Which vessel is guarded by a semilunar valve at its base?
A) superior vena cava B) pulmonary trunk C) pulmonary vein D) coronary sinus
Answer: B
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What attaches epithelial cells to the basement membrane?
A. gap junction B. hemidesmosomes C. adhesion belt D. tight junction E. desmosomes
Which of the following events is NOT a characteristic of an action potential?
A. In repolarization, K+ flow out of the cell. B. As Na+ enter, the inside of the plasma membrane becomes more negative. C. The plasma membrane becomes highly permeable to Na+ and depolarization results. D. At the peak of depolarization, Na+ channels begin to close and K+ channels open. E. Action potentials occur according to the all-or-none principle.
________ are immature erythrocytes that are present in the circulation
A) Erythroblasts B) Normoblasts C) Myeloblasts D) Band cells E) Reticulocytes
Myopia generally occurs when the ________.
A. cornea is uneven B. eyeball is too long C. lens is uneven D. eyeball is too short