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16 Cards in this Set
- Front
- Back
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What are the two types of mechanical junctions joining myocytes?
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Fascia adherenes and desmosomes.
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Describe sequence of actions in a pacemaker cell
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Vm drifts positive because of open Na+ gates.
K+ channels close. At a given Vm, Ca+ channels open and membrane reaches action potential. K+ gates open and sequence starts over. |
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During what period do the ventricles contract?
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During the S-T seqment.
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Give the sequence of events for the contraction of cardiac muscle.
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Action potential arrives.
Voltage-gates Na+ gates open. K+ gates close. Volage-gated slow Ca++ gates open and allow Ca++ from ECF to enter the cell. Calcium-gated calcium gates open and allow Calcium to flow from the ER into the cell ISF. >90% Ca++ comes from ER. Ca++ binds to Troponin and triggers contraction. Ca++ channels close and K+ channels open. => Vm (resting) |
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For Mitral valve (bi-cuspid A-V) stenosis, will the resulting murmer be heard in the disastolic or systolic phase?
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Diastolic
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For an Aortic valve regurgitation murmer, will this be heard in the systolic or diastolic phase?
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Diastole
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For a Mitral valve (AV) regurgitation murmer, will this be heard in the systolic or diastolic phase?
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Systolic
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What is the consequence of an aortic valve stenosis?
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Increased resistance for the heart to work against.
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What is the consequence of a mitral valve stenosis?
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May result in insufficient filling of the ventricle which in turn may starve the systemic system for blood if the opening is too narrow.
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What is the result of Aortic regurgitation?
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May reduce the pressure that the ventricle can attain.
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What are the 3 layers of a blood vessels - not capilaries?
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Tunical externa
Tunica media Tunica intima. |
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What is contained within the tunica externa?
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Consists of conncetive tissue. It anchors the vessel and provides passage for small nerve, lymphatic vessels, and smaller blood vessels.
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What are the characteristics of the tunica media?
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Usually the thickest layer of the tunica. It consists of smooth muscle, collagen and sometimes elastic tissues.
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What are the characteristics of the tunica intima?
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Simple squamous fibrous tissue. The endothelium acts as a selctively permeable barrier to blood solutes. Secretes vasoconstrictors and vasodilators.
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What is the medullary ischemic reflex?
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Drop in perfusion of the brain which results in increased BP and contractility of the heart.
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For an aortic valve stenosis murmur, will this occur in the systolic or diastolic phase?
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Systolic
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