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 embryo is surrounded by the thin membranes of the amniotic sac, the umbilical cord is seen in the center, attaching the embryo to the placenta. Cross section of umbilical cord. Top right and top left: umbilical artery, bottom: umbilical vein, middle: remnant of allantois.