Control of Cardiac Output

Question 0

_____ is the amount of blood flowing from tissues into the right atrium.

Answer 0

Venous return

Question 1

_____ is the sum of blood flow to all tissues of the body.

Answer 1

Cardiac output

Question 2

Overtime cardiac output must equal ______.

Answer 2

Venous return

Question 3

When may cardiac output differ from venous return?

Answer 3

For several heartbeats while volume is moved into or out of the heart and lungs.

Question 4

️CO is affected by: (3)

Answer 4

Overall metabolic activity of body including exercise
Body mass (CO vs cardiac index)
Age

Question 5

CO is controlled by _____.

Answer 5

Venous return

Question 6

Explain how venous return controls cardiac output.

Answer 6

How peripheral circulation affects the flow of blood from tissues into right atrium.

Question 7

Frank-Starling law of the heart allows the heart to increase or decrease _____ as the volume of venous return changes.

Answer 7

Stoke volume

Question 8

What effects does increased venous return have on the heart?

Answer 8

Increased myocardial stretch which increased SV and HR

Question 9

With a constant MAP as metabolism changes ____ has to change.

Answer 9

SVR

Question 10

Increased metabolism causes ____ arterial constriction which results in ____ tissue flow.

Answer 10

Decreased arteriole constriction

Increased tissue flow

Question 11

Without _____, MAP decreases as SVR decreases with a small change in CO.

Answer 11

Autonomic Nervous Control

Question 12

Overall metabolic activity of body determines ____.

Answer 12

Cardiac output

Question 13

The highest rate of metabolism is from _____, with a cardiac index of _____.

Answer 13

Birth to about 10 years old

4.0 L/min/m^2

Question 14

Decreasing cardiac index with age is due to:

Answer 14

Decreasing muscle mass and overall decrease in activity.

Question 15

Cardiac index at age 80 is about _____.

Answer 15

2.4 L/min/m^2

Question 16

Healthy young males have a normal cardiac output of _____.

Answer 16

5.6 L/minute

Question 17

Healthy young females have a normal cardiac output of _____.

Answer 17

4.9 L/minute

Question 18

Average cardiac output for resting adult is _____.

Answer 18

5 L/minute

Question 19

Average weight = _____

Answer 19

70 kg

Question 20

Average surface area = _____.

Answer 20

1.7 m^2

Question 21

Average cardiac index = ______.

Answer 21

3 L/min/m^2

Question 22

Hearts with increased levels of cardiac output are called _______.

Answer 22

Hypereffective

Question 23

Hypereffectiveness is caused by: (2)

Answer 23

Increased levels of sympathetic nervous tone

Hypertrophy

Question 24

Increased levels of cardiac output results from changes in _____ and _____.

Answer 24

Contractility | HR

Question 25

Any factor that decreases the heart's ability to pump blood causes _____.

Answer 25

Hypoeffectivity

Question 26

Hypoeffectiveness of the heart can be caused by: (8)

Answer 26

* Increased arterial pressure against which the heart must pump (such as HTN) * Inhibition of nervous excitation of the heart * Pathological factors that cause abnormal heart rhythm and HR * Coronary artery blockage, causing a "heart attack" * Valvular heart disease * Congenital heart disease * Myocarditis (an inflammation of the heart muscle) * Cardiac hypoxia

Question 27

Under normal conditions with normal ANS tone: Resting values: RAP = _____ —> CO = _____ MAX values: RAP = _____ —> CO = _____

Answer 27

Rest: RAP = 0 mmHg —> CO = 5 L/minute Max: RAP ≥ 4 mmHg —> CO = 13 L/minute

Question 28

With a hypereffective heart (nervous response) | MAX values: RAP = _____ —> CO = _____

Answer 28

MAX values: RAP ≥ 4 mmHg —> CO = 20 L/min

Question 29

A hypereffective heart (hypertrophy) has a _____% increase in muscle mass.

Answer 29

50 to 75

Question 30

A hypereffective heart (hypertrophy) has a _____% increase in CO.

Answer 30

60 to 100

Question 31

``` Hypereffective heart (hypertrophy) MAX values: RAP ≥ _____ —> CO = _____ ``` The max values represent the summation of nervous response and hypertrophy.

Answer 31

MAX values: RAP ≥ 4 mmHg —> CO = 20 L/min

Question 32

The plateau of the cardiac function curve represents _____.

Answer 32

Maximal cardiac output

Question 33

The heart moves between the different cardiac function curves based on the level of _______.

Answer 33

️sympathetic tone

Question 34

Intrapleural pressure affects _____.

Answer 34

Venous return

Question 35

What does a 2 mmHg increase in intrapleural pressure mean? | Which way does the cardiac output vs. external pressure curve shift?

Answer 35

It means it would require an additional 2 mmHg to fill the right atrium. The curve shifts right

Question 36

Factors that alter external pressure: (5)

Answer 36

* Cyclic changes in respiration * Breathing against negative pressure * Positive pressure breathing * Opening thoracic cage * Cardiac tamponade

Question 37

Breathing against negative pressure causes the cardiac output vs. external pressure curve to shift ____.

Answer 37

Left

Question 38

Positive pressure breathing causes the cardiac output vs. external pressure curve to shift _____.

Answer 38

Right

Question 39

Opening the thoracic cage causes the intrapleural pressure to = _____ and shifts the cardiac output vs. external pressure curve to the ____.

Answer 39

0 mmHg | Right 4 mmHg

Question 40

_____ is the volume required to fill the systemic vascular system without stretching the vessels giving an overall pressure of 0 mmHg.

Answer 40

Anatomic volume

Question 41

The mean systemic filling pressure (Psf) is _____.

Answer 41

7 mmHg

Question 42

When does the body have a mean systemic pressure or 7 mmHg?

Answer 42

When there is no flow.

Question 43

____ includes the pulmonary circulation.

Answer 43

Mean Circulatory Filling Pressure (Pmf)

Question 44

️Compliance of arteries

Answer 44

2 mm/mmHg

Question 45

️compliance of peripheral venous compartment

Answer 45

110 mL/mmHg

Question 46

RA and the central veins in the thorax comprise the ____ compartment.

Answer 46

Central venous compartment (CVC)

Question 47

What does the volume in the central venous compartment depend on?

Answer 47

Volume coming into the compartment (venous return) | Volume leaving the compartment (cardiac output)

Question 48

Pressure in peripheral venous compartment is usually equal to ____.

Answer 48

Psf = 7 mmHg

Question 49

How is venous resistance determined? Not 100% on this one

Answer 49

(Veins + arterioles resistance) / small arteries resistance | 1.4 mmHg/L/min

Question 50

Pressure in the central venous compartment usually = ____.

Answer 50

0 mmHg

Question 51

Formula for venous return

Answer 51

VR = (Psf - RA) / venous resistance VR = (7-0) / 1.4 = 5 L/minute

Question 52

Looking at the Venous Function Curve: ____ = independent variable ____ = dependent variable

Answer 52

RA pressure = independent | VR = dependent

Question 53

Looking at the Venous Function Curve an increase in RAP will cause a ____ in venous return.

Answer 53

Decrease

Question 54

What is the intersection of the cardiac function curve and venous function curve determine?

Answer 54

CO VR CVP

Question 55

What does an increased CVP do to CO and venous return? Explain why.

Answer 55

Increased CVP —> increased CO —> decreased venous return More volume leaves the CVC than enters causing a decrease in CVP. This continues until back at equilibrium.

Question 56

____ is driven to the value where CO and venous return are equal.

Answer 56

CVP

Question 57

Where on the cardiac and venous function curves shows that CO and venous return have stabilized?

Answer 57

The point where the two curves intersect.

Question 58

What 2 things cause the cardiac function curve to shift?

Answer 58

* Change in cardiac effectiveness | * Change in external pressure

Question 59

What 2 things cause venous function curve to shift?

Answer 59

* Change in mean systemic filling pressure | * Change in venous resistance

Question 60

Increase blood volume —> ____ in mean system filling pressure (Psf).

Answer 60

Increase

Question 61

What result does increased blood volume have on venous resistance? Explain.

Answer 61

Decrease venous resistance The increased blood volume distends the blood vessels.

Question 62

Increased cardiac output —> ____ capillary pressure (meaning ______) —> ____ in circulating blood volume —> resulting in ____.

Answer 62

Increased CO Increased capillary pressure causes increased movement out of caps Decrease in circulating blood volume shifting Psf back to normal

Question 63

Stimulation of auto-regulation of tissues causes ___ in SVR which also ___ in venous resistance shifting the venous curve ___.

Answer 63

Increase SVR —> increased venous resistance Shifts curve back toward normal

Question 64

Storage of blood in the liver and spleen result in ____.

Answer 64

Further reduction in Psf

Question 65

What does the response to hemorrhage chart NOT show?

Answer 65

Any changes in venous resistance