PATHOLOGY

Detailed explanation-1: -Nephrons filter out harmful substances in the blood so that we can excrete them into the urine. Each nephron is made up of the glomerulus, or a tiny clump of capillaries, where blood filtration begins. These capillaries have very thin walls and they act like a coffee filter.

Detailed explanation-2: -Water reabsorption is a passive process: water is reabsorbed by osmosis. In most of the nephron there is unregulated isosmotic reabsorption of water and solute, in other words, water reabsorption is coupled to solute reabsorption.

Detailed explanation-3: -Sodium is actively pumped out, while potassium and chloride diffuse down their electrochemical gradients through channels in the tubule wall and into the bloodstream. The walls of the thick ascending limb are impermeable to water, so in this section of the nephron water is not reabsorbed along with sodium.