Q. No.The sinoatrial node is the normal pacemaker of the human heart because it:
1. can form action potentials that can spread throughout the rest of the heart
2. depolarizes to its threshold potential before other pacemakers in the heart
3. is located in the top of right atrial wall
4. is most likely to form an ectopic focus
1. can form action potentials that can spread throughout the rest of the heart
2. depolarizes to its threshold potential before other pacemakers in the heart
3. is located in the top of right atrial wall
4. is most likely to form an ectopic focus
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What is the ejection fraction that is achieved by the left ventricle in a healthy heart?
1. 10(--)15%
2. 25(--)33%
3. 60(--)70%
4. 98(--)100%
Veins are said to have a higher ____ than arteries because they expand more easily and a higher ___________ because they contain more blood.
1. compliance; capacitance
2. elasticity; compliance
3. elasticity; capacitance
4. None of the above
How can adrenaline have different effects on blood vessels - vasodilation in skeletal muscle but vasoconstriction in the skin?
1. sympathetic fibers secrete epinephrine in the muscle and acetylcholine in the skin
2. bradykinin stimulates constriction of arterioles in the dermis
3. the muscles have cholinergic sympathetic fibers and the skin has adrenergic fibers
4. the muscle arterioles and the skin arterioles have different types of receptors for adrenaline
In most normal people [not trained athletes] the increase in cardiac output is due mainly to:
1. increase in stroke volume
2. decrease in ejection fraction
3. decrease in end-diastolic volume
4. increase in heart rate
Severe dyspnea due to pulmonary edema will be caused most likely by:
1. cardiogenic shock
2. anaphylactic shock
3. right-sided congestive heart failure
4. left-sided congestive heart failure
The average life span of human red blood cells is:
| 1. | 10 days | 2. | 120 days |
| 3. | 21 days | 4. | three months |
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In the early fetal life the main site for red blood cell formation is:
1. bone marrow
2. kidney
3. liver
4. spleen
Tissue death (necrosis) due to inadequate blood supply to the affected area, such as the heart, is:
| 1. coronary thrombosis | 2. angina pectoris |
| 3. ischemia | 4. infarction |
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