Question

B. SHORT QUESTIONS Answer in the booklet provided. Ensure the correct numbering. A 2-lead electrocardiogram (ECG) trace below shows a progressive prolongation of PR interval (more than 0.2 sec) which result in a dropped QRS complex. PR PR PR PR 1. Which pathophysiological condition does the ECG trace above represent? 2. Br-adrenegic receptor blocker reduces blood pressure by inhibiting both the chronotrophic (affecting the heart rate) and inotropic (affecting contractility) effects on the heart however also decrease the release of a specific enzyme from the kidneys. Name the enzyme. 3. Which part of the vascular tree (capillaries, arteries, veins, venules and arterioles) serve as a large blood reservoir? 4. Which cardiac structures attach to the cusps of the atrio-ventricular valves via the chordae tendinae and contract to prevent inversion or prolapse of these valves? 5 Which structure(s) deliver deoxygenated blood from the myocardium to the right atrium? 130 120 110 100 80 70 -60 50 20 10 160 140 100 120 60 80 40 Left ventricular volume (ml) With reference to the diagram (pressure-volume loop) above identify: 6. a) the valvular event at point C a point or segment (e.g A-B, B-C etc.) that best correspond with the second heart sound. b) c) a point or segment (e.g A-B, B-C etc) that best correspond with the S-T segment of a 2- lead ECG trace. a point or segment that best correspond with the diastolic blood pressure. d) (1) e) a point or segment that best correspond with the left ventricular end-systolic volume. 7. What name or term is given to the proportion of blood expelled from the ventricle during systole? 8. Write the formulae one can use to calculate the cardiac output (CO), given the right atrial pressure, total peripheral resistance, systolic and diastolic blood pressure. 9. What enzyme reaction regulates cardiac musdle relaxation by promoting pumping of cytoplasmic Ca back into the sarcoplasmic reticulum by SR Ca-ATPase? Myocardial infarction (MI) is associated with a decreased activity of which pump? The pump will cause Na ions to be exchanged for Ca2 and therefore cardiac intracellular fluid Ca2+ will increase. 10. 10 of 15

Answer 1

1 heart block

2 angiotensin converting enzyme

3 capillaries

4 capillary muscle

5 coronary veins

6 a aortic valve opens

B E aortic valve closes

C EA ventricular diastole

E E LV end systolic volume

7 stroke volume

8 CO= 80*(Mean arterial pressure- Right atrial pressure)/ Systemic vascular resistance

9 protein kinase A