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Flashcards in Autonomic nervous system Deck (18)
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1
Q

Function of autonomic nervous system

A

Regulates functions with little or no voluntary control via a pair of opposing systems - parasympathetic (comfort) vs sympathetic (crisis)
Tissues that can be innervated: smooth muscle, cardiac muscle, exocrine glands, endocrine glands, fat cells

2
Q

Function of parasympathetic nervous system

A
  • Constricts pupils
  • Stimulates salivary glands
  • Decreases heart rate
  • No effect on arterioles
  • Constricts bronchi
  • Stimulates peristalsis
  • Stimulates contraction of bladder
  • No effect on sweat glands
3
Q

Function of sympathetic nervous system

A
  • Dilates pupils
  • Inhibits salivary glands
  • Increases heart rate
  • Constricts arterioles
  • Dilates bronchi via adrenaline
  • Inhibits peristalsis
  • Inhibits bladder contraction
  • Stimulates sweat glands via ACh receptors
4
Q

Which areas of the body does the sympathetic nervous system innervate?

A

T1-L2

5
Q

Which areas of the body does the parasympathetic nervous system innervate?

A

S2, S3, S4

Cranial nerves 3,7,9,10

6
Q

Characteristics of parasympathetic pathway

A

2 neurones - long pre-ganglionic and short post-ganglionic
Ganglia close to final destination
Vagus nerve 0 autonomic functions and motor and sensory output to larynx/pharynx for speech and airways

7
Q

Characteristics of sympathetic pathway

A
  • 2 neuron pathway - short pre-ganglionic and long post-ganglionic
  • Ganglia mostly in sympathetic chain (ascends to supply head, descends to supply pelvis)
  • Also directly innervates adrenal medulla - directly from pre-ganglionic neuron and releases adrenaline
8
Q

Symptoms of Horner’s syndrome

A

Constricted pupil
Eyelid droops
Dry eyes

9
Q

What will be the first neurotransmitter in either nervous system?

A

ACh which binds to nAChR

10
Q

Which neurotransmitter affects sweat glands in the sympathetic nervous system?

A

ACh

11
Q

Parasympathetic acting distally in organ

A
  • Ganglion - ACh: nictinic
  • Terminal synapse - ACh: muscarinic
  • Nicotinic: ligand-gated ion channel (Na+), e.g. neural and muscle
  • Muscarinic: G-protein couples, e.g. M1, M2, M3, M4, M5, some Gi and Gq
  • ACh is recycling mechanism - broken down to clear synaptic cleft
12
Q

What is the neurotransmitter in all parasympathetic mAChR receptors?

A

ACh

13
Q

Sympathetic neurotransmitters acting distally in organ

A
  • Ganglion - ACh: nicotinic
  • Terminal synapse - NA (ACh for sweating)
  • Adrenoreceptors: all G protein coupled
  • A1 receptor: Gq sub-type, activates phospholipase C
  • B1 receptor: Gs sub type, activates adenylate cyclase
  • Noradrenaline is primarily post-ganglionic transmitter
  • Adrenaline is primarily released from adrenal medulla
14
Q

What class of drug would help to pass urine?

A
  • Drugs can either stimulate a receptor (agonist) or inhibit the receptor (antagonist)
15
Q

What classes of drug would be used to increase heart rate?

A

B1 agonist or muscarinic antagonist

  • The anti-muscarinic drug atropine is usually used for bradycardia
  • Alternatively, isoprenaline or adrenaline can be used, acting via stimulation of B1 receptors
16
Q

What type of receptor stimulates an increase in sweating?

A

Cholinergic muscarinic

  • Sweating mediated by sympathetic cholinergic fibres
  • Hyperhidrosis can be treated by botox injections locally, which reduces synaptic ACh release
17
Q

What is the likely mechanism of action to constrict pupil?

A

Muscarinic agonist

  • Pilocarpine (selective M3 agonist) treats glaucoma by constricting pupil
  • A1 blockers can have similar action although rarely used to treat glaucoma
18
Q

What are the main actions you would want from the ideal drug to treat an anaphylactic reaction?

A

A1 agonist and B2 agonist

  • Anaphylaxis results in profound histamine-induced hypotension and/or bronchospasm
  • Adrenaline is drug of choice, by stimulating A1 and B2