BIOL10002 Lecture Notes - Osmotic Concentration, Osmoregulation, Molality
Wednesday, April 18, 2018
Lecture 19: Osmoregulation and the Kidney
Excretory Organs (Function)
-Maintain osmotic concentration
-Maintain body fluid volume
-Maintain proper conc. of ions
-Remove metabolic end product
-Remove foreign substance
Osmoregulation
-Cells need consenter osmotic internal & external environment
-Constant regulation of internal water & salt balance
-Animals in freshwater, seawater & land face diff. water & salt balance problems
Osmosis
-Osmolarity: conc. of mol of active solute per liter of solvent
•Calculating this: #ions present eg. CaCl2 will have 3 Osm/L (1 Ca2+ ; 2Cl-)
-Osmotic pressure: Force created by the movement of water
-Osmolality: conc. of solute per kg of solvent
-Tonicity: conc. of non-permeable solutes per liter of solvent (cannot enter biological
membrane)
Excretory Organs
-Excrete water & solute in excess
-Conserve water & solute in short supply
-Output of excretory system = urine
!1
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Wednesday, April 18, 2018
•Major excretory substances = Ammonia, Urea, Uric Acid (Nitrogenous waste
from protein & nucleic acids) ; CO2, H20
-Ammonia: Uses lots of water, easy, toxic to release
-Urea: Metabolic pathway in the liver uses energy but saves water
-Uric acid: Desperate times to conserve water
Challenge of diff. environment
-Marine animals: Conserve water & excrete excess salt (environment is more conc in
salt)
-Freshwater animals: Excrete excess water and conserve salts
-Terrestrial animals: Conserve water and salts
-Osmoconformer vs Osmoregulator
**No freshwater osmoconformers not enough salt in the environment anyways
Marine fish
-Water lost through gills & skin
-Gills: Chloride cells act as salt pumps to active transport salt from blood into
environment
-Fish also have kidneys
-Nitrogenous waste: Ammonia
•Principle nitrogenous waste in aquatic invertebrates & bony fishes
Terrestrial animals
-In from drinking, water in food, metabolic
-Out from evaporation, urine, feces
-Water conservation is very important
!2
find more resources at oneclass.com
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Document Summary
Cells need consenter osmotic internal & external environment. Constant regulation of internal water & salt balance. Animals in freshwater, seawater & land face diff. water & salt balance problems. Osmolarity: conc. of mol of active solute per liter of solvent: calculating this: #ions present eg. cacl2 will have 3 osm/l (1 ca2+ ; 2cl-) Osmotic pressure: force created by the movement of water. Osmolality: conc. of solute per kg of solvent. Tonicity: conc. of non-permeable solutes per liter of solvent (cannot enter biological membrane) Conserve water & solute in short supply. !1: major excretory substances = ammonia, urea, uric acid (nitrogenous waste. Wednesday, april 18, 2018 from protein & nucleic acids) ; co2, h20. Ammonia: uses lots of water, easy, toxic to release. Urea: metabolic pathway in the liver uses energy but saves water. Uric acid: desperate times to conserve water. Marine animals: conserve water & excrete excess salt (environment is more conc in salt)
