Afterbirth: The placenta and fetal membranes that are expelled from the uterus following the baby’s birth. Hence, the “afterbirth.” The placenta is what joins the mother and fetus. It also permits the flow of oxygen and nutrients to the fetus besides the release of carbon dioxide and waste products from the fetus to the mother. As a uniquely disposable organ, the placenta is disk-shaped and at full term, measures about 7 inches (18 cm) in diameter and little under less than 2 inches (4 cm) thick. The fetal membranes – the chorion is the outer one and the amnion is the inner one – envelop the embryo and contain the amniotic fluid. The word “afterbirth” entered the English language in the 16th century. The term has also been applied to a child born after the father’s death or last testament.
Agammaglobulinemia: Total or near-total absence of infection-fighting antibodies belonging to the class called gamma globulins. Agammaglobulinemia can be due to certain genetic diseases or caused by acquired diseases, including AIDS.
- Age by decade
Age by decade: A term designating someone’s age by decade. For example, a septuagenarian refers to someone in his or her seventies (age 70 to 79). The prefix in such terms is always from the Latin. For example, the Latin septuageni = seventy. Denarian: Someone age 10 to 19. Vicenarian: Someone in his or her […]
- Age-related macular degeneration
Age-related macular degeneration: An eye disease with its onset usually after age 60 that can progressively destroy the macula, the central portion of the retina, impairing central vision. Age-related macular degeneration (AMD or ARMD) rarely causes blindness because only the center of vision is affected. However, injury to the macula in the center of the […]
Agenesis: Lack of development. For example, agenesis of a toe means the toe failed to form.
- Agency for Toxic Substances and Disease Registry
Agency for Toxic Substances and Disease Registry: An agency of the U.S. Department of Health and Human Services under the Public Health Service that works with states and other federal agencies to prevent exposure to hazardous substances from waste sites. The agency conducts public health assessments, health studies, surveillance activities, and health education training in […]