ANS Neurotransmitters and Receptors

Question 1

Cholinergic neurons…

Answer 1

release acetylcholine

Question 2

In the ANS, cholinergic neurons include:

Answer 2

1. all sympathetic and parasympathetic pre-ganglionic neurons
2. sympathetic post-ganglionic neurons that innervate most sweat glands
3. all parasympathetic post-ganglionic neurons

Question 3

Cholinergic receptors…

Answer 3

1. Nicotinic receptors

2. Muscarinic receptors

Question 4

Nicotinic receptors in:

Answer 4

1. plasma membrane of dendrites and cell bodies of sympathetic and parasympathetic post-ganglionic neurons
2. plasma membranes of chromaffin cells of the adrenal medullae
3. motor end plate at neuromuscular junction

Question 5

Muscarinic receptors in:

Answer 5

1. plasma membranes of all effectors (smooth muscle, cardiac muscle and glands) innervated by parasympathetic post-ganglionic axons
2. most sweat glands have muscarinic receptors but are innervated by cholinergic sympathetic post-ganglionic neurons

Question 6

Activation of nicotinic receptors by ACh causes

Answer 6

depolarisation = excitation of the postsynaptic cell

Question 7

Activation of muscarinic receptors by ACh causes

Answer 7

sometimes depolarisation (excitation), sometimes hyperpolarisation (inhibition) depending on cell bearing receptors.

Question 8

Adrenergic receptors release…

Answer 8

norepinephrine (NE) AKA noradrenalin

Question 9

Most sympathetic post-ganglionic neurons are..

Answer 9

adrenergic

Question 10

Adrenergic receptors bind

Answer 10

both norepinephrine and epinephrine.

Question 11

Two main types of adrenergic receptors:

Answer 11

1. alpha receptors

2. beta receptors

Question 12

Adrenergic receptors found

Answer 12

on visceral effectors innervated by most sympathetic post-ganglionic axons.

Question 13

Norepinephrine stimulates alpha receptors..

Answer 13

more strongly than beta receptors

Question 14

Epinephrine potent stimulator of

Answer 14

both alpha and beta receptors.

Question 15

Compared to ACh, norepinephrine…

Answer 15

lingers in the synaptic cleft for a longer time = longer lasting effects.

Question 16

Which ANS neurons are adrenergic?

Answer 16

Most sympathetic post-ganglionic neurons.

Question 17

What types of effector tissues contain muscarinic receptors?

Answer 17

All effectors innervated by parasympathetic post-ganglionic axons and most sweat glands have muscarinic receptors even though they’re innervated by cholinergic sympathetic post-ganglionic neurons.