sentences:  The hypothalamus responds to these motivations by regulating activity in the endocrine system to release hormones to alter the behaviour of the animal.These hormones include epinephrine (adrenalin) to increase blood flow and heart rate for a sufficient fight-or-flight response, and ghrelin, which is commonly described as “the hunger hormone”.Species from other phyla than vertebrates, such as arthropods and sponges, do not possess a hypothalamus.