Structur Of Autonomic Nervous System

Question 1

What are the division of the ANS?

Answer 1

Sympathetic system (FFF)
Parasympathetic system ( rest and digest)

Question 2

What happens during the fight or flight response?

Answer 2

Increase heart ionotropy and chronograph
Vasoconstriction of the gut
Vasodilation of smooth muscle
Sensory awareness (dilatation Of pupil)
Sweat production

Question 3

What is the difference between pathways in the somatic and autonomic nervous system?

Answer 3

Somatic involves only one neutron ( alpha spinal motor neurone)
Autonomic has 1 pre and 1 post ganglionic fibres.

Question 4

What are the characteristics of ganglionic fibres in para and sympathetic nervous system?

Answer 4

Sympathetic: short pre (T1-L2) and long post ganglionic fibre
Parasympathetic: long pre and short post ganglionic fibres

Question 5

What are the prevertebral ganglia?

Answer 5

Celiac ganglion
superior cervical ganglion
Superior mesenteric ganglia

Question 6

Explain the 4 sympathetic outflow from the spinal cord

Answer 6

1. Afferent nerve from sensor passes through dorsal horn before entering the spinal column and synapse with the cell body of the preganglionic fibre. The signal then leaves the spinal cord via the ventral horn, into the white myelinated ramus and synapse in the sympathetic ganglion with the post ganglionic fibre. This leave via the grey unmyelinated ramus by an efferent nerve that control the target tissue.
2. Same as 1 except the Post ganglionic fibre moves up the paravertebral chain. It can go to one or several spinal segments up.
3. Here, the pre ganglionic fibre is situated within the CNS, instead of synapse get with post ganglionic fibre at the same spinal segment, the nerve extends several spinal segments upwards before synapsing (eg: eye)
4. Pre ganglionic fibre leave the spinal cord, move through the paravertebral chain, exit at its base and synapse with post ganglionic fibre the take the signal to the gut. (Coeliac plexus, aortic plexus, pulmonary plexus)

Question 7

What are the neurotransmitter and receptors used by the parasympathetic and sympathetic nervous systems? What are the exceptions?

Answer 7

Parasympathetic NS: acetylcholine is released at pre and post ganglionic fibres on nicotinic and muscarinic receptors respectively
Sympathetic NS: Ach is released by pre ganglionic fibre on nicotinic receptors, whereas NA/A is released by post ganglionic fibre to act on adrenoceptors (adrenergic fibres….all the eothers are cholinergic)
Exception: in sweat glands and piloerectors muscles, in the sympathetic NS, the post ganglionic fibre is cholinergic and hence release Ach to act on muscarinic receptors.
Also, in the adrenal medulla, there is no post ganglionic fibre so the pre ganglionic fibre release Ach that acts directly on the adrenals themselves.

Question 8

Name the tissues with only sympathetic innervation and the ones with only parasympathetic innervation

Answer 8

Sympathetic: sweat glands, spleen, piloerector muscle, many blood vessels, adrenal medulla
Parasympathetic: ciliary muscle and constrictor papillae of the eye

Question 9

What is the function of radial muscles (dilator pupillae)?

Answer 9

Increase diameter of pupil through contraction (supplied by sympathetic NS)

Question 10

What is the function of circular muscles (sphincter pupillae )?

Answer 10

Constrict the pupil by contraction (supplied by parasympathetic)