1. The Excretory System Aorta Renal Artery Right Kidney Renal Vein
Vena cava
Ureter
Bladder
Sphincter Muscle
Urethra

2. The kidney Renal Capsule
Cortex; dark red, full of blood vessels, where ultrafiltration takes place
Medulla; pink, fewer blood vessels
Pyramid; urine drains from these into the pelvis
Ureter; urine flows from the kidney to the bladder down this tube
Nephron; filtering tubes
Pelvis

3. Role of the Kidney All small molecules are removed from the blood
Most are then returned to the blood before it leaves the kidneys
Any that are not needed or any surplus become part of the urine.
The urine passes from the kidneys to the bladder where it is stored until full

4. Nephrons
There are about one million of these microscopic tubes in each kidney
The blood is filtered in these
Nephron

5. A Nephron Afferent Arteriole Glomerulus Efferent Arteriole Renal vein
Bowman’s capsule
Second coiled tubule
First coiled tubule
Collecting
Duct
Descending Loop
Ascending Loop
Loop of Henle
A Nephron

6. Ultrafiltration
The high pressure in the Glomerulus forces small molecules out of the blood into the Bowman’s capsule, e.g amino acids, glucose, water
The ultrafiltrate is formed
Ultrafiltration occurs in the glomerulus forming ultrafiltrate in the bowman’s capsule

7. Selective Reabsorption
First coiled tubule
70% of water, all glucose, some salts and some amino acids are reabsorbed back into the capillaries surrounding the tubule
Loop of Henle
Some water is reabsorbed
Second coiled tubule
Some water (affected by ADH) and some salts are reabsorbed
Collecting Duct
Some water is reabsorbed (affected by ADH)

8. Reabsorption of water occurs in the collecting duct
Selective Reabsorption in the first coiled tubule
Reabsorption of water in the Loop of Henle by osmosis
Some water and some salts are reabsorbed in the second coiled tubule
Osmosis: water moves from a high concentration of water to a low concentration

9. Osmoregulation; regulation of the concentration of water and salt concentration in the blood*
*Makes cells in collecting duct and second coiled tubule more permeable to water

10. INTAKE cm3 OUTPUT cm3 Food 800 Sweat 600 Drink 1500 Breath 400
BALANCE OF WATER
INTAKE cm3
OUTPUT cm3
Food
Sweat
Drink
Breath
Metabolism 350
Faeces
Urine
TOTAL
TOTAL