Lecture 9 - Overview of Circulation

Question 1

Arterial P range

Answer 1

80-120 mmHg

Question 2

Systemic capillary pressure range

Answer 2

10-35 mmHg

Question 3

Systemic circulation P at the vena cavae

Answer 3

0 mmHg

Question 4

Pulmonary systolic P

Answer 4

25 mmHg

Question 5

Pulmonary diastolic pressure

Answer 5

8 mmHg

Question 6

What “propels” blood forward during diastole?

Answer 6

Elasticity of arteries

Question 7

What part of the circulatory system acts as “control conduits” by changing vessel diameter?

Answer 7

Arterioles

Question 8

The functional portion of the circulatory system where nutrient/waste exchange occurs.

Answer 8

Capillaries

Question 9

Act as a “blood reservoir”

Answer 9

Veins

Question 10

Give blood distribution (%) in systemic circulation

Answer 10

64% veins
13% arteries
7% arterioles/capillaries

Question 11

Give blood distribution (%) in pulmonary circulation

Answer 11

9% lungs

7% heart

Question 12

Formula for blow flow in circulation.

Answer 12

V=F/A

V-velocity
F-blood flow
A-cross sectional area

Question 13

Blood flow to tissues is precisely controlled according to tissue needs. This is accomplished by _____.

Answer 13

Changing the diameter of the muscular arterioles

Question 14

Cardiac output is determined by the sum of all tissue flow/needs. How is this accomplished?

Answer 14

By the heart’s response to tissue needs (primarily through SNS/PNS control)

Question 15

What are the two major, rapidly occurring mechanisms for increasing pre-load during hypotension?

Answer 15

• constriction of skeletal m. compresses veins (skel m. Pump)
• construction of arterioles

Kidneys increase BP after continued hypoTN and take time to do so

Question 16

What two variables primarily determine blood flow?

Answer 16

• pressure gradient (P1-P2: between vessel ends)

- resistance (controlled by changing vessel diameter)

Question 17

Flow through a vessel formula

Answer 17

F=(P1-P2)/R

Question 18

The two “functional parts” of the circulatory system.

Answer 18

Pulmonary and systemic circulation

Question 19

Smooth (“streamlined”) blood flow.

Answer 19

laminar

Question 20

Along what area (center of vessel or outer edges of vessel) is blood flow velocity greater?

Answer 20

center (less turbulent)

Question 21

This is rough (or “eddy current”) blood flow

Answer 21

turbulent

Question 22

List some causes of turbulent blood flow:

Answer 22

• vessel length is very long
• blood passes an obstruction/rough surface
• blood must make sharp turn

Question 23

Turbulent blood flow is measured by what eqiatopm?

Answer 23

Reynold’s number

Question 24

Turbulent blood flow is directly proportional to what factors?

Answer 24

velocity of flow, vessel diameter, and blood density

Question 25

Turbulent blood flow is inversely proportional to what factor?

Answer 25

Viscosity (increased viscosity -> more "sticky" -> decreased flow)

Question 26

What blood component determines blood density?

Answer 26

Red blood cell concentration; protein concentration

Question 27

What is meant by "viscosity" of blood?

Answer 27

The "stickiness" of blood

Question 28

The tendency for turbulence is measured by _____.

Answer 28

The Reynold's number

Question 29

Turbulence increases with?

Answer 29

velocity, blood density, and vessel diameter

Question 30

The tendency for turbulence is inversely proportional to?

Answer 30

Blood viscosity

Question 31

Force exerted by blood against a unit area of vessel wall.

Answer 31

Blood pressure

Question 32

Pressure difference from systemic arteries to systemic veins

Answer 32

100 mmHg (why important?)

Question 33

Constriction of blood vessels strongly _____ resistance; this mechanism of constriction occurs through the _______.

Answer 33

increases; sympathetic nervous system

Question 34

Formula for resistance of vessels in parallel

Answer 34

1/Rtotal=1/R1+1/R2+1/R3...

Question 35

Formula for resistance of vessels in series:

Answer 35

Rtotal=R1+R2+R3...

Question 36

Measure of blood viscosity is called the _____

Answer 36

Hematocrit (HCt)

Question 37

Viscosity is a measure of a fluid's _____.

Answer 37

Internal resistance

Question 38

Blood vessels can undergo autoregulation between what arterial pressures?

Answer 38

70-175 mmHg

Question 39

The factors that determine blood flow resistance.

Answer 39

Radius, viscosity, length

Question 40

At any time time, our heart contains what % of circulating blood volume?

Answer 40

7%

Question 41

At any time time, our lungs contain what % of circulating blood volume?

Answer 41

9%