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15 Cards in this Set
- Front
- Back
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Damage to the semi-lunar valve of the right ventricle would affect blood flow into which vessel
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the pulmonary trunk
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what prevents the AV valves from swinging into the atria
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chordae tendineae
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Why is the left ventricle more muscular than the right ventricle?
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because it must generate enough force to propel blood throughout the body (except the lungs). the right ventricle must generate only enough force to propel blood a few cm to the lungs.
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How does the fact that cardiac muscle does not undergo tetanus affect the functioning of the heart
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because they have a longer refractory period than skeletal muscle. meaning that they relax long enough so the hearts chambers can refill with blood.
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if the cells of the SA node were not functioning, how would the heart rate be affected?
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cells of the AV node would become the pacemaker cells, so the heart would continue to beat but at a slower rate.
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why is it important for the impulses from the atria to be delayed at the AV node before passing into the ventricles
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if they were not delayed, they would be conducted through the ventricles so quickly by the bundle branches and purkinje fibers that the ventricles would begin contracting immediately, before the atria had finished contracting. as a result, the ventricles would not be as full of blood as they could be, and the pumping of the heart would not be as efficient, especially during activity.
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what might cause an increase in the size of the QRS complex in the EKG?
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larger-than- normal amount of electrical activity during ventricular depolarization in an enlarged heart.
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Provide the alternate terms for the contraction and relaxation of the heart chambers
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contraction- systole
relaxation- diastole |
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is the heart always pumping blood when pressure in the left ventricle is rising? explain
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no. when pressure in the left ventricle first rises, the heart is contracting but no blood is leaving the heart. during the initial phase of contraction, bot the av and semi-lunar valves are closed. the increase in pressure results from increased tension as the cardiac muscle contracts. when ventricular pressure exceeds the pressure in the aorta, the aortic semi-lunar valves are forced to pen and blood is rapidly ejected.
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what events cause the "lubb-dupp" heart sounds as heard with a stethoscope?
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lubb is produced by the simultaneous closing of the av valves and the opening of the semi-lunar valves. dupp is produced when the semi-lunar valves close.
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Define cardiac output
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amount of blood pumped by the left ventricle in one minute
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if the cardioinhibitory center of the medulla oblongata were damaged, which part of the Autonomic nervous system would be affected, and how would the heart be influenced.
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parasympathetic nervous system- result in fewer parasympathetic action potentials to the heart and an increase in heart rate due to the sympathetic dominance.
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what effect does stimulation of the ACh receptors of the heart have on cardiac output?
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lowers the heart rate and a reduction in cardiac output
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what effect does increased venous return have on stroke volume
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the more the heart muscle is stretched by returning blood ( venous return), the more forcefully it will contract and the more blood it will eject with each beat (stroke volume)
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why is it a potential problem if the heart beats too rapidly?
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if it beats to fast, it has too little time to fill completely between beats. the heart pumps in proportion to the amount of blood that enters. the less blood that enters, the less the heart can pump. if it beats too fast, very little blood will enter the bloodstream.
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