History Bookmarks People Window Help Quiz: Unit 06 Lecture Quiz ?D Microsoft Wor

Question

History Bookmarks People Window Help Quiz: Unit 06 Lecture Quiz ?D Microsoft Word -18_TestBank x x x DEICC Connect Home X acconline.instructure.com/courses/17981/quizzes/150182/take Increases in preload O stretch the cardiac muscle O increase the contractile force of the ventricle O result from increased venous return O all of the above are correct D Question 5 0.5 pts Referring to the EKG: The beginning of atrial excitation to the beginning of ventricular excitation is recorded by the O P-R interval O S-T segment O Q-T interval ?) Question 6 0.5 pts Which of the following is greater? o heart rate when acetylcholine is released on the S-A node O heart rate when norepinephrine is released on the S-A node uestion 7 0.5

Explanation / Answer

Answer 5: Referring to the EKG, beginning of arterial to beginning of ventricular excitation is represented by P-R interval. Therefore, the correct answer is first option.

Explanation: P represent the atrial phase in the EKG, QRS wave represent the ventricular contraction phase in the EKG and T wave represent the repolarization or relaxation of the ventricles. The P-R interval represents the conduction time from beginning of atrial excitation to beginning of ventricular excitation.

Answer 6: Correct option is the second option.

Explanation: Both, acetylcholine and norepinephrine are involved in the regulation of the heart rate. However, both have opposite actions. Acetylcholine is responsible to slow down the heart rate and it is known as parasympathetic control. Norepinephrine is responsible to increase the heart rate and it is known as sympathetic control. Therefore, the correct answer is “heart rate is greater when norepinephrine is released at the S-A node”.

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