Cardiac Muscle Flashcards
What does cardiac muscle have more of than skeletal muscle?
Greater oxidative capacity
What is the calcium binding protein in cardiac muscle?
troponin C
What is required for cardiac muscle contraction?
Extracellular and intracellular Ca++ - CICR
How does cardiac muscle behave?
As an electrical syncytium
Is there summation in cardiac muscle (temporal or spatial)?
No
How does calcium function in cardiac muscle?
L-type voltage gated Ca++ channels sense the arrival of an AP which facilitates calcium entry from ECF which then induces calcium release from SR
How does calcium enter the ECF during relaxation?
Na+/Ca++ antiporter
How long is a cardiac muscle AP and what does it stop?
200-250ms and prevents tetany
How do you increase the force of contraction of cardiac muscle?
Increase in intracellular Ca++ - SNS stimulation
Increased stretch on cardiac muscle as an intrinsic mechanism
What increases the intracellular calcium transient?
Isoproterenol - beta agonist
What does noradrenaline release in cardiac muscle?
cAMP
What does increased cAMP do?
Increases PKA causing phosphorylation of several proteins including the calcium channel and SR phospholamban
Increased SR calcium release for more actin-myosin cross bridges
What is thought to facilitate calcium channel?
AKAP
What is the function of titin in the sarcomere?
Monitors length of cardiac myocytes
Contributes to elasticity of muscle
What can cause a certain type of cardiomyopathies?
Titinopathies
