Cardiac Function Curves + Pressure-Volume Loops Quiz 6.

Question 1

What does the Pressure-Volume Loop Tell us?

Answer 1

It shows the pressure-volume relationship in the left ventricle during one cardiac cycle - one systole and one diastole. It provides an assessment of the systolic and diastolic functions as well as the integrity of the cardiac valves. It does not measure heart rate or linear time.

Question 2

What are the 3 functions of veins?

Answer 2

1. Conduits for return of blood to the heart
2. Reservoir for the cardiovascular system (70% of total blood volume)
3. Maintain cardiovascular stability through changes in capacitance (through sympathetic-mediated smooth muscle tone)

Question 3

What is venous return?

Answer 3

The amount of blood returned back to the right atrium via the venous system over the course of a minute.

Question 4

What is the cardiac function curve?

Answer 4

Frank Starling Curve
It demonstrates the Frank-Starling Relationship.

Question 5

How do venous compliance changes affect the venous return curve?

Answer 5

Increasing resistance to venous return decreases the slope of the venous return curve.

Question 6

How does Contractility affect Cardiac Function Curve?

Answer 6

↑Contractility = Up and Left

↓Contractility = Down and Right

Question 7

What is the venous return curve?

Answer 7

describes the inverse relationship between venous pressure and cardiac output

Question 8

How does afterload affect Cardiac Function Curve?

Answer 8

↑Afterload = Down and Right

↓Afterload = Up and Left

Question 9

Why does the venous return curve plateau as RA pressure becomes negative?

Answer 9

At negative RAP, veins collapse as they enter thorax and restricts venous return

Question 10

How do blood volume changes affect Venous Return Curve?

Answer 10

↑TBV =

↑Venous Return

↑RAP

↑MCFP

Question 11

How do venous compliance changes affect Venous Return Curve?

Answer 11

↓Compliance =

↑Venous Return

↑RAP

↑MCFP

Question 12

Mean Circulatory Filling Pressure

Answer 12

Circulatory Pressure when heart is stopped and there is no flow

Arterial Pressure falls & Venous Pressures rise until equal

MCFP = 8 mmHg

Question 13

What factors affect MCFP?

Answer 13

TBV & Compliance

Venous Compliance will have most impact

Question 14

Does CO = Venous Return?

Answer 14

It should according to Frank Starling

Question 15

What is thought to be the mechanism behind Frank Starling Relationship?

Answer 15

Optimization of Myosin & Actin - more Ca⁺ to bind to cardiac muscles

Question 16

Factors that Effect Cardiac Function Curve

Answer 16

Afterload & Contractility

Question 17

Blood Reservoirs (6)

Answer 17

Spleen

Liver

Large Abdominal Veins

Venous Plexus under Skin

Heart & Lungs

Question 18

What is Unstressed Volume?

Answer 18

Amt of blood in the vein before pressure is generated

Question 19

When are different Venous Curves parallel?

Answer 19

Changes in Blood Volume or Venous Compliance

Question 20

How do resistance changes effect Venous Return Curve?

Answer 20

↑SVR = Down and Left

↓SVR = Up and Right

No MCFP Change

Curves Unparallel

Question 21

Are pressure generated loops made in a counterclockwise fasion?

Answer 21

Yes

Question 22

What is the point of Intercept between the Starling Curve and Venous Return Curve?

Answer 22

Equilibrium point where
Cardiac Output = Venous Return

Question 23

What happens to the Starling Curve & Venous Return curve during exercise?

Answer 23

Sympathetic stimulation & Small ↑CO & Venous Return

then

Big ↑CO, Venous Return, MCFP

Question 24

What is the Y-axis on Pressure-Volume Loop

Answer 24

Pressure

Question 25

What is the X-axis on the Pressure Volume Loop

Answer 25

Volume

Question 26

What is time’s role in Pressure Volume Loops?

Answer 26

Time plays no role

Question 27

List 1-4

Answer 27

1: Filling
2: Isovolumic Contraction
3: Ejection
4: Isovolumic Relaxation

Question 28

List 1-4

Answer 28

1: Mitral Valve Open
2: Mitral Valve Close
3: Aortic Valve Open
4: Aortic Valve Close

Question 29

List 1-2

Answer 29

1: End-Diastole
2: End-Systole

Question 30

What is the Red Line?

Answer 30

End-Systolic Pressure-Volume Relationship

(ESPVR)

Question 31

End Systolic Pressure Volume Relationship Changes

Answer 31

Change of Intercept Point = ΔAfterload

Change in Slope = ΔContractility

Question 32

What is this showing?

Answer 32

End-Diastolic Pressure-Volume Relationship

Ventricular Compliance

Red line indicates stiff ventricle & higher filling pressure

Question 33

Whats happening here?

Answer 33

Increased Afterload
⬇️ cardiac muscle shortening ⬇️ stroke volume (⬇️ chamber emptying and ⬆️ end-systolic volume).

The loop gets narrower, taller and shifts the ESV to the right.

Question 34

Whats happening Here?

Answer 34

Increased Contractility
⬆️ cardiac muscle shortening
⬆️ stroke volume (⬆️ chamber emptying > ⬇️ end-systolic volume).

The loop gets wider, taller and shifts to the left.

Question 35

Whats happening here?

Answer 35

Increased Preload

(⬆️ End-diastolic volume)
⬆️ Cardiac Muscle shortening and ⬆️ Stroke volume
The loop gets wider but returns to the orginal end-systolic volume.

Question 36

How are changes in stroke volume demonstrated by a pressure-volume loop?

Answer 36

SV = EDV - ESV

The width of the loop represents the difference between EDV and ESV, which is SV.