Physiology and Pharmacology of the Autonomic Nervous System

Question 1

What is the autonomic nervous system split into

Answer 1

Sympathetic and parasympathetic

Question 2

What is the effect of the sympathetic and parasympathetic systems on the eyes, lungs, heart and liver

Answer 2

eyes - dilate pupils, constricts pupils
lungs - dilates bronchi, constricts bronchi
heart - accelerates heart rate, decreases heart rate
liver - stimulates glucose production + release, stimulates bile release

Question 3

What controls the autonomic nervous system

Answer 3

Nucleus tractus solitarius

Question 4

Where does the sympathetic nervous system emanate from

Answer 4

T1-L3 on the spinal cord

Question 5

Describe the sympathetic short pre-ganglionic neurone

Answer 5

Arises from the lateral horn of grey matter
Emerges from the ventral root of the spinal cord
Enters the ventral rami of T1-L3
Detours via white rami communicans to enter the sympathetic ganglion

Question 6

Describe the sympathetic ganglia

Answer 6

Exists as sympathetic trunks
Contains cell bodies of post ganglionic neurones
Short pre ganglionic neurone synapses with the longer post-ganglionic neurones
ACh is the NT for pre-ganglionic neurones

Question 7

Describe the sympathetic long post-ganglionic neurone

Answer 7

Exits via the grey ramus communicans and innervates the effector

Question 8

What are the roles of the sympathetic system

Answer 8

Fight or flight
Constrict/dilate the blood vessels
Heart beat harder and faster
Dilation of pupils
Dilation of the trachea

Question 9

Which nerves make up the parasympathetic system

Answer 9

Sacral splanchnic nerves S2-S4

Cranial nerves III, VII, IX, X

Question 10

Which nerves are involved in the following processes: pupil constriction, salivation, bradycardia and gastric motility

Answer 10

Pupil constriction - III oculomotor
Salivation - VII facial nerve & IX glossopharyngeal
Brady cardia and gastric motility - X vagus

Question 11

How does the sympathetic and parasympathetic differ in ganglion

Answer 11

Sympathetic - Ganglia is outside the target organ

Parasympathetic - Ganglia is inside the target organ

Question 12

Describe the parasympathetic long pre-ganglionic neurone

Answer 12

Arises from the brainstem and lateral horn of grey matter in the sacral spinal cord segments
brainstem: pre-ganglionic neurone travels with cranial nerves 3,7,9,10
sacral spinal cord: Pre-ganglionic neurone enters ventral rami of S2-S4 spinal nerves and branch off to form pelvic splanchnic nerves
Synapse with short post ganglionic neurones

Question 13

Which parasympathetic ganglia associate with the cranial nerves

Answer 13

Ciliary
Pterygopalatine
Submandibular
Otic

Question 14

What are the functions of the parasympathetic nervous system

Answer 14

Rest and digest
Heart beats slower
Constrict the pupils
Constricts the trachea
Increased motility tone, secretions and contraction

Question 15

Compare the sympathetic to parasympathetic pathway

Answer 15

sympathetic - short (nicotinic ACh) to long (Adrenoreceptors NA)
parasympathetic- long (nicotinic ACh) to short (muscarinic ACh)

Question 16

What are the two exceptions to the general structure of (para)sympathetic pathways

Answer 16

1. Short pre-ganglionic neurone to the adrenal medulla
2. Nicotinic ACh receptor
3. Chromaffin cells in adrenal medulla release catecholamines
4. Adrenoreceptors
5. Short pre-ganglionic neurone to the sympathetic trunk
6. Nicotinic ACh receptor
7. Long post-ganglionic neurone releasing ACh
8. Muscarinic ACh receptor

Question 17

What is the excitatory neurotransmitter for the pre-symapthetic neurones

Answer 17

Glutamate

Question 18

Where is acetylcholine used as a neurotransmitter for the postganglionic neurones

Answer 18

heart kidney, vessels, sweat glands

Question 19

What neurotransmitter is used for the post ganglionic neurones in the renal vessels

Answer 19

Dopamine

Question 20

Describe the biosynthesis of acetylcholine

Answer 20

1. Acetyl CoA
Choline acetyl transferase
2. AcetylCholine + CoA
acetylcholinesterase
3. Acetate + Choline

Question 21

Describe the biosynthesis of noradrenaline

Answer 21

1. Tyrosine
	Tyrosine hydroxylase
2. DOPA
	DOPA decarboxylase
3. Dopamine 
Dopamine hydroxylase in the vesicle
4. Noradrenaline
a. Uptake into the pre-synaptic bulb -> MAO-A
b. Postsynaptic uptake+ peripheral uptake -> COMT
5. Metabolites

Question 22

Describe nicotinic receptors

Answer 22

Ionotropic receptors type 1
Present at all autonomic ganglia (both sympathetic and parasympathetic) hence why tubocurarine increases heart rate
Allows action potential generation
ACh

Question 23

Describe muscarinic receptors

Answer 23

G-protein coupled type 2
Effector organs with parasympathetic innervation
Stimulated by all postganglionic PNS neurons also stimulated by SNS at selected sites
ACh

Question 24

Describe adrenergic receptors

Answer 24

All adrenergic receptors are G-protein coupled type 2
Effector organs with sympathetic innervation
Majority uses noradrenaline
A1 & A2 = Smooth muscle contraction (e.g. blood vessels, ureter, bronchioles)
B1 = Heart
B2 = Relax smooth muscle, contract sphincters of GI tract

Question 25

Explain bladder control

Answer 25

When bladder fills this stimulates the micturition reflex where there is activation of the PNS and inhibition of the SNS PNS causes contraction of the detrusor muscle and relaxation of the internal sphincter Sympathetic control causes contraction of the internal sphincter There is also somatic control over the external sphincter

Question 26

Where are the baroreceptors located

Answer 26

Aorta and carotid aorta -> IX glossopharyngeal carotid -> X vagus

Question 27

Describe the response to a small increase in blood pressure

Answer 27

Great increase in baroreceptor firing rate | Hypertensive patients will have a greater set point that blood pressure is controlled at

Question 28

Describe the regulation of GI function

Answer 28

Innervation by the vagus nerve Sight, smell, and taste of food causes saliva production Release of acid into the stomach Cephalic response (response before digestion) where insulin is produced

Question 29

What are the sensing mechanisms of the GI tract

Answer 29

Stomach - Mechanoreceptors that sends information to the brain via the vagus nerve The intestines release GLP-1, PYY and CCK which sends signals via the vagus nerve to the brain stem

Question 30

What are the sensing mechanisms of the respiratory system

Answer 30

Central chemoreceptors exist on the brainstem which recognise a change in pH (CO2) Mechanoreceptors exist in the lungs which are involved in the hering-breuer reflex to to prevent over-inflating the lungs. Connected to the vagus nerve.

Question 31

How is the respiratory system innervated (accessory muscles, diaphragm, intercostal muscles, abdominal muscles)

Answer 31

C1-C3 = accessory muscles C3-C5 = diaphragm T1-T11 = intercostal muscles T6-L1 - abdominal muscles

Question 32

What are the types of sympathetic adrenoreceptors

Answer 32

alpha 1 - A, B, D alpha 2 - A, B, C beta 1 beta 2

Question 33

What does atropine do

Answer 33

Targets the organ receptor acting as a competitive muscarinic receptor antagonist Increases heart rate Decreases sweat production Dry mouth

Question 34

What does tubocurarine do

Answer 34

Nicotinic receptor antagonist (rarely used as it causes paralysis due to NMJs) Decreases respiration rate Increases heart rate

Question 35

What is shy-drager syndrome

Answer 35

``` Synucleopathy, PD and lew body dementia Associated with loss of intermediolateral cell bodies and striatonigral brain areas Symptoms: Orthostatic hypotension Impotence Hypohidrosis Dry mouth Urinary retention Incontinence ```

Question 36

What is primary hypertension caused by

Answer 36

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

Question 37

What is heart failure

Answer 37

Inability to pump sufficient blood to meet oxygen demand Associated with increased sympathetic nerve activity to the renal bed Leads to hypervolemia and hypernatraemia Increased strain on cardiac tissue

Question 38

Describe Parkinsons

Answer 38

Early signs is autonomic dysfunction (see above) | Emerging evidence that vagus nerve may be involved

Question 39

Explain the process of adrenaline synthesis

Answer 39

``` 1. Tyrosine Tyrosine hydroxylase 2. DOPA DOPA decarboxylase 2. Dopamine Dopamine hydroxylase 3. Noradrenaline PNMT 4. Adrenaline ```