Midterm 3 - Q&A - F08

Midterm 3 - Q&A - F08 - Term Test 3 Questions and Answers...

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Term Test 3 Questions and Answers
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1. Diagram the action potential of a ventricular myocyte and describe the ion movement and ion channels involved in establishing this action potential. Describe the effect that epinephrine released from the adrenal gland has on the ventricular myocyte. 1. Voltage gated Na + channels open – increase Na + flux in b cell depolarization 2. Voltage gated Na + channels inactivate – Na + flux in decreases 3. K + ions move out of the cell down the concentrations and electrical gradients 4. Voltage gated Ca ++ channels open – increase Ca ++ flux into the cell 5. Ca ++ flux in = K + flux out (plateau) 6. Voltage gated Ca ++ channels inactivate – Ca ++ flux in decreases 7. K + flux out > Ca ++ flux in – repolarization 8. Voltage gated Na + and Ca ++ channels close 9. Ca ++ removed from cell via Na + Ca ++ exchanger, and Ca ++ ATPases on plasma membrane 10. Na + K + ATPase restore Na + and K + gradients. K + permeability must decrease throughout the duration of AP so that the cell doesn’t immediately repolarize. Epinephrine released from the adrenal gland will bind to ß adrenergic membrane receptors, which will change a G protein that will increase adenylate cyclase activity and increase the production of cAMP. Increased cAMP will lead to increased activity of protein kinase and increased phosphrylation of: (a) Voltage dependent Ca ++ channels and increase the number of channels open allowing a greater flux of Ca ++ into the cell (increases trigger Ca ++ ) which increases myocyte contractility (b) Ca ++ ATPase, which will remove more Ca ++ from the intracellular space, decreasing myocyte relaxation time and increasing the speed of contraction. 1 2 3 4 5 6 7 8 9 10
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2. Diagram and describe the events of the pressure/volume relationship of the left ventricle through diastole and systole showing the relationship between ventricular pressure and ventricular volume. Explain the changes that would occur in this relationship in the presence of a decreased afterload. Aortic 1. Diastole – ventricle relaxed and filling * atrial contraction – increase volume and pressure in the ventricle 2. Systole – ventricular contraction -mitral valve closed due to vent pr. > atrial pr. -aortic valve is still closed due to vent pr. < aortic pr.
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This note was uploaded on 12/13/2010 for the course HK 3940 taught by Professor Murrant during the Fall '10 term at University of Guelph.

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Midterm 3 - Q&A - F08 - Term Test 3 Questions and Answers...

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