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FHB Exam 1 - Cardiovascular Physiology > Lecture 12 - Cardiac Function > Flashcards

Lecture 12 - Cardiac Function Flashcards

1
Q

What affect does the fact that AFTERLOAD is not constant, have on the shape of the ejection phase of the P-V loop?

A

since after load is not constant,

the PV loop at ejection is NOT FLAT

  • curved due to changing after load in aorta
    (rapid & reduced ejection)
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2
Q

What is the ejection fraction of the Ventricle? State the components of the nominator and denominator

A

EF = (EDV - ESV)/ EDV * 100

Ejection fraction is the fraction of blood ejected during one stroke of the heart in relation to the total left ventricular END- DIASTOLIC Volume

  • stroke volume/ end-diastolic volume
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3
Q

What clinical index is the ejection fraction used for?

A

CONTRACTILITY

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4
Q

What is a normal ejection fraction?

A

60%

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5
Q

What affect does preload have on:

  1. resting tension
  2. On maximum tension development
  3. Shortening
A
  1. Increasing preload - increases resting tension
  2. Maximum tension development is NOT changed by an increase in preload
  3. MORE SHORTENING
    - move up the resting tension curve, which allows for a greater change in muscle length (increased muscle shortening)
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6
Q

What affect does an increase in preload have on:

  1. EDP
  2. Stroke Volume
  3. ESP
A
  1. End-Diastolic Pressure INCREASES when preload increases
  2. Stroke volume increases
  3. NO CHANGE on end systolic pressure
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7
Q

What affect does changing the after load have on

  1. Tension Development
  2. Shortening
A
  1. Increases the Tension Development
    - moves from one value on peak Isometric tension curve to a higher value on the curve
  2. Decreases shortening
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8
Q

What affect does changing the after load have on:

  1. Pressure Development Before Ejection
  2. Stroke Volume
A
  1. Increased pressure development
    - increased energy used
  2. Decrease in Stroke Volume
    - blocking a tube that is trying to force water out - result is less water can go out

END-SYSTOLIC VOLUME changes to a higher value -

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9
Q

What affect does changing the Contractility have on the muscle/tension graph?

A

SHIFT UP AND LEFT w/ an increase in contracttility

  1. More muscle shortening
    - after load and preload not changed
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10
Q

What affect does changing contractility have on the PV graph?

  1. Stroke Volume
  2. Ejection velocity
A
  1. Increased Stroke Volume

2. Increased Ejection Velocity

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11
Q

What are 3 ways to maximize shortening of muscle or STROKE volume in the heart?

A
  1. Increase preload
  2. Decrease after load
  3. Increase contractility
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12
Q

What is heart failure?

A

Condition in which the heart fails to provide cardiac output sufficient to meet the needs of the body.

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13
Q

What are 2 types of Heart failure?

A
  1. Systolic

2. Diastolic

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14
Q

What changes in Systolic & Diastolic Heart Failure? How is the curve of the diastolic and diastolic graph changed?

A
  1. Systolic - decrease in contractility
    - curve shifted down
  2. Diastolic - decrease in compliance
    - curve shifted up (decrease compliance increases the slope and thus increases the pressure exerted on the ventricle)
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15
Q

What 4 changes in Stroke Volume as a result of changes in Preload

A
  1. Pressure Gradient
  2. Time for Ventricular Filling
  3. Ventricular COmpliance
  4. Atrial Function
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16
Q

How does changing the pressure gradient result in a change in the preload? How does it affect the end-diastolic pressure as a result?

A
  • if there is a decrease in the pressure gradient between the atria and ventricles, there is less passive outflow to fill the ventricle
  • this increases end-diastolic pressure and decreases ventricular filling
17
Q

How can time for ventricular filling change, resulting in a change in the preload?

A
  • increasing the heart rate, decreases ventricular filling time
18
Q

How can ventricular compliance change, resulting in a change in the preload?

A

Less compliance results in a decrease in filling

19
Q

How can Atrial Function change, resulting in a change in the preload?

A

Decreased atrial function due to ATRIAL FIBRILLATION decreases the filling time

20
Q

How can contractility be changed in the heart?

A
  1. Sympathetic nerve activity increases contractility (enhances relaxation via Ca increases)
  2. Drugs (digitalis)
    - increases contractility, by inhibiting Na/K pump and causing the Na/Ca pump to leave more Calcium in
  3. Disease (loss of myocardium/ dysfunctional myocardium)
21
Q

What are three common changes in after load that change the stroke volume?

A
  1. Aortic pressure
  2. Ventricular Outflow Resistance
  3. Ventricular Size
22
Q

What is a way of increasing aortic pressure? What is the result?

A
  1. Hypertension (disease)

- increase in AFTERLOAD

23
Q

What is a way of increasing ventricular outflow tract resistance?What is the result?

A
  1. STENOSIS!!! - valvular stenosis to be specific

2. Increase in after load

24
Q

How is ventricular size (wall tension) change the after load?

A

Increasing the ventricular size (dilated hearts) results in higher wall tension

therefore a LARGER AFTERLOAD
- hard to overcome

25
Q

How does changing heart rate affect:

  1. Contractility
  2. Ventricular FIlling time
A
  1. Increased HR - INCREASES contractility due to the force- frequency relationship
    - increase stimulation of L-Type calcium channels, Na/K ATP as does not keep up with influx of Na - less time for CALCIUM HANDLING
  2. Increased HR - Decreases ventricular filling time
26
Q

What 3 factors influence HR?

A
  1. Pacemaker Function
  2. AV Nodal COnduction
  3. ventricular Arrhythmias
27
Q

How can pacemaker function be changed?

A
  • activation of latent pacemaker changes the ventricular rate
  • enhancing or depressing the pacemaker function with Autonomics (changing slope, the maximum diastolic potential, or threshold of diastolic depolarization)
28
Q

How can AV nodal Conduction be changed?

A
  1. 2nd or 3rd degree heart block

2. Atrial Fibrillation and Atrial FLutter
can progress to affect ventricles

29
Q

Ventricular Arrhythmias do not affect heart rate. True or False.

A

FALSE

30
Q

How does load affect the following:

  1. velocity of shortening in the ventricle? (ejection velocity)
  2. Amount of Shortening in the ventricle? (stroke volume)
A
  1. Increasing the load decreases the velocity of shortening

2. increasing load - decreases shortening

31
Q

How does a change in contractility affect:

  1. Velocity of Shortening
  2. Amount of Shortening
    - in cardiac muscle
A
  1. Increased contractility increases velocity of shortening

2. Increasing contractility INCREASES amount of shortening as well

FHB Exam 1 - Cardiovascular Physiology (26 decks)

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