Dictionary

efferent nerve A nerve that carries impulses away from the central nervous system.

efferent vessel A vessel that carries blood away from the heart. Hence, an efferent vessel is an artery or an arteriole (a little artery).

effusion Too much fluid, an outpouring of fluid. For example, a pleural effusion is an abnormal accumulation of fluid in the pleural space between the lungs and the chest wall, while a knee effusion is an abnormal amount of fluid in the knee joint. A hemorrhagic effusion contains blood in the fluid.

effusion, pericardial Too much fluid within the fibrous sac (pericardium) that surrounds the heart. The inner surface of the pericardium is lined by a layer of flat cells (mesothelial cells) that normally secrete a small amount of fluid, which acts as a lubricant to allow normal heart movement within the chest. A pericardial effusion involves…

effusion, pleural Excess fluid between the two membranes that cover the lungs (the visceral and parietal pleurae) separating the lungs from the chest wall. A small quantity of fluid is normally spread thinly over the visceral and parietal pleurae and acts as a lubricant between the two membranes. Any significant increase in the quantity of…

EGD Esophagogastroduodenoscopy. See endoscopy, upper.

EGG See electrogastrogram.

egg sac See ovary.

Ehlers-Danlos syndrome A heritable disorder of connective tissue that is characterized by easy bruising, joint hypermobility (loose joints), skin laxity, and weakness of tissues. Abbreviated EDS. There are a number of different types of EDS, each of which has these characteristic features. The variations of EDS are treated according to their particular manifestations. Skin protection…

ehrlichiosis An acute tick-borne disease first reported in humans in 1986. Erlichiosis is due to infection by the rickettsia microbe, Ehrlichia canis, which is usually carried by the brown dog tick. Erlichiosis is similar to Rocky Mountain spotted fever, characterized by high fever, headache, malaise, and muscle pain, but without the rash. See also rickettsial…

eight-day measles Rubeola (measles). See also measles.

ejaculation Ejection of sperm and seminal fluid during an orgasm in a male.