Lecture 9 Overview of Circulation Flashcards Preview

Human Physiology 1 -- Zach H. > Lecture 9 Overview of Circulation > Flashcards

Flashcards in Lecture 9 Overview of Circulation Deck (70)
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1

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

a) viscosity
b) vessel diameter
c) density
d) both A and C

b) vessel diameter

2

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

a) tendency for turbulence
b) blood pressure
c) conductance
d) resistance

a) tendency for turbulence

3

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

a) 1.5
b) 3
c) 38
d) 42

b) 3

4

What properties of arteries maintain the pressure in systemic circulation?

elasticity

5

What is the systolic pulmonary artery pressure that is generated by the right ventricle?

25 mmHg

6

What is the pulmonary diastolic pressure that remains in the right ventricle?

8 mmHg

7

84% of blood volume is in the systemic circulation. What percentage at any one time is found in the arteries?

13% is in the arteries

8

What percentage of blood in the systemic circulation is found in the systemic arterioles and capillaries?

7%

9

Of the total blood volume in the body, what percentage is found in the heart and lungs at any one time?

16% of blood volume

10

How do you calculate the velocity of blood flow (V)?

V = F / A

*V is velocity of blood flow
*F is volume of blood flow
*A is cross-sectional area

33 cm/sec in aorta at rest (area = 2.5 cm2)
0.3 mm/sec in capillaries at rest (area = 2500 cm2)

11

The cross-sectional area of capillaries is much greater than that of any other vessel in the human body. Why is this, and why is it important?

Velocity of blood flow is inversely proportional to vascular cross-sectional area. Thus, the increased cross-sectional area of capillaries results in a small velocity, which in-turn slows down blood flow so that adequate exchange of nutrients and gases can occur.

12

How is cardiac output controlled?

Mainly by the sum of all the local tissue flows.

13

True or False:

Arterial pressure regulation is generally independent of either local blood flow control or cardiac output control.

True

*Tissue demand when they need increased blood flow. The heart has no say in which tissues get the majority of blood flow. Controlled by activation of tissues and there nutrient needs.

14

84% of the 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

c) veins

15

The rate of blood flow to each tissue of the body is almost always precisely controlled in relation to the tissue need. The tissue is monitored for [oxygen], other nutrients, CO2 accumulation, and tissue waste product accumulation. How does the monitoring microvessels act on local blood vessels to accommodate the tissue's needs?

Act directly on local blood vessels and dilate or constrict accordingly.

16

True or False:

Arterial pressure regulation is generally independent of either local blood flow control or cardiac output control.

True

17

Since arterial pressure regulation is generally independent of either local blood flow control or cardiac output control. What reflex (control mechanism) kicks in if arterial pressure falls below 100 mmHg?

nervous reflexes
-increase force of heart pumping
-constrict large venous reservoirs
-generally constrict most of the arterioles throughout the body (increases arterial pressure)
-kidneys may later play important role in pressure control

18

What is a pressure gradient?

The pressure difference between the two ends of a vessel.

19

What is this definition describing:

"impediment to blood flow through the vessel"

Resistance

20

Flow through a vessel can be calculated by Ohm's law (Poiseuille equation), what is the equation?

F = difference P / R

*difference P = (P1-P2)
*F = flow in mL/min
*P1 = upstream pressure
*P2 = pressure at end of segment
*R = resistance between P1 and P2

21

Fill in the Blank:

Flow is _______ proportional to pressure difference but ________ proportional to resistance.

directly ; inversely

22

What is the overall blood flow (cardiac output) of an adult at rest?

5000 ml/min or 5 L/min

23

What are the characteristics of laminar blood flow (streamline flow)?

Blood flows at a steady rate

Blood vessel is long and smooth

Blood flows in streamlines (layers)

24

One of the characteristics of laminar blood flow is that the blood flows in streamlines (layers). For this, is the velocity of fluid flowing in the center or the vessel greater than that of the fluid flowing towards the outer edge, or vice versa?

The velocity of fluid flowing in the center is greater than that of fluid flowing towards the outer edge.

25

If laminar flow is layered (streamline) flow, then what is turbulent flow?

Nonlayered flow

26

True or False:

Turbulent flow produces less resistance than laminar flow?

False - turbulent flow produces more resistance than laminar flow.

27

Of the two different blood flows, turbulent and laminar, which one is responsible for creating heart mururs?

Turbulent Flow

28

What are the 4 things that cause turbulent flow to occur?

1) when flow is too great
2) when blood passes an obstruction within the vessel
3) when blood has to make a sharp turn
4) when blood passes over a rough surface

29

True or False:

Blood flows with greater resistance when eddy currents occur.

TRUE

30

Tendency for turbulent flow increases when?

1) in direct proportion to velocity of blood flow
2) in direct proportion to the diameter of the vessel
3) in direct proportion to the density of the blood
4) inversely to the viscosity of the blood