Autonomic NS Flashcards

1
Q

What does autonomous mean?

A

Self-governing –> subconscious control

e.g. HR, pupil diameter, blood vessel contractility, hormonal secretions

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2
Q

Why is the autonomic NS important?

A

It maintains homeostasis

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3
Q

What part of the NS is the autonomic NS?

A

It’s is part of the peripheral NS

In the AFFERENT division - carries instruction to CNS

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4
Q

What does the somatic nervous system do?

A

Conscious control of skeletal muscles

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5
Q

What does the autonomic nervous system do?

A

Unconscious control of cardiac, smooth muscle & glands

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6
Q

What are the two divisions of the ANS?

A

Parasympathetic & sympathetic

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7
Q

What are the roles of the parasympathetic and the sympathetic NS?

A

This division is anatomical

Based on the CNS location of cell body of preganglionic nerve

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8
Q

What are the two divisions of the peripheral NS?

A
  • Somatic
  • Autonomic
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9
Q

Insert somatic and autonomic comparison image here

A

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10
Q

What is the structure of the autonomic NS?

A

It is a two neurone chain

  • The preganglionic (first) neurone - extends to the ganglion
  • The postganglionic (second) neurone extends from the ganglion to effector organ
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11
Q

What are ganglia?

A

Cell bodies of many peripheral autonomic neurones occur in clusters & form swelling on nerve trunks

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12
Q

What is at the end of the postganglionic neurone?

A

Many varicosities from which NTs are released

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13
Q

What are preganglionic neurones?

A

Axons that form synapses with ganglion cells

(Preganglionic autonomic fibres)

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14
Q

What are postganglionic neurones?

A

Axons innervating effector cells

(Postganglionic autonomic fibres)

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15
Q

What are the preganglionic nerves in the ANS?

A

Acetylcholine (ACh)

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16
Q

What are the postganglionic nerves in the ANS?

A

Acetylcholine (ACh)

Noradrenaline (NA)

17
Q

What are the pre- and postganglionic nerves in the ANS?

A

Non-adrenergic non-cholinergic neurotransmission (NANC)

18
Q

What does the ANS do overall?

A

Conveys all outputs from the CNS to the rest of the body except motor innervation of skeletal muscle

19
Q

What does the ANS do in homeostasis?

A

It regulates most non-voluntary processes in homeostasis

19
Q

What are some of the non-voluntary processes in homeostasis that the ANS regulates?

A
  • Heartbeat
  • Contraction of smooth muscle of various organs & blood vessels
  • Exocrine (& some endocrine) secretions
  • Energy metabolism (e.g. liver & skeletal muscle)
20
Q

How do the sympathetic and parasympathetic interact?

A

They function separately

Have opposing effects in some states (e.g. HR, GI tract) –> but not in some others (e.g. salivary gland secretion)

21
Q

Give some examples of what the sympathetic NS does

A
  • Pupils dilated
  • Hair erected
  • Inc blood sugar
  • Inc HR
  • Inc blood flow through muscle
  • Blood diverted from GI tract
22
Q

When does sympathetic activity increase?

A

During stress

23
Q

When does Parasympathetic activity mostly happen?

A

It predominates during satiation & repose: “rest & digest”

24
What is the ANS influenced by?
Sensory info via control centres in the brain
25
Where does cranial sacral outflow happen?
The parasympathetic NS
26
How does cranial sacral outflow work?
- Preganglionic axons emerge from cranial & sacral regions of CNS - Preganglionic axons form synapses in ganglia near to/adjacent to/within effector tissues
27
What are sacral nerves?
Form pelvic plexuses containing scattered ganglia & also some ganglia within tissue - these are pelvic & abdominal viscera
28
What do parasympathetic ganglia look like?
Preganglionic fibres are short and post are long
29
What are the 3 ways that the preganglionic sympathetic axons enter sympathetic chains?
- Paraverbal sympathetic chains - Prevertebral ganglia - Adrenal medulla