Kidneys

Role of the Kidneys

• To filter stuff out of the blood then reabsorbing the stuff that's useful
• Kidneys adjust water content to maintain a constant blood water level using a hormone called ADH
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• Caption: Kidney Diagram

Nephrons and their jobs

• There are thousands of nephrons in each kidney and each have the purpose of filtering the blood.
• Ultrafiltration
• The process by which blood is filtered.
• Reabsorbtion
• Useful substances are selectively reabsorbed.
• Release of waste substances
• Substances not reabsorbed in the form of water, slats and urea form urine. This then goes to the bladder before being excreted.
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• Caption: A Nephron

Ultrafiltration

• This is the process by which blood is filtered in order to maintain it's purity
• 1. Blood from renal artery flows through the Glomerulus
• 2. High pressure is built up which squeezes water, urea, salts and glucose out of the blood to the Bowman's Capsule
• 3. Big molecules like proteins and blood cells aren't squeezed out

Reabsorbtion

• The blood filtered from ultrafiltration is then selectivley reabsorbed in order to keep the stuff your body want and actually needs.
• 1. All glucose is reabsorbed from the proximal convoluted tubule by active transport
• 2. A sufficient quantity of salt is reabsorbed, any excess salt is not.
• 3. A sufficient quantity of water is also reabsorbed from the collecting duct and goes back into the bloodstream.
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Waste Release

• Any remaining substances (urea, excess salts and water) form urine. this is sent out of the nephron to the bladder where it is expelled from the body

Osmoregulation

• Kidneys also control your blood water level in order to keep you hydrated.
• Your blood water level is controlled by ADH, or Anti Diuretic Hormone.
• ADH makes your pituitary gland more or less permeable, allowing more or less water out of the gland, in order to maintain a healthy level of hydration.