Electrical Conduction
Which structure is known as the natural pacemaker of the heart?
A. AV node
B. Bundle of His
C. SA node
D. Purkinje fibers
C. SA node
What is systole?
A. The relaxation phase of the heart when chambers fill with blood
B. The contraction phase of the heart when blood is pumped out of the chambers
C. The electrical resetting of the heart
D. The period when the heart valves are closed and no blood is moving
B. The contraction phase of heart when blood is pumped out of the chambers
1. What initiates the cardiac cycle?
A. Atrial contraction
B. Ventricular relaxation
C. Electrical impulse from the SA node
D. Closure of semilunar valves
C. Electrical impulse from the SA node
1. What is cardiac output?
A. The pressure in the arteries during a heartbeat
B. The amount of blood ejected per heartbeat
C. The volume of blood pumped by the heart per minute
D. The rate at which the heart beats
C. The volume of blood pumped by the heart per minute
Where does the electrical impulse travel immediately after the SA node?
A. Purkinje fibers
B. AV node
C. Left atrium
D. Aortic valve
B. AV node
What is diastole?
A. The phase when the heart contracts and pumps blood
B. The relaxation phase when the heart chambers fill with blood
C. The time between heartbeats when there is no activity
D. The phase when the semilunar valves are open
B. The relaxation phase when the heart chambers fill with blood
2. During which phase are the ventricles filling with blood?
A. Ventricular systole
B. Ventricular diastole
C. Atrial systole
D. Isovolumetric contraction
B. Ventricular diastole
2. Which two main factors directly determine stroke volume?
A. Blood pressure and heart rate
B. Preload and afterload
C. Contractility and preload
D. Heart rate and blood pressure
C. Contractility and preload
Which structure carries the electrical impulse from the AV node into the interventricular septum?
A. Purkinje fibers
B. SA node
C. AV bundle (bundle of His)
D. Mitral valve
C. AV bundle (bundle of His)
What is the primary role of atrial contraction in the cardiac cycle?
A. To initiate ventricular contraction
B. To close the semilunar valves
C. To eject blood from the ventricles into the arteries
D. To complete ventricular filling by pushing additional blood into the ventricles
D. To complete ventricular filling by pushing additional blood into the ventricles
3.What causes the first heart sound ("lub") heard during auscultation?
A. Closure of the semilunar valves
B. Opening of the AV valves
C. Atrial contraction
D. Closure of the AV valves
D. Closure of the AV valves
3. How does the autonomic nervous system regulate cardiac output?
A. It changes the oxygen content of the blood
B. It alters blood viscosity
C. It increases or decreases heart rate and contractility
D. It controls the opening and closing of heart valves
C. It increases or decreases heart rate and contractility
Which fibers are responsible for spreading the electrical impulse throughout the ventricles?
A. SA node
B. Purkinje fibers
C. AV node
D. Bundle of His
B.Purkinje fibers
Which of the following correctly describes the events during ventricular systole and diastole?
A. During systole, ventricles relax and AV valves open to allow blood inflow.
B. During diastole, ventricles contract and semilunar valves open.
C. During systole, ventricles contract, AV valves close, and semilunar valves open.
D. During diastole, ventricles contract and AV valves remain closed
C. During systole, ventricles contract, AV valves close, and semilunar valves open.
4.What happens during isovolumetric contraction?
A. Blood is ejected from the ventricles
B. Atria contract to fill the ventricles
C. Ventricles contract with all valves closed
D. Semilunar valves open
C. Ventricles contract with all valves closed
4. What effect does increased afterload have on cardiac output?
A. It increases stroke volume and cardiac output
B. It decreases stroke volume, which can reduce cardiac output
C. It has no effect on cardiac output
D. It directly increases heart rate
B. It decreases stroke volume, which can reduce cardiac output
Why is there a delay at the AV node?
A. To allow blood to flow into the atria
B. To prevent overexcitation of the ventricles
C. To allow the atria to fully contract before the ventricles
D. To slow the heart rate during sleep
C.To allow the atria to fully contract before the ventricles
Which of the following occurs during ventricular relaxation (diastole)?
A. AV valves close, and the ventricles eject blood into the arteries.
B. Semilunar valves open to allow blood into the ventricles.
C. Ventricular pressure decreases, AV valves open, and blood flows from the atria into the ventricles.
D. Ventricles contract, increasing pressure and closing the AV valves.
C. Ventricular pressure decreases, AV valves open, and blood flows from the atria into the ventricles.
5. When do the semilunar valves open?
A. When atrial pressure exceeds ventricular pressure
B. When ventricular pressure exceeds arterial pressure
C. During atrial contraction
D. At the end of diastole
C. During atrial contraction
5. A patient has a heart rate of 90 bpm and a stroke volume of 70 mL. If their afterload suddenly increases significantly, how might their cardiac output change and why?
A. It increases because the heart pumps harder
B. It decreases because stroke volume decreases
C. It stays the same because heart rate is unchanged
D. It increases due to higher blood pressure
B. It decreases because stroke volume decreases