Humans feel hungry when their empty stomachs contract and when glucose levels in the blood drop. Both of these
situations stimulate neurons that send messages to the brain which are interpreted as hunger. What body systems are
involved in this process as described?
digestive, muscular, integumentary, and respiratory
digestive, excretory, integumentary, and respiratory
circulatory, excretory, nervous, and skeletal
circulatory, digestive, muscular, and nervous