BIOL10002 Lecture Notes - Lecture 5: Aquaporin 1, Aldosterone, Podocyte
31 May 2018
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Monday, 1 May 2017
Osmoregulation
Excretory Organs
-Maintain osmotic concentrations
-Maintain body fluid volume
-Maintain ion concentrations
-Remove metabolic end products
-Remove foreign substances
Osmoregulation (water balance)
Cells need constancy which requires regulation
Osmolarity- concentration of moles of active solutes (per litre of solvent)
Osmotic pressure- force associated with the movement of water (dependent on
number of molecules in it- dissociation)
Osmolality- concentration of solute (per kilogram)
Tonicity- is the conc. of non-permeable solutes per litre
How do we manage?
-Excrete water and solutes in excess
-Conserving water/solutes that are valuable (i or in short supply e.g. glucose)
-Urine is the output of the excretory system
Excreting nitrogen: kidney
Nitrogenous waste - toxic (Ureotelic (us))
Urea synthesis: Costs energy, synthesised from carbon dioxide, water, aspirate and
ammonia (UREA?ORNITHINE CYCLE), in liver
Challenges of different environments:
Marine animals- conserve water, excrete salts
Freshwater animals- excrete water, conserve salts
Terrestrial animals- conserve water and salts
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Monday, 1 May 2017
Osmoconformers
-All marine invertebrates
-Can’t be freshwater
-Fluctuates with environment
-Don’t spend energy regulating (salinity relatively constant in ocean)
-No physiological mechanisms to deal with change
Fish
Teleost fish (bony, marine): Internal environment is hypo-osmotic to external
environment
- Drink seawater
- Losing water
- Produce little urine (kidney has reduced output)
- Eliminated the salts ingested from salt water
Fish in freshwater:
- Drink little water
- Produces lots of urine
- Losing salts
-Chloride cells in gills actively transport salts from the body into the environment
-Excrete ammonia (plenty of water)- “ammonotelic animals”
-Excreted by diffusion across the gill membrane
-Easily removed (soluble)
Terrestrial animals
!2
find more resources at oneclass.com
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Document Summary
Osmolarity- concentration of moles of active solutes (per litre of solvent) Osmotic pressure- force associated with the movement of water (dependent on number of molecules in it- dissociation) Tonicity- is the conc. of non-permeable solutes per litre. Conserving water/solutes that are valuable (i or in short supply e. g. glucose) Urine is the output of the excretory system. Urea synthesis: costs energy, synthesised from carbon dioxide, water, aspirate and ammonia (urea?ornithine cycle), in liver. Don"t spend energy regulating (salinity relatively constant in ocean) No physiological mechanisms to deal with change. Teleost sh (bony, marine): internal environment is hypo-osmotic to external environment. Produce little urine (kidney has reduced output) Eliminated the salts ingested from salt water. Chloride cells in gills actively transport salts from the body into the environment. Excrete ammonia (plenty of water)- ammonotelic animals . Excreted by diffusion across the gill membrane. Diet determines whether salts must be conserved or excreted. Aestivation- low metabolic activity so low h2o turnover.
