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Neuroscience and Mental health > 11. Physiology and pharmacology of ANS > Flashcards

11. Physiology and pharmacology of ANS Flashcards

1
Q

Describe the sympathetic responses

A

Pupils dilate: allows more light in
HR increases: better O2 supply to muscles
Increases diameter of bronchioles: allows more O2 into lungs
Stimulates glucose release: to feed muscles
Increases sweat production: to prevent from overheating

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2
Q

Describe the parasympathetic responses

A 
Pupils constrict
Stimulates flow of saliva
HR decreases
Constricts bronchi
Stimulates peristalsis and secretion
Stimulates bile release
Contracts bladder
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3
Q

Describe the overall pathway of the sympathetic nervous system

A

THORACOLUMBAR outflow
Hypothalamus
Pre-sympathetic neurone synapses onto pre-ganglionic neurone
Pre-ganglionic neurones in thoracolumbar spinal cord
Emanates from spinal cord
Sympathetic ganglion in sympathetic trunk
Postganglionic neurone
Effector

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4
Q

Describe the overall pathway of the parasympathetic nervous system

A 
CRANIOSACRAL outflow
Hypothalamus 
Pre-ganglionic neurones in brainstem (cranial nerves) and sacral spinal cord
Ganglion near organ/ viscera
Post ganglionic neurone
Effector organ
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5
Q

Describe the pathway of the sympathetic pre-ganglionic neurone

A

Short pre-ganglionic neurone arises from lateral horn of grey matter in T1-L2 spinal segments
Emerges from from ventral root of spinal cord to join T1-L2 spinal nerves
Enters ventral rami of T1-L2 spinal nerves
Detours via white rami communicantes to enter sympathetic ganglion where it synapses with longer post ganglionic neurone

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6
Q

How do Sympathetic ganglia exist?

A 
Exist as sympathetic trunks:
3 cervical ganglia
12 thoracic ganglia
5 lumbar ganglia
5 pelvic ganglia
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7
Q

What do ganglia contain?

A

cell bodies of post ganglionic neurones

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8
Q

How do ganglia differ between sympathetic and parasympathetic nervous systems?

A

Sympathetic: Ganglia in sympathetic chain (outside organs)
Parasympathetic: Ganglia inside target organs

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9
Q

Describe the neurotransmitters used at different stages by the sympathetic nervous system

A

Presympathetic: Glu
Preganglionic: ACh
Postganglionic: NA to target organs e.g. heart, kidney and blood vessels

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10
Q

What neurotransmitter is used by sympathetic postganglionic neurones innervating sweat glands?

A

Acetylcholine (ACh)

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11
Q

What neurotransmitter is used by sympathetic postganglionic neurones innervating renal vessels?

A

Dopamine (DA)

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12
Q

How does the sympathetic nervous system target the adrenal medulla?

A

Doesn’t go through sympathetic ganglia

ACh released into adrenal medulla, causes release of adrenaline and noradrenaline into the blood

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13
Q

Describe the neurotransmitters used by the parasympathetic neurones

A

ACh

At preganglionic synapse and postganglionic synapse

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14
Q

Describe the neurotransmitters used at different stages by the somatic nervous system

A

CNS to motor neurone: Glu

Motor to effector organ: ACh

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15
Q

Describe the pathway of the parasympathetic pre-ganglionic neurone

A

Long pre-ganglionic neurone arises from brainstem and lateral horn of grey matter in sacral spinal cord segments
Brainstem: pre-ganglionic neurone travels with cranial nerves III, VII, IX and X
Sacral spinal cord: pre-ganglionic neurone enters ventral rami of S2-S4 spinal nerves and branch off to form pelvic splanchnic nerves

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16
Q

Describe the 4 parasympathetic cranial nerves

A

III Oculomotor: pupil constriction
VII Facial nerve: Salivation
IX Glossopharyngeal: Salivation
X Vagus: bradycardia, gastric motility, digestion

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17
Q

Describe the biosynthesis of Noradrenaline

enzymes used to make next product

A 
L-Phenylalanine
L-Tyrosine (Tyrosine hydroxylase)
L-DOPA (DOPA decarboxylase)
Dopamine (Dopamine hydroxylase)
Noradrenaline
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18
Q

Describe the biosynthesis of Acetylcholine

enzymes used to make next product

A

Acetate + Choline (choline acetyltransferase)

Acetylcholine + CoA

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19
Q

Describe the removal of noradrenaline from the synaptic cleft

A

Presynaptic uptake: MAO-A

Postsynaptic uptake: COMT

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20
Q

Describe the removal of acetylcholine from the synaptic cleft

A

Acetylcholinesterase breaks ACh into Acetate + Choline

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21
Q

Describe the biosynthesis of Adrenaline

enzymes used to make next product

A 
L-Tyrosine (Tyrosine hydroxylase)
L-DOPA (DOPA decarboxylase)
Dopamine (Dopamine hydroxylase)
Noradrenaline (PNMT)
Adrenaline
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22
Q

How do baroreceptors communicates the brain?

A

1 in Aortic arch: Vagus nerve (X)

2 in Carotids: Glossopharyngeal nerve (IX)

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23
Q

What happens at high BP? (regulatory function of ANS)

A

Baroreceptors become activated
Increased baroreceptor firing rate
Parasympathetic innervation of heart to decrease CO and via sympathetic inhibition, dilate blood vessels to decrease BP

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24
Q

How set point of BP that causes increased baroreceptor firing rate different in hypertensive patients?

A

Their set point is higher

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25
Q

Which nerve is involved in regulation of GI function?

A

Vagus nerve

26
Q

How does the vagus nerve effect the pancreas and stomach in the cephalic response?

A

Pancreas: Insulin released
Stomach: Gastric juices released

27
Q

Describe the action of mechanoreceptors in the regulation of GI function

A

Detect distension of stomach wall and duodenum
Send info via Vagus nerve to brainstem (to tell brain you’ve eaten)
Degree of distension increases firing rate proportionally

28
Q

Describe the action of chemoreceptors in the regulation of GI function

A

Released when food enters GI tract

Signal via vagus nerve to brainstem to tell you to stop eating

29
Q

How is the mechanoreceptor in obese people different?

A

Mechanoreceptor sensitivity and firing is dulled,
need more food in stomach to cause firing,
need more food to feel full

30
Q

Why is the vagus nerve described as plastic?

A

Can change its expression of receptors:
if hungry, don’t want to be able to respond to satiety hormones so wont express satiety receptors, so wont be able to “feel full”.
Once start eating, start expressing satiety receptors.

31
Q

Describe the 3 respiratory centres in brain that determine respiratory rate

A

Pontine respiratory centre: Coordinates rate and pattern of breathing
Ventral group: Coordinates rhythmicity
Dorsal group: Responsible for inspiration and control of diaphragm

32
Q

Which chemoreceptors related to respiratory function transmit via which nerve?

A

Aortic chemoreceptors: Vagus nerve (X)

Carotid body chemoreceptors: Glossopharyngeal nerve (IX)

33
Q

How do central and peripheral chemoreceptors respond to changes in O2, pH and CO2?

A

Communicate to dorsal group in brainstem to increase respiration.

34
Q

What is the protective reflex preventing over inflation of the lungs? How does this work?

A

Hering-Bruer reflex
Mechanoreceptors in lung transmit via Vagus nerve (X)
Work to inhibit outflow of dorsal group to decrease respiration

35
Q

Describe the regulation of bladder control by the ANS

A

When bladder fills this stimulates the micturition reflex where there is activation of the PNS and inhibition of the SNS
PNS: contraction of the detrusor muscle and relaxation of the internal sphincter
Sympathetic: contraction of the internal sphincter
Somatic control of external sphincter

36
Q

How do afferent mechanoreceptors send info on distension of bladder wall to the brain?

A

Via S2-S4 (parasympathetic nerves)

37
Q

Describe the receptors used in the parasympathetic nervous system

A

CHOLINOCEPTORS (Nicotinic and Muscarinic)
Pre-ganglionic: Nicotinic ACh receptor
Post-ganglionic: Muscarinic ACh receptor

38
Q

Describe the receptors used in the sympathetic nervous system

A

ADRENOCEPTORS
Pre-ganglionic: Nicotinic ACh receptor
Post-ganglionic neurone: Adrenoreceptors (NA)

39
Q

Describe the types of adrenoreceptors

A

Alpha: Alpha 1 (A, B, D), Alpha 2 (A,B, C),
Beta: Beta 1, Beta 2

40
Q

What are the 2 types of receptor?

A

Ion channels

G-protein coupled receptors (GPCR)

41
Q

How does an ion channel work?

A

Ligand binds to receptor
Causes conformational shape change in receptor
Allows ions to pass through
Changes membrane potential- triggers/ inhibits AP

42
Q

How does an GPCR work?

A

Ligand binds to outer membrane
Activates downstream signalling components
Long lasting effects due to downstream signalling (vs ion channels which are rapid opening/closing)

43
Q

What are the 2 types of receptor locality?

A

Presynaptic receptors work to control amount of neurotransmitter released (regulatory)
Postsynaptic receptor on post synaptic terminal respond to neurotransmitters from presynaptic neurone and propagate AP through next neurone

44
Q

Describe the events in cholinergic receptors of the PNS

A

Parasympathetic preganglionic targets the organ
1st synapse: ACh binds to Nicotinic receptor on postganglionic neurone
Post ganglionic releases ACh onto tissue which binds to Muscarinic receptor

45
Q

Nicotinic receptors (location, stimulus, type)

A

Location: All autonomic ganglia
Stimulus: ACh
Type: Ionotropic

46
Q

Muscarinic receptors (location, stimulus, type)

A

Location: Effector organs with parasympathetic innervation (and sympathetic at certain sites)
Stimulus: ACh
Type: G-protein coupled

47
Q

Adrenoreceptors (location, stimulus, type)

A

Location: Effector organs with sympathetic innervation
Stimulus: NA/A
Type: G-protein coupled

48
Q

Give 2 examples of cholinergic drugs and what they do

A

Atropine: Competitive muscarinic receptor antagonist (Increases HR)
Tubocurarine: Nicotinic receptor antagonist (Increases HR, decreases respiration)

49
Q

Why is tubocurarine rarely used?

A

It will act on nicotinic receptors at the NMJ

Results in muscle paralysis

50
Q

Where are each of the adrenoreceptors found?

A

Alpha 1: on effector organ e.g. blood vessel
Alpha 2: PRESYNAPTIC receptors, prevent release of more NA into synapse
Beta 1: exclusively in cardiac tissue
Beta 2: involved in relaxing certain muscle e.g. sphincters of GI tract

51
Q

What drug would you use to target the Alpha 1 adrenoreceptor? What does this cause?

A

Doxazosin (Alpha 1 receptor antagonist)
Causes smooth muscle dilation
(could be used as an anti-hypertensive)

52
Q

What drug would you use to target the Alpha 2 adrenoreceptor? What does this cause?

A

Medetomidine (Alpha 2 receptor agonist)

Causes reduction in NA release

53
Q

What drug would you use to target the Beta 1 adrenoreceptor? What does this cause?

A

Atenolol (Beta 1 receptor antagonist)

Heart specific: reduces HR

54
Q

What drug would you use to target the Beta 2 adrenoreceptor? What does this cause?

A

Salbutamol (Beta 2 receptor agonist).
Relaxes smooth muscles.
Could be used to treat an asthma attack.

55
Q

Describe Shy-Drager Syndrome/Multiple System Atrophy

A 
Neurodegenerative disease (Synucleopathy)
Loss of intermediolateral cell bodies and striatonigral brain areas
Rare
56
Q

List 6 symptoms of Shy-Drager Syndrome/Multiple System Atrophy

A 
Orthostatic hypotension
Impotence
Hypohidrosis (no sweat)
Dry mouth
Urinary retention
Incontinence
57
Q

How is hypertension considered a disorder of the autonomic nervous system?

A

Exaggerated sympathetic nerve activity to blood vessels and renal bed leads to increased circulating volume and vascular tone

58
Q

How is heart failure considered a disorder of the autonomic nervous system?

A

Inability to pump sufficient blood to meet oxygen demand
Increased sympathetic nerve activity to renal bed:
Leads to hypervolaemia and hypernatraemia
Increases strain on cardiac tissue

59
Q

How is Parkinson’s Disease considered a disorder of the autonomic nervous system?

A

Early sign of PD is autonomic dysfunction (orthostatic hypotension, constipation)
Vagus nerve may be involved in aetiology

60
Q

Nucleus Tractus Solitarius (NTS)

A

Receives input from CN IX and X
Sends info up to hypothalamus for integration
Signals return down the dorsal motor nucleus of the vagus, controlling the output or directly to intermediolateral ells columns

61
Q

Intermediolateral cell column

A

T1-L2
Target of pre-sympathetic neurones
Site where sympathetic neurones emirate from, travelling to the sympathetic ganglia outside of the cord, synapsing to post-ganglionic neurones

62
Q

Describe which segments of the spinal vertebrae innervate which areas

A

C1-C3: Accessory muscles
C3-C5: Diaphragm (via phrenic nerve)
T1-T11: Intercostal muscles
T6-T11: Abdominal muscles

Neuroscience and Mental health (11 decks)

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