1. kidney

2. kidney

3. URINARY FORMATION II
Dr Farzana Salman

4. Reabsorption Three walls/ membranes
Glomerular filtration Relatively non selective
Tubular reabsorption Highly Selective

5. Types of Transport Active Transport
Primary active transport Sodium
Secondary active transport --- Co transport ( Sodium + Glucose)
( Sodium + Amino acids)
Counter Transport ( Sodium+ Hydrogen)
Passive Transport

6. Primary Active Transport (Sodium)

7. Co Transport .(Sodium +Glucose)

8. Counter Transport. ( Sodium+ Hydrogen)

9. Types of Transport Transport Maximum
Substances that are 1. Actively reabsorbed
2. Actively secreted
Gradient Time Transport
Substances that are Passively reabsorbed

10. Transport Maximum
The maximum rate of reabsorption is transport maximum which is reached when all the transporters are saturated

11. Transport Maximum Important Definitions
Tubular load: Amount of solute delivered to the tubules
= GFR x Plasma concentration
Threshold: It is the plasma level at which the substance first appears
in the urine.
= Transport maximum ÷ GFR

12. Transport Maximum of Glucose
= 375 mg/min in males
= 300 mg/min in females
Tubular load of Glucose
GFR x Plasma concentration
=125 ml/min x 1 mg/ml
= 125 mg/min

13. Transport Maximum of Glucose
Threshold =TmG ÷ GFR
= 375 ÷ 125= 3 mg/ml= 300mg/100ml
Actual threshold = 200 mg/100 ml of arterial plasma
= 180 mg /100 ml of venous blood.
Some nephrons have less Transport Maximum

15. PINOCYTOSIS
Large particles like proteins

16. Gradient Time Transport
Passive absorption
1. Electrochemical gradient
2. Permeability
3. Time

17. Gradient Time Transport
Proximal tubule
Active transport + Gradient time transport
Distal Parts
Transport Maximum
Tighter junction
Aldosterone