Post on 23-Feb-2018
The Excretory System
Waste Products of Metabolism
Protein
Amimo Acids
Ammonia
Ammonia Uric Acid Urea(Fish) (Insects, Reptiles, Birds) (Mammals)
The Urinary SystemAnd
Excretion
Vena cava
Aorta
Renal vein
renal
Renal Cortex
Medulla
Peritubular Capillary
Proximal Tubule
Distil Tubule
Nephron Loop
Collecting Duct
Gradient of Increasing S
odium C
oncentration
------- ---- ---- -------------------Cortex
Medulla
Renal Artery
Glomerulus
Nephron Capsule
Gradient of Increasing S
odium C
oncentration
------- ---- ---- -------------------Cortex
Medulla
13
14
15
Gradient of Increasing S
odium C
oncentration
------- ---- ---- -------------------Cortex
Medulla
11
12
1. Glomerularfiltration
2. Tubularreabsorption
3. Tubular secretion
Peritubular capillary
RenalArtery
Glomerulus
NephronCapsule
PeritubularCapillary
Proximal Tubule1. 70% Na+ actively reabsorbed2. 70% Cl- passively follows Na+
3. H2O passively follows NaCl4. Glucose is 100% actively
reabsorbedDistilTubule
CollectingDuct
Nephron Loop
--------- ---- ---- ---------------------Cortex
Medulla
Gradient of Increasing S
odium C
oncentration
300 mOsm 300mOsm
1200 1200mOsm
Urine
600mOsm
400mOsm300
500
700 800mOsm
900 1000mOsm
Water Balance
Input = Output
Water Balance in K-Rats
• Input– Drinking– Food– Metabolic Water
(C6H12O6 + 6O6 6CO2 + 6H2O + E)
• Output– Urine– Feces– Evaporation
• Via skin• Via respiration
Water Balance in Kangaroo Rats
Table of Water Balance (149)
• Input (in milliliters)– Drinking 0– Metabolic water 54– Food 6**
– Total 60
**At 20% relative humidity 100g of barley contains 6ml of water
• Output (ml)– Urine 13.5– Feces 2.6– Evaporation 43.9*
– Total 60
*Respiration is responsible for significant evaporative water loss
Water Balance in Kangaroo Rats
The Three Process InUrine Formation
1. Glomerular filtration• Small substances are
forced by blood pressurethrough the glomerulusinto the nephron capsule
2. Tubular Reabsorption• Water, salt, and glucose
are reabsorbed into theblood stream. Most ofthe reabsorption takesplace in the proximaltubule
3. Tubular Secretion• Substances are secreted
from the bloodstreaminto the distil tubule
Glomerulus