Q. No.Thrombocytes:
1. have a life span of about 60 days
2. are also called megakaryocytes
3. release a chemical called serotonin that constricts blood vessels
4. are not involved in hemostasis
1. have a life span of about 60 days
2. are also called megakaryocytes
3. release a chemical called serotonin that constricts blood vessels
4. are not involved in hemostasis
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What is true regarding pulmonic and aortic semilunar valves in the human heart?
1. They prevent the backflow of blood from the ventricles into the atria
2. They are open during the relaxation phase of the ventricles
3. They are held tightly closed by papillary muscles and chordae tendineae
4. They regulate the passage of blood from the ventricles into the pulmonary artery and the aorta
Which of the following causes the second heart sound [dub]?
1. opening of the AV valves at the start of diastole
2. closing of the AV valves at the start of systole
3. opening of the semilunar valves at the start of systole
4. closing of the semilunar valves at the start of diastole
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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 |
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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
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