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Flashcards in The sympathetic nervous system Deck (42)
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1

What is the structure of Acetylcholine, label the charges if there are any present?

2

What are the substrates of Acetylcholine?

The substrates are Choline and AcetylCoA

3

How is choline taken up into the nerve terminal?

By a choline transporter in the membrane, this is the rate limiting step for synthesis 

4

What is the reaction for the production of Acetylcholine? 

Whats the by product? 

What enzyme is used?

AcetylCoA + Choline --> Acetylcholine + CoA 

Enzyme: Choline Acetyltransferase (CAT)

5

How is Ach taken up in vesicles? 

Are these pre or post synaptic vesicles? 

What can this process be blocked by?

ACh is taken up into presynaptic Vesicles by an active transport process. This can be blocked by Vesamicol

6

What is ACh released in response to?

ACh is released in response to calcium entry into the presynaptic terminal

7

How is ACh inactivated?

What are the stages to this process?

  1. Following release into the synaptic cleft, ACh is available to active receptors
  2. The synaptic cleft is also rich in the enzyme Acetylcholinesterase which breaks ACh down into choline and acetic acid
  3. choline is taken back up into the nerve terminal by the choline transporter. this is blocked by Hemicholinium 

8

What 3 compounds did dale use to characterise cholinergic transmission?

  • Muscarine 
  • Nicotine
  • Atropine 

" two distinct types of action can be detected- a 'muscarine' action, paralysed by atropine, and a 'nicotine' action, paralysed by excess of nicotine"

9

What did Dale's experiment show using ACh?

  • It produces 2 different effects on blood pressure 
  • Why does the same compound triggers two dose-dependent opposite responses? 
  • Shows muscarinic and nicotinic receptors 

10

Draw the parasympathetic organ synapse 

11

Draw the structure of Muscarine 

12

WIth muscarinic transmission, what is the main agonist?

Muscarine 

13

Table showing how different drugs effect different chemicals actions 

14

Tell me the effects that the agonists have on the below organ system when they bind to muscarinic receptors? 

  • Cardiovascular system 
  • Gastrointestinal actions 
  • Exocrine gland secretion

  • Cardiovascular decreases HR, CO and vasodilation
  • Gastrointestinal actions increased activity (GIT smooth muscle contracts and increased peristaltic activity)
  • Exocrine gland secretion increased sweating, lacrimation and salivation (contracts bladder and bronchial smooth muscles; sweating, lacrimation, salivation, bronchial secretion)

15

Why does a decrease in HR and CO result in a sharp fall in BP?

mAChR result in release of NO which causes vasodilation

16

What is the treatment of acute angle-closure Glaucoma?

  • parasympathetic innervation of constrictor pupillae 
  • parasympathetic innervation of ciliary muscles: use of pilocarpine in glaucoma to relieve pressure 
  • contracts ciliary muscle in the eye- this can help relieve increased intraocular pressure in glaucoma (commonest cause of blindness).  (pilocarpine can be used)

17

What are the main muscarinic receptor subtypes and what type of receptors are they?

M1: Neural 

M2: Cardiac 

M3: Glandular 

They are all G protein coupled receptors (GPCRs)

18

Tell me the following about the M1 receptor... 

  • Main location 
  • Cellular action
  • Function

19

Tell me the following about M2 receptors... 

Main location

Cellular action 

Function

20

Tell me the following about M3 receptors 

Main location

Cellular action 

Function

21

What muscarinic receptors are stimulatory and which are inhibitory?

Stimulatory: M1, M3, M5

Inhibitory: M2 and M4

22

Muscarinic 

23

Name the muscarinic receptor antagonists?

Atropine 

Pirenzepine 

24

What are the effects of muscarinic antagonists?

  • inhibition of secretions
  • effect on heart rate
  • effects on the eye
  • effects on the gut
  • effects on other smooth muscle
  • effects on the CNS
  • CLINICAL USES

25

What are the receptors for ACh in the sympathetic and parasympathetic nervous system?

Muscarinic is the receptor in the parasympathetic nervous system 

Nicotinic is the receptor in the sympathetic nervous system 

26

What enzyme is used to break down the neurotransmitter ACh?

Acetylcholinesterase 

27

Draw and explain nicotinic transmission at autonimic ganglia 

28

What type of channels are nicotinic receptors and what are they permeable to?

All nicotinic receptors are ligand-gated ion channels are are permeable to cations

29

Whats different with the nicotinic receptors compared to those from the muscle?

The isoform at the ganglia is different from the muscle 

30

When ACh binds to the nicotinic receptor, what movement of ions occurs?

Na+ are imported and K+ exported