L8- Cholinergic and adrenergic transmission and the ANS

Question 1

What does cholinerigc transmission involve?

Answer 1

Acetylcholine

Question 2

What is this?

CH3-CO-O-CH2-CH2-N+-3(CH3)

Answer 2

Acetylcholine

It has an ester linkage and a positive permanent charge

Question 3

What important feature of acetyl choline allows it to bind to its receptors?

Answer 3

Permanent positive charge.

Question 4

What does the positive charge of acetylcholine mean for it?

Answer 4

Can bind to receptors

Also wont dissolve in the membrane

Question 5

WHy is the ester linkage important in ACh?

Answer 5

The breakdown of ACh. It’s the point at which the molecule is cleaved to terminate its synaptic action

Question 6

Which enzyme breaks down acetylcholine?

Answer 6

Acetylcholinesterase

INto acetate and Choline by cleaving the ester bond

Question 7

What does Ca2+ do at the cholinergic synapse?

Answer 7

Ca2+ stimulates vesicle fusion with the presynaptic membrane. So ACh is exocytosed- out into synapse

Question 8

What happens to the choline from ACH?

Answer 8

It’s taken back into the nerve terminal via a carrier. Made back into ACh by the enzyme- choline acetyl transferase.

Question 9

What happens to the ACh when it’s remade?

Answer 9

The acetyl choline made is then transportd into vesicles and stored ready for release

Question 10

What are the 2 divisions of ACh receptors?

How fast are they?

Answer 10

Muscarinic= slow

Nictotinic=fast

Question 11

Where are muscarinic and nictontic receptors important?

Answer 11

muscarinic- to effector organis the in the Parasympathetic NS and some SNS.

nictotinic- skeletal neuromuscular junction and autonomic ganglia

Question 12

Whats the differenc ein structure between noradrenaline and adrenaline?

Answer 12

adrenaline has an extra methyl group on the end.

Question 13

What type of molecule are noradrenaline and adrenaline?

Answer 13

Catecholamine. They have an amine group and a catechol group

Question 14

What do sympathetic neurones release at synapses?

Answer 14

Noradrenaline

Question 15

What does the adrenal medulla sympathetic tissue release?

Answer 15

adrenaline and noradrenaline in a ratio of 4:1

Question 16

What happens to noradrenaline and adrenalline released from the adrenal medulla?

Answer 16

adrenaline- goes into blood stream, acts as a hormone.

It’s receptors are the same as noradrenaline which goes through the neurones

Question 17

What are the steps in adrenaline synthesis?

Answer 17

Tyrosine

DOPA

Dopaminne

Noradrenaline

Adrenaline

Question 18

How is noradrenaline terminated?

Answer 18

NA actions are terminated by uptake (rather than enzymatic cleavage like ACh)

Question 19

What are the receptors at the ganglion and at the target tissue in the sympathetic and parasympathetic neurones?

Answer 19

1. sympathetic- ganglion- nicotinic acetylcholine receptors
   target tissue- adrenergic receptors
2. para- nicotinic acetylcholine receptors
   target tissue- muscarinic acetylcholine receptors.

Question 20

Where is the first cell body and the ganglion between the neurones?

Answer 20

First cell body is in the CNS. The ganglion in sympathetic is by the spinal column, paras. closer tot he target tissue.

Question 21

Where are ths sympathetic ganglia mostly located?

Answer 21

Close to the spinal cord in a chain. paravertebral ganglia

Question 22

What’s the adrenal medulla derived from?

Answer 22

Neuronal tissue

Question 23

Whats the adrenal medullla? What are its cells like? What does it release?

Answer 23

Specialised part of the sympathetic nervous system. Its cells are essentially neurones that have no axons. They release A and NA into circulation where they act as hormones

Question 24

Where’s the output in parasympathetic nervous system?

Answer 24

The medullary and sacral regiions

Question 25

What does the vagus nerve do?

Answer 25

Releases acetylcholine to muscarinic receptors at the SAN. This slows heart rate

Question 26

What happens when atropine is added at the SAN?

Answer 26

Atropine blocks the ACh from the vagus nerve so the SAN fires at its natural rate. Much faster HR.