1. Learning Objective: To Know The Function Of The Bowman’s Capsule
Ultrafiltration
Learning Objective:
To Know The Function Of The Bowman’s Capsule

2. Spec
(c) (i) the structure, mechanisms of action and functions of the mammalian kidney (ii) the dissection, examination and drawing of the external and internal structure of the kidney (iii) the examination and drawing of stained sections to show the histology of nephrons
To include the gross structure and histology of the kidney including the detailed structure of a nephron and its associated blood vessels AND the processes of ultrafiltration, selective reabsorption and the production of urine. PAG1, PAG2

3. Success Criteria
Describe the process of ultrafiltration in the production of urine

4. Starter: Label the Nephron

5. Nephron

6. Urine Formation Urine formation is a 2 stage process:
Ultrafiltration: where the blood is filtered of small molecules: importanly Urea
Selective Reabsorption: Where essential molecules are taken back into the blood from the nephron

7. Bowmans (Renal) Capsule & Glomerulus
Ultrafiltration occurs at the renal capsule where the blood is filtered from the glomerulus into the proximal convoluted tubule.

8. Ultrafiltration Filtration at the molecular level In Glomerulus
large molecules are left in blood
Small molecules pass into Bowman’s capsule

9. Ultrafiltration 2 Afferent arteriole is wider than efferent
Blood in glomerulus under higher pressure than B’sC
Pressure difference pushes fluid from G to B’sC

10. Ultrafiltration 3 3 layers between Blood in G and fluid in B’sC
All are adapted to allow ultrafiltration
Endothelium: narrow gaps between cells
Basement membrane: fine mesh of collagen fibres and glycoproteins
Epithelial cells in B’sC (called podocytes) has finger-like projections (called major processes) these ensure gaps between cells
3 layers between Blood in G and fluid in B’sC
Endothelium of capillary
Basement membrane
Epithelial cells in B’sC

11. Basement membrane around capillaries and podocytes of Bowman’s capsule improve filtration
Endothelium of Capillary of glomerulus
Podocytes (wall of B’s C
Glomerular flitrate

12. Ultrafiltration 4 Filtered out of blood Left in capillary Water
Amino Acids
Glucose
Urea
Inorganic ions
Left in capillary
Blood cells
Proteins
Some Water (proteins ensure very low water potential)

13. Glomerular Filtration
Substance
Concentration in blood plasma (g dm-3)
Concentration in Filtrate (g dm-3)
Water
900
Proteins
80.0
0.05
Amino acids
0.5
Glucose
1.0
Urea
0.3
Uric acid
0.04
Creatinine
0.01
Na+, K+, Cl-
7.2
Above Relative Molecular Mass of 69,000 cannot pass through!

14. Group Task
Sketch the glomerulus and Bowman’s capsule, adding as much detail as you can

15. Factors Affecting RATE of Glomerular Filtrate
Water potential of blood in capillaries & filtrate in the renal capsule (greater in blood due to….)
Pressure of blood in glomerulus
125cm3min-1

16. PPQ

17. Markscheme

19. Markscheme

20. Markscheme