All of the following are true regarding a normal cardiac cycle except
|A)||the ventricles receive 70% of the blood from the atria passively during ventricular diastole|
|B)||the aortic valve closes when left ventricular pressure falls below aortic pressure|
|C)||there is a point where the atrioventricular and semilunar valves are open at the same time|
|D)||the atria and ventricles are both in diastole for a brief period of the cardiac cycle|
The two major heart sounds are a result of
|A)||blood entering the atria in large volumes|
|B)||closing of heart valves|
|C)||contraction of the myocardium|
|D)||changes in the blood flow rate through the chambers of the heart|
A mass of merging cells that act as a unit, 2 of which are found in the heart, is called
|B)||a functional syncytium|
|C)||the sinoatrial node|
|D)||the cardiac conduction system|
The cells that initiate the stimulus for contraction of the heart muscle are located in the
|D)||Bundle of His (AV Bundle)|
Which of the following sequences correctly describes the conduction pathway of cardiac impulses?
|A)||SA node, AV node, Purkinje fibers, AV bundle, Bundle branches|
|B)||AV node, Bundle branches, SA node, AV bundle, Purkinje fibers|
|C)||AV bundle, Purkinje fibers, Bundle branches, AV node, SA node|
|D)||SA node, AV node, AV bundle, Bundle branches, Purkinje fibers|
The P wave on an ECG represents
|D)||impulse transmission at the AV node|
Ventricular repolarization is represented by the
Concentrations of which of the following electrolytes have direct effects on the myocardium?
|A)||calcium and potassium|
|B)||potassium and bicarbonate|
|C)||calcium and chloride|
|D)||sodium and chloride|
The middle layer of arterial walls is composed of
|C)||smooth muscle and elastic connective tissue|
|D)||fibrous connective tissue|
The blood vessel that participates directly in the exchange of substances between body cells and the blood is the
The amount of blood that flows into capillaries is regulated by
|A)||constriction and dilation of capillaries|
|C)||the amount of extracellular tissue|
Deposits of fatty materials on the inside of arterial walls are called
Plasma proteins help retain water in the blood by maintaining
The middle layer of the walls of veins differs from arteries in that
|A)||it contains less fibrous connective tissue|
|B)||it contains less smooth muscle|
|C)||it is thicker in veins|
|D)||it contains some striated muscle|
Systolic pressure is the
|A)||lowest pressure in the arteries when the heart is relaxed|
|B)||highest pressure in the arteries, which occurs during contraction of the heart|
|C)||pressure that forces fluid out of the capillaries into the tissue|
|D)||pressure generated in each atrium during contraction|
Which of the following will cause blood pressure to increase?
|A)||a decrease in arteriole diameter|
|B)||a decrease in stroke volume|
|C)||increased parasympathetic activity|
The Frank-Starling law is related to which of the following cardiac structures?
The right and left ___________ veins merge to form the superior vena cava.
Which of the following vessels carries oxygen-rich blood?
|D)||inferior vena cava|
Which vessel supplies blood to the liver, stomach and spleen?
|A)||inferior mesenteric artery|
|C)||superior mesenteric artery|
Tissues depend on a functional circulatory system to supply nutrients and oxygen and to remove accumulated wastes.
The pericardial cavity contains fluid that reduces the friction produced by the motion of the heart as it contracts.
The ventricles are the upper chambers of the heart; the atria are the lower chambers.
When the papillary muscles contract, they pull the cusps of the mitral and tricuspid valves down into the ventricles.
The wall of the right ventricle is thicker than that of the left ventricle.
The skeleton of the heart is composed of dense connective tissue, which provides sites of attachment for heart valves and muscle fibers.
Blood is supplied to the myocardium by the coronary arteries, the first branches of the aorta.
Most of the blood from the atria enters the ventricles during atrial contraction.
The AV node is the pacemaker of the heart under normal conditions.
Atrial repolarization is not seen as a separate wave on the ECG.
Increasing temperature slows the heart rate.
The right and left brachiocephalic arteries supply blood to the head and upper limbs.
The superior mesenteric vein drains directly into the inferior vena cava.