Sympathetic system

The 'fight or flight' system that turns on in emergencies

Parasympathetic system

The 'rest and digest' system that turns on when you eat or relax

Adrenalin (epinephrine)

The hormone released from your adrenal medulla when you are under stress

Noradrenaline (norepinephrine)

A compound related to adrenalin, with the same effects, but it is released from nerves of the sympathetic system

Catecholamines

A name for all the neurotransmitters which are similar in structure to adrenalin and noradrenalin.

Adrenergic receptors

Receptors that can accept adrenalin or noradrenalin

 Vagus nerve

 The parasympathetic nerve to the visceral organs and heart

 Sympathetic chain ganglia

 A chain of ganglia on each side of the spinal cord. These carry sympathetic nerve impulses and connect with one another to cause whole-body sympathetic responses

 Nicotinic receptors

 Ach receptors that will also bind to nicotine. Responsible for (among other things) skeletal muscle contraction

 Muscarinic receptors

 Ach receptors that will also bind to muscarine. Responsible for (among other things) vasodilation and secretion of digestive enzymes

 Alpha-1 receptors

 Adrenergic receptors responsible for (among other things) constricting blood vessels in the skin guts, and kidneys

 Alpha-2 receptors

 Adrenergic receptors responsible for stopping the sympathetic system when enough catecholamines have been released

 Beta-1 receptors

 Adrenergic receptors responsible for (among other things) increasing heart rate and strength

 Beta-2 receptors

 Adrenergic receptors responsible for (among other things) dilating the bronchioles to make breathing easier

 monoamine oxidase (MAO)

 enzyme that breaks down norepinephrine and epinephrine, removing them from the receptors