Chapter_44

Chapter_44 - Chapter44: RegulationofInternalEnvironment:

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Chapter 44: Regulation of Internal Environment: Animals maintain homeostasis even when put in conditions toxic for individual  cells 3 functions of homeostasis 1. Thermoregulation – maintain body temperature 2. Osmoregulation (kidney) – regulate solute balance and gain/loss of H2O 3. Excretion – removal of nitrogen wastes from proteins and nucleic acid  metabolism  Humans:  Must regulate composition of body fluids in terms of H2O and solutes Must remove metabolic waste before accumulation to toxic levels Osmoregulation – maintains internal composition of cells indirectly  by regulating ISF and blood Transport epithelia of kidney (simple Cuboidal)  -specialized for osmotic exchange  -high surface area Because metabolic wastes dissolved in H 2 O, solute amount will  affect H 2 O balance  Breakdown of proteins and nucleic acids   NH 3  (ammonia)  produced   toxic -NH 3  converted to urea (made in the liver, but excreted by kidney) in  liver (Figure 44.9) by combining with CO 2 -urea 10^5 X less toxic than NH 3 Osmolarity    solute concentration of solution  -determines movement of H 2 O across a selectively  permeable membrane If solutions differ in osmolarity, flow of H2O is from  hypoosmotic to hyperosmotic solution (Figure 44.2) Human blood 300 mosm/L Seawater 1000 mosm/L (Figure 44.4)
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This note was uploaded on 09/24/2011 for the course BIO 100 taught by Professor John during the Spring '11 term at Harvard.

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Chapter_44 - Chapter44: RegulationofInternalEnvironment:

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