The squirrel gets energy from eating its diet. When the hawk eats it, that energy is transferred from the squirrel into the hawk. Nutrients the hawk needs gets absorbed into the bloodstream through arteries and veins in the stomach to the brain, and these nutrients can be turned into amino acids, with help grow necessary things on your body, such as hair, nails, or, in this case, feathers and claws. Any unneeded matter is flushed out of the body in the form of waste.
Involuntary functions of the body system; processes taking place in the body that is done without conscious efforts such as digestion, bloodflow, the heartbeat are controlled by the autonomic nervous system which is a part of the peripheral nervous system.
