BIOL 103 Lecture Notes - Renal Medulla, Saltwater Fish, Renal Cortex

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Published on 22 Apr 2013
School
Queen's University
Department
Biology
Course
BIOL 103
Biology Lecture #6 Excretion and Ion Transport
Lecture covers nitrogenous wastes, salt and water balance as well as kidney function
Obligatory Exchanges
Many vital processes have potential to disturb the balance between salt and water
concentrations
Obligatory exchanges are necessary as part of respiration or elimination of wastes
Water and salt will be loss through body respiration, ingestion of food will be eliminated as
waste (unnecessary parts) as well as through metabolism
Nitrogenous Waste
Product of the breakdown of amino acids and nucleic acid degradation
The waste produced is species and environment dependent, such as ammonia, urea and
uric acid
Most aquatic animals excrete ammonia or ammonium ions
Little energy required for production, high amount of water needed to excrete and has
high toxicity
Most mammals, amphibians, marine fishes and terrestrial invertebrates excrete urea
Requires moderate energy and moderate amount of water for excretion, has a low
toxicity
Birds, insects and most reptiles excrete uric acid
Requires a lot of energy but little water to excrete, and has a low toxicity
Example of a freshwater fish
Body is hyperosmotic and danger of being water logged due to constant osmotic
pressure of water which is why water travels in from gills via osmosis
Produce large amount of dilute urine to remove water
Risk of losing salts, so taken in by active up taking of na+ and cl- into their capillaries
Example of a Saltwater fish
Body is hyperosmotic and in danger of dehydrating with water lost across their gills
Need to drink much seawater
Excreted ammonia is diluted with as little water as possible, meaning urine is
concentrated
Excess salt is transported out of body by specialized cells in the gills
Anatomy of Bird Egg
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Document Summary

Biology lecture #6 excretion and ion transport. Lecture covers nitrogenous wastes, salt and water balance as well as kidney function. Many vital processes have potential to disturb the balance between salt and water concentrations. Obligatory exchanges are necessary as part of respiration or elimination of wastes. Water and salt will be loss through body respiration, ingestion of food will be eliminated as waste (unnecessary parts) as well as through metabolism. Product of the breakdown of amino acids and nucleic acid degradation. The waste produced is species and environment dependent, such as ammonia, urea and uric acid. Most aquatic animals excrete ammonia or ammonium ions. Little energy required for production, high amount of water needed to excrete and has high toxicity. Most mammals, amphibians, marine fishes and terrestrial invertebrates excrete urea. Requires moderate energy and moderate amount of water for excretion, has a low toxicity. Birds, insects and most reptiles excrete uric acid.

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