Introduction to the ANS

Question 1

What are the three branches to the CNS

Answer 1

ANS, somatic nervous system and neuroendocrine system

Question 2

What are the two basic responses of the ANS?

Answer 2

SNS - fight and flight

PNS - rest and digest

Question 3

Give some examples of targets of the ANS

Answer 3

Pupillary constriction - constriction mediated by PNS CN3
Cephallic and gastric phases of digestion - vagal nerve PNS mediation
Basal heart rate - PNS is dominant at rest (SNS dominant in increasing HR)

Question 4

Does the SNS or ANS innervate blood vessels

Answer 4

Only SNS

Question 5

What neurotransmitter do all pre-ganglionic fibres release, regardless of type?

Answer 5

ACh

Question 6

How long are the pre and post ganglionic fibres in the parasympathetic NS

Answer 6

Long pre-ganglionic

Short post-ganglionic

Question 7

How long are the pre and post ganglionic fibres in the sympathetic NS

Answer 7

Short pre-ganglionic

Long post-ganglionic

Question 8

What neurotransmitters are released in the parasympathetic nervous system?

Answer 8

All transmitters are ACh

Question 9

What neurotransmitters are released in the sympathetic nervous system?

Answer 9

Releases mainly Adrenaline and Noradrenaline

Question 10

How many pre-ganglionic fibres join to how many post-ganglionic fibres in parasympathetic nervous system?

Answer 10

1:1 pre vs post

Is discrete

Question 11

How many pre-ganglionic fibres join to how many post-ganglionic fibres in sympathetic nervous system?

Answer 11

1:20 pre vs post

Is divergent

Question 12

Where are the sensory receptors in the enteric nervous system found?

Answer 12

In the mucosal chemoreceptors and stretch receptors detect chemical substances in the gut lumen or tension in the gut wall caused by food

Question 13

How is sensory information relayed in the enteric nervous system? What plexus do they go into?

Answer 13

By interneurones to submucosal and myenteric plexus

Question 14

What neurotransmitter do motor neurones in the enteric nervous system release? What do these NTs do?

Answer 14

ACh or SubstanceP to contract SM

Vasoactive intestinal peptide or NO to relax smooth muscle

Question 15

What neurotransmitters do the somatic nervous system release?

Answer 15

ACh

Question 16

Where are nicotinic receptors found?

Answer 16

At all autonomic ganglia

Question 17

What neurotransmitters/chemicals stimulate nicotinic receptors?

Answer 17

Nicotine/ACh

Question 18

What type of protein receptor do nicotinic receptors have?

Answer 18

Type 1 - ionotropic ie ligand bind, gate opens

Question 19

Where are muscarinic receptors found?

Answer 19

At the effector organs innervated by PNS and rarely SNS post ganglionic fibres

Question 20

What neurotransmitters/chemicals stimulate muscarinic receptors?

Answer 20

Muscarine

ACh

Question 21

What type of protein receptor do muscarinic receptors have?

Answer 21

Type 2 - G protein coupled (SLOWER than type 1)

Question 22

Which of the following effects would be observed after blockade of nicotine ACh receptors in an individual at rest?

1. Bronchoconstriction
2. Increased sweat production
3. Constipation
4. Increased urinary freq.
5. Short sightedness

Answer 22

3. Constipation due to blockage of PNS - decreased gut motility

Question 23

What effect would a blockade of nicotinic acetylcholine receptors have on heart rate at rest?

Answer 23

PNS is normally dominant at rest so an increase in HR if PNS blocked

Question 24

What effect would a blockade of nicotinic acetylcholine receptors have on heart rate during exercise?

Answer 24

SNS is dominant so decrease in HR if SNS blocked

Question 25

What are the types of muscarinic receptors?

Answer 25

M1 – Neural – e.g. forebrain (learning and memory) M2 – Cardiac – e.g. inhibitory autoreceptors M3 – Exocrine & smooth muscles – e.g. hypothalamus M4 – Periphery – e.g. prejunctional nerve endings (inhibitory). M5 – Striatal dopamine release.

Question 26

What type of G protein coupled receptor do M1, M2 and M3 use?

Answer 26

M1 - Gq M2 - Gi M3 - Gq

Question 27

Where are adrenoceptors found?

Answer 27

At all effector organs innervated by post-ganglionic SNS glands (but not sweat glands)

Question 28

What type of protein receptor are G protein receptors

Answer 28

Type 2 G protein coupled

Question 29

What enzyme is involved in acetylcholine production?

Answer 29

Choline acetyl transferase

Question 30

What enzyme is involved in acetylcholine degradation?

Answer 30

Acetylcholinesterase

Question 31

What is the formula for acetylcholine production?

Answer 31

Acetyl CoA + Choline -> ACh + CoA

Question 32

How is Dopamine made?

Answer 32

Tyrosine -> DOPA with tyrosine hydroxylase | DOPA -> Dopamine with DOPA decarboxylase

Question 33

How is Noradrenaline made?

Answer 33

Make dopamine and then Dopamine -> NA with dopamine beta hydroxylase

Question 34

How is Adrenaline made

Answer 34

Dopamine -> NA -> A via PNMT

Question 35

What are the two uptake channels for adrenaline/noradrenaline?

Answer 35

Uptake 1. Monoamine oxidase A - MAO-A | Uptake 2. Cathecol-O-Methyl Transferase - COMT