Role of the Kindey

• Bowmans Capsule- Filtration under pressure occurs here. Glucose, urea, salts and water are forced out of the blood and into the capsule.
• Tubule- All the glucose, some of the water and salts are selectively reabsorbed into the blood capillaries surrounding it.
• Collecting Duct- Under the control of ADH, this controls how much water can move back into the blood by osmosis.
• Red blood cells in urine indicate kidney damage or disease. Glucose in the urine indicates diabetes.
• Excretory System- Removes urea which is a waste product of metabolism and regulates the water content of the blood.
• Transplant- Can last 12-15 years with minimal medical intervention. However, immunosuppressant drugs must be taken to avoid rejection and a donor who has a similar tissue type to the recipient must be found. A family member is preferable.
• Dialysis- Immediately available, non-invasive. However, a long time is spent in hospital attached to a dialysis machine every week and diet is restricted.
• Blood from the aorta moves into the renal artery and into the kidney. The kidney filters the blood and removes some water, urea and excess salts. Cleaned blood returns to the heart in the vena cava. The filtrate called urine leaves the kidneys in the ureters and is stored in the bladder. Urine is passed out of the body through the urethra
• The brain detects the water content of the blood is too low. More ADH is released into the blood from the pituitary gland. Blood takes more ADH to the collecting duct of the kidney. The collecting duct becomes more permeable to water. Water in the collecting duct is reabsorbed into the blood by osmosis. A small volume of concentrated urine is released.
• Dialysis fluid contains equal concentration of glucose and salts that should not be removed from the blood. It contains no urea and so urea will diffuse from a high concentration in the blood out into the dialysis fluid which is then disposed of.
• Counter-current system in a dialysis machine ensures that a diffusion gradient for urea is always maintained.
• Biuret Solution turns blue to lilac in the presence of protein.
• The nephrons are located in the cortex of the kidney, whilst the collecting duct is located in the medulla.