Delete Content. A plasma membrane is permeable to specific molecules that a cell needs. Transport proteins in the cell membrane allow for selective passage of specific molecules from the external environment. Each transport protein is specific to a certian molecule (indicated by matching colors).
The pancreas contains cells which release both insulin and glucagon. The endocrine system consists of a number of different glands which secrete hormones that dictate how cells and organs behave.
The secretion of ADH occurs in the pituitary gland, a gland at the base of the brain. Impaired vasopressin secretion results in diabetes insipidus. Blood pressure drops cause ADH release. ADH causes the kidneys to reabsorb water rather than excreting it as urine.