741. Which of the following is true concerning the heart
A. Increased volume work produces an increase in 02 consumption than increased pressure work
B. Cardiac work is the product of heart rate and stroke volume
C. The heart in its rested state gains 60% of its caloric requirements from fat
D. The work of the left ventricle is twice that of the right due to higher pressures in the systemic circulation
E. Increased preload has a greater effect on 02 consumption of the heart than increased afterload
742. Of the following, which is correct
A. The normal cardiac index is 3.2L
B. Increased heart rate with exercise in a transplanted heart is due to a heterometric regulation mechanism
C. Increased heart rate with exercise in a transplanted heart is due to a homometric regulation mechanism
D. The normal ejection fraction is 65%
E. All of the above
743. Which of the following does NOT cause an increase in cardiac output
A. Eating
B. Moderate increase in environmental temperature
C. Pregnancy
D. Exercise
E. Anxiety
744. Blood flow
A. In the right coronary artery is greater in systole than diastole
B. Is increased in the cerebral circulation by hyperventilation
C. Is greater in the epicardial arteries than the subendocardial arteries at the left ventricle in diastole
D. Is lower towards the centre than the periphery of large vessels
E. In the left coronary artery is decreased by moderate hypoxaemia
745. Myocardial contractility is increased by all of the following EXCEPT
A. Activation of adenylyl cyclase
B. Vagal stimulation
C. Digoxin
D. Mobilisation of calcium from longitudinal tubule systems
E. None of the above
746. All of the following are true of venule walls except
A. Are slightly thinner than capillaries
B. Are thin and easily distended
C. Contain relatively little smooth muscle
D. Venoconstriction is caused by noradrenergic nerves and noradrenaline
E. All are correct
747. Which of the following is incorrect concerning biophysical characteristics of blood flow
A. Blood flow can be measured by the Poiseuille-Hagan formula even though blood is not a perfect fluid
B. Viscosity of blood is a function of the haematocrit
C. Blood flow is normally laminar
D. Velocity is proportional to flow (Q) divided by the area (A)
E. Critical closing pressure occurs when capillary pressure exceeds tissue pressure
748. Which of the following is incorrect
A. The law of Laplace explains the difference between intraliminal and transmural pressure
B. The smaller the radius of a blood vessel the lower the wall tension to balance distension pressure
C. Veins are referred to as capacitance vessels and arterioles as resistance vessels
D. The recoil effect in blood vessels is known as the Windkessel effect
E. The mean pressure is the average pressure in the cardiac cycle and is calculated as diastolic pressure plus 113 pulse pressure
749. Concerning capillary circulation, which of the following is incorrect
A. 5% of circulating blood is in the capillaries at any one time
B. Transport of substances from the capillaries into tissue occurs via fenestrations, vesicular transport and cytoplasmic transport
C. The rate of transport along a capillary depends on Starling forces
D. Oncotic and filtration pressure gradients are the same for all capillaries
E. Transit time from arteriolar and to venular end, averages 1-2 seconds
750. All of the following concerning lymphatics and lymph flow are true EXCEPT
A. The normal lymph flow is 2-4 Ll24 hours
B. The two types of lymph vessels are interstitial and collecting
C. Collecting lymphatics have valves and smooth muscles in their walls
D. Flow in the collecting lymphatics is aided by skeletal muscle movements
E. Functions of the lymphatics are recycling of protein and transport of long chain fatty acids