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.
By 5 weeks, the embryoâs heart is tubular in shape and begins to beat. The connections between the pregnant woman and the embryo are developing to form the placenta. The placenta will nourish the embryo, then the fetus, for the remainder of its stay in the uterus.