Epinephrine (also known as adrenaline) is a hormone and a neurotransmitter produced by the adrenal glands, it helps to regulate cellular energy metabolism and increases the heart rate.
Epinephrine adheres to certain receptors that are exposed on the surface of a large number of body cells. This receptor, called beta-adrenergic, is a receptor that is embedded in the plasma membranes of these cells. Adrenaline does not penetrate the cell, instead, joining for a short period of time to its receptor, induces it to release biochemical signals to the cytoplasm of cells. This steric change, affects the configuration of the cytoplasmic domain of the protein, this is the "link" of the receptor that protrudes in the cytoplasm.
the brain has to grow it happens because of the nervous system 1.The heart is Beating 2. It is kicking A baby is safe in the womb because it is well insulated and designed as the perfect baby carrier