30 Questions
What are the three variables that may influence stroke volume?
Venous return, presence of inotropic agents, and afterload
What is the typical end-diastolic volume (EDV) in a resting adult?
130 mL
What is the typical end-systolic volume (ESV) in a resting adult?
60 mL
What is the formula for calculating stroke volume?
SV = EDV - ESV
Which of the following is NOT a factor that influences end-diastolic volume (EDV)?
Afterload
How does end-systolic volume (ESV) affect stroke volume?
Decreasing ESV increases stroke volume
What initiates cardiac muscle contraction?
Binding of calcium ions to troponin
What is the role of ATP in cardiac muscle contraction?
All of the above
What is the role of the sarcoplasmic reticulum in cardiac muscle relaxation?
To reuptake calcium ions from the sarcoplasm
What happens during the powerstroke in cardiac muscle contraction?
The myosin head swivels, pulling the thin filament
What is the role of plasma membrane calcium pumps in cardiac muscle relaxation?
To remove calcium ions from the cardiac muscle cell
What happens to the sarcomeres during cardiac muscle relaxation?
They return to their resting length
Which of the following statements is true about ventricular balance?
Both ventricles pump equal amounts of blood.
Why is the left ventricle larger and stronger than the right ventricle?
To pump the same amount of blood through the longer systemic circulation.
What condition can result from sustained pumping of unequal amounts of blood by the ventricles?
Edema
What is the analogy used to explain the difference in work required by the left and right ventricles?
Throwing a baseball two different distances
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.
What information is provided in Figure 19.24?
All of the above.
What happens to the overlap of thick and thin filaments in cardiac muscle cells during a more forceful ventricular contraction?
Increases
How does a decrease in venous return affect the formation of crossbridges in cardiac muscle cells?
Decreases the formation of crossbridges
What causes venous return to increase according to the text?
High arterial pressure
How does a decrease in venous return affect ventricular contraction strength?
Decreases ventricular contraction strength
What analogy is provided in the text to explain venous return?
Filling a balloon with water
Why does venous return increase during exercise according to the text?
Higher venous pressure
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.
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.
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.
What causes the AV valves to open during the cardiac cycle?
The pressure within the ventricles decreases below the pressure within the atria.
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.
What is the significance of the cardiac cycle being repeated with each heartbeat?
It ensures a consistent flow of blood throughout the body.
Learn about the steps involved in cardiac muscle contraction within sarcomeres, including crossbridge formation and the powerstroke. Understand the process of calcium ions binding to troponin and initiating muscle contraction. Explore the similarities and differences between cardiac muscle and skeletal muscle contraction.
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