ICPP - Autonomic Nervous System Flashcards Preview

CJ: UoL Medicine Semester One (ESA1) > ICPP - Autonomic Nervous System > Flashcards

Flashcards in ICPP - Autonomic Nervous System Deck (39):
1

The autonomic nervous system and the somatic nervous system form part of what?

The peripheral nervous system

2

What does the autonomic nervous system split into?

Sympathetic and para-sympathetic

3

Where is the term "autonomic" derived from?

Greek 'autos' (self) and 'nomos' (law), meaning self-governing

4

Does the ANS control voluntary or involuntary functions?

Involuntary, eg heart rate, blood pressure, GI motility

5

Is the ANS efferent or afferent?

Entirely efferent, but regulated by afferent inputs

6

Briefly outline the roles of the sympathetic and parasympathetic nervous systems.

Sympathetic - responds to stressful situations, "fight or flight" response, increases heart rate/force of contraction/blood pressure

Parasympathetic - regulates basal activities, "rest and digest"

7

What are the five sections that the ANS is divided into? What do they control?

Medullary - eye, lacrimal + salivary glands

Cranial

Thoracic - Structures in head and neck, heart, lungs, adrenal medulla, liver, GI tract, bladder, genitalia

Lumbar - also controls bladder and genitalia

Sacral - Lower GI tract, bladder, genitalia

8

Which sections of the brain and spinal cord are under sympathetic control and which are under parasympathetic?

Sympathetic - thoracic and lumbar
Para-sympathetic - medullary, cranial and sacral

9

Where do parasympathetic nerves originate?

Lateral horn of the medulla

10

Describe the pre- and postganglionic fibres in the PNS.

- long myelinated pre-ganglionic fibres
- short unmyelinated post-ganglionic fibres

11

Where are the ganglia located in the PNS?

Within innervated tissues

12

Where do sympathetic nerves originate?

In the lateral horn of the lumbar and thoracic spinal cord

13

Describe the pre- and post-ganglionic fibres of the SNS.

- short myelinated preganglionic fibres
- long unmyelinated post-ganglionic fibres

14

Where are the ganglia located in the SNS?

In the paravertebral chain close to the spinal cord

15

What are the principal neurotransmitters in the ANS?

Acetylcholine (ACh) and noradrenaline (NA)

16

What sort of channels are nicotinic ACh receptors?

Ligand-gated ion channels

17

What neurotransmitter do all pre-ganglionic neurones use?

ACh

18

Which neurotransmitter do post ganglionic sympathetic and parasympathetic neurons use?

PNS - ACh
SNS - NA

19

Which receptors does ACh act on?

Muscarinic ACh receptors (GCPRs) - m1, m2, m3, m4, m5 and nAChR

20

Which receptors does NA interact with?

Alpha-adrenoceptors and beta-adrenoceptors (a1, a2, b1, b2, b3)

21

Can some specialised sympathetic post-ganglionic neurons be cholinergic rather than noradrenergic?

Yes, eg sweat glands and hair follicles

22

What are NANC transmitters?

Non-adrenergic, non-cholinergic transmitters. Examples include ATP, nitric oxide, serotonin and VIP

23

Why are sympathetic post-ganglionic neurons in the adrenal glands different?

They form neurosecretory chromaffin cells, which can be considered as post-ganglionic sympathetic neurons. On sympathetic stimulation, they release adrenaline into the bloodstream.

24

Give some consequences of parasympathetic release of ACh.

- heart slows
- bronchial contraction
- increased intestinal mobility
- increased sweat/salivary/lacrimal secretion

25

Give some consequences of sympathetic release of noradrenaline.

- tachycardia and positive inotropy
- bronchiolar relaxation
- increased salivary secretion
- renin release from kidneys

26

What is the umbrella term for distinct malfunctions of the ANS?

Dysautonomia

27

Which parts of neurotransmission across a synapse can be targeted by drugs?

- degradation of transmitter
- interaction with post-synaptic receptors
- inactivation of transmitter
- re-uptake of transmitter
- interaction with pre-synaptic receptors

28

How is acetylcholine synthesised?

Acetylcholine CoA + choline -> acetylcholine + coenzyme A

This uses choline acetyltransferase (CAT)

29

How is acetylcholine degraded?

Acetylcholine -> acetate + choline

This uses acetylcholinesterase (AChE)

30

Why is it difficult to treat disorders with drugs that affect muscarinic receptors?

There are five mAChR subtypes, but few subtype-selective agonists/antagonists, meaning they have a large amount of side effects

31

What side effects would a non-selective, muscarinic ACh receptor agonist be likely to cause?

- decreased heart rate and cardiac output
- increased bronchoconstriction and GI tract peristalsis
- increased sweating and salivation

32

What are the pathological effects indicative of massive discharge of the parasympathetic nervous system? (SLUDGE)

Salivation
Lacrimation
Urination (relaxation of sphincter)
Defecation
Gastrointestinal upset
Emesis

33

When are the SLUDGE symptoms usually encountered?

- drug overdose
- ingestion of magic mushrooms
- exposure to organophosphorus insecticides or nerve gases (theses covalently-modify AChE, so ACh levels are raised)

Treated with atropine, palidoxime or other anti-cholinergic agents

34

Give some clinical uses of mACh receptor agonists/antagonists.

- pilocarpine and bethanechol (agonists) treat glaucoma and stimulate bladder emptying respectively

- ipratropium and tiotropium (antagonists) treat athsma and COPD

35

What is a "varicosity" in a post-ganglionic sympathetic neuron?

A bulge in the axon which serves as a specialised site for Ca2+ dependent noradrenaline release

36

How is noradrenaline synthesised?

Tyrosine -> DOPA -> dopamine (passes from cytosol to vesicle) -> noradrenaline

Within adrenal medulla, an enzyme converts noradrenaline to adrenaline

37

Which ion is required for exocytosis release of NA?

Ca2+

38

What is the difference between uptake 1 and uptake 2 in noradrenergic transmission?

Uptake 1 - NA actions terminated by re-uptake into pre-synaptic terminal by Na+ dependent, high affinity transporter
Uptake 2 - left over NA is taken in by lower affinity, non-neuronal mechanism

39

What happens to NA once it's taken into the pre-synaptic terminal?

- some goes into vesicles where it's stored for re-use
- remainder is susceptible to metabolism by monoamine oxidase (MAO) or COMT

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