Lecture 9: Overview of Circulation

Question 1

84% of blood volume is in the systemic circulation. Of this, 64% is in which of the following vessels?

A. capillaries
B. systemic arterioles
C. veins
D. arterioles

Answer 1

C. veins

Question 2

Blood flow resistance is indirectly proportional to which of the following?

A. viscosity
B. vessel diameter
C. density
D. both A and C

Answer 2

B. vessel diameter

Question 3

Reynolds number is a measure of which of the following parameters?

A. tendency for turbulence
B. blood pressure
C. conductance
D. resistance

Answer 3

A. tendency for turbulence

Question 4

Which of the following represents the viscosity of a blood with a hematocrit of 38-42?

A. 1.5
B. 3.0
C. 38
D. 42

Answer 4

B. 3.0

Question 5

Ohm’s Law/Poiseuille’s Eqn

Answer 5

F=∆P/R (F=flow, P=pressure, R=resistance)

Question 6

Laminar Flow

Answer 6

streamline, steady flow in layers; vessel will be long and smooth

Question 7

Turbulent Flow

Answer 7

non-layered flow, creates murmurs, higher resistance than in laminar flow; may occur due to increased flow, obstruction, or rough surface

Question 8

Reynold’s Number

Answer 8

Re = (v x d x ρ)/η; measure of tendency for blood to become turbulent (above 200-400=turbulence in some regions of vessel, above 2000=turbulence occurs even in a straight vessel)

Question 9

Pulse Pressure

Answer 9

Difference between systolic and diastolic pressure

Question 10

PRU

Answer 10

Peripheral Resistance Unit, measured by pressure/(volume/time); 1 PRU is normal systemic resistance (0.14 in pulmonary)

Question 11

Conductance

Answer 11

1/resistance; directly proportional to diameter4

Question 12

Poiseuille’s Law

Answer 12

F=π∆Pr4/8ηl

Question 13

Normal Hematocrit, Normal Viscosity

Answer 13

Hematocrit=38-42, Viscosity=3.0

Question 14

Anemia, Polycythemia

Answer 14

Anemia=blood viscosity too low; Polycythemia=blood viscosity too high