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 umbilical cord is the life-line that attaches the placenta to the fetus. The umbilical cord is made up of three blood vessels: two smaller arteries which carry blood to the placenta and a larger vein which returns blood to the fetus. It can grow to be 60 cm long, allowing the baby enough cord to safely move around without causing damage to the cord or the placenta.