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VSC226 > Autonomic NS > Flashcards

Autonomic NS Flashcards

1
Q

What does the autonomic NS comprise of?

A

Sympathetic and parasympathetic NS.

Smooth muscle, cardiac muscle, glands.

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2
Q

What is the principal function of the Autonomic NS?

A

Homeostasis

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3
Q

What is the main difference between the somatic and autonomic NS?

A

Somatic NS is a one motor neuron system - one neuron runs from the spinal cord to the skeletal muscle.
Autonomic NS is a two neuron system - preganglionic fibre runs from the spinal cord to a ganglion. From here a postganglionic fibre runs to smooth and cardiac muscle and glands.

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4
Q

Describe the anatomy of the parasympathetic NS.

A

Long Preganglionic fibres from brain stem or sacral spinal cord (cranio-sacral system).
Includes cranial nerves 3(oculomotor), 7(facial), 9(glossopharyngeal), 10(vagus).
Pelvic nerves
Ganglia are located near effector organs.

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5
Q

Describe the anatomy of the sympathetic NS.

A

Preganglionic fibres from thoracic and lumbar spinal cord.
Thoraco-lumbar system.
Ganglia arranged in three anatomical patterns; sympathetic chain, adrenal medulla, collateral ganglia.

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6
Q

Describe the anatomy of a sympathetic chain in relation to the SNS.

A

Short axons
Exit spinal cord via ventral roots.
Travel to organ as spinal nerve.

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7
Q

Describe the anatomy of the adrenal medulla in terms of the SNS?

A

Long preganglionic fibres

Chromaffin cells are modified post-ganglionic cells

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8
Q

Describe the collateral ganglia in terms of the SNS?

A

Pre-ganglionic axons pass through sympathetic chain without synapsing.
Ganglion located close to effector organ.

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9
Q

What are the three paths that an axon can take in relation to the SNS?

A
  1. Enter sympathetic chain via White ramus and terminate there.
  2. Enter the sympathetic chain via the White ramus and ascend or descend a few segments before terminating.
  3. Enter via the White ramus and exit via a splanchnic nerve and terminate in a prevertebral ganglia.
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10
Q

What are the three receptor types of the ANS?

A

Adrenergic
Nicotinic
Muscarinic

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11
Q

What are adrenergic receptors?

A

Respond to adrenaline and noradrenaline. Have alpha and beta receptors. Signal transduction is via activation of IP3 for alpha1, inhibition of cAMP for alpha2 and activation of cAMP for the three beta receptors.
Effector organs include vascular smooth muscle, adipose tissue, CNS, platelets, adrenergic nerve terminals, uterus, respiratory tract, cardiac muscle, kidney.
IP3 receptors are faster than cAMP.

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12
Q

What are cholinergic receptors?

A

Muscarinic-responds to acetylcholine, PNS, postganglionic fibres to effector organ.
Nicotinic - SNS and PNS, preganglionic fibres transmitting to ganglion of ANS.

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13
Q

Discuss muscarinic receptors.

A

All G-protein linked second messenger pathways.
Specific to organs, can be inhibitory or excitatory.
Specific agonists and antagonists.
Acetylcholine natural agonist (ligand).
5 types; M1-CNS, M2-heart, M3-smooth muscle, M4-CNS, M5-CNS

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14
Q

Discuss nicotinic receptors.

A

Can be N1/Nm - neuromuscular junction, or N2/Nn - autonomic ganglia, CNS and adrenal medulla.

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15
Q

What are the two major neurotransmitters of the ANS?

A

SNS-noradrenaline/adrenaline. Effector organ receptor is adrenergic.
PNS-acetylcholine. Effector organ receptor is muscarinic cholinergic.
Receptor on the ganglion for both PNS and SNS is nicotinic cholinergic and neurotransmitter is acetylcholine.

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16
Q

What are the characteristics of sympathetic nerve function?

A

Release noradrenaline at the nerve endings (adrenergic nerves).
All postganglionic sympathetic nerves release norepinephrine except sweat glands, piloerector muscles and select blood vessels.

17
Q

What are noradrenaline and adrenaline synthesised from?

A

AA tyrosine.

Tyrosine - DOPA - dopamine - noradrenaline.

18
Q

What are the characteristics of parasympathetic function?

A

Postganglionic parasympathetic nerves release acetylcholine at their nerve endings (cholinergic nerves).

19
Q

True or false. All preganglionic sympathetic and parasympathetic nerves release acetylcholine?

A

True

20
Q

What is dual innervation?

A

Innervation of tissue by both the SNS and PNS.
Aids homeostasis maintenance.
Cardiac muscle, smooth muscle, glands, adipose tissue.

21
Q

What is the function of the adrenal medulla?

A

Large sympathetic ganglion.
Releases adrenaline (80%), and noradrenaline (20% ) into the blood.
Causes prolonged activity of the substances through stimulation of cardiovascular function and metabolic rate.
Helps the body deal with stress.

22
Q

What is meant by parasympathetic and sympathetic ‘tone’?

A

Basal rate of activity of each system.
Sympathetic tone normally causes about 50% vasoconstriction.
Parasympathetic tone provides background GIT activity.

23
Q

What is the stress response?

A

Mass sympathetic discharge.
Increased arterial pressure, heart rate and contractility, blood flow to muscles, blood glucose, metabolic rate, muscle strength, mental activity, blood coagulation.
Prepares body for vigorous activity - fight or flight.

24
Q

In terms of the heart, what effect does innervation of the SNS and PNS have?

A

SNS - increases heart rate, contractility and conduction velocity.
PNS - decreases all of the above.

25
Q

In terms of the blood vessels, what effect does innervation of the SNS and PNS have?

A

SNS - vasoconstriction or vasodilation if epinephrine present.
PNS - no effect

26
Q

In terms of the lungs, what effect does innervation of the SNS and PNS have?

A

SNS - relaxation and inhibition of secretion.

PNS - contraction and stimulation of secretion.

27
Q

In terms of the GIT, what effect does innervation of the SNS and PNS have?

A

SNS - decreased motility and inhibited secretions. Contraction of sphincters.
PNS - increased motility and stimulated secretions. Relaxation of sphincters.

28
Q

In terms of the pancreas, what effect does innervation of the SNS and PNS have?

A

SNS - inhibits secretions from exocrine and endocrine glands.
PNS - stimulates secretion from both glands.

29
Q

In terms of the salivary glands, what effect does innervation of the SNS and PNS have?

A

SNS - stimulates mucous secertion.

PNS - stimulates watery secretion.

30
Q

In terms of the kidneys, what effect does innervation of the SNS and PNS have?

A

SNS - stimulates renin release.

PNS - no effect.

31
Q

In terms of the bladder, what effect does innervation of the SNS and PNS have?

A

SNS - relaxation of bladder wall and contraction of sphincter.
PNS - contraction of bladder wall and relaxation of sphincter.

32
Q

In terms of metabolism, what effect does innervation of the SNS and PNS have?

A

SNS - stimulates glycogenolysis, gluconeogenesis, lipolysis.

PNS - no effect.

33
Q

Which nerves are involved in the visceral afferent systems?

A 
Facial nerve (CN 5) - middle ear, blood vessels of head.
Glossopharyngeal nerve (CN 9) - caudal tongue, pharynx, carotid body and sinuses.
Vagus nerve (CN 10) - pharynx, larynx, thoracic and abdominal cavities.
Splanchnic nerves - peripheral branches of SNS trunk, intestines and lumbar region.
34
Q

Which organ is responsible for overall integration of the ANS?

A

Hypothalamus.

Coordinates cardiac activity, BP, body temp, water balance, endocrine function, emotion and biological drives.

35
Q

Which system can override the SNS?

A

Limbic system.

VSC226 (5 decks)

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