Cardiac Cycle Flashcards
Which part of the conduction system is responsible for atrial systole?
SA node
When considering SA node cells, what event is occurring right before the cells reach threshold?
Sodium is leaking into the cells.
The closure of which valves produces the second heart sound?
Pulmonary and aortic valves
Endurance athletes typically have lower resting heart rates compared to non-athletes, even though both bodies require the same cardiac output. When an endurance athlete trains, one of the results is increasing the amount of proteins in cardiac muscle cells, resulting in stronger contractions. Considering cardiac output, how does the athlete’s stroke volume compare to the non-athlete’s?
The athlete has a larger stroke volume
Skeletal muscle sarcomeres tend to have an optimal resting length while cardiac muscle sarcomeres tend to have a shorter than optimal resting length (see arrow). What will happen to the sarcomere length as the heart fills (stretches) with blood?
Sarcomeres approach optimal length
What will happen to the amount of tension (y-axis) generated by the sarcomere as EDV increases in the heart?
Tension will increase (stronger contraction)
Rigorous exercise results in more blood returning to the heart (rather than pooling in vessels). This contributes to higher EDV. If a person has an EDV of 300 mL, what is the resulting stroke volume?
150 mL
A patient with normal baseline contractility of the heart has an EDV of 60 mL. He is treated with the positive inotropic agent dopamine. What is his new SV?
47 mL
After recovering and returning to normal contractility, this same patient with a baseline EDV of 60 mL is treated with the negative inotropic agent acetylcholine. What is his new SV?
18 mL
If there is nothing blocking its path, blood will flow from _________________________.
High to low pressure
When the chamber of a heart contracts, the pressure in the chamber ________________ compared to when it is relaxed.
Increases
During which stage do the atrioventricular (AV) valves close?
Isovolumetric contraction (systole)
The semilunar valves will close when the pressure in the arteries (arterial pressure) is _________________ the pressure in the ventricles.
greater than
During isovolumetric contraction and relaxation, the volume of blood in the ventricles stays constant (there is no blood entering or exiting from the ventricles).
True
