Central organ of the lymphatic system is:
(a) tonsils
(b) thymus
(c) spleen
(d) lymph nodes
Ans: (b) thymus
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The basic structural unit of compact bone is the __________.
Fill in the blank(s) with the appropriate word(s).
Which respiratory drug category decreases the viscosity of respiratory secretions?
a. expectorant b. mucolytic c. antitussive d. decongestant
Which of the following best explains the drop in blood pressure that occurs when one goes from lying down to standing up?
A. An increase in afterload causes a drop in stroke volume, cardiac output, and blood pressure. B. Venous compliance allows blood to pool in the legs, decreasing venous return. This causes a drop in cardiac output and blood pressure. C. An increase in preload causes a drop in stroke volume, cardiac output, and blood pressure. D. The heart rate decreases. This is due to the baroreceptor reflex reducing sympathetic output to the SA node.
Voltage-gated Na+ ion channels are sensitive to changes in the extracellular concentration of
A) Ca2+ ions. B) Cl- ions. C) K+ ions. D) proteins.