Question

making sense of osmoregulation in the kidney investigation
extra credit questions:

1. if someones urine is very dark, explain what is happening in the blood and kidney. use the terms

concentration, solute, water, and osmosis.

Explanation:

Dark urine often means dehydration. In blood, water level is low, so solute (e.g., waste, ions) concentration is high. In kidneys, during osmoregulation, due to low water in blood, the kidneys reabsorb more water (via osmosis, water moves to area of higher solute concentration in renal tubules from filtrate) to conserve it. This leaves less water in the urine, so solute concentration in urine is high, making it dark (since urine has more solutes relative to water, and less water diluting the pigments and wastes).

Answer:

When urine is very dark, it indicates dehydration. In the blood, the water level is low, so the solute (e.g., metabolic wastes, ions) concentration is high. In the kidney, during osmoregulation, the nephrons (kidney tubules) reabsorb more water from the filtrate (urine - forming fluid) via osmosis (water moves from the filtrate, where solute concentration is lower, to the blood, where solute concentration is higher, to balance blood volume and solute levels). With less water remaining in the urine, the solute concentration in urine becomes very high, concentrating wastes (like urea) and pigments, which makes the urine appear dark.