37 Questions
In the cardiac cycle, which event is correctly correlated with the opening of the aortic valve?
B: Diastasis, all valves are open
On the volume-pressure diagram, which phase includes atrial contraction?
C: Mitral valve closes
Which statement about the cardiac muscle action potential is correct?
D. Cardiac muscle is refractory to restimulation during the action potential.
Which event in the cardiac cycle is correctly correlated with isovolumetric relaxation and open A-V valves?
B: Isovolumetric contraction (the ventricular pressure increases but the ventricular volume is constant)
Which phase of the cardiac cycle includes rapid inflow and an open mitral valve?
D: Period of filling
Which curve on the volume-pressure diagram represents atrial pressure?
C: Phonocardiogram
Which of the following statements about the composition of faeces is true?
10 to 20 per cent of the solid matter is represented by fat
What causes the odor of faeces?
Hydrogen sulfide
Which statement about the cardiac cycle for left ventricular function is correct?
Ejection → C
What role does aldosterone play in sodium transport capability?
It enhances sodium transport capability
Which ion is absorbed in an exchange transport process by the mucosa of the large intestine?
Chloride ions
What causes the brown color of faeces?
Derivatives of bilirubin
Which of the following statements about the strength of contraction of cardiac muscle is correct?
The strength of contraction of cardiac muscle depends to a great extent on the concentration of calcium ions in the extracellular fluids
What occurs during the period of isovolumic (isometric) relaxation in the cardiac cycle?
The cardiac muscle tension is increasing but little or no shortening of the muscle fibers is occurring
Which statement about the A-V valves and the semilunar valves is correct?
The A-V valves prevent backflow of blood from the ventricles to the atria during systole
What does the electrocardiogram (ECG) wave represent?
The P wave is caused by spread of depolarization through the atria
What happens when the left ventricular pressure rises slightly above 8 mm Hg in the cardiac cycle?
The ventricular pressures push the semilunar valves open
Which of the following statements about the ejection fraction is correct?
The ejection fraction is usually equal to about 0.6 (or 60 percent).
During diastole, what happens to the volume of each ventricle?
It increases to a volume called the end diastolic volume.
When does the pressure in the aorta increase?
Increasing after open aortic valve.
When does the pressure in the left ventricle increase?
Increasing after closing the mitral valve.
When does the A-V valve close?
Closes after atrial repolarization.
Which statement about heart sounds is correct?
When the valves open, the vanes of the valves and the surrounding fluids vibrate under the influence of sudden pressure changes, giving off sound that travels in all directions through the chest.
Which statement accurately describes the afterload of the left ventricle?
The afterload is usually considered to be the pressure in the aorta leading from the right ventricle.
Which statement accurately describes the effect of vagal stimulation on the heart?
Inhibition of the parasympathetic nerves to the heart can decrease cardiac pumping to a moderate extent.
Which statement accurately describes the effect of body temperature on the heart?
Prolonged elevation of temperature exhausts the metabolic systems of the heart and eventually causes spastic contraction.
Which statement accurately describes the effect of potassium concentration on the heart?
Elevation of potassium concentration to only 8 to 12 mEq/L can cause severe weakness of the heart, abnormal rhythm, and death.
Which statement accurately describes the cardiac muscle contraction process?
Without the calcium from the T-tubules, the strength of cardiac muscle contraction would be reduced considerably.
Which effect is accurately associated with sympathetic stimulation on the heart and vessels?
Bronchodilation (β2 adrenergic receptors)
In the rhythmical and conductive system of the heart, what is the purpose of the internodal pathways?
Conduct impulses from the sinoatrial node to the atrioventricular node
What is the intrinsic discharge rate of the A-V valve in the normal heart?
70-80/ minute
After closing of the mitral valve, what happens to the intraventricular pressure?
Rapidly increases
Which structure brings depolarization from the S-A node according to the organization of the atrioventricular (A-V) node?
Transitional fibers
What happens if the conductive system of the heart stops?
The ventricles contract 0.16’’ before the atria
What is the function of the Purkinje fibers in the rhythmical and conductive system of the heart?
Conduct cardiac impulses to all parts of the atria
What is true about the pacemaker of the heart?
The sinus node is almost always the pacemaker of the normal heart
What is true about the intervals of time needed to pass different structures of conductive system?
Delay in sinus node = 0.03 seconds
Test your knowledge about the cardiovascular system with a focus on the electrical depolarization of ventricles and the ejection fraction. Choose the correct statement(s) regarding cardiac function and volume dynamics.
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