Cardiac Muscle Mechanical Properties

Question 1

ventricular myocytes

Answer 1

gap junction communication

-axual t tubules

Question 2

initial increase in Ca2+?

Answer 2

L-type Ca channels

• leads to Ca2+ induced Ca2+ release
• through RYR2

Question 3

tropomyosin

Answer 3

in the way of troponin

Question 4

relaxation of cardiac myocytes depends on?

Answer 4

1 extrusion of Ca2+ to ECF
2 reuptake of Ca2+ from cytosol to ER
3 dissociation of Ca2+ from troponin C

Question 5

what extrudes Ca to EDF?

Answer 5

sarcolemma pump

Ca/Na exchanger

Question 6

what is reuptake of Ca to SR?

Answer 6

SERCA pump

Question 7

phospholamban?

Answer 7

inhibits SERCA
-phosphorylation inhibits phospholamban

then SERCA works more

• increased relaxation speed
• more Ca2+ reuptake ot SR

Question 8

beta1 agonists?

Answer 8

promote phosphorylation of troponin I

-enhance disocciation of Ca2+ from troponin C

Question 9

disatole?

Answer 9

like passive length tension

Question 10

systole?

Answer 10

like active length tension

Question 11

increased afterload?

Answer 11

decreased velocity of contraction

Question 12

increased preload?

Answer 12

increased velocity of contraction

Question 13

increased heart rate?

Answer 13

increased tension in myocardia
-bc increased Ca2+

3 causes:
1 - longer L type Ca entry
2 - depolarization leads to Na/Ca exchanger reverse
3 - increased SERCA activity

Question 14

isometric contraction?

Answer 14

isovolumetric contraction