A. valves closing. B. heart contraction. C. heart relaxing. D. blood flowing. 50

Question

A. valves closing. B. heart contraction. C. heart relaxing. D. blood flowing. 50. The first heart sound "lub" is made by A. closure of the AV valves. B. closure of the semilunar valves. C. contraction of the ventricles. D. contraction of the atria. 51. The sound of a heart murmur is created from A. acid reflux in the esophagus. B. fluid in the lungs. C. leaky heart valves. D. a hiccup 52. How is the heart muscle nourished? A. by blood in the left ventricle B. by the coronary arteries C. by the cardiac vein D. by the carotid artery 53. What initiates the heartbeat and is called the pacemaker? A. nerves B. AV node C. SA node

Explanation / Answer

50. The first heart sound 'lub' is caused by the closing of the atrioventricular valves- the mitral valve and tricuspid valve.

51. The heart murmurs are a result of faulty valves. They can either be stenotic or congenitally malformed.

52. The cardiac myocytes are nourished by the coronary arteries. The source of their nutrition is mostly fatty acids.

53. The SinoAtrial Node also known as the SA Node is the pacemaker of the heart. It initiates the contraction of the heart.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.