ANS

Question 1

What and how many nerves of the ANS are contained within the Brain stem?

Answer 1

Parasympathetic (12)

Question 2

What and how many nerves of the ANS are contained within the spinal cord?

Answer 2

Parasympathetic and sympathetic (31)

Question 3

What is the distribution of nerves and bones in the spinal cord?

Answer 3

Cervical - 8 nerves (7 bones)
Thoracic - 12 sympathetic nerves (12 bones)
Lumbar - 5 sympathetic nerves (5 bones)
Sacral - 5 parasympathetic nerves (5 bones)
Coccygeal - 1 nerve (4 fused bones)

Question 4

What are the receptors and agonists of the somatic nervous systems?

Answer 4

Somatic -

Influx of Ca2+ releases ACh to nAChR, influx of Na+, efflux of K+ in skeletal muscle causes contraction

Question 5

What are the receptors and agonists of the parasympathetic nervous system?

Answer 5

Parasympathetic -

Influx of Ca2+ releases ACh to nAChR, Influx of Ca2+ releases ACh to GPCR on mAChR

Question 6

What are the receptors and agonists of the sympathetic nervous system?

Answer 6

Sympathetic -
Influx of Ca2+ releases ACh to nAChR, Influx of Ca2+ releases Nor-A to GPCR on adrenoceptors
Influx of Ca2+ releases ACh to nAChR, Influx of Ca2+ releases ACh to GPCR on mAChR in hair follicles/sweat glands
Influx of Ca2+ releases ACh to nAChR in chromaffin cells (adrenal medulla), adrenaline

Question 7

What are the other transmitters found in the ANS and how are they released?

Answer 7

Co-released with ACh and Nor-A
NANC (Non-adrenergic, Non-cholinergic):
ATP
Nitrous Oxide (NO)
Serotonin (5HT)
Neuropeptides (Vasoactive Intestinal Peptide)
Substance P

Question 8

How is ACh synthesised?

Answer 8

Acetyl-CoA + Choline —> Acetylcholine + CoA

Choline Acetyl Transferase

Question 9

How is ACh degraded?

Answer 9

Acetylcholine —> Acetate + Choline

Acetyl Choline Esterase

Question 10

What does the over-stimulation of mAChR cause?

Answer 10

Stimulation of glands
S - salivation
L - lacrimination
Relaxation of sphincters
U - urination
D - defecation
Changes in smooth muscle tone
G - GI upset
E - emesis (vomiting)

Question 11

What specialised feature do postganglionic sympathetic neurones contain?

Answer 11

Variscosities:
Bulging nodes filled with vesicles of Nor-A
In between the nodes fibres are myelinated

Question 12

How is Nor-A synthesised?

Answer 12

Cytosol:
Tyrosine —> DOPA (Tyrosine Hydroxylase)
DOPA —> Dopamine (DOPA decarboxylase)
Vesicle:
Dopamine —> Nor-A (Dopamine beta-Hydroxylase)
Adrenal medulla:
Nor-A —> Adrenaline

Question 13

How is Nor-A degraded?

Answer 13

Captured by cells and metabolised

Question 15

How is Nor-A metabolised?

Answer 15

Taken into vesicles
Metabolised by:
Monoamine oxidase (MAO)
Catechol-o-methyl transferase (COMT)

Question 16

How is Nor-A terminated?

Answer 16

Uptake 1: High affinity Na+ symporter in presynaptic membrane
Uptake 2: Low affinity capture into the post-synaptic (non-neuronal cell) membrane