Final answer:
The hormone that increases the reabsorption of water in the collecting tubules by stimulating the insertion of water channels is antidiuretic hormone (ADH), which acts by inserting aquaporins into cell membranes.
Step-by-step explanation:
The hormone responsible for increasing the reabsorption of water in the collecting tubules by stimulating the insertion of water channels into the membranes of tubule cells is antidiuretic hormone (ADH). ADH acts on the collecting ducts of the kidneys to regulate water balance in the body. When ADH is released from the pituitary gland, it travels to the kidneys where it binds to receptors on the cells of the collecting tubule, leading to the insertion of aquaporins into the plasma membrane. This process dramatically increases the flow of water out of the tubule and back into the bloodstream, thus concentrating the urine and reducing water loss.
Aldosterone also plays a role in water reabsorption by increasing the retention of sodium, which in turn draws water back into the blood via osmosis. However, it does not directly stimulate the insertion of water channels into tubule cell membranes. Therefore, when considering the specific action of stimulating water channel insertion in collecting tubule cells, ADH is the correct answer. Other hormones such as renin, angiotensin, and insulin do not have this specific effect on water channel insertion and reabsorption in the collecting tubules. To the answer is antidiuretic hormone.