Autonomics

Question 1

What neurotransmitter and Receptor is used at the ganglion in both sympathetic and parasympathetic signaling?

Answer 1

Acetylcholine is released from pre-synaptic nerves

Acetylcholine binds to nicotinic cholinergic receptors (nAchR) on the poet-synaptic nerve dendrites

Once the Receptor-transmitter are bound, Na+ channels open causing depolarization

Question 2

What are varicosities?

Answer 2

Swellings along post-ganglionic axons that act as synapses and readily secrete neurotransmitters on target tissue.

Found in both sympathetic and parasympathetic post-ganglionic neurons

Question 3

What neurotransmitters and receptors are used in post-ganglionic parasympathetic neurons?

Answer 3

Acetylcholine

It binds to Muscarinic cholinergic receptors

M1 - Gq
M2-Gi
M3-Gq

Gq: IP3 + DAG cause release of intracellular calcium stores
Gi: inhibits adenylyl cyclase

Question 4

What neurotransmitters and receptors are used by post-ganglionic sympathetic neurons?

Answer 4

Norepinephrine

It binds to Adrenergic Receptors

Alpha-1: Gq
Alpha-2:Gi
Beta-1:Gs
Beta-2:Gs

Question 5

What’s different about the sympathetic signaling at the adrenal gland?

Answer 5

Pre-ganglionic Sympathetic nerve leaves the spinal and cord, travels through the sympathetic trunk, and synapses onto Chromaffin cells in the adrenal medulla.

Pre-ganglionic nerves release acetylcholine which activated the chromaffin cells, causing the release of epinephrine (and some norepinephrine) into the blood stream.