One of the most remarkable examples of cell communication is the fight or flight response. body handle extraordinary situations. responses involved in the fight or flight response. place in the movie. 0:16 An environmental signal travels into the brain. a nerve impulse to the hypothalamus (not shown).
Umbilical cord. In placental mammals, the umbilical cord (also called the navel string, birth cord or funiculus umbilicalis) is a conduit between the developing embryo or fetus and the placenta.
the thin outer membrane that encloses the embryo. Placenta. a temporary organ that forms within the uterus to allow the exchange of nutrients, oxygen, and waste between the mother and the fetus without allowing maternal and fetal blood to mix. Afterbirth. the placenta that is expelled after delivery.