Biology 240W Notes for Exam - Biology 240W Notes for Exam#2...

Info icon This preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Biology 240W  Notes for Exam #2 Homeostasis I:  Osmoregulation -Critical for organisms to balance water and solute concentration to maintain  cytoplasm of their cells at optimal state for cellular reactions -many solutes dissolved in body fluids are necessary for organisms to function  properly; some are generated as metabolic byproducts and can be harmful to the  organism - osmoregulation  ( def : process to rid bodies of waste products while maintaining  proper amount of water) Diffusion and Osmosis -2 solutions separated by semi-permeable barrier -H20 and solutes will move across until no net movement  (equilibrium) -solute movement ( diffusion ) results from this concentration gradient - uncharged solutes:  HIGH  LOW concentration   (water also moves) - osmotic pressure  is generated in a solution; it is  proportional  to  osmolarity  ( def : combined concentration of all solutes in a solution) - LOW HIGH osmolarity  ( osmosis ) -solutes also move  against  concentration gradient (LOW HIGH) in  active  transport : -requires input  of energy -water content is  controlled -used to control H20 movement (by osmosis) and solute concentration (by  osmoregulation) Osmoregulation in Aquatic Organisms -animals in aquatic environments have  large surfaces  where solute and water exchange  can occur between organism and its environment -separated into 2 groups based on how they balance their osmolarity: 1.   Osmoconformers - equilibrate  their internal osmolarity to match their external  environments -uncommon; only some small marine invertebrates which can tolerate high  tissue osmolarity 2.   Osmoregulators a.  Freshwater -have  higher tissue osmolarity than their environments   ( hypertonic ) which cause them to  take up water by osmosis  and  lose solutes by diffusion Rid Excess H20 :
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
-Protists forcibly pump H20 out with  contractile vacuoles -Large organisms excrete large volumes of very dilute urine;  manage salt loss by using active transport pumps to acquire  salt from their environment b.  Saltwater -body fluids are  hypotonic  ( have lower osmolarity ) to  surroundings and tend to  lose water by osmosis  and  gain salt by  diffusion Marine Bony: -to prevent dehydration, consume large volumes of seawater  and actively pump salt out of their bodies Marine Cartilaginous: -maintain body fluids at higher osmolarity than surroundings  by building up surroundings to metabolic waste products  (urea)  Osmoregulation in Terrestrial Organisms -most critical challenge to living on land is water conservation (humans die after  >10% water loss) -also need to rid metabolic wastes: -primitive form of waste is ammonia which is very toxic so must modify it  to create less toxic waste product (i.e. urea in mammals)
Image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern