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Year 2 - Musculoskeletal (DP) > Pharmacology > Flashcards

Flashcards in Pharmacology Deck (81)
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1

Where are motor neurone cell bodies located?

Grey matter:
- Inner spinal cord
- Surface of brain

2

Are motor neurones myelinated?

Yes

3

Are motor neurone branches supplying individual muscle fibres myelinated?

No

4

What does each branch of a motor neurone divide into? What is the function of this?

Terminal bouton:
- Forms a chemical synapse at NMJ
- Releases ACh

5

Where do synaptic vesicles move to in the terminal bouton to release ACh?

Active zones

6

What part of the muscle fibre receives the incoming ACh?

End-plate

7

What happens to the sarcolemma in the end-plate?

Thrown into folds:
- Nicotinic ACh receptors at junctional folds

8

Describe briefly an overview of synaptic transmission

1. Choline + AcetylCoA = ACh
2. ACh storage
3. ACh release upon Calcium influx
4. Receptor activation
5. ACh inactivation by acetylcholinesterase
6. Re-uptake of choline and acetylCoA

9

How is choline transported into the pre-synaptic nerve?

Via choline transporter:
- Symported with sodium

10

Where dose the AcetylCoA come from for ACh formation?

Mitochondria

11

Where is ACh synthesised and what enzyme catalyses it?

Cytosol
Choline acetyltransferase

12

What happens when an action potential arrives at the pre-synapse?

1. Depolarisation
2. Opening of voltage-gated calcium channels
3. Calcium influx

13

What happens after calcium influx?

ACh-containing vesicles exocytose into cleft at active zones

14

What is the structure of the nicotinic ACh receptor?

Pentamer of glycoprotein subunits:
- [(Alpha1)2, Beta1, Delta, Epsilon]

15

What is the epsilon subunit in embryonic muscle nicotinic ACh receptors?

A Gamma subunit

16

What does the nicotinic ACh receptor surround?

Central, cation sensitive pore:
- Five M2 helices

17

What is the conformation of the pore in:
1. Absence of ACh
2. The binding of one ACh
3. The binding of two ACh
4. The binding of three ACh

1. Closed
2. Closed
3. Open
4. Not possible

18

Which one of the following values is the rough true value for the permeability ratio of the nicotinic ACh pore to potassium and sodium (PK+/PNa+):
A) 0.7
B) 0.9
C) 1.1
D) 1.4
E) 2.3

C) 1.1
They have roughly the same permeability

19

What ions move in/out of the pore in the sarcolemma?

Sodium in
Potassium out

20

At resting potential, which effect is the greatest; the sodium driving force or the potassium driving force and what does this result in?

Sodium driving force since sodium in > potassium out:
- Depolarisation -> End Plate Potention (e.p.p.)

21

How do we describe the amount of ACh contained in a vesicle?

A quantum

22

What do we call the electrical response on the sarcolemma upon exposure to one quantum of ACh?

Miniature e.p.p.

23

What dose the term 'Electrotonic repsonse' mean?

Many m.e.p.p. sum to produce the e.p.p

24

What does the End Plate Potential need to be greater than to trigger an 'all-or-nothing' AP to be generated?

Threshold

25

What happens when threshold is reached?

Voltage-activated sodium channels open up along the sarcolemma resulting in contraction along the muscle

26

Why do we need sodium channels along the length of the muscle fibre?

To allow AP propagation

27

What feature of the sarcolemma does the AP enter that is in close proximity to the sarcoplasmic reticulum?

Transverse (T) Tubules

28

What does the AP trigger when it gets close to the SR?

Calcium release

29

When calcium is released from inside the SR into the cell what happens?

It interacts with troponin on myofibrils -> Contraction

30

What does acetylcholinesterase hydrolyse ACh into?

Choline and acetate