The ANS 1

Question 1

What does the ANS do?

Answer 1

Controls all vegetative (involuntary) functions.
Is separate from the voluntary motor system.
Is entirely efferent (delivers to peripheral) but is regulated by afferent inputs (peripheral inputs)

Question 2

What are the 2 anatomically defined divisions of the ANS?

Answer 2

The Sympathetic division

The Parasympathetic division

Question 3

In general what does the Parasympathetic and sympathetic nervous system do?

Answer 3

Sympathetic=responds to stressful situations, “fight or flight”, generally activates systems

Parasympathetic=regulates basal activities, ie slowing HR using vagul tone, “rest and digest”

Question 4

Where does the sympathetic nervous system emerge from in the spinal chord?

Answer 4

The Thoracic and Lumbar regions

Question 5

Where does the Parasympathetic nervous system emerge from in the spinal chord?

Answer 5

The medullary, cranial and sacral regions

Question 6

Compare the pre and post-ganglionic lengths of the parasympathetic and sympathetic nervous systems.

Answer 6

In parasympathetic system, the preganglionic myelinated neurone is very long. It synapses in or near the target tissue and so the postganglionic unmyelinated neurone is very short.

In sympathetic system, the preganglionic myelinated neurone is very short so synapses near the chord. This means that postganglionic unmyelinated neurone is very long to reach the tissues.

Question 7

What are the 2 principle neurotransmitters in the ANS?

Answer 7

Acetylcholine (Ach)

Noradrenaline (NA)

Question 8

What do all pre-ganglionic neurones have in common in the ANS?

Answer 8

They are all cholinergic. (All use Ach as their neurotransmitter)

Question 9

What does pre-ganglionic release of Ach lead to?

Answer 9

Results in the activation of postganglionic nicotinic Ach receptors

Question 10

What type of channel are nicotinic ACh receptors?

Answer 10

Ligand-gated ion channels

Question 11

What does the Ach released by parasympathetic post-ganglionic neurones do?

Answer 11

Real ease ACH which acts on muscurinic Ach receptors (mACh) in the target tissue

Question 12

What type of receptor are mAch receptors?

Answer 12

G-protien coupled receptors.

There are 5 subtypes

Question 13

What neurotransmitters do the Parasympathetic and sympathetic post-ganglionic neurone use?

Answer 13

Parasympathetic are Cholinergic (use ACh)

Sympathetic are mostly noradrenergic (use NA)

Question 14

What are the 2 major classes of adrenoreceptor?

Answer 14

A-adrenoreceptor (alpha)
B-adrenoreceptor (beta)

These can be further divided into a1 and a2 and b1,b2 and b3 subtypes

Question 15

What sympathetic post-ganglionic neurones don’t follow the noradrenergic rule and are cholinergic?

Answer 15

Those that innervate sweat glands and hair follicles.

Question 16

What other transmitters can be found in the ANS?

Not Ach and NA

Answer 16

Non-Adrenergic, Non-Cholinergic (NANC) transmitters

May be co-released with NA or AcH
Eg, ATP, Nitric Oxide

Question 17

What is the debated 3rd division of the ANS?

Answer 17

The Enteric system

It control the GI tract and is capable of operating independently of the CNS

Question 18

Why are sympathetic post-ganglionic neurones in the adrenal gland different?

Answer 18

They differentiate to form neurosecretory Chromaffin cells. They do not project to a target tissue. Instead upon sympathetic stimulation the release Adrenaline into the bloodstream. (Hormonal repsonse)

Question 19

Gives some examples of physiological consequences of parasympathetic ACh release.

Answer 19

Bradycardia
Reduced cardiac conduction velocity 
Bronchiole contraction 
Increased intestinal secretion 
Bladder contraction+relaxation 
Penile erection (NO generation)
Ciliary muscle contraction 
Iris sphincter contraction
Increased sweat,salivary secretion

Question 20

Give some examples of physiological effects caused by sympathetic release of Noradrenaline.

Answer 20

Tachycardia
Positive inotropy
Arteriolar+venous contraction
Bronchiole relaxation 
Intestine+uterine relaxation 
Bladder sphincter contraction 
Radial muscle contraction 
Increased viscous secretion 
Renin release