Lecture15 - Lecture 20: Osmoregulation and Kidney Chapter...

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Lecture 20: Osmoregulation and Kidney Chapter 44
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Animal cells lack cell walls, and therefore substantial water loss or gain spells doom for these cells Osmoregulation - how organisms regulate solute concentrations and balance the gain and loss of water
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Osmosis - the diffusion of water across a selectively permeable membrane- osmolarity - total solute concentration expressed as molarity water will move from an area of lower osmolarity (less solutes/liter) across a membrane to an area of higher osmolarity (greater solutes/liter)
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outside cell lower osmolarity equal osmolarity higher osmolarity inside cell higher osmolarity equal osmolarity lower osmolarity cell is: hyperosmotic isoosmotic hypoosmotic solution is: hypoosmotic isoosmotic hyperosmotic
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osmoconformer - an animal that does not actively adjust its internal osmolarity because it is isoosmotic with its surroundings osmoregulator - an animal whose body fluids have a different osmolarity than the environment and that must either discharge excess water if it lives in a hypoosmotic environment or take in water if it inhabits a hyperosmotic environment
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stenohaline - referring to organisms that cannot tolerate substantial changes in external osmolarity euryhaline - referring to organisms that can tolerate substantial changes in external osmolarity; e.g., tilapia can tolerate changes from ~0.5mosm/L (fresh water) to 2000mosm/L (twice that of sea water)
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Marine animal adaptations to their environment 1. osmoconformer - many marine invertebrates 2a. osmoregulator - many bony fishes drink large volumes of seawater (actively removing chloride ions and as a result sodium ions) and excrete highly concentrated fluid- hypoosmotic inside compared to hyperosmotic environment 2b. osmoregulator - sharks remove salts via kidneys, rectal gland, and feces; maintain high concentrations of urea and trimethylamine oxide (TMAO) bind to make less toxic - results in hyperosmotic body to salt water
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This note was uploaded on 11/24/2011 for the course BIOLOGY 110 taught by Professor Bentz during the Spring '09 term at Drexel.

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Lecture15 - Lecture 20: Osmoregulation and Kidney Chapter...

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