Biology 30s - Heart Quiz
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What is the role of the sinoatrial node (SA node)?
Initiates the cardiac cycle causing the atria to contract.
What is the role of the atrioventricular node (AV node)?
Briefly delays the impulse from the SA node to allow the atria to contract and empty its contents.
What is the role of the Bundle of His?
Causes the ventricles to contract.
Explain the significance of the delay in impulse conduction of the AVN.
Allows the atrial contraction to finish before the ventricles contract.
What is the formula for cardiac output?
stroke volume x heart rate
What happens in during the P wave?
Atrial depolarization (atria contract)
What happens during the QRS wave?
Ventricular depolarization (ventricles contract)
What happens during the T wave?
Ventricular repolarization (ventricles relax)
Describe the cardiac cycle. (8)
- Blood enters and fills both atria simultaneously.
- Atria contract in a wave-like motion starting from the top of the atria towards the bottom of the atria.
- The atrioventricular valves are pushed open.
- Ventricles fill.
- Atrioventricular valves shut (LUB).
- Ventricles contract in a wave-like motion starting at the bottom of the ventricles towards the top of the ventricles.
- Blood does not flow back into the atria because the AV valves are shut.
- Blood flows from ventricles through the semilunar valves and out of the pulmonary arteries (right side) or aorta (left side).
Define heart conduction.
Heartbeat is controlled by a series of nerve impulses called conduction.
What is wave conduction initiated by?
Sinoatrial node (SA node) through the atria via gap junctions
What is the pathway of the heart impulses? (9)
medulla > cranial nerves > cardioaccelerator or vagus nerve > SA node > atria contract > AV node > bundle of his > purkinje fibers > ventricles contract
What happens if the heart rate is too slow?
Medulla sends impulses through vagus nerve to increase heartbeat.
What happens if the heart rate is too fast?
Medulla sends impulse through vagus nerve to decrease heartbeat.
What factors affect heart rate? (4)
- emotional state
- activity level
What factors contribute to resting heart rate? (2)
What is the average heart rate for an infant, a teenage, and an adult? (3)
- infant - 130 bpm
- teenager ~60 bpm
- adult - 60-80 bpm
Define maximum heart rate.
The maximum rate at which your heart can beat to supply your muscles in one minute.
What is the formula to calculate maximum heart rate for both men and women? (2)
- women: 226 - age = max HR
- men: 220 - age = max HR
Define recovery heart rate.
Rate at which your heart rate can recover and return to normal after exercise.
Define electrocardiogram. (3)
- Recording of the electrical activity of the heart muscle.
- Impulses carried by the nervous system contract and relax the heart produce an electrical current.
- The electrical current is strong enough to be detected as the surface of the body.
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