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As the fetal hypothalamus matures, the activation of the hypothalamic–pituitary–adrenal (HPA) axis initiates labor through two hormonal mechanisms. The end pathway of both mechanisms lead to contractions in the myometrium, a mechanical cause of placental separation, which is due to the sheer force and contractile and involutive changes that occur within the uterus, distorting the placentome.
Once the fetus is sufficiently developed, chemical signals begin the process of birth, which begins with the fetus being pushed out of the birthing canal. The newborn, which is called an infant in humans, should typically begin respiration on its own shortly after birth. Not long after, the placenta eventually falls off on its own.
Mother with newborn baby. The postpartum (or postnatal) period begins after childbirth and is typically considered to last for six to eight weeks. [1] There are three distinct phases of the postnatal period; the acute phase, lasting for six to twelve hours after birth; the subacute phase, lasting six weeks; and the delayed phase, lasting up to six months.
In humans, the embryonic period ends nine weeks after conception, after which time the term fetus is used instead of embryo. In many other animals, embryogenesis is considered complete only after hatching or birth. embryology embryonate Containing a developing embryo; e.g. an embryonated hen's egg, as opposed to an unfertilized egg. [2] endoderm
This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms.It is intended as introductory material for novices; for more specific and technical definitions from sub-disciplines and related fields, see Glossary of cell biology, Glossary of genetics, Glossary of evolutionary biology, Glossary of ecology ...
Development before birth, or prenatal development (from Latin natalis ' relating to birth ') is the process in which a zygote, and later an embryo, and then a fetus develops during gestation. Prenatal development starts with fertilization and the formation of the zygote , the first stage in embryonic development which continues in fetal ...
After birth, the fundus contracts downward into the pelvis one centimeter each day. After two weeks the uterus will have contracted and return into the pelvis. [ 9 ] The sensation and strength of postpartum uterine contractions can be stronger in women who have previously delivered a child or children.
Also called functionalism. The Darwinian view that many or most physiological and behavioral traits of organisms are adaptations that have evolved for specific functions or for specific reasons (as opposed to being byproducts of the evolution of other traits, consequences of biological constraints, or the result of random variation). adaptive radiation The simultaneous or near-simultaneous ...