Muscle Contraction and Relaxation

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Which protein is involved in calcium-induced calcium release in cardiac muscle?

Troponin-C (correct)

Myosin

Actin

Tropomyosin

What is the role of the sodium-calcium exchanger in cardiac muscle?

To pump sodium ions out of the sarcoplasmic reticulum

To pump calcium ions out of the sarcoplasmic reticulum (correct)

To pump calcium ions into the sarcoplasmic reticulum

To pump sodium ions into the sarcoplasmic reticulum

What is the relationship between intracellular free calcium concentration and force generation by cardiac muscle?

Force generation is independent of intracellular free calcium concentration

As intracellular free calcium concentration increases, force generation increases (correct)

Intracellular free calcium concentration does not affect force generation

As intracellular free calcium concentration increases, force generation decreases

Which of the following is responsible for the strength of contraction of each myocardial cell?

Excitation-contraction coupling processes Signup and view all the answers

What is the main role of the T-tubular system in cardiac muscle?

Carry action potentials into the cell interior Signup and view all the answers

What is the function of the sarcoplasmic reticulum in excitation-contraction coupling?

Store and release Ca2+ Signup and view all the answers

How does Ca2+ induce muscle contraction in cardiac muscle?

Ca2+ binds to troponin C, unblocking actin active sites Signup and view all the answers

Which of the following is NOT a mechanism that impacts contractility in the heart?

Decreasing extracellular Na+ Signup and view all the answers

What is the effect of heart rate on contractility in the heart?

Increased heart rate increases contractility Signup and view all the answers

Can cardiac muscle be tetanized?

No, because the duration of the effective refractory period is approximately equal to the duration of the mechanical event Signup and view all the answers

How do defects in the sarcoplasmic reticulum Ca pump (SERCA) affect contractility in the heart?

They decrease contractility Signup and view all the answers

Which mechanism actively transports Ca2+ out of the cell by exchanging 3 Na+ for 1 Ca2+?

Na+-Ca2+ exchanger (NCX) Signup and view all the answers

Which mechanism actively transports Ca2+ back into the sarcoplasmic reticulum (SR) by using ATP?

ATP-dependent Ca2+-pump (SERCA) Signup and view all the answers

What is the term for the intrinsic ability of cardiac muscle to develop force at a given muscle length?

Contractility Signup and view all the answers

Which mechanism increases the force of cardiac contractility by increasing the rate and magnitude of Ca2+ release from the sarcoplasmic reticulum (SR)?

Sympathetic stimulation of cardiac contractility Signup and view all the answers

Muscle Contraction and Relaxation

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Questions and Answers

Which protein is involved in calcium-induced calcium release in cardiac muscle?

What is the role of the sodium-calcium exchanger in cardiac muscle?

What is the relationship between intracellular free calcium concentration and force generation by cardiac muscle?

Which of the following is responsible for the strength of contraction of each myocardial cell?

What is the main role of the T-tubular system in cardiac muscle?

What is the function of the sarcoplasmic reticulum in excitation-contraction coupling?

How does Ca2+ induce muscle contraction in cardiac muscle?

Which of the following is NOT a mechanism that impacts contractility in the heart?

What is the effect of heart rate on contractility in the heart?

Can cardiac muscle be tetanized?

How do defects in the sarcoplasmic reticulum Ca pump (SERCA) affect contractility in the heart?

Which mechanism actively transports Ca2+ out of the cell by exchanging 3 Na+ for 1 Ca2+?

Which mechanism actively transports Ca2+ back into the sarcoplasmic reticulum (SR) by using ATP?

What is the term for the intrinsic ability of cardiac muscle to develop force at a given muscle length?

Which mechanism increases the force of cardiac contractility by increasing the rate and magnitude of Ca2+ release from the sarcoplasmic reticulum (SR)?

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