2006 Fall Bio 328 Exam 3 (2)

2006 Fall Bio 328 Exam 3 (2) - BIO 328 Examination 3 4...

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BIO 328 Examination 3 4 December 2006 Page 1 FOR EACH QUESTION, SELECT THE MOST INCORRECT ANSWER Mark your answers on the op-scan sheet with a No.2 pencil. If you change your answer, be sure to erase thoroughly. There are 20 Questions on this examination so be sure to answer all of them. Fill in your name and SBU ID number (NOT YOUR SS#) on the answer sheet. 1) Extrinsic control of heart rate: a) Activation of β -receptors on SA node cells leads to the opening of voltage-gated fast Na + channels and voltage-gated long-lasting Ca ++ (L) channels. b) Activation of muscarinic receptors on SA node cells results in the opening of a voltage-gated K + channel, followed by membrane potential hyperpolarization and a change in the slope of the pacemaker potential. c) Activation of β -receptors in the heart results in an increased slope of the pacemaker potential in SA node cells and additionally, has a positive dromotropic effect at the AV node. d) If plasma levels of epinephrine are normal, and the heart is denervated, heart rate with increase due to the removal of a tonic inhibitory influence. e) Absent the existence of damage at the AV node, or the bundle of His, or left and right bundle branches, or left and right Purkinje fibers, heart rate will be determined by the slope of the SA node cells pacemaker potential. 2) Physiological regulation of stroke volume: a) An increase in ejection fraction due to an increase in stroke volume suggests an increase in sympathetic cardiac nerve activity. b) If ejection fraction remains constant while end-diastolic volume increases, then the cardiac muscle is performing as predicted by the Frank-Starling mechanism. c) An increase in stroke volume associated with a more forceful contraction is due to either or both of the following: (1) an increase in ventricular muscle sarcomere length, (2) an increase in the amount of Ca ++ released through Ca ++ -induced Ca ++ release. d) Since cardiac output = venous return, then when heart rate and peripheral resistance are constant, stroke volume = venous return. e) Venoconstriction would likely result in an increased stroke volume due to changes in contractility associated with increased ventricular muscle length. 3) Cardiac output (all variables not mentioned are held constant): a) If ejection fraction remained unchanged when EDV increased, cardiac output would increase. b) If you administered digitalis to an otherwise healthy subject, cardiac output would increase. c) If an individual had a tumor of the adrenal medulla that increased the secretion of chromaffin cells, the subject would likely exhibit an increase in cardiac output. d) An increase in parasympathetic cardiac nerve activity will decrease heart rate, stroke volume and cardiac output.
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This note was uploaded on 03/28/2011 for the course BIO 328 taught by Professor Cabot during the Fall '07 term at SUNY Stony Brook.

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2006 Fall Bio 328 Exam 3 (2) - BIO 328 Examination 3 4...

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