The Autonomic Nervous System 1

Question 1

Two components of the ANS?

Answer 1

Sympathetic NS - fight or flight

Parasympathetic NS - rest and digest

Question 2

Parasympathetic nervous system features and roles?

Answer 2

Controls a number of functions in non-stressful conditions

Opposes actions of the SNS in many cases

Question 3

Features of sympathetic nerves?

Answer 3

Arise in thoracic and lumbar regions of spinal cord
Pre-ganglionic fibre SHORT
Post-ganglionic fibre LONG
Ganglia are located in a chain close to vertebral column (paravertebral ganglia) or closer to target tissue (coeliac ganglion)

Question 4

Features of parasympathetic nerves?

Answer 4

Arise in cranial and sacral regions of spinal cord
Pre-ganglionic fibre LONG
Post-ganglionic fibre SHORT
Ganglia are located in or very close to effector cell/target tissue

Question 5

What is important about the connections between sympathetic ganglia?

Answer 5

Allows for MASS ACTIVATION

Question 6

How does the adrenal medulla act as a modified ganglion?

Answer 6

Made up of secretory cells (chromaffin cells) innervated by sympathetic pre-ganglionic fibres
These cells release catecholamines directly into the bloodstream to travel to their target via the circulation

Question 7

The two effects of sympathetic stimulation of the heart and their overall combined effect?

Answer 7

Inotropic effect - Increased force of contraction
Chronotropic effect - Increased heart rate
Overall effect of increasing cardiac output

Question 8

Effects and mechanism of sympathetic control of total peripheral resistance?

Answer 8

Increased sympathetic activity increases general vasoconstriction and increased TPR and vice versa
Leads to an increase in mean arterial blood pressure as well

Question 9

Controllers of vasodilation?

Answer 9

Mainly due to decreased sympathetic tone
Can be caused by sympathetic activity to skeletal muscle blood vessels, localised vasodilators, or increased parasympathetic stimulation to certain blood vessels to discrete glands/organs

Question 10

Effect of sympathetic and parasympathetic activity on GI tract?

Answer 10

Sympathetic - Inhibits peristalsis
- Generally decreases motility and tone
- Contraction of sphincters
- Inhibits secretory activity
Parasympathetic - Stimulates peristalsis
- Opposite effects to sympathetic

Question 11

Sympathetic effects on the lungs?

Answer 11

Dilates bronchi and bronchioles

Question 12

Sympathetic and parasympathetic effects on penis?

Answer 12

Parasympathetic - erection

Sympathetic - flaccidity and ejaculation

Question 13

Sympathetic and parasympathetic effects on eye muscles?

Answer 13

Sympathetic - Contracts radial muscles, pupil dilation

Parasympathetic - Contracts papillary sphincter for pupil contraction, contracts ciliary muscle for near vision

Question 14

What is the smooth muscle called that surrounds the bladder and what is the main influence on it?

Answer 14

Detrussor muscle

Parasympathetic control is main influence

Question 15

Internal and external sphincters controlled by?

Answer 15

Internal sphincter - sympathetic control

External sphincter - motor nerves/voluntary control

Question 16

What is the micturition reflex?

Answer 16

Registering of increased pressure in the bladder leading to relaxation of internal and external sphincters and urination
Leads to decreased bladder pressure

Question 17

Mechanism of micturition reflex control?

Answer 17

Increased pressure in bladder increases afferent activity to spinal cord
Increased parasympathetic activity via pelvic nerve leads to contraction of depressor muscle
Decreased sympathetic activity via the hypogastric nerve relaxes the internal sphincter
Central inhibition of voluntary control via the pudendal nerve relaxes the external sphincter and begins urination leading to drop in pressure in the bladder

Question 18

The 3 neurotransmitters used by the ANS?

Answer 18

Acetylcholine
Noradrenaline
Adrenaline

Question 19

Parasympathetic pre- and post-ganglionic fibre neurotransmitter released?

Answer 19

Cholinergic (acetylcholine)

Question 20

Sympathetic pre- and post-ganglionic fibre neurotransmitter released?

Answer 20

Pre-ganglionic - cholinergic

Post-ganglionic - noradrenergic (noradrenaline)

Question 21

What are the two sympathetic nervous system exceptions in neurotransmitter release?

Answer 21

Adrenal medulla - innervated by pre-ganglionic cholinergic fibres, acts as its own release site, releases catecholamines into circulation
Sweat glands - innervated by post-ganglionic CHOLINERGIC fibres

Question 22

What are the two types of acetylcholine receptors?

Answer 22

Nicotinic

Muscarinic

Question 23

What are the two types of adrenoreceptors? (receptors for both adrenaline and noradrenaline)

Answer 23

Alpha and Beta

Question 24

What type of receptor is the ganglionic acetylcholine receptor?

Answer 24

Nicotinic receptor

Ligand-gated ion channels

Question 25

What type of acetylcholine receptor is used at effector organs?

Answer 25

Muscarinic receptor

G-protein coupled receptor