Neurotransmitters

what are the major neurotransmitters of ANS

acetylcholine (ACh) and norepinephrine (NE)

what is acetylcholine released by

cholinergic fibers

where is acetylcholine released by cholinergic fibers

at all ANS preganglionic axons

all parasympathetic postganglionic axons

what is norepinephrine (noradrenalin) released by

adrenergic fibers

where is norepinephrine released by adrenergic fibers

at almost all sympathetic postganglionic axons - except those at sweat glands and some blood vessels in skeletal muscles

what do the effects of neurotransmitters depend on

whether is binds to cholinergic receptor or adrenergic receptor

What are the two cholinergic receptors that bind ACh

Nicotinic receptors

Muscarinic receptors

Where are nicotinic receptors found

postganglionic neurons (sympathetic and parasympathetic)

hormone-producing cells of adrenal medulla

sarcolemma of skeletal muscle cells at neuromuscular junction

the effect of ACh at nicotinic receptors is always

stimulatory

where are muscarinic receptors found

found on all effector cells stimulated by postganglionic cholinergic fibers

what is the effect of ACh at muscarinic receptors

can be inhibitory or excitatory - depends on the receptor

What are the two major classes of adrenergic receptors that respond to NE or epinephrine

Alpha receptors: divided into subclasses a1, a2

Beta receptors: divided into subclasses B1, B2, B3

Effects of NE or epinephrine of adrenergic receptors depends on

which receptor subclass is on target organ