###### Page 6, USMLE, Dr. D. Penney

USMLE-Type Examination Questions - Hemodynamics:

```220.  The French physician Jean L.M. Poiseuille (1799­1869) defined the factors that regulate the flow of water through a single, rigid cylindrical tube.  Which of the following is correct with regard to flow rate as expressed in the Poiseuille equation?
(A)	inversely proportional to perfusion pressure
(B)	directly proportional to viscosity
(C)	directly proportional to length
(D)	directly proportional to radius to the third power
(E)	directly proportional to radius to the fourth power

221.  Which of the following statements derived from the Poiseiulle equation is correct?
(A)	the formula, resistance = (P1 - P2)/Q, is used to calculate resistance in the cardiovascular system
(B)	the formula, resistance = (P1 - P2)/L, is used to calculate resistance in the cardiovascular system
(C)	in the above formula, (P1 - P2) is pulse pressure
(D)	in the above formula, Q is compliance
(E)	in the above formula, L is viscosity

222.  Under which of the following conditions is an increase in arterial pressure associated with a decrease in peripheral resistance?
(A)	when there is turbulence
(B)	when there is an increased hematocrit
(C)	when there is vasoconstriction
(D)	when there is vasodilation
(E)	when there is an increased cardiac output

223.  The total resistance offered by three resistances - 0.2, 0.4, and 0.2 - arranged in parallel would be
(A)	0.8 PRU
(B)	0.4 PRU
(C)	0.3 PRU
(D)	0.2 PRU
(E)	0.08 PRU

224.	In the horizontal subject, the greatest pressure head (ie, P1 - P2) exists between
(A)	the ascending aorta and the anterior tibial artery
(B)	the anterior tibial artery and the anterior tibial vein
(C)	the anterior tibial vein and the right atrium
(D)	the pulmonary artery and the pulmonary vein
(E)	the efferent renal arteriole and the renal vein

225.  A 70-kg, 6-ft, normal, healthy subject standing quietly erect for 30 seconds has a mean arterial pressure of 100 mmHg in the ascending aorta and a venous pressure of 2 mmHg in the superior portion of the inferior vena cava.  What is the pressure in the veins of the dorsum of the foot?
(A)	less than 0 mmHg (ie, below atmospheric pressure)
(B)	2 mmHg
(C)	4 mmHg
(E)	above 40 mmHg

226.  A soldier stands at attention for 30 seconds.  How can his femoral vein pressure best be decreased?
(A)	by decreasing the heart rate
(B)	by dilating the systemic arterioles
(C)	by constricting the systemic arterioles
(D)	by having him hold his breath
(E)	by having him take one step forward

227.  The only factor that does not normally facilitate venous return of blood to the right heart
(A)	increasing minute ventilation
(B)	exercising the leg muscles
(C)	increasing venous sympathetic tone
(D)	standing up from a supine position
(E)	going to a condition of zero gravity

247.  Unitary expression of vascular resistance
(A)	poise
(B)	erg
(C)	PRU
(D)	CPU
(E)	BID

252.  Condition normal for the aorta due to the high blood flow velocity there, but usually not seen in other large arteries.
(A)	erythrocyte deformation
(B)	functional turbulence
(C)	hyperkalemia
(D)	hyperthermia
(E)	streamline flow

256.  The only factor that does not cause an increase in total systemic peripheral resistance is
(A)	a decreased blood volume (ie, hemorrhage)
(B)	changing from a standing to a reclining position