Autonomic Nervous System Flashcards

1
Q

Define the autonomic nervous system?

A

Involuntary nervous system

Visceral motor system

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2
Q

What is the purpose of the ANS?

A

Homeostasis

Allostasis

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3
Q

What sorts of actions can the ANS have?

A

Part of simple reflexes
Involve coordinated regulation of multiple sites
Associated with more complex behaviour

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4
Q

What are the features of the ANS?

A

Precise
Flexible
Integrativ

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5
Q

What are the targets of autonomic nerves?

A
Smooth and cardiac muscle
Epithelial transport of ions
Hormones and mucous secretions
Metabolism
Immune cells
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6
Q

What are the components of the ANS?

A

Sympathetic
Parasympathetic
Enteric

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7
Q

Where are the parts of the sympathetic and parasympathetic nervous systems?

A

CNS

PNS

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8
Q

Do the sympathetic and parasympathetic nervous systems require the CNS for function?

A

Yes

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9
Q

Where is the enteric nervous system?

A

In GIT

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10
Q

Does the enteric nervous system need the CNS to function?

A

No, can function independently

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11
Q

What neurons make up the enteric nervous system?

A

Sensory
Motor
Interneurons

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12
Q

Do the sympathetic and parasympathetic nervous systems influence the enteric nervous system?

A

Yes

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13
Q

How are the sympathetic and parasympathetic nervous systems defined?

A

By their anatomy - location of their preganglionic neurons

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14
Q

Where are the sympathetic preganglionic neurons?

A

In thoraco-lumbar region of spinal cord

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15
Q

Where are the parasympathetic preganglionic neurons?

A

In cranio-sacral region of spinal cord

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16
Q

Which areas of the spinal cord have no visceral fibres?

A

Cervical and lumbar enlargements

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17
Q

What nucleus in the spinal cord are sympathetic preganglionic cell bodies located?

A

Intermediolateral nucleus

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18
Q

What are the two types of sympathetic ganglia?

A
Paravertebral = sympathetic chain
Prevertebral = mesenteric ganglia
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19
Q

Other than the sympathetic ganglia, what else do preganglionic sympathetic neurons innervate?

A

Adrenal medulla

20
Q

What is the sympathoadrenal system?

A

Preganglionic sympathetic neurons and adrenal medulla

21
Q

Where are the preganglionic parasympathetic cell bodies located?

A

Brainstem nuclei

Sacral spinal cord

22
Q

What are the preganglionic parasympathetic nuclei of the brainstem?

A

Edinger-Westphal nucleus
Salivatory nuclei
Dorsal motor nucleus of vagus and nucleus ambiguus

23
Q

Where do neurons project to from the Edinger-Westphal nucleus, and what do they control?

A

To ciliary ganglion to control sphincter pupillae and ciliary muscle

24
Q

Where do neurons project to from salivatory nuclei, and what do they control?

A

To submandibular, sphenopalatine, and otic ganglia to control lacrimal, salivary, sublingual, nasal, and palatine glands

25
Q

Where do neurons project to from the dorsal motor nucleus of vagus and nucleus ambiguus, and what do they control?

A

To microganglia near and on outer surface of thoracic and abdominal organs, controlling many functions

26
Q

Where in the sacral spinal cord is the parasympathetic preganglionic nucleus?

A

Interomediolateral nucleus

27
Q

Where are sacral postganglionic parasympathetic neurons?

A

In pelvic/inferior hypogastric plexus

28
Q

Are the pelvic ganglia purely parasympathetic?

A

No, they contain many sympathetic neurons > mixed ganglia

29
Q

What is the clinical significance of the long axons of the pelvic plexus?

A

Vulnerable to surgical injury

30
Q

Are ANS neurons myelinated or unmyelinated?

A

Unmyelinated

31
Q

Where are neurotransmitters stored in postganglionic fibres?

A

In swellings along axon = varicosities

Can be released from any of them

32
Q

What is the significance of transmitter release from varicosities?

A

Transmitter released over large area so it has large effect in coordinated way

33
Q

What is the preganglionic transmitter, and what receptor does it act on?

A

ACh

Nicotinic receptors

34
Q

What is the postganglionic sympathetic neurotransmitter and what receptor does it act on?

A

NA (most)
Alpha/beta adrenoceptors
ACh (few)
Muscarinic receptors

35
Q

What is the postganglionic parasympathetic neurotransmitter, and what receptor does it act on

A

ACh

Muscarinic receptors

36
Q

How many subtypes of ACh and NA receptors are there?

A

Many

37
Q

Are ACh and NA the only transmitters used by the ANS?

A

No, many others used

38
Q

How does the ANS gather information?

A

Caudal part of nucleus of thee solitary tract (NTS) in medulla receives sensory input

39
Q

What is the major integrative centre of autonomic function?

A

NTS

40
Q

Where is sensory information distributed to?

A

Provide feedback to reflexes > control organ/tissue function

Provide info to higher centres to drive more complex responses

41
Q

What is the role of the hypothalamus in the ANS?

A

Receives
- Sensory inputs
- Contextual info from other brain regions
- Hormonal signals
Compares situation to biological set points > adjusts behaviour, autonomic and endocrine function

42
Q

What does the fight or flight response involve?

A

Mass activation of many sympathetic pathways at once to overcome/escape from major threat

43
Q

Why doe mass activation and synchronisation occur in the fight or flight response?

A

CNS activates many preganglionic pathways at once
Some preganglionic neurons have many axon collaterals > activate many postganglionic neurons at once
When adrenal medulla activated catecholamine hormones spread through bloodstream

44
Q

When is mass activation of the sympathetic nervous system relevant?

A

Extreme situation

45
Q

How does the sympathetic nervous system mediate functions essential for normal living?

A

Individual cells/tissues/organs precisely and independently activated
Adrenal medulla nerves not always activated

46
Q

Why is there limited mass activation of different types of parasympathetic pathways?

A

No equivalent of adrenal gland
Preganglionic neurons don’t have as many axon collaterals to simultaneously activate numerous postganglionic neurons
Most coordination of pathways between different regions occurs by brain mechanisms