Question

7. Correlate heart sounds with heart action The first heart sound results from the closing of which valves? The second heart sound results for the closing of which valves? 8. Describe the basic contraction characteristics of the heart. Contraction of the heart muscle is referred to as Relaxation of the heart muscle is referred to as Remember the ventricles contract 'upward from the apex to the base-forcing blood out of the heart, and that the atria contract downward' from the base to the apex - forcing blood into the ventricles. 9. Describe the function and significance of the refractory period of cardiac muscle. Use the manual and the Powerpoint to complete the following study notes: The twitch of cardiocytes is different than that of skeletal muscle fibers. In cardiocytes, the twitch is longer - msec compared to 2 msec. This is caused by a in the repolarization of the cell due to the opening of and the movement of that ion into the cytosol. The resulting refractory period, lasts almost as long as a muscle twitch, thereby preventing , which would be dangerous for the heart. Repolarization, on the other hand, occurs relatively quickly. 10. Explain the effect of Vagus nerve stimulation to the heart and Vagal Escape. Use the manual to complete the following study notes: that innervate the The Vagus nerve conveys is released by this node. The neurotransmitter

Answer 1

Ans) 7) First heart sound: caused by atrioventricular valves – Mitral (M) and Tricuspid (T).

Second heart sound caused by semilunar valves – Aortic (A) and Pulmonary/Pulmonic (P).

8) Systole

Explaination:

- The period of contraction that the heart undergoes while it pumps blood into circulation is called systole.

Diastole

Explaination:

- The period of relaxation that occurs as the chambers fill with blood is called diastole.