Questions: What is it called when waste ions and hydrogen ions pass from the blood in the capillaries into the renal tubules? a. Micturition b. Reabsorption c. Secretion d. Filtration

The answer is the third one (c): Secretion.

Explanation for each option:

a. Micturition: This refers to the process of urination, where urine is expelled from the bladder through the urethra. It is not related to the movement of ions and hydrogen ions from the blood into the renal tubules.

b. Reabsorption: This is the process by which substances are taken back into the blood from the renal tubules. It is the opposite of what the question describes, as it involves moving substances from the tubules back into the bloodstream.

c. Secretion: This is the correct answer. Secretion is the process by which waste ions and hydrogen ions are actively transported from the blood in the capillaries into the renal tubules. This process helps in the removal of waste products and the regulation of blood pH.

d. Filtration: This is the process that occurs in the glomerulus, where blood plasma is filtered into the Bowman's capsule. It involves the movement of water and solutes from the blood into the renal tubules, but it is not specifically about the active transport of waste ions and hydrogen ions.

In summary, the process described in the question is called secretion.