#1
Which phase of the cardiac cycle involves ventricular filling?
Ventricular diastole
ExplanationPeriod of relaxation during which ventricles fill with blood.
#2
Which component of the blood carries oxygen from the lungs to the rest of the body?
Red blood cells
ExplanationSpecialized cells transporting oxygen bound to hemoglobin.
#3
What is the sequence of electrical conduction in the heart?
SA node → AV node → Bundle of His → Purkinje fibers
ExplanationOrderly electrical stimulation of heart chambers, initiating contraction.
#4
What determines the direction of blood flow through the heart?
Pressure gradients created by the heart's pumping action
ExplanationPressure differences propelling blood through heart chambers.
#5
The QRS complex on an electrocardiogram (ECG) represents:
Ventricular depolarization
ExplanationElectrical activity during ventricular contraction.
#6
What is the primary function of the atrioventricular valves in the heart?
To prevent backflow into the atria during ventricular contraction
ExplanationValves ensuring one-way flow, closing during ventricular contraction.
#7
During which phase of the cardiac cycle does the aortic valve close?
Isovolumetric relaxation
ExplanationPeriod after ejection when ventricles relax and aortic valve closes.
#8
What is the term for the volume of blood pumped by the heart in one minute?
Cardiac output
ExplanationMeasure of heart's efficiency in circulating blood per minute.
#9
In the context of the circulatory system, what does the term 'preload' refer to?
The volume of blood in the ventricles at the end of diastole
ExplanationAmount of blood stretching heart muscle before contraction.
#10
Which vessel type is primarily responsible for controlling blood flow distribution to various tissues by vasoconstriction and vasodilation?
Arterioles
ExplanationSmall arteries regulating blood flow to tissues by constriction or dilation.
#11
What is the effect of increased afterload on the heart's function?
Both a and c
ExplanationIncreased resistance heart must overcome, affecting workload and oxygen demand.
#12
The Frank-Starling law of the heart states that:
Stroke volume increases with an increase in venous return
ExplanationHeart's intrinsic ability to adjust output based on venous return.
#13
Which law explains the relationship between blood flow, pressure gradient, and resistance?
Poiseuille's law
ExplanationMathematical equation defining factors affecting blood flow in vessels.
#14
The term 'afterload' is best described as:
The resistance left ventricle must overcome to circulate blood
ExplanationPressure against which the heart must pump to eject blood.
#15
What effect does an increase in heart rate have on the cardiac cycle?
Decreases the duration of diastole more than systole
ExplanationShortens relaxation phase more than contraction phase.