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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
Which nerve is involved in regulation of GI function?
Vagus nerve
26
How does the vagus nerve effect the pancreas and stomach in the cephalic response?
Pancreas: Insulin released Stomach: Gastric juices released
27
Describe the action of mechanoreceptors in the regulation of GI function
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
Describe the action of chemoreceptors in the regulation of GI function
Released when food enters GI tract | Signal via vagus nerve to brainstem to tell you to stop eating
29
How is the mechanoreceptor in obese people different?
Mechanoreceptor sensitivity and firing is dulled, need more food in stomach to cause firing, need more food to feel full
30
Why is the vagus nerve described as plastic?
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
Describe the 3 respiratory centres in brain that determine respiratory rate
Pontine respiratory centre: Coordinates rate and pattern of breathing Ventral group: Coordinates rhythmicity Dorsal group: Responsible for inspiration and control of diaphragm
32
Which chemoreceptors related to respiratory function transmit via which nerve?
Aortic chemoreceptors: Vagus nerve (X) | Carotid body chemoreceptors: Glossopharyngeal nerve (IX)
33
How do central and peripheral chemoreceptors respond to changes in O2, pH and CO2?
Communicate to dorsal group in brainstem to increase respiration.
34
What is the protective reflex preventing over inflation of the lungs? How does this work?
Hering-Bruer reflex Mechanoreceptors in lung transmit via Vagus nerve (X) Work to inhibit outflow of dorsal group to decrease respiration
35
Describe the regulation of bladder control by the ANS
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
How do afferent mechanoreceptors send info on distension of bladder wall to the brain?
Via S2-S4 (parasympathetic nerves)
37
Describe the receptors used in the parasympathetic nervous system
CHOLINOCEPTORS (Nicotinic and Muscarinic) Pre-ganglionic: Nicotinic ACh receptor Post-ganglionic: Muscarinic ACh receptor
38
Describe the receptors used in the sympathetic nervous system
ADRENOCEPTORS Pre-ganglionic: Nicotinic ACh receptor Post-ganglionic neurone: Adrenoreceptors (NA)
39
Describe the types of adrenoreceptors
Alpha: Alpha 1 (A, B, D), Alpha 2 (A,B, C), Beta: Beta 1, Beta 2
40
What are the 2 types of receptor?
Ion channels | G-protein coupled receptors (GPCR)
41
How does an ion channel work?
Ligand binds to receptor Causes conformational shape change in receptor Allows ions to pass through Changes membrane potential- triggers/ inhibits AP
42
How does an GPCR work?
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
What are the 2 types of receptor locality?
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
Describe the events in cholinergic receptors of the PNS
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
Nicotinic receptors (location, stimulus, type)
Location: All autonomic ganglia Stimulus: ACh Type: Ionotropic
46
Muscarinic receptors (location, stimulus, type)
Location: Effector organs with parasympathetic innervation (and sympathetic at certain sites) Stimulus: ACh Type: G-protein coupled
47
Adrenoreceptors (location, stimulus, type)
Location: Effector organs with sympathetic innervation Stimulus: NA/A Type: G-protein coupled
48
Give 2 examples of cholinergic drugs and what they do
Atropine: Competitive muscarinic receptor antagonist (Increases HR) Tubocurarine: Nicotinic receptor antagonist (Increases HR, decreases respiration)
49
Why is tubocurarine rarely used?
It will act on nicotinic receptors at the NMJ | Results in muscle paralysis
50
Where are each of the adrenoreceptors found?
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
What drug would you use to target the Alpha 1 adrenoreceptor? What does this cause?
Doxazosin (Alpha 1 receptor antagonist) Causes smooth muscle dilation (could be used as an anti-hypertensive)
52
What drug would you use to target the Alpha 2 adrenoreceptor? What does this cause?
Medetomidine (Alpha 2 receptor agonist) | Causes reduction in NA release
53
What drug would you use to target the Beta 1 adrenoreceptor? What does this cause?
Atenolol (Beta 1 receptor antagonist) | Heart specific: reduces HR
54
What drug would you use to target the Beta 2 adrenoreceptor? What does this cause?
Salbutamol (Beta 2 receptor agonist). Relaxes smooth muscles. Could be used to treat an asthma attack.
55
Describe Shy-Drager Syndrome/Multiple System Atrophy
``` Neurodegenerative disease (Synucleopathy) Loss of intermediolateral cell bodies and striatonigral brain areas Rare ```
56
List 6 symptoms of Shy-Drager Syndrome/Multiple System Atrophy
``` Orthostatic hypotension Impotence Hypohidrosis (no sweat) Dry mouth Urinary retention Incontinence ```
57
How is hypertension considered a disorder of the autonomic nervous system?
Exaggerated sympathetic nerve activity to blood vessels and renal bed leads to increased circulating volume and vascular tone
58
How is heart failure considered a disorder of the autonomic nervous system?
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
How is Parkinson's Disease considered a disorder of the autonomic nervous system?
Early sign of PD is autonomic dysfunction (orthostatic hypotension, constipation) Vagus nerve may be involved in aetiology
60
Nucleus Tractus Solitarius (NTS)
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
Intermediolateral cell column
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
Describe which segments of the spinal vertebrae innervate which areas
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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