2.5 concentration

Glomerulus The glomerulus is the functional unit of the kidney It consists of Bowman’s capsule, the proximal tubule, the distal tubule and the collecting duct A knot of small capillaries, the glomerulus carries blood to the capsule.

Blood is filtered through the glomerulus Only fluid, ions and small molecules enter Bowman’s capsule Blood cells and proteins remain in the blood

Most of the glucose, sodium and amino acids are reabsorbed in the proximal tubule 90% of the fluid is reabsorbed

Concentration The extracellular gradient created by active chloride transport draws water from the collecting duct. The permeability of the collecting duct is controlled by ADH Only birds and mammals can excrete a urine that is saltier than the blood.