BILD 2: Multicellular Life[Website: http://www.biology.ucsd.edu/classes/bild2.WI11.1]Instructor: Darwin K. [email protected] 40-4 Internal exchange surfaces of complex animalsExternal environmentFood CO2O2MouthAnimalbodyRespiratorysystemCirculatorysystemNutrientsExcretorysystemDigestivesystemHeartBloodCellsInterstitialfluidAnusUnabsorbedmatter (feces)Metabolic wasteproducts (urine)The lining of the small intestine, a diges-tive organ, is elaborated with fingerlikeprojections that expand the surface areafor nutrient absorption (cross-section, SEM).A microscopic view of the lung reveals that it is much more spongelike than balloonlike. This construction provides an expansive wet surface for gas exchange with the environment (SEM).Inside a kidney is a mass of microscopic tubules that exhange chemicals with blood flowing through a web of tiny vessels called capillaries (SEM). 0.5 cm10 m50 mFig. 40-5aEpithelial TissueCuboidalepitheliumSimplecolumnarepitheliumPseudostratifiedciliatedcolumnarepitheliumStratifiedsquamousepitheliumSimplesquamousepitheliumFig. 40-5bApical surfaceBasal surfaceBasal lamina40 mFig. 40-5cConnective TissueCollagenous fiberLooseconnectivetissueElastic fiber120 mCartilageChondrocytes100 mChondroitinsulfateAdiposetissueFat droplets150 mWhite blood cells55 mPlasmaRed bloodcellsBloodNucleiFibrousconnectivetissue30 mOsteonBoneCentral canal700 mFig. 40-5jMuscle Tissue50 mSkeletalmuscleMultiplenucleiMuscle fiberSarcomere100 mSmoothmuscleCardiac muscle NucleusMusclefibers25 mNucleusIntercalateddiskFig. 40-5nGlial cellsNervous Tissue15 mDendritesCell bodyAxonNeuronAxonsBlood vessel40 mTissue layers of the stomach, a digestive organLumen ofstomachMucosa. The mucosa is anepithelial layer that linesthe lumen.Submucosa. The submucosa isa matrix of connective tissuethat contains blood vesselsand nerves.Muscularis. The muscularis consistsmainly of smooth muscle tissue.0.2 mmSerosa. External to the muscularis is the serosa,a thin layer of connective and epithelial tissue.Table 40-1Fig. 40-17Organic moleculesin foodExternalenvironmentAnimalbodyDigestion andabsorptionNutrient moleculesin body cellsCarbonskeletonsCellularrespirationATPHeatEnergy lostin fecesEnergy lost innitrogenouswasteHeatBiosynthesisHeatHeatCellularworkFig. 40-16Sweat glands secretesweat, which evaporates,cooling the body.Thermostat in hypothalamusactivates cooling mechanisms.Blood vesselsin skin dilate:capillaries fill;heat radiatesfrom skin.Increased bodytemperatureDecreased bodytemperatureThermostat inhypothalamusactivates warmingmechanisms.Blood vessels in skinconstrict, reducingheat loss.Skeletal muscles contract;shivering generates heat.Body temperatureincreases; thermostatshuts off warmingmechanisms.Homeostasis:Internal temperatureof 36–38°CBody temperaturedecreases;thermostatshuts off coolingmechanisms.Figure 48-4 Structure of a vertebrate neuron and asynaptic connectionDendritesStimulusNucleusCellbodyAxonhillockPresynapticcellAxonSynaptic terminalsSynapsePostsynaptic cellNeurotransmitterFigure 48-5 Structural diversity of vertebrate neuronsDendritesAxonCellbodySensory neuron InterneuronsPortionof axonCell bodies ofoverlapping neurons80 mMotor neuronTHE END(for today)(TA meeting today right after lecturein 3502 Pacific Hall 11-12
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