pharmacology

Question 1

where are the cell bodies of pre and post ganglionic fibres located

Answer 1

pre- brainstem and post- bronchi/bronchioles wall

Question 2

what does parasympathetic stimulation of cholinergic fibres cause

Answer 2

it causes the bronchial smooth muscle contraction mediated by M3 muscarinic ACh receptors on ASM cells and increased mucus secretion mediated by the M3 muscarinic ACh receptors on the gland (goblet) cells.

Question 3

What does parasympathetic stimulation of the post ganglionic noncholinergic fibres cause

Answer 3

bronchial smooth muscle relaxation mediated by nitro oxide (NO) and vasoactive intestinal peptide (VIP)

Question 4

How does sympathetic stimulation affect the respiratory system

Answer 4

bronchial smooth muscle relaxation via the beta2-receptors on ASM checks activated by adrenaline released from the adrenal glands. Decreased mucous production from the beta2-receptors working on the gland (goblet) cells. Increased mucociliary clearance mediated by the beta2-adrenoceptors on epithelial cells. And vascular smith muscle contraction mediated by the alpha1-adrenoceptors on vascular smooth muscle cells.

Question 5

what causes contraction

Answer 5

contraction results from the phosphorylation of the regulatory myosin light chain (MLC) in the presence of elevated intracellular Ca2+ (and ATP).

Question 6

What causes relaxation

Answer 6

relaxation results from the dephosphorylation of myosin light chain (MLC) by myosin phosphatase which has constitutive activity

Question 7

why does Ca2+ have to return to basal level in order for relaxation to occur

Answer 7

because in the presence of elevated Ca2+ the rate of phosphorylation exceeds the rate of dephosphorylation