Cardiovascular System - Circulation

Question 1

Functional Parts of Circulation

Answer 1

• arteries
• arterioles
• capillaries
• venuoles
• veins

Question 2

Volume of Blood in the Heart

Answer 2

7%

Question 3

Volume of Blood in the pulmonary system

Answer 3

9%

Question 4

Volume of Blood in the rest of the system (other than heart and pulmonary system)

Answer 4

84%

Question 5

Volume of Blood in the Veins

Answer 5

64%

Question 6

Volume of blood in the arteries

Answer 6

13%

Question 7

Volume of Blood in the Arterioles and Capillaries

Answer 7

7%

Question 8

Time for transmission of pulse to aorta

Answer 8

3-5 m/sec

Question 9

Time for transmission of pulse to Large Arteries

Answer 9

7-10 m/sec

Question 10

Time for transmission of pulse to small arteries

Answer 10

15 - 35 m/sec

Question 11

Time for transmission of pulse to arterioles and capillaries

Answer 11

0 m/sec - damping of pressure pulses

Question 12

what is hematocrit ratio?

Answer 12

% by volume of whole blood that is composed of cells

40% (men)

36% (women)

Question 13

Viscosity of Blood

Answer 13

3-4x that of water

Question 14

viscosity of plasma

Answer 14

1-1.5 times that of water

Question 15

2 factors that determine blood flow through the vessels

Answer 15

• Pressure Differece (delta P): tends to push blood through the vessels
• Resistance (R): resists blood flow through the vessel

Relationship: Q=(deltaP)/(R)

Question 16

Laminar Flow

Answer 16

• streamlined flow in concentric layers
• max flow velocity is in the center

Question 17

Turbulent Flow

Answer 17

absence of streamline flow when eddy currents are formed

tendency for turbulent flow to occur can be measured by calculating Reynolds # which represents the relationship between vessel diameter, blood viscosity, blood density and flow velocity

Question 18

principal determinant of resistance to blood flow

Answer 18

diameter of the vessel

Question 19

Poiseuille’s Law

Answer 19

resistance to flow is inversely proportional to the fourth power of the radius of the tube

so, small changes in radius cause large changes in resistance

so, sympathetis vasoconstrictor mechanisms in te small arteries and arterioles are the primary regulators of blood flow

Question 20

how resistance is measured

Answer 20

in preipheral resistance units (PRU) total peripheral resistance of the systemic circulation is appx. 1 PRU

Question 21

Volume of Blood Flow

Answer 21

product of inverse relationship of blood flow velocity and vascular cross section area

cross section of area of systemic circulation:

aorta - 2.5 cm^2

capillaries - 2500 cm^2

Vena Cava + right atrium - 8 cm^2

Question 22

Critical Closing Pressure

Answer 22

blood vessels collapse when elastic and muscular forces in the vascular wall, coupled with the extravascular tissue pressure, exceed intravascular distending pressure

Question 23

Transmural Pressure

Answer 23

pressure difference between the inside and outside of the vessel wall

Question 24

At what presuure do the vessels usually collapse?

Answer 24

when distending pressure falls below appx. 20mmHg

Question 25

Vascular Compliance

Answer 25

change in blood pressure stretches more or less blood vessel walls and causes an increase or decrease in the volume of the blood vessels.

Veins are 5x more compliant than Arteries

Capitance vessels

• distensibility of blood cells that varies with pressure

Question 26

most to least compliant

Answer 26

• veins
• aorta
• arteries
• arterioles