Chronic Cardiac Adaptation

Question 1

What happens to heart with chronic exercise and pregnancy

Answer 1

physiological hypertrophy

incr myocyte length, incr end diastolic volume, incr volume
no fibrosis
no cardiac dysfunction

Question 2

What causes physiological hypertrophy

Answer 2

chronic exercise

pregnancy

Question 3

What happens to heart with chronic hypertension and aortic valve stenosis

Answer 3

pathological hypertrophy

incr myocyte width
maybe cardiac dysfunction
decr end diastolic volume

Question 4

what causes pathological hypertrophy

Answer 4

chronic HTN

aortic valve stenosis

Question 5

what happens to heart with MI and DCM

Answer 5

cardiac dilation
INCR MYOCYTE length
extensive fibrosis
myocyte death
advanced cardiac dysfunction 

thin walls

Question 6

what was historical view of heart

Answer 6

relatively inert

cardiac enlargement doesn’t affect intrinsic contractile properties

Question 7

2 myosin heavy chain isoforms

Answer 7

alpha and beta

Question 8

each myosin has ___ heads and ___ chains

Answer 8

2 heads

2 chains

Question 9

what are the different heterodimers

Answer 9

aa
ab
bb

Question 10

what makes heterodimers of myosin distinct?

Answer 10

distinct ATPase activity

Question 11

which has greater ATPase activity, alpha or beta

Answer 11

ALPHA HAS GREATER ATPase activity

Question 12

alpha and beta myosin heavy chain are ___

Answer 12

encoded by different genes and transcriptionally regulated expression

Question 13

Physiological hypertrophy has ____ ATPase and ___ MHC

Answer 13

increase in ATPase

aa MHC

Question 14

Pathological hypertrophy has ___ ATPase and ___ MHC

Answer 14

Decrease in ATPase

bb MHC

Question 15

Contemporary view of heart

Answer 15

Heart has both phenotypic and genotypic plasticity

Question 16

Phenotypic adaptations may involve both ___ and ___

Answer 16

transcriptional and post-translational modifications

Question 17

Long term effect of HTN

Answer 17

heart ejecting against high pressure so cardiac contraction slower
(less ATPase) –> slower contraction

Question 18

Over time, the effect of HTN

Answer 18

1) HTN
2) develop LVH and increase EDV
3) heart eject against increased afterload (hypertrophy)
4) Frank starling curve shifts down
5) as heart fails, PV curve shifts right so volume incr but SV decr

Question 19

Cellular effects of LVH

Answer 19

1) incr Ca2+ current via L-type Ca2+
2) decr SR pump function by incr PLB/SERCA2 ratio so more cyto Ca2+
3) decr myofilament relax
4) incr cytosolic Ca2+ and new steady state

Question 20

What is Calcineurin?

Answer 20

Phosphatase activated in response to Calcium

long onset so need sustained Ca2+ to activate

Question 21

Effect of calcineurin

Answer 21

1) calcineurin dephos NFAT
2) NFAT translocate to nucleus
3) heart looks like dilated cardiomyopathy

Question 22

Effect of P4H on LVH function

Answer 22

NO EFFECT!!!!

Question 23

Positive feedback in CHF

Answer 23

1) Primary muscle damage
2) Pump dysfunction
3) decr CO
4) neurohumoral activation
5) apoptosis

Question 24

2nd positive feedback loop in CHF

Answer 24

1) Primary muscle damage
2) Pump dysfunction
3) decr CO
4) LVH
5) ventricular remodeling

Question 25

Effects of CHF

Answer 25

edema
tachycardia
congestion