#1
Which structure is responsible for initiating the electrical impulse in the heart?
Sinoatrial node (SA node)
ExplanationThe SA node generates the electrical signal that starts the heartbeat.
#2
What is the average resting heart rate for adults?
50-70 beats per minute
ExplanationThe normal resting heart rate for adults ranges between 50 and 70 beats per minute.
#3
Which chamber of the heart receives oxygenated blood from the lungs?
Left atrium
ExplanationThe left atrium receives oxygenated blood from the lungs before pumping it into the left ventricle.
#4
Which ion is primarily responsible for depolarization during the cardiac action potential?
Sodium (Na+)
ExplanationSodium ions play a key role in the depolarization phase of the cardiac action potential.
#5
What is the main function of the atrioventricular node (AV node) in the heart conduction system?
To conduct the electrical impulse from atria to ventricles
ExplanationThe AV node facilitates the transmission of electrical signals from the atria to the ventricles.
#6
What is the term for the period during which the cardiac muscle cannot be stimulated to contract again?
Refractory period
ExplanationThe refractory period is the phase when the cardiac muscle cannot be re-stimulated to contract.
#7
Which part of the autonomic nervous system primarily slows down heart rate?
Parasympathetic nervous system
ExplanationThe parasympathetic nervous system has a decelerating effect on heart rate.
#8
Which of the following hormones increases heart rate and contractility?
Epinephrine
ExplanationEpinephrine is a hormone that enhances both heart rate and contractility.
#9
Which of the following factors does NOT affect stroke volume?
Heart rate
ExplanationStroke volume is unrelated to heart rate; it's influenced by other factors.
#10
What is the term for the volume of blood ejected by each ventricle during one contraction?
Stroke volume
ExplanationStroke volume is the amount of blood expelled by a ventricle in a single contraction.
#11
Which of the following statements about the Frank-Starling mechanism is true?
It controls the strength of ventricular contraction
ExplanationThe Frank-Starling mechanism regulates the force of ventricular contraction based on the volume of blood received.