5 Questions
During which phase of the cardiac cycle do the atrioventricular valves open?
Diastole
What happens to the semilunar valves during diastole?
They are closed
What is the average cardiac output at rest?
5-6 liters per minute
What happens to cardiac output during exercise or physical activity?
It increases
What is cardiac output calculated by multiplying?
Heart rate and stroke volume
Study Notes
Cardiac Cycle
Diastole
- Period of heart muscle relaxation
- Lasts approximately 2/3 of the cardiac cycle
- Heart chambers fill with blood
- Atrioventricular valves open, allowing blood to flow from atria to ventricles
- Semilunar valves closed, preventing backflow into pulmonary and aortic arteries
Systole
- Period of heart muscle contraction
- Lasts approximately 1/3 of the cardiac cycle
- Heart chambers pump blood out
- Atrioventricular valves closed, preventing backflow into atria
- Semilunar valves open, allowing blood to flow into pulmonary and aortic arteries
Cardiac Output
- Total volume of blood pumped by the heart per minute
- Calculated by multiplying heart rate (beats per minute) by stroke volume (volume of blood pumped per beat)
- Average cardiac output: 5-6 liters per minute at rest
- Increases with exercise or physical activity
Cardiac Cycle
Diastole
- Lasts approximately 2/3 of the cardiac cycle
- Heart muscle relaxes, allowing heart chambers to fill with blood
- Atrioventricular valves open, facilitating blood flow from atria to ventricles
- Semilunar valves remain closed, preventing backflow into pulmonary and aortic arteries
Systole
- Lasts approximately 1/3 of the cardiac cycle
- Heart muscle contracts, pumping blood out of heart chambers
- Atrioventricular valves close, preventing backflow into atria
- Semilunar valves open, enabling blood flow into pulmonary and aortic arteries
Cardiac Output
- Total volume of blood pumped by the heart per minute
- Calculated by multiplying heart rate (beats per minute) by stroke volume (volume of blood pumped per beat)
- Average cardiac output at rest: 5-6 liters per minute
- Increases during exercise or physical activity
Learn about the cardiac cycle, including the periods of diastole and systole, and how they relate to heart muscle relaxation and contraction. Understand the flow of blood through the heart chambers and valves.
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