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2.1 Control and Integrative Physiology > Mairead - The Heart - values and forces > Flashcards

Mairead - The Heart - values and forces Flashcards

1
Q

What is the cardiac cycle

A

The period between the start of one heartbeat and the start of the next

Alternating cycles of contraction and relaxation

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2
Q

What is systole

A

The period of contraction (emptying)

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3
Q

What is diastole

A

The period of relaxation (and filling)

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4
Q

What is cardiodynamics

A

The movements and forces generated during cardiac contraction

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5
Q

What is EDV?

A

End diastolic volume

The volume of blood in the ventricles at the end of atrial contraction/systole

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6
Q

What is ESV

A

End systolic volume

The volume of blood in the ventricle at the end of ventricular systole

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7
Q

What is SV

A

Stroke volume

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8
Q

What is the equation for stroke volume?

A

Sv = EDV - ESV

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9
Q

What is ejection fraction?

A

The % of EDV that becomes the SV

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10
Q

What is cardiac output

A

The amount of blood flow in the circulation

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11
Q

What is the equation for CO?

A

Cardiac output = SV X HR

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12
Q

What is the equation for blood flow?

A

Pressure/resistance

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13
Q

How might SV be changed?

A

By increasing venous return

By altering the force of contraction of the heart

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14
Q

How can heart rate be changed?

A

It can be increased/decreased by changing the pacemaker excitability

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15
Q

How might heart rate by altered?

A

By autonomic innervation

By hormones

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16
Q

How can cardiac output by altered?

A

Changed in heart rate or stroke volume

17
Q

What determines EDV?

A

Venous return

Filling time

18
Q

What is filling time

A

The duration of ventricle diastole: this depends on heart rate

19
Q

What is venous return

A

The rate of blood flow during ventricular diastole (filling)

20
Q

What affects venous return

A

CO

Blood volume

Peripheral circulation (vasoconstriction/vasodilation)

Skeletal muscle activity

Respiratory pump

Hormones

21
Q

What factors affect end systolic volume?

A

Preload
Contractility of the ventricles
Afterload

22
Q

What is preload
(5)

A

The degree of stretching of the ventricle prior to contraction

This is produced by blood returning from the veins

This affects muscle tension

There is a physiological range of preload

Optimum preload is with a degree of stretch so that greater tension can develop when the ventricles contract

23
Q

What two factors cause preload to vary?

A

Posture
Exercise

24
Q

What is Frank starling Principle/ Starling’s Law of the heart

A

Within physiological limits the heart pumps out all the blood pumped into it

More in = more out

25
Q

What is contractility?

A

The amount of force produced during a contraction at a given preload

26
Q

What is contractility determined by?

A

ANS

Hormones

Extracellular ions

27
Q

How is contractility affected by ANS and hormones?

A

They have an ionotrophic effect on Ca++

28
Q

What is a positive ionotrophic effect?
(2)

A

Where there is an increase in Ca++ entry during contraction

This increases the force and duration of contraction

29
Q

What is negative ionotrophic effect?

A

Where the Ca++ entry is blocked

30
Q

What is afterload

A

The amount of tension the contracting ventricles must generate to open the semilunar valves

31
Q

What affects afterload and how?

A

High aortic pressure will increase the time of isovolumetric contraction and decrease the time of emptying

32
Q

What are two causes of high pressure?

A

Blood vessel constriction

Circulatory blockage

2.1 Control and Integrative Physiology (21 decks)

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