What keeps the HCN channels open?
A. G-proteins
B. cAMP
C. Ca2+
D. ATP
Answer: B
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Match the type of immunity to its description.
1. present at birth 2. Secreted lysozyme kills bacteria. 3. NK cells cause apoptosis of viral-infected cells. 4. Antibodies in breast milk protect a newborn baby from pathogens. 5. Infected cells are killed by perforin and granzymes. A. specific B. nonspecific
Active immunity
a. is self-generated upon exposure to antigen b. can be produced only as a result of a person actually having the disease c. involves administration of preformed antibodies d. is shorter in duration than passive immunity e. is acquired in the newborn as a result of the transfer of antibodies across the placenta during intrauterine development
The ability of the kidney to concentrate urine depends on
A. a high medullary concentration gradient. B. proximal convoluted tubule reabsorption. C. a low medullary concentration gradient. D. rapid removal of filtrate. E. osmosis.
Carbonic anhydrase is crucial for
a. CO2 transport in blood. b. conversion of CO2 into bicarbonate ion. c. production of NO. d. both (a) and (b) above. e. both (a) and (c) above.