102SN5 - Biology 102 Study Notes Exam 5 Chapter 38: Body...

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Kevin Kelleher, MTC Biology 102 Study Notes Exam 5 1 Biology 102 Study Notes Exam 5 Chapter 38: Body Fluid Regulation and Excretion Body Fluid Regulation - Water and Ion Balance o the excretory system regulates body fluid concentrations by regulating the water and mineral ions (i.e., Na + , CI - , K + , and HCO 3 - ) in body fluids o water enters animals when they eat foods and drink water, and by metabolism where cellular respiration produces water o water is lost by evaporation from skin and lungs, through feces, and by excretion o to be in balance, the water entering the body must equal the water lost o if osmolarity differs between two regions, water moves into the region with the higher amount of solutes o marine environments are high in salt and promote the loss of water and the gain of ions by drinking water o freshwater promotes water gain by osmosis & ion loss as excess water is excreted o terrestrial animals tend to lose both water and ions to the environment - Aquatic Animals o Cartilage Fishes and Marine Invertebrates : sharks and rays are nearly isotonic with seawater; yet they do not contain the same amount of salt as seawater their blood has high concentrations of urea to match the tonicity of seawater; for some reason this is not toxic to them o Marine Bony Fishes constantly drink seawater ; they are prone to water loss and could become dehydrated to remove excess salt, they actively export Na + and Cl - ions at the gills bony fishes have a moderate salt level compared to seawater, their common ancestor probably evolved in freshwater o Freshwater Bony Fishes never drink water ; they passively gain water which makes their body fluids hypertonic to freshwater they take in salts at the gills and pass large quantities of hypotonic urine because this causes them to lose salts, they actively import Na + and Cl - ions into the blood at the gills some fish can move between marine and freshwater environments (salmon begin life in freshwater streams, mature in oceans and breed in freshwater) - Terrestrial Animals : some terrestrial animals near oceans are able to drink seawater despite its high osmolarity - such birds and reptiles have a nasal salt gland that excretes concentrated salt solution o Water Loss Prevention : some animals excrete insoluble nitrogenous waste animal skin is adapted to moist (thin, permeable skin) or dry (thick, impermeable skin) environments some animals have other unique adaptations to prevent water loss (the camel and kangaroo rat absorb moisture from exhaled air) o Most terrestrial animals must drink fresh water often; however, the kangaroo rat
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Kevin Kelleher, MTC Biology 102 Study Notes Exam 5 2 completely avoids drinking water (metabolic water is enough; forms concentrated urine & dry fecal waste) Nitrogenous Waste Products - Eliminating Nitrogenous Wastes : the breakdown of nucleic acids and amino acids results in nitrogenous wastes o amino acids are used to synthesize body proteins; unused amino acids are
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102SN5 - Biology 102 Study Notes Exam 5 Chapter 38: Body...

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