Which two substances function as agonists in the sympathetic nervous system?

Epinephrine and norepinephrine are key catecholamines in the sympathetic nervous system, acting as agonists. These two substances bind to adrenergic receptors, which are integral to the body's 'fight or flight' response.

Epinephrine, often referred to as adrenaline, is produced primarily by the adrenal medulla and causes widespread effects throughout the body, including increased heart rate, enhanced blood flow to muscles, and the release of glucose for energy. Norepinephrine, produced both in the adrenal medulla and by sympathetic nerve terminals, primarily influences blood vessel tone and constriction, increasing blood pressure and redirecting blood flow to critical organs during stress or emergency situations.

Together, they play a vital role in physiological responses that prepare the body to react to stress or danger. Their agonist action is characterized by their ability to activate adrenergic receptors, thereby producing a sympathetic response.

Acetylcholine serves a different role in the autonomic nervous system, primarily associated with the parasympathetic system and is not an agonist in the sympathetic context. Similarly, substances like levenordephrin, while they may have some sympathomimetic effects, are not as directly involved as epinephrine and norepinephrine in standard