BRS PHYSIOLOGY EXAM QUESTIONS AND ANSWERS WITH COMPLETE SOLUTIONS VERIFIED LATEST UPDATE 2024/2025
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Course
BRS PHYSIOLOGY
Institution
BRS PHYSIOLOGY
BRS PHYSIOLOGY EXAM QUESTIONS AND ANSWERS WITH COMPLETE SOLUTIONS VERIFIED LATEST UPDATE 2024/2025
1. A 53-year-old woman is found, by
arteriography, to have 50% narrowing of
her left renal artery. What is the expected
change in blood flow through the stenotic
artery?
(A) Decrease to 1⁄2
...
The answer is D [II C, D]. If the radius of the artery decreased by 50% (1/2), then
resistance
would increase by 24, or 16 (R = 8ηl/πr4). Because blood flow is inversely proportional
to resistance (Q = ΔP/R), flow will decrease to 1/16 of the original value.
2. When a person moves from a supine
position to a standing position, which of the
following compensatory changes occurs?
(A) Decreased heart rate
(B) Increased contractility
,(C) Decreased total peripheral resistance
(TPR)
(D) Decreased cardiac output
(E) Increased PR intervals
The answer is B [IX A; Table 3-4]. When a person moves to a standing position, blood
pools in the leg veins, causing decreased venous return to the heart, decreased cardiac
output, and decreased arterial pressure. The baroreceptors detect the decrease in
arterial
pressure, and the vasomotor center is activated to increase sympathetic outflow
and decrease parasympathetic outflow. There is an increase in heart rate (resulting in a
decreased PR interval), contractility, and total peripheral resistance (TPR). Because
both heart rate and contractility are increased, cardiac output will increase toward
normal.
3. At which site is systolic blood pressure the
highest?
(A) Aorta
(B) Central vein
(C) Pulmonary artery
(D) Right atrium
(E) Renal artery
(F) Renal vein
The answer is E [II G, H, I]. Pressures on the venous side of the circulation (e.g., central
vein, right atrium, renal vein) are lower than pressures on the arterial side. Pressure in
,the
pulmonary artery (and all pressures on the right side of the heart) are much lower than
their counterparts on the left side of the heart. In the systemic circulation, systolic
pressure
is actually slightly higher in the downstream arteries (e.g., renal artery) than in the
aorta because of the reflection of pressure waves at branch points.
4. A person's electrocardiogram (ECG) has
no P wave, but has a normal QRS complex
and a normal T wave. Therefore, his pacemaker
is located in the
(A) sinoatrial (SA) node
(B) atrioventricular (AV) node
(C) bundle of His
(D) Purkinje system
(E) ventricular muscle
The answer is B [III A]. The absent P wave indicates that the atrium is not depolarizing
and, therefore, the pacemaker cannot be in the sinoatrial (SA) node. Because the QRS
and
T waves are normal, depolarization and repolarization of the ventricle must be
proceeding
in the normal sequence. This situation can occur if the pacemaker is located in the
atrioventricular (AV) node. If the pacemaker were located in the bundle of His or in the
Purkinje system, the ventricles would activate in an abnormal sequence (depending on
, the exact location of the pacemaker) and the QRS wave would have an abnormal
configuration.
Ventricular muscle does not have pacemaker properties.
5. If the ejection fraction increases, there
will be a decrease in
(A) cardiac output
(B) end-systolic volume
(C) heart rate
(D) pulse pressure
(E) stroke volume
(F) systolic pressure
The answer is C [IV G 3]. An increase in ejection fraction means that a higher fraction of
the end-diastolic volume is ejected in the stroke volume (e.g., because of the
administration
of a positive inotropic agent). When this situation occurs, the volume remaining in
the ventricle after systole, the end-systolic volume, will be reduced. Cardiac output,
pulse
pressure, stroke volume, and systolic pressure will be increased.
An electrocardiogram (ECG) on a person
shows ventricular extrasystoles.
6. The extrasystolic beat would produce
(A) increased pulse pressure because contractility
is increased
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