12. Anatomy of ANS/ Autonomic reflexes

Question 1

Define the autonomic nervous system with 4 points

Answer 1

Maintains homeostasis of internal environment
Involuntary control of the viscera and glands
Influences respiration, digestion, excretion, thermoregulation and cardiovascular action
3 divisions: Sympathetic, Parasympathetic and Enteric

Question 2

In the autonomic nervous system, a sequence of how many neurones are there between the CNS and innervated structure?

Answer 2

There are a sequence of 2 neurones between CNS and the innervated structure:
Preganglionic neurone and Postganglionic fibre

Question 3

Which CNS structure provides high level regulation of autonomic activity?

Answer 3

Hypothalamus
Part of the limbic system (emotional centre)
Responds to changes from internal and external environments

Question 4

Where do sympathetic neurones synapse?

Answer 4

Mainly within the sympathetic chain (paravertebral ganglia)
Also:
Splanchnic nerves: coeliac, superior mesenteric, inferior mesenteric ganglia (prevertebral)
NO synapse for adrenal gland innervation

Question 5

From what spinal cord segments do the preganglionic sympathetic neurons emerge from?

Answer 5

Thoracolumbar outflow
Preganglionic fibres of sympathetic system emerge from thoracic (T1-12) and upper lumbar (L1-2/3) spinal cord segments as spinal nerves

Question 6

Name 4 structures the sympathetic nervous system innervates

Answer 6

Eye
Glands and mucous membranes within the head and neck
Thoracic, abdominal and pelvic viscera (internal organs)
Blood vessels, sweat glands, erector pili

Question 7

Where do parasympathetic neurones synapse?

Answer 7

Found close to or even in the organ/viscera they innervate

Ganglia (head and neck): ciliary, pterygopalatine, submandibular

Question 8

From what spinal cord segments do the preganglionic parasympathetic neurons emerge from?

Answer 8

Craniosacral outflow

Preganglionic fibres of the parasympathetic system emerge as cranial nerves and sacral spinal nerves (S2-S4)

Question 9

Which cranial nerves are associated with the parasympathetic nervous system?

Answer 9

III Oculomotor (synapses in ciliary ganglion)
VII Facial (splits and synapses in 2 ganglia: pterygopalatine and submandibular)
IX Glossopharyngeal (synapses in Otic ganglion)
X Vagus (synapses in walls of viscera)

Question 10

Which structures does the parasympathetic nervous system innervate?

Answer 10

Eye
Glands and mucous membranes within the head and neck
Thoracic, abdominal and pelvic viscera
NO innervation to adrenal gland, BVs, sweat glands and erector pili

Question 11

Why does the anatomy of the sympathetic and parasympathetic nervous systems differ?

Answer 11

Sympathetic: sympathetic chain allows for interconnectivity which can produce a mass response, mobilises body energy for increased activity
Parasympathetic: discrete/ localised, conserves body energy

Question 12

What is the difference between the White and Grey rami communicantes?

Answer 12

White: going into the sympathetic trunk
Grey: going out of the sympathetic trunk

Question 13

Which autonomic nervous system are Rami communicantes associated with and what is their function?

Answer 13

Sympathetic

Connect spinal nerves to sympathetic chain

Question 14

What is the difference in the direction of ventral and dorsal flow?

Answer 14

Ventral: OUTflow
Dorsal: Inflow