Life 103 Week 13
Life 103 Week 13 LIFE 103
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This 3 page Class Notes was uploaded by Caroline Hurlbut on Friday April 22, 2016. The Class Notes belongs to LIFE 103 at Colorado State University taught by Jennifer L Neuwald; Tanya Anne Dewey in Fall 2016. Since its upload, it has received 14 views. For similar materials see Biology of Organisms-Animals and Plants in Biology at Colorado State University.
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Date Created: 04/22/16
Osmoregulation & Excretion • osmosis requires semi-permeable membrane • hypertonic solution - higher solute concentration, lower H2O concentration —>desiccation of cell • hypotonic solution - lower solute concentration, higher H2O concentration —>swelling of cell • isotonic solution - same concentration of solute/H2O on both sides of membrane • net movement of water is toward more solute ex. marine ﬁsh are hypotonic to sea water and sea water is hypertonic to marine ﬁsh • • osmoconformers vs osmoregulators —osmoconformers: isoosmotic with environment but differ in speciﬁc solutes in tissues (mostly marine invertebrates) —osmoregulators: expend energy to control water uptake or loss in hypo/ hypertonic environment (all other aquatic animals) • marine vs freshwater osmoregulation —marine ﬁsh are hypoosmotic to environment and must expend energy to lose salt/ions and avoid water loss —freshwater ﬁsh are hyperosmotic to environment and must expend energy to lose water and avoid solute loss • terrestrial animals - challenge is desiccation —have body coverings and use physiological and behavioral mechanisms to avoid water loss —3 ways to get water A. ingest it from food B. drinking free water C. metabolic production (cellular respiration) —3 ways to lose water A. gas exchange (lose water through moist epithelia) B. urination and defecation (lose nitrogenous wastes) • transport epithelia - specialized cells for moving particular solutes into/out of body (ex. salt glands and kidneys) • nitrogenous wastes created by metabolism of proteins —must be excreted in solution—>water loss —nitrogen removed in the form of highly toxic ammonia, can be transformed into urea or uric acid (low toxicities and require less water to excrete, but also require more energy) • waste products depend on phylogeny and habitat —most aquatic animals produce ammonia —mammals and most amphibians produce urea —most reptiles produce uric acid • excretory process —ﬁltration: body ﬂuid comes into contact with transport epithelium membrane and hydrostatic pressure drives water and small solutes across membrane (ﬁltrate) —reabsorption: valuable molecules actively transported back into body ﬂuids —secretion: additional wastes actively transported into waste ﬂuid —excretion: ﬂuid wastes removed from body • excretory system in mammalian kidney —kidneys: set of tubes that create large surface area for exchange of water and solutes via transport epithelia —kidneys receive blood from renal vein, most blood is ﬁltered and reabsorbed into blood ﬂuid, remaining ﬂuid leaves body as urine • tubules arranged into nephrons, where ﬁltration, reabsorption, and secretion occur —Glomerulus and Bowman’s capsule: ﬁltrates collected —proximal tubule: valuable molecules transported out of ﬁltrate and reabsorbed —loop of Henle A. descending limb: water ﬂows out of ﬁltrate B. ascending limb: solutes move out of ﬁltrate into medulla, ﬁltrate becomes more dilute as it ascends —distal tubule: regulates K+ and NaCl concentration in body ﬂuids via reabsorption and secretion —collecting duct: water ﬂows out of ﬁltrate and travels back through medulla • ﬂow of water through kidney creates concentration gradient • types of nephrons —cortical: reach short distance into medulla —juxamedullary: extend deep into medulla, critical for concentrating urine Gas Exchange respiratory exchange surfaces - must be moist because gases cannot cross • membranes unless in aqueous solution • most diverse groups of animals use internal exchange surfaces —lungs —gills —tracheal systems • gas exchange - uptake of O2 from environment and discharge of CO2 • partial pressure - pressure exerted by a particular gas in mix of gases —O2 less soluble in water than air—>concentration O2 in air higher than in water at same partial pressure respiratory media • —terrestrial breathing doesn’t have to be very efﬁcient—>medium doesn’t have to be dense or viscous (air) —aquatic animals need efﬁcient O2 extraction—>medium must be dense and viscous (water) • rates of diffusion increase as —surface area increases —distance decreases —concentration gradient increases • ventilation - movement of respiratory medium across respiratory surface —nondirectional —unidirectional —tidal • nondirectional ventilation - no movement of respiratory medium, concentration of gases in medium inﬂuences efﬁciency • unidirectional ventilation - diffusion of O2 through gills into blood —ﬂowing of blood in opposite directions—>countercurrent exchange system • tidal ventilation - diffusion of O2 through lungs into blood (can also be unidirectional) —rib muscles contract and relax —fresh O2 in new breath mixes with O2 in lungs after last breath • elephant seals allow lungs to collapse and store O2 in massive blood volume and myoglobin in muscles to dive for hours at depths up to a mile
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