Cardiac Function

Question 1

hooks law

Answer 1

the more you stretch the more tension you develop (up until the plastic point)

Question 2

isometric

Answer 2

states the same length

Question 3

isotonic

Answer 3

same rate, tone, afterload

Question 4

how do you” make muscle work better”

Answer 4

1.) Increase preload 2.) Change contractility (ionotropic state)

Question 5

relationship between ionotropy and velocity

Answer 5

increased ionotropy results in increased velocity due to more calcium availibility

Question 6

Vmax (muscle) definition

Answer 6

velocity of shortening without weight

Question 7

relationship between Vmax and prelaod

Answer 7

Vmax is independent of preload - Vmax depends on how much Ca is available

Question 8

Relationshop between afterload and velocity of shortening

Answer 8

as afterload is decreased the velocity of shortening increases. When afterload is 0 the velocity of shortening is Vmax

Question 9

Relationship between Velocity and ionotropic state

Answer 9

Vmax increases with increasing velocity (even when preload is unchanged)

Question 10

Vmax is a measure of what

Answer 10

contractility

Question 11

End diastolic volume

Answer 11

correlate of muscle fiber stretch prior to contraction ( preload)

Question 12

afterload

Answer 12

pressure the heart must work agianst during shortening (ventricular pressure during systolic ejection)

Question 13

what relates end diastolic pressure to end diastolic volume

Answer 13

compliance

Question 14

Laplaces Law

Answer 14

Hypertrophy can thickin wall and narrow chamber

Question 15

Concentric Hypertrophy is due to

Answer 15

Pressure overload

Question 16

Eccentric Hypertrophy is due to

Answer 16

volume overload

Question 17

Cardiac Pump function

Answer 17

ability of the heart to do something. Can be defined in terms of many differnent parameters ( CO, stroke volume, ect)

Question 18

Myocardial performance is dependent on what 4 factors

Answer 18

1.) Prelaod 2.) Contractility 3.) Afterload 4.) Heart rate

Question 19

Starlings Law of the Heart

Answer 19

the more you strech the more contractile tension on excitation thereby increasing stroke volume

Question 20

list factors that change contractility

Answer 20

increase - neural influences (sympathetic discharge, circulating NE) Decrease- hypoxia, hypercapnia, ischemia, and acidosis

Question 21

Afterlaod effect

Answer 21

stroke volume decreases with increased afterload (decreased ejection fraction and rise in end systolic volume)

Question 22

what compensations can occur for increased afterload

Answer 22

1.) Starlings Law (blood left behind will result in increased preload when the new blood comes in) 2.) Anrep Effect

Question 23

Anrep Effect

Answer 23

contractility is increased by increased coronary artery perfusion pressure

Question 24

How does heart rate affect heart performance

Answer 24

INDIRECTLY. Increases contractility (more Ca) and decreases preload due to less diastolic filling time - net result is more or less a wash

Question 25

Treppe (Bowdich Effect)

Answer 25

Staircase effect - as rate is increased over range of 20 bmp to 200 bpm the force of cardiac contraction increases

Question 26

rest potentiation

Answer 26

if there is an extended interval between beats then the subsequent beat shows increased force of contraction

Question 27

Post-extrasystolic potentiation

Answer 27

premature ventricular depolarization results in weak contraction but the subseqent beat shows increased force of contraction

Question 28

Ecjection Fraction

Answer 28

ratio of blood ejected (SV) to the total blood contained in the ventricle at the end of diastole

Question 29

Stroke volume

Answer 29

End Diastolic volume - End Systolic Volume

Question 30

relationship between afterload and stroke volume and ejection fraction

Answer 30

increase in afterload decreases stroke volume and decreases ejection fraction

Question 31

which way does increased contractility move the end systolic volume line

Answer 31

up and to the left

Question 32

relationship between contractility and stroke volume and ejection fraction

Answer 32

increased stroke volume and increased ejection fraction

Question 33

what are we measuring when we look at dp/dt max

Answer 33

contractility

Question 34

where in the cardiac cycle is Vmax

Answer 34

opening of aortic and pulmonary valves