ANS intro

Question 1

principal efferents from CNS?

What do they innervate?

Answer 1

ANS: exo glands, smooth muscle, cardiac muscle, metab., host defence

SNS: skeletal muscle, inc. diaphragm + resp muscle

Neuroendocrine system: growth, meab., reproduction, development, salt/water balance, host defence

Question 2

Divisions of ANS

Answer 2

Sympathetic: fight/flight

Parasympathetic: rest/digest

Question 3

Explain innervation of pupillary constriction/dilation

Answer 3

Occulomotor nerve (PNS) - constriction

Sympathetic nerve - dilation (via iris)

Question 4

Explain innervation of stomach when hungy.

Answer 4

Vagus nerve (PNS).

cephalic + gastric phases stimulated (secretion + motility)

Question 5

Explain basal control of heart rate with reference to PNS and SNS.

Answer 5

Intrinsic rate lowered by Vagus (PNS), raised by sympathetic.

Raised BP –> baroreceptor firing –> stimulate PNS, inhibit SNS.

Question 6

principal targets + functions of ANS diagram.

Answer 6

Question 7

Outline typical parasympathetic nerve: origin, length, neurotransmitter.

Answer 7

Cranial/sacral.

Long pre-ganglionic, short post-ganglionic.

ACh

Question 8

Oultine typical sympathetic nerve: neurotransmitters, origins, lengths, exceptions.

Answer 8

Thoracic/lumber origin.

Short pre-ganglionic, long post-ganglionic.\

Ach to ganglion, NA to effector.

Adrenal gland - releases Adrenaline (80%) and NA to bloodstream, ACh syimulates.

Sweat glands - ACh = post-ganglionci neurotransmitter.

Question 9

Differences in actions between SNS and PNS.

Answer 9

PNS = discrete, localised. little divergence.

SNS = coordinated (due to close alignment with stress response). Lots of divergence.

(most sympathetic ganglai in sympathetic trunk)

Question 10

Outline neuronal action in ENS.

Answer 10

sensory neurones - connected to stretch receptors/mucosal chenmical receptors. Detect stretch + substances. Info relayed to submucosal/myenteric plexus by interneurons.

Motor neurons - ACh release/substance P –> smooth muscle contraction. Vasoactive intestinal peptide/nitric oxide –> relax.

Question 11

explain how ACh works. Receptor types.

Answer 11

membrane bound receptors pre-ganglionic + pre effector organ.=

nicotinic + muscarinic.

Question 12

3 characteristics of niucotinic receptors.

Answer 12

at all autonomic ganglia

stimulated by nicotine/ACh

type 1 ionotropic

Question 13

3 characteristics of muscarinic receptors.

Answer 13

At all effector organs innervated by post-ganglionic PNS fibres.

Stimulated by ACh/muscarine

Type 2 - G protein coupled.

Question 14

What are 5 subtypes of muscarinic receptors?

Answer 14

M1 – Neural (Forebrain – learning & memory)

M2 – Cardiac (Brain – inhibitory autoreceptors)

M3 – Exocrine & smooth muscle (Hypothalamus – food intake)

M4 – Periphery: prejunctionalnerve endings (inhibitory)

M5 – Striatal dopamine release

Question 15

Where are adrenoreceptors?

What stimulates them?

Generic mechanism?

What types of adrenoreceptors are there?

Answer 15

At all effector organs innervated by post ganglionic sympathetic fibres

Stimulated by noradrenaline/adrenaline

Type 2 – G-protein coupled

a1, a2, b1, b2

Question 16

Drug to increase stomach action (mucarinic receptor)

What is target?

Where is target?

End result of interaction?

Answer 16

Muscarinic receptor (subtype 3)

Gastrict smooth muscle/endocrine gastrin producer etc.

increased contractility/secretion etc.

Question 17

Generic diagram to show release/ reuptake of neurotransmitter.

Answer 17

Question 18

Diagram for Ach release/reuptake.

Answer 18

Question 19

NA release/reuptake

Answer 19

NB. slightly slower uptake, so longer lasting effect.