721. In a healthy person in standard conditions with a POz of 60 mmHg, which is the correct Hb saturation
A. 75%
E. 85%

722. Pulmonary compliance
A. Is decreased in emphysema
B. Is defined as the change in pressure per unit change in volume
C. Compliance is slightly greater when measured during deflation than when measured during inflation
D. Is increased by pulmonary fibrosis
E. Is independent of lung volume

723. With regard to pulmonary function
A. Tidal volume is the volume of each maximal inspiration
B. Residual volume is the volume remaining at the end of passive expiration
C. Residual volume can be measured directly
D. Vital capacity is equivalent to the total of inspiratory reserve volume, tidal volume and expiratory reserve volume
E. Tidal volume is measured by single breath nitrogen technique

724. Exposure to altitude
A. Shifts the 02-Hb dissociation curve to the right due to alkalosis
B. Is associated with an increase in RBC 2,3-DPG
C. Is associated with a decrease in P50
D. Is associated with a respiratory acidosis
E. Has no effect on erythropoietin secretion

725. Heart rate is accelerated by
A. Grief
B. Increased baroreceptor activity
C. Increased atrial stretch receptor activity
D. Expiration
E. A direct effect of angiotensin

726. Vagal stimulation of SA node
A. Leads to increased conductance of calcium into the cell
B. Leads to increased conductance ofK into the cell
C. Leads to raised intracellular cAMP
D. Decreases the slope of the prepotential of the SA node
E. Inhibits the B 1 receptor directly

727. The ejection fraction represents
A. % of blood remaining in the ventricle following systole
B. % of atrial volume ejected into the ventricles with atrial systole
C. Aortic blood flow
D. % of ventricular volume ejected with each stroke
E. Left ventricular pressure

728. The C wave of the jugular venous pressure corresponds to
A. Atrial systole
B. Rise in atrial pressure prior to tricuspid opening
C. Aortic valve snapping shut
D. Bulging of the tricuspid valve into the atrium
E. Atrial diastole

729. Regarding cardiac output, which one of the following is IN CORRECT
A. Resting cardiac output correlates with body surface area
B. Cardiac output is not affected by moderate changes in environmental temperature
C. Heterometric regulation is changing contractility of the heart independent of length
D. The output per minute per square metre of body surface is the cardiac index
E. Cardiac output is not affected by sleep

730. The rate of pacemaker cells in the heart can be slowed by all of the following EXCEPT
A. More negative diastolic potential
B. Reduction of the slope of diastolic depolarisation
C. More positive threshold potential
D. Prolongation of action potential
E. Increased phase 4 depolarisation slope