A level kidney introduction

1. Excretion

2. • Homeostasis is the maintenance of a
stable internal environment
– in cells
– in the tissue fluid around the cells
– in the blood plasma
• For example:
– Temperature
– Water
– Glucose

3. negative feedback mechanisms

4. • Excretion is the removal, from the body, of
unwanted waste from metabolic reactions
• For example:
– CO2 from respiration in all body cells is
carried by the blood to the lungs and excreted
– Urea from the deamination of excess

5. Deamination

6. Excretory System

7. Kidney: external view
Adrenal gland
Cortex
Renal artery – brings blood in
Pelvis – continues into ureter
Renal vein – removes blood
Ureter – urine to bladder

8. Kidney: section
Capsule – tough outer layer
Renal sinus – continues to pelvis
Renal pelvis – continuous with
ureter
Renal pyramid – part of medulla
Medulla – mostly collecting ducts
Cortex – glomeruli are found here

10. Renal Cortex
This is where
the kidney
nephrons are
found
There is a rich
supply of
capillaries

11. Detail of nephron
Nephrons are long tubes
that start at a Bowman’s
capsule and finally flow into
the pelvis of the kidney

12. Nephron

13. Renal Artery
blood comes in rich in urea

14. Glomerulus
This is a knot of capillaries Water and
solutes are forced out

15. Bowman’s capsule
The filtrate flows into this
capsule

16. Proximal Convoluted Tubule
All the glucose, amino acids and
some water and salts move back
into the blood here

17. Peritubular capillaries
These surround the tubules
and pick up substances from
the filtrate

18. Loop of Henle
This is important in re-
absorption of water

19. Distal covoluted tubules
Na+ is reabsorbed here

20. Collecting duct
More water is
reabsorbed and
osmoregulation
happens here

21. Urine
Leaves
the
kidney,
Removing
urea and
excess
salt and
water

22. Renal Vein
blood leaving the kidney has very little urea and
some of the salts and water removed