Pharmacology

Question 1

In parasympathetic nerves what are the two types of postganglionic fibres?

Answer 1

• cholinergic (contraction)

- non cholinergic (relaxation)

Question 2

Where are the preganglionic neurons found?

Answer 2

brain stem

Question 3

Where are the postganglionic neurons found?

Answer 3

Embedded in the walls of bronchi and bronchioles

Question 4

Describe the two results of stimulation of postganglionic cholinergic fibres

Answer 4

• bronchial smooth muscle contraction mediated by M3 muscarinic ACh receptors on ASM cells
• increased mucus secretion mediated by M3 receptors on gland cells

Question 5

Describe the effect of stimulating postganglionic noncholinergic fibres

Answer 5

bronchial smooth muscle relaxation mediated by NO and vasoactive intestinal peptide

Question 6

In the sympathetic system what does stimulation of postganglionic fibres cause?

Answer 6

1. bronchial smooth muscle relaxation by B2 adrenoreceptos on ASM cells activated by adrenaline released by adrenal glands
2. decreased mucus secretion by mediated B2 adrenoreceptors on gland cells
3. increased mucociliary clearance mediated by B2 adrenoreceptors on epithelial cells
4. vascular smooth muscle contraction mediated by alpha 1 adrenoreceptors

Question 7

Describe the pathway by which a transmitter or hormone results in calcium release

Answer 7

1. It activates GPCR
2. PLC is released
3. PIP2 binds to PLC to form IP3
4. IP3 moves out of the cells and calcium moves in

Question 8

Describe the pathway by which depolarisation causes calcium release

Answer 8

1. Calcium channels open

2. Calcium moves out of the cell causing other calcium to move in

Question 9

How does movement of calcium result in contraction?

Answer 9

1. Calcium binds to caladium to form calcium caladium
2. This activates myosin light chain kinase
3. ATP breaks down to ADP + Pi
4. Myosin cross bridge is phosphorylated and thus activated
5. myosin binds to actin generating force contraction

Question 10

How does relaxation of smooth muscle occur?

Answer 10

Myosin phosphatase dephosphorylates myosin light chain and therefore returns calcium to basal level

Question 11

What process (phosphorylation or dephosphorylation) is faster in the case of high intracellular calcium?

Answer 11

Phosphorylation

Question 12

What happens when a beta 2 adrenoreceptor is activated by adrenaline (pathway of relaxation)?

Answer 12

1. Stimulatory G protein is released activating AC which causes ATP to turn into cAMP.
2. PDE degrades cAMP to 5’AMP
3. cAMP activates PkA

Question 13

What does activation of PkA result in?

Answer 13

1. Phosphorylation and stimulation of myosin phosphatase to facilitate relaxation
2. phosphorylation and inhibition of myosin light chain kinase to inhibit relaxation