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1. Foundations of Medicine PoNF > Autonomic Physiology > Flashcards

Autonomic Physiology Flashcards

1
Q

Function of the autonomic nervous system

A

To control things you dont want to think about:
* Smooth muscle: blood vessels/airways/bladder/eye/gut/sex organs
* Cardiac muscle
* Glands

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2
Q

How can we divide the PNS

A

Afferent division
Efferent division:
* Autonomic NS (sympathetic, parasympathetic, enteric NS)
* Somatic NS - voluntary (muscles)

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3
Q

Describe the somatic nervous system in terms of nerves/recepotors

(briefly)

A

Nerve emerging from ventral root and sysnapeses onto skeletal muscle (n-m junction)

see sheet

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4
Q

Describe the autonomic nervous system in terms of nerves/recepotors

(briefly)

A

Pre-ganglionic fibre (small myelinated) —> synapse and ganglion —> post-ganglionic fibbre (unmyelinated) —> synaps onto smooth/cardiac muscle, gands, GI neurons

see sheet

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5
Q

Breifly describe the main features of synapses in the somatic nervous system

A
  • Specialised NMJ
  • Ionotropic (nicotinic cholonergic) receptors which act as monovalent cation channels
  • Graded potential called end plate potential which always ecites target
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6
Q

Breifly describe the main features of synapses in the autonomic nervous system

A
  • Less specialised junction
  • Metabotropic receptors - G-protein coupled
  • Can be exitory or inhibitory
  • Neurotransmitter released into ISF until it finds receptors, therfore 1 postganglionic fiber innervates a large tissue area
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7
Q

2 main divisions of the autonomic nervous system

Give key rhymes for each

A
  • Sympathetic - fight or flight
  • Parasympathetic rest and digest
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8
Q

Outflow of sympathetic division of NS

A

Thoratic (T1-T12) region of spinal cord and first 2 lumbar levels (L1-L2) - thoracolumbar outflow

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9
Q

Describe ganglia/fibres of sympathetic NS

A

Very short pre-ganglionic fibres (ganglia close to spinal cord). Most found in sympathetic chain, aka the paravertebral ganglia
And then we’ve got some in these other ganglia called the collateral (or prevertebral) ganglia.
After the synapse, there are very long post-ganglionic fibres that go all the way up to their targets.

Ganglia lie close to spina cord

see diagram

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10
Q

Outflow of parasympathetic division of (autonomic) NS and what does it supply

A

Cranial (3,7,9,10) and sacral (S2-S4) regions of spinal cord - craniosacral

Cranial nerves supplies head/eyes/salivary glands but vagus nerve goes on an adventure (e.g. lungs/hear/liver/intestine…)!

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11
Q

Describe ganglia/fibres of parasympathetic NS

A

Very long pre-ganglionic fibres and very short post-ganglionic fibres which lie within the target/very close to it.

Ganglia lie close to/within target

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12
Q

Neurotransmitters and receptors of somatic nervous system

A

Only has n-m junctions so:
* Neurotranmitter: acetylcholine
* receptors: nicotinic/muscarinic cholinergic receptors

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13
Q

Autonomic transmitters

A
  • Acetylcholine: acts on cholonergic receptors: nicotinic (iontropic) and muscarinic (g-protein coupled) receptors
  • Noradrenaline: acts on adrenergic receptors: a and B receptors
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14
Q

What neurotransmitters do sympathetic/parasympathetic release over course of efference

Key flashcard

A
  • preganglionic fibres for both release ACh which acts on nicotinic cholinergic receptors
  • parasympathetic postganglionic fibres release ACh which acts on muscarine cholinergic receptors
  • Sympathetic postganglionic fibres release noradrenaline which acts on a or B adrenergic receptors

Remember that ther are a couple of exeptions

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15
Q

Explain “special” part of the sympathetic nervous system

A

Fibre goes straight out of the spinal cord, through the sympathetic chain without synapsing, goes straight through the collateral/prevertebral ganglia again without synapsing and comes all the way out to its target: adrenal medulla gland that sits above the kidney. Finally synapses his here onto the post-ganglionic cell. But it doesn’t have an axon, and instead releases its neurotransmitter into the bloodstream which then acts as a hormone.

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16
Q

What do sympatheticd postganglionic cells of the adrenal medulla release

A

Adrenaline and noradrenaline into the blood: which act on a or B adrenergic receptors - hormonal component and often allows for whole body response!!!

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17
Q

List 3 complexities to the sympathetic/parasympathetic NS that don’t follow previous “rules”

A
  • Sympathetic cholinergic fibres (due to length of pre/post ganglionic fibres) innervate sweat glands - expect post-G fibre to release norarenaline but instead, releases Ach
  • Some postganglionic fibres use non-adrenergic non-cholinergic (NANC) transmitters (e.g. peptides)
  • Sometimes co-released with the orthodox transmitter

Point 2 and 3 linked

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18
Q

In what 3 ways do somatic and autonomic efferent differ

(brief)

A

Tragets, axons, synapses

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19
Q

In what ways do sympathetic and parasympathetic efferent differ

(brief)

A

spinal outflow, location of ganglia, transmitters used, functions

20
Q

Summarise the lengths of ganglia for the sypathetic and parasympathetic branches of the autonomic NS

A
  • Sympathetic: short pre-ganglia, long post-ganglia fibres
  • Parasympathetic: long pre-ganglia, short post-ganglia fibres
21
Q

List features when sympathetic NS has taken over

A
  • Airways dilate
  • Heart beats faster
  • Heart beats stronger
  • Blood diverts to muscle
  • Gut motility decreases
  • Enzyme secretion in gut generally inhibited
  • Stored energy is released
  • Pupils dilate
  • Eye focus far way
  • Hair stands on end
  • Mouth becomes dry
22
Q

List features when parasympathetic NS has taken over

A
  • Airways constrict
  • Heart beats slower
  • Heart beats weaker
  • Blood diverts to gut
  • Gut motility increases
  • Enzyme secretion in gut generally stimulated
  • Energy is stored
  • Pupils constrict
  • Eyes focus close up
  • Hair lies flat
  • Mouth starts drooling
23
Q

What determines weather the sympathetic or parasympathetic NS is more “activated”

A
  • Neurotransmitter released
  • And receptor type that it acts on
24
Q

Explain how the sympathetic/parasympathetic NS is more “activated” in terms of neurotransmitters and their receptors

A
  • Acetylcholine: Cholinergic nicotinic (sympathetic) or muscarinin (parasympathetic) receptors
  • Noradrenaline/adrenaline: a or B receptors (sympathetic)

ACh—>nicotinic receptors: S and P pre-ganglionic fibres
ACh —> P post-ganglionic fibres
Noradrenaline/Adrenaline—> S post-ganglionic fibres

25
Q

Describe the response of the eye in the Sympathetic NS

Include details of receptors and their effects

A
  • Activates a1 receptors (through 2nd messenger pathway) on radial muscle of the iris: radial muscle contracts and makes pupil larger
  • Activates B2 recepors on ciliary muscle around lense: ciliary muscle relaxes and eye focuses far away
26
Q

Describe the response of the eye in the Parasympathetic NS

Include details of receptors and their effects

A
  • Activates muscarinic receptors on sphincter muscle of the iris: contracts and makes pupil smaller
  • Activates muscarinic receptors on ciliary muscle around the lens: muscle contracts and eye focuses close up
27
Q

Describe the response of the heart in the sympathetic NS

Include details of receptors and their effects

A
  • Activates B1 receptors on pacemaker cells: increases heart rate
  • Activates B1 receptors on myocytes: inc strength of contraction
28
Q

Describe the response of the heart in the parasyympathetic NS

Include details of receptors and their effects

A
  • Activates muscarinic receptos on pacmaker cells: dec heart rate
  • Little effect on myocytes: little effect on strength of contraction
29
Q

Describe the response of the lungs in the sympathetic NS

Include details of receptors and their effects

A
  • Activates B2 receptors on smooth muscles of airways: relaxes and dilates airways
30
Q

Describe the response of the lungs in the parasympathetic NS

Include details of receptors and their effects

A
  • Activates muscarinic receptors: makes smooth muscle contract and constricts airways
31
Q

theraputic usefulness of drugs on lungs/heart in relation to S nervous system

Examples + explanation

A
  • B2 agonist (salbutamol) dilate airways but little effect on heart
  • B1 antagonist (atenolol) dec heart rate but limited effect on airways

This is because different organs have recepors/specificity for different neurotransitters which thus, allows us to artifcially target certain parts of the P/S nervous system.

32
Q

Describe the response of the blood vessels in the sympathetic NS

Include details of receptors and their effects

A
  • Activates a1 receptors on smooth muscle of vessels: contracts and dec blood flow
  • Activates B2 receptors on smooth muscle of vessels: relaxes and blood flow inc - ex. inc cardiac and skeletal muscle

Response depend on where vessel is in body

33
Q

Describe the response of the blood vessels in the parasympathetic NS

Include details of receptors and their effects

A

Usually no effect
- salivary glands and genetalia are exeptions

34
Q

What do blood vessels have (in terms of innervation)

A

Single innervation from the sympathetic nervous system

35
Q

What are blood vessels an example of?

And define it

A

The importance of tone in single innervation

Tone = the level of activation in a system when it is not doing anything

36
Q

Describe the response of the salivary glands in the sympathetic NS

Include details of receptors and their effects

A

Activates B receptors: stimulates thick secrection rich in enzymes

37
Q

Describe the response of the salivary glands in the parasympathetic NS

Include details of receptors and their effects

A

Activates muscarine receptors: stimulates profuse watery secretion

38
Q

What are salivary glands an example of?

A

Dual innervation with non-antagonistic actions

39
Q

Describe the response of the bladder in the sympathetic NS

Include details of receptors and their effects

A
  • Activates B2 receptors on smooth muscle of bladder wall: relaxes smooth muscle and reduces pressure on bladder
  • Activates a1 receptors on smooth muscle of sphincter: contracts smooth muscle and stops urination
40
Q

Describe the response of the bladder in the parasympathetic NS

Include details of receptors and their effects

A
  • Activates muscarinic receptors on bladder wall: contracts smooth muscle and increases pressure
  • Activates muscarininc receptors on sphincter: relaxes smooth muscle and causes urination
41
Q

Describe the response of the **reproductive tract ** in the both the sympathetic and parasympathetic NS

A

Sympathetic:
* activates a1 receptors on smooth muscle of urethra: contracts smooth muscle and causes ejaculation
Parasympathetic:
* Activates muscarinic receptors on smooth muscle of corpus cavernosum: relaxes smooth muscle and causes erection

Point and Shoot

42
Q

What is the reproductive tract and example of

A

dual innervation with complementary effects

43
Q

What controls the S/P NS

A

Autonomic reflexes

44
Q

Explain Autonomic reflexes

A
  • Spinal reflexes (urination in babies)
  • Higher control (learned reflexes)
45
Q

Explain central control for the autonomic NS

A

Integrated in brain (hypothhalamus, thalamus and brainstem)
Detects change, looks at info, coordinates sympathetic and parasympathetic outflow accordingly

46
Q

Explain dual and single innervation

how common, effects/control/ examples

A
  • Dual: many tissues: effects usually antagonistic (bladder/eyes/lungs) , but could be complementary (salivary glands/reproductive tract)
  • Single: some tissues (blood vessels): controled by varying tone

antagonistic/complementary = between S and P NS

1. Foundations of Medicine PoNF (22 decks)

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