HMB201H1 Lecture Notes - Lecture 16: Organism, Keratin, Dissolved Load
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Lecture 16 BIOB34
The last part of the course:
Osmoregulation
Key thoughts:
Osmoregulation in different environments
Control of ion and water balance:
•Osmoregulation
•Ionic regulation
•Excretion of nitrogenous wastes
Animals and their environments:
-Environment has several different meanings:
1. External world for the whole animal
2. Extracellular fluid for a cell ( own fluid and own cell) ( REGULAT
ION TRANSPORT)
3. Cytoplasm for intracellular enzymes ( RELATIVE TO
EVERYTHING)
-Animals use different combinations of tissues to control ion balance in
various internal and external environments. ( conformers and
regulators) ( outer protective layers, and exchange organs)
Water balance and Concentration:
- Internal Environment= aqueous solution
•Volume and composition must be maintained within narrow
limits ( ions and proteins in fluids and have to stay in a narrow
minute)
- Composition different from external environment
•Composition tends to change towards eqm with the
environment
- Organism must control changes in composition of body fluids
•Overall solute concentration ( Osmotic
concentration) ( concentration of solute in the cells)
•Concentration of specific solutes ( non salt related)
Major types of hydric environments: DEPENDS ON TYPE OF ANIMALS
Aquatic animals- high water availability:
•Marine ( High solute concentration) ( Salt animals, sodium chloride)
•Fresh water ( Low solute concentration)( LAKES AND PONDS)
Terrestrial: Low water availability
•Prevent water loss and maximize efficient osmo regulation because they
are at a risk because the type of water they live in
Ionic and osmotic Challenges:
•Marine animals where animal tend to gain salts and lose water
•Fresh water animals tend to lose salts and gain water
•Terrestrial animals tend to lose water
MOST ANIMALS MOVE BETWEEN ENVIRONMENTS AND MUST BE ABLE TO
ALTER THEIR HOMEOSTATIC MECHANISMS!!
1) Marine invertebrates:
- Typically osmoconformers:
SHRIMP: concentration that is around them elevates the osmotic
concentration to near these levels.
Body fluids are isosmotic to sea water. THEY ARE HYPER OSMOTIC. Tend to
have low relative osmotic concentration by hyper osmotic
2) Marine Vertebrates:
SHARKS: ionic regulators, salt concentration 1/3 of sea salt and osmotic
concentration because of the presence of organic solutes like urea
- The salt levels are maintained at low levels:
1. Kidney: remove many ions, regulate ions and concentration
2. Rectal glad excretes fluid with high NACL concentration , remove
high salt
3. Potential active excretion by gills, not fully known but there is
some
- Body fluids are slightly hyper osmotic: strict ionic regulators, can still
regulate ions
1. Tends to draw water into the body
2. Water used in urine formation and rectal glad secretion
3) Fresh water invertebrates: Lobsters:
- Typically osmoregulaters
- Maintain hyper osmotic body fluid
- Water tends to flow into the animal and they have osmotic uptake
and ions tend to leave the body
- HAVE DIFFUSION AND EXECRETION
4) Fresh water teleosts:
- Hyperosmotic blood: water enters through the gills
- Excrete dilute urine: Lose lots of solutes ( High volume)
- Ions tend to be lost from the gills : Ions taken up in the food, active
uptake of ions into the gills
The role of epithelial tissues:
- These tissues form boundary between animal and environment:
External surfaces like skin and gills. Internalized surfaces like human
digestive systems and excretory systems
- These tissues have physiological functions in respiration, digestion
and ion wand water regulation
- Protective coatings
- Not just serve the purpose for ion exchange, for digestion and
respiration and what not. THEY HELP FOR GAS EXCHANGE and what
not
Terrestrial organisms:
Easy access to oxygen