Review quiz 4 - Lectures 6-7

Review quiz 4 - Lectures 6-7 - heart c Sympathetic...

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Choose the most incorrect answer. 1. Cardiac action potentials a. Normally, ventricular myocytes do not display intrinsic automaticity. b. The resting membrane potential of SA nodal cells is not stable. c. When HCN channels begin to open, more Na + enters the cell than K + leaves the cell. d. In SA nodal cells, there is delayed opening of K + channels after Na + channels have closed. e. When HCN channels open, the membrane potential is closer to the K + equilibrium potential than to the Na + equilibrium potential. 2. Cardiac action potentials a. Application of acetylcholine increases K + ion conductance in SA nodal cells. b. The pacemaker potential of a denervated heart is less steep than that of a normal
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Unformatted text preview: heart. c. Sympathetic stimulation leads to an increase in cAMP and phosphorylation of the HCN channel. d. The receptor for noradrenaline is not an ion channel. e. Under resting conditions, parasympathetic input to the heart predominates over sympathetic input. 3. Genetics a. Much of human genetic variation is due to single nucleotide polymorphisms. b. Base substitutions at the third position in a codon are frequently benign. c. In LQTS, K + and Ca 2+ currents can be affected. d. The QT interval corresponds to ventricular depolarization and ventricular repolarization. e. Drugs that activate the M-current may be used to treat epilepsy....
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