Cardiac Muscle Contraction: Sarcomere Steps

Play an AI-generated podcast conversation about this lesson

What are the three variables that may influence stroke volume?

Venous return, presence of inotropic agents, and afterload (correct)

End-diastolic volume, end-systolic volume, and preload

Venous return, presence of inotropic agents, and preload

Venous return, end-diastolic volume, and end-systolic volume

What is the typical end-diastolic volume (EDV) in a resting adult?

150 mL

130 mL (correct)

60 mL

100 mL

What is the typical end-systolic volume (ESV) in a resting adult?

30 mL

75 mL

45 mL

60 mL (correct)

What is the formula for calculating stroke volume?

SV = EDV - ESV Signup and view all the answers

Which of the following is NOT a factor that influences end-diastolic volume (EDV)?

Afterload Signup and view all the answers

How does end-systolic volume (ESV) affect stroke volume?

Decreasing ESV increases stroke volume Signup and view all the answers

What initiates cardiac muscle contraction?

Binding of calcium ions to troponin Signup and view all the answers

What is the role of ATP in cardiac muscle contraction?

All of the above Signup and view all the answers

What is the role of the sarcoplasmic reticulum in cardiac muscle relaxation?

To reuptake calcium ions from the sarcoplasm Signup and view all the answers

What happens during the powerstroke in cardiac muscle contraction?

The myosin head swivels, pulling the thin filament Signup and view all the answers

What is the role of plasma membrane calcium pumps in cardiac muscle relaxation?

To remove calcium ions from the cardiac muscle cell Signup and view all the answers

What happens to the sarcomeres during cardiac muscle relaxation?

They return to their resting length Signup and view all the answers

Which of the following statements is true about ventricular balance?

Both ventricles pump equal amounts of blood. Signup and view all the answers

Why is the left ventricle larger and stronger than the right ventricle?

To pump the same amount of blood through the longer systemic circulation. Signup and view all the answers

What condition can result from sustained pumping of unequal amounts of blood by the ventricles?

Edema Signup and view all the answers

What is the analogy used to explain the difference in work required by the left and right ventricles?

Throwing a baseball two different distances Signup and view all the answers

Which of the following is true about the pressure within the left atrium, left ventricle, and aorta during the cardiac cycle?

The pressure changes in these chambers are shown in Figure 19.24. Signup and view all the answers

What information is provided in Figure 19.24?

All of the above. Signup and view all the answers

What happens to the overlap of thick and thin filaments in cardiac muscle cells during a more forceful ventricular contraction?

Increases Signup and view all the answers

How does a decrease in venous return affect the formation of crossbridges in cardiac muscle cells?

Decreases the formation of crossbridges Signup and view all the answers

What causes venous return to increase according to the text?

High arterial pressure Signup and view all the answers

How does a decrease in venous return affect ventricular contraction strength?

Decreases ventricular contraction strength Signup and view all the answers

What analogy is provided in the text to explain venous return?

Filling a balloon with water Signup and view all the answers

Why does venous return increase during exercise according to the text?

Higher venous pressure Signup and view all the answers

What causes the semilunar valves to close during the cardiac cycle?

The pressure within the ventricles is greater than the pressure within the arterial trunks. Signup and view all the answers

Why do the AV valves remain closed during the phase when the semilunar valves are closed?

The pressure within the ventricles is still greater than the pressure within the atria. Signup and view all the answers

What happens to the blood volume within the ventricular chambers during the phase when all heart valves are closed?

The blood volume remains the same. Signup and view all the answers

What causes the AV valves to open during the cardiac cycle?

The pressure within the ventricles decreases below the pressure within the atria. Signup and view all the answers

What is the purpose of the opening of the AV valves during the cardiac cycle?

To allow blood to flow from the atria into the ventricles for ventricular filling. Signup and view all the answers

What is the significance of the cardiac cycle being repeated with each heartbeat?

It ensures a consistent flow of blood throughout the body. Signup and view all the answers