practice questions

Question 0

beta blockers…

Answer 0

can inhibit the release of renin by the kidney

Question 1

what is true about the macular region of the retina?

Answer 1

it contains fewer rods than cones, and few blood vessels transverse this region

Question 2

the effects of propranolol in man include?

Answer 2

tiredness
peripheral vasoconstriction
bradycardia
lethargy

Question 3

what happens in ventricular myocytes during contraction…

Answer 3

calcium overload can result in release of calcium from the sarcoplasmic reticulum, which is not synchronised to the action
calcium overload can result in waves of sarcoplasmic calcium release which propagates via calcium induced calcium release
contraction of the myofilaments involves calcium binding to troponin
most of the calcium that activates the myofilaments is released from the sarcoplasmic reticulum

Question 4

plasmids are..

Answer 4

closed circles of DNA
can be used to express recombinant protein
contain an origin of replication
have a selectable marker such as an antibiotic resistance gene

Question 5

regarding recombinant DNA techniques…

Answer 5

restriction enzymes recognition sites can be added to the ends of fragments of DNA amplified by PCR
beta-lactamase cleaves ampicillin in order to inactivate it
plasmids used in cloning have both an origin of replication and a selectable marker
transmission of plasmids between bacterial species is a common cause of antibiotic resistance in hospitals

Question 6

propranolol cannot be administered to a subject who had a resting heart rate <70bpm, why ? (5 marks)

Answer 6

propranolol is a non-selective beta-blocker
it can block the beta-1 receptors on the heart and prevent noradrenaline binding
this inhibits sympathetic activity and causes bradycardia
the reduction in HR will cause a decrease in CO which can cause fatigue because insufficient oxygen is reaching tissue

Question 7

DBP= 76mmHg
SBP= 104mmHg
HR= 87bpm
what is their MAP and PP?

Answer 7

MAP= DBP+(SBP-DBP/3) = 85.3 mmHg 
PP= SBP-DBP= 28mmHg

Question 8

subject was administered 500micrograms of GTN sublingually what happens to their resting MAP and HR over a 30 min period and why ?

Answer 8

it should cause MAP to decrease because the SBP and DBP will both decrease
blood pressures decrease because GTN is a nitric oxide donor so it increases the availability of NO which activates guanyl cyclase, increases cGMP, increases protein kinase G which increase potassium efflux and activation of myosin light chain phosphatase which causes vasodilation
it may cause a small tachycardia because