What are the hormones secreted by the adrenal medulla? What are their respective functions?
The medullary portion of the adrenals secretes hormones of the catecholamine group: adrenaline (also known as epinephrine) and noradrenaline (also known as norepinephrine). Besides their hormonal function, adrenaline and noradrenaline act as neurotransmitters too. The neurons that use them as neurotransmitters are called adrenergic neurons. Adrenaline increases the glycogen breaking into glucose (glycogenolysis) thus increasing glycemia and the basal metabolic rate of the body. Adrenaline and noradrenaline are released during situations of danger (fightfight or flight response) and they intensify the strength and rate of the heartbeat and selectively modulate the blood irrigation in some tissues by selective vasodilation and selective vasoconstriction. By vasodilation they increase the blood supply to the brain, the muscles and the heart and by vasoconstriction they reduce the blood supply to the kidneys, the skin and the gastrointestinal tract. Substances like adrenaline and noradrenaline that promote vasodilation or vasoconstriction are called vasoactive substances.
