Session 8

Question 1

• To understand the anatomical and neurochemical divisions of the ANS
• To be able to compare and contrast neurotransmitter synthesis, storage, release and signal termination at cholinergic and adrenergic synapses
• To be able to list the mechanisms by which drugs influence neurotransmission and the major drug classes that exert all, or a part of their actions through altering ANS function

Question 2

What does the ANS do ?

1. The ANS controls all vegetative?
2. The ANS is separate from the voluntary (?) motor system
3. Is it efferent of afferent

Answer 2

1. (involuntary) functions e.g. heart rate - blood pressure - GI motility - iris diameter
2. somatic
3. Entirely efferent (but is regulated by afferent inputs)

Question 3

1. The ANS has two anatomically:
2. State some effects of the sympathetic NS

Answer 3

1. • The sympathetic division
     - The parasympathetic division

2.

Question 4

Answer 4

Question 5

Answer 5

Question 6

Draw the neurones in the PNS and SNS

Answer 6

Question 7

State the structure of Parasympathetic nerves

Answer 7

1. Originate in the lateral horn of the medulla [and sacral spinal cord]
2. Have long myelinated preganglionic fibres
3. Have short unmyelinated postganglionic fibres
4. Ganglia are located within the innervated tissues
5. Have actions that oppose the sympathetic nervous system

Question 8

State the structure of sympathetic nerves

Answer 8

1. Originate in the lateral horn of the lumbar and thoracic spinal cord
2. Have short myelinated preganglionic fibres
3. Have long unmyelinated postganglionic fibres
4. Ganglia are located in the paravertebral chain close to the spinal cord
5. Have actions that oppose the parasympathetic nervous system

Question 9

1. Neurotransmitters in the ANS (1). The principal (but by no means the only) neurotransmitters in the ANS are:
2. All pre-ganglionic neurons are ? i.e. they use ? as their neurotransmitter
3. Parasympathetic and sympathetic pre-ganglionic release of ACh results in the ?

Answer 9

1. • acetylcholine (ACh)

• noradrenaline (NA) (US name: norepinephrine)

2. cholinergic, ACh,
3. activation of post-ganglionic nicotinic ACh receptors (ligand-gated ion channels)

Question 10

Answer 10

Question 11

1. Parasympathetic post-ganglionic neurons are also ?
2. They release ACh which acts on ?
3. Most sympathetic post-ganglionic neurons are ?
4. NA interacts with one of two major classes of adrenoceptors

Answer 11

1. cholinergic
2. muscarinic ACh receptors in the target (‘effector’) tissue (GPCRs)
3. Noradrenergic i.e. they use noradrenaline (NA) as the principal neurotransmitter
4. • α-adrenoceptors and β-adrenoceptors

• These can be further subdivided into α1, α2 and β1 and β2, B3 subtypes

Question 12

Answer 12

Question 13

What type of receptors are they?

Answer 13

Question 14

1. Some specialized sympathetic post-ganglionic neurons are cholinergic, not noradrenergic e.g. ?
2. Other transmitters are found in the ANS. these are called? And may be?
3. E.g.s

Answer 14

1. those innervating sweat glands, hair follicles (piloerection)
2. • Non-Adrenergic, Non-Cholinergic (NANC) transmitters
     - These may be co-released with either NA or ACh
3. • ATP
     - nitric oxide (NO)

• 5-hydroxytryptamine (5HT; serotonin)
• neuropeptides (e.g. VIP (vasoactive intestinal peptide), substance P)

Question 15

Sympathetic postganglionic neurons in the adrenal glands are different:

Answer 15

• They differentiate to form neurosecretory chromaffin cells
• Chromaffin cells can be considered as postganglionic sympathetic neurons that do not project to a target tissue
• Instead, on sympathetic stimulation these cells release adrenaline (US name: epinephrine) into the bloodstream