers in lining or covering surfaces of the body, and is involved in allergic responses. Eosinophils can also help in the destruction of parasitic worms.
Ephemeral is anything that lasts for a brief time; transitory.
Ephyrae are free-swimming larvae of a jellyfish that result from the strobilation (division into segments) of a larval polyp (juvenile form of a jellyfish).
Epidemiological refers to epidemiology, the study of disease, with a view to finding means of control and future prevention. This not only applies to the study of such classic epidemics as plague and cholera, but also includes all forms of disease that relate to the environment and ways of life. It thus includes the study of the links between smoking and cancer, and diet and coronary disease, as well as communicable diseases.
Epinephrine (also called adrenaline) is a hormone secreted by the adrenal medulla section of the adrenal gland and released primarily in response to hypoglycemia; it is also produced as a synthetic drug. A powerful vasopressor substance, epinephrine acts to increase blood pressure and stimulate the heart muscle, accelerating the heart rate and increasing cardiac output.
An epithelial tissue is a tissue that covers the external surface of the body and lines hollow structures inside the body.
Equilibrium is a state of balance, a condition in which the contending forces are equal.
An ergometer is a rotary pedal device (i.e., static exercise bicycle) that provides a calibrated, or specific, resistance. The force required to overcome the resistance is measured as work.
An erythrocyte is more commonly known as a red blood cell, which is the most numerous type of blood cell. Erythrocytes contain the red pigment hemoglobin and are responsible for oxygen transport. In humans, the number of erythrocytes in the blood varies between 4.5 and 5.5 million per cubic millimeter. They survive for about four months and are then destroyed in the spleen and liver.
Erythrokinetics is a quantitative, dynamic study of in vivo (occurring within the body) production and destruction of erythrocytes (red blood cells).
Erythron is an element of the blood-forming system of the body that is involved in the production of red blood cells; it is not a single organ but is dispersed throughout the blood-forming tissue of the bone marrow.
Erythropoiesis is the process of red blood cell production, which normally occurs in the blood-forming tissue of the bone marrow.
Erythropoietin is a hormone secreted by certain cells in the kidney in response to a reduction in the amount of oxygen reaching the tissues; it stimulates red blood cell production.
Ethylenediaminetetraacetic acid (EDTA)
In biochemical research, ethylenediaminetetraacetic acid (EDTA) is used to remove Mg2+, Fe2+, etc. from reactions affected by such ions. A a sodium salt, it is used as a water softener, to stabilize drugs rapidly decomposed in the presence of traces of metal ions, and as an anticoagulant. EDTA is also used to treat lead poisoning.
Etiocholanolone is a metabolite of adrenocortical and testicular hormones and is an important 17-ketosteroid. It produces fever when given to humans.
Etiology refers to the study of all factors that may be involved in the development of a disease, including susceptibility of the patient, the nature of the disease agent, and the way in which the patient's body is invaded by the agent.
European Space Agency (ESA)
The European Space Agency (ESA) sponsors space research and technology among 13 member states (Austria, Belgium, Denmark, France, Germany, Ireland, Italy, The Netherlands, Norway, Spain, Sweden, Switzerland, and the United Kingdom), one associate member (Finland), and one country under cooperative agreement (Canada). The agency is headquartered in Paris, France.
The eustachian tube is a tube, lined with mucous membrane, that joins the nasopharynx and the middle ear, allowing equalization of the air pressure in the middle ear with atmospheric pressure.
Evacuate means to empty or remove the contents.
In neurophysiology, excitability refers to the triggering of a conducted impulse in the membrane of a muscle cell or nerve fiber. During excitation, a polarized membrane becomes momentarily depolarized and an action potential is set up.
Excreta is waste matter eliminated or separated from an organism.
Excretion is the transport and expulsion of waste products such as urine or carbon dioxide. It also refers to the release of hormones or protein products from cells or tissues.
Exercise capacity is the maximum ability of the body to take up and use oxygen to do work. This is often reported as the maximum number of liters of oxygen that the body can use in a minute.
Exocrine glands discharge secretions by means of a duct, which opens onto an epithelial surface (a tissue that covers the external surface of the body and lines hollow structures inside the body).
Extended Duration Orbiter Medical Project (EDOMP)
The Extended Duration Orbiter Medical Project (EDOMP) was conducted from 1989 to 1996 to address concerns about the physiologic condition of Shuttle astronauts on missions up to 16 days in duration. Before this project began, the Shuttle had not flown longer than 10 days. Space travelers may faint when they stand up (orthostatic intolerance) after all but the shortest flights, and their muscle strength may be reduced. The program focused on ensuring that the crew could land the Orbiter and exit from it without help after a 16-day flight. Astronauts on 40 Shuttle flights (STS-32 through STS-72) participated in 36 EDOMP investigations. The results of these investigations were used to make rules and recommendations for 16-day flights. Several types of exercise devices (i.e. a treadmill, a cycle ergometer, and a rower) were among the devices and procedures developed to prevent the deconditioning of the body that occurs during space flight. The crew transport vehicles, in which astronauts are now transported after landing, were built to enhance medical capabilities at the landing site as well as crew comfort and safety. A database, 125 formal publications, and 299 abstracts, technical papers, and presentations have also resulted from the EDOMP.
An extensor is a type of muscle which works to straighten a limb, the antagonist of a flexor.
Extensor Digitorum Longus
The extensor digitorum longus is a superficial muscle of the lower leg which allows one to extend the foot.
Extracellular fluid is the fluid which is inside the body, but outside the cells that are within the body.
Extracellular fluid volume
Extracellular fluid volume is the volume of the fluid external to the body's cells.
Extravehicular Activity (EVA)
An Extravehicular Activity, or EVA, is any activity that occurs external to the space vehicle requiring a crew member to wear a life support suit and exit the vehicle.
Exudative refers to a substance that may ooze or pass gradually out of a body structure or tissue. Specifically, this refers to a fluid or semisolid which may become encrusted or infected because of injury or inflammation.
The eye grounds is the fundus of the eye, the fundus being the base or the deepest part of an organ or the portion farthest from the mouth of an organ.