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Flashcards in pump Deck (31):
1

Cardiac Output (CO) is the

volume of blood pumped per minute by the heart (~5 L/min at rest)

2

CO =

HR x SR

cardiac output = heart rate x stroke volume

3

Stroke volume is the

amount of blood pumped per beat.

Representative numbers for “average” person at rest
HR ~ 70 beats/min
SV ~ 70 ml/beat
CO = HR x SV ~ 4.9 L/min

4

two ways to control cardiac output

1. HR
2. SV

5

heart rate is set by

sinoatrial (SA) node

It is highly regulated by autonomic nervous system and humoral agents

6

Stroke volume is dependent on

1. preload
2. afterload
3. strength of contraction

7

preload is the

venous return

8

afterload is the

resistance to flow (normally aortic pressure)

9

Strength of contraction

Length-dependent intrinsic regulation (Starling’s Law) and length-independent regulation via sympathetic nervous system

10

During diastole (filling phase), the mitral valve is

open

11

during systole, (contraction phase) the aortic valve is

closed

12

EDPVR stands for

end diastolic pressure volume relationship

13

EDPVR is the

Pressure-volume relationship during filling of heart BEFORE contraction

14

EDPVR corresponds to

passive elastic properties of ventricle (slope is inverse of compliance)

15

EDPVR slope is

shallow in normal physiological range (high compliance)

16

The EDPVR represents the

PRELOAD on the left ventricle

17

SPVR stands for

systolic pressure volume relationship

18

SVPR pressure-volume relationship at

peak of isometric contraction

19

SVPR represents the

Maximum pressure that can be developed for a given set of circumstances

20

SVPR curve is

Steeper than EDPVR – pressure increases a lot for small changes in volume

21

SVPR includes

active plus passive properties

22

preload is the

1. volume entering the ventricles
2. The load/length to which a muscle is subjected before shortening.

23

afterload is the

1. resistance that the left ventricle must overcome to circulate blood
2. the load against which a muscle contracts

24

preload range

values lie along the diastolic pressure-volume curve.

25

preload for left ventricle

~ end diastolic volume.

26

afterload for the left ventricle is

~aortic pressure

27

afterload range

(without changes in contractility) lie along the systolic pressure-volume curve

28

Ventricular Function (Starling) curve

1. Difference between SPVR and EDPVR
2. Represents ACTIVE tension (i.e., that generated by contraction)
3. Ascending & descending limbs
4. Analogous to sarcomere length-tension curves
5. Families of Starling curves for different inotropic states
6. Multiple ways to plot (y-axis = pressure, tension, cardiac output, stroke volume; x-axis = volume or length)

29

Starling’s Law is an _____ property of the heart.

INTRINSIC

30

starling's law is independent of

autonomic nervous system regulation

31

starling's law is analogous to

and dependent on, the sarcomere length-tension relationship