Compared to the skeletal muscle, cardiac muscle fibers ---------------------. A. Generate action potentials with a long plateau phase B. Cell membrane remain in a refractory state until the heart has returned to a relaxed state C. Do not have summation of contractions D. All of the above are correct E. None of the above are correct
24. Compared to the skeletal muscle, cardiac muscle fibers ---------------------.
A. Generate action potentials with a long plateau phase
B. Cell membrane remain in a refractory state until the heart has returned to a relaxed state
C. Do not have summation of contractions
D. All of the above are correct E. None of the above are correct
25. In case of fight or flight, ---------------------.
A. Norepinephrine released from sympathetic neurons and epinephrine released from the adrenal medulla work on β1-adrenergic receptor of cardiac pacemaker cells
B. Less Na+ and Ca2+ channels open in cardiac pacemaker cells
C. There is a decrease in cardiac muscles contractility
D. All of the above are correct
E. None of the above are correct
26. Rest and digest will, ---------------------.
A. Increases the heart rate
B. Increases potassium conductance in the cardiac pacemaker cells
C. Hypo polarize pacemaker cells
D. All of the above are correct
E. Only B and C are correct
27. All of the followings are incorrect about adult human heart, except ---------------------.
A. There is a lower systemic than pulmonary arterial blood pressure
B. There are four chambers in the heart
C. The right atrium receives blood directly from pulmonary veins
D. In adults, right atrium is connected to the left atrium by the foramen ovale
E. The right atrium is electrically coupled to the right ventricle by the SA node
28. All of the followings are incorrect, except ---------------------.
A. Continuous capillaries like those we see in skeletal muscles are the least permeable
B. The fenestrated capillaries like those of the liver have Intermediate permeability
C. The sinusoidal capillaries like those of the kidney are the most permeable
D. Arterial side of the capillaries are suitable for absorption
E. In the venous sides of the capillaries, the lower blood pressure will favor filtration
29. All of the followings are correct, except ---------------------.
A. The mean blood pressure decreases with distance from the heart.
B. The linear rate of blood flow is inversely proportional to total cross-sectional area.
C. The highest blood velocity occurs at the capillaries.
D. Capillaries consist of a single layer of endothelial cells surrounded by basement membrane and some contractile pericytes
E. Substances move across walls of blood capillaries either through or between endothelial cells
30.Cardiac output is ---------------------.
A. volume of blood pumped per unit time from a ventricle.
B. amount of blood ejected from a ventricle by the heart with each beat
C. volume of blood in the ventricle after filling
D. volume of blood remaining in ventricle after heart beat
E. All of the above are correct
31. A man survives for 2 days in the desert with no water to drink. His blood level of antidiuretic hormone (ADH) will be ------------------------------. A. Lower than usual.
B. Higher than usual.
C. The same as usual.
D. Zero.
E. None of the above is correct
32. All of the followings are components of the extracellular fluid, except ----------------.
A. The interstitial fluid.
B. The cerebrospinal fluid
C. Blood plasma
D. lymph
E. Sweat
33. The reabsorption of glucose occurs in the ------------------------.
A. Proximal part of loop of Henle
B. the proximal convoluted tubule
C. distal convoluted tubule
D. Bowman’s capsule
E. All of the above
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