Connective - Central Bucks School District



OLD NOTES – FOR REFERENCE ONLY!Chapter 40 – Introduction to Animal Structure and FunctionAnatomy – study of structurePhysiology – study of functionStructure follows function:Cells → Tissues → Organs → Organ SystemsTissues = group of cells with common structure and function4 main tissue categories:EpithelialConnectiveNervousMuscleEpithelial Sheets of tightly packed cells; covers outside of body; lines organs and cavitiesRiveted together by tight junctionsClassification of epithelial cells:4781550165735Fig. 40.1 pg. 83600Fig. 40.1 pg. 836# of cell layers → Simple (single layer)Stratified (multiple layers)Shape of cells →Cuboidal (dice)Columnar (bricks on end)Squamous (flat)Glandular epithelial – absorb/ secrete chemical solutions (ex. secrete mucous membranes)ConnectiveFunction: to bind and support other tissues3 types of fibers:Collagenous fibers → made of collagen (protein); non-elastic; do not tear easilyElastic fibers → made of elastin (protein); rubbery quality; restore to original shapeReticular fibers → thin and branched; form tightly woven fabrics that join connective tissue to other tissue; made of collagenTypes of connective tissue:Loose connective tissue → most abundant, “packing material” – holds organs in placeTypes of cells:Fibroblasts = secrete extracellular fibersMacrophages = engulf bacteria and debrisEx. adipose tissue (stores fat/ insulates)Fibrous connective tissue → dense; lots of collagen fibers; found in:Tendons = connects muscles to bonesLigaments = connects bones at jointsCartilage → much collagen; strong yet flexible; embryonic skeleton starts as cartilageBone → mineralized connective tissueOsteoblasts = bone forming cells that deposit matrix of collagenBlood → transportsLeukocytes = WBC’s = defenseErythrocytes = RBC’s = carry oxygenNervous TissueSenses stimuli and transmits signalsFunctional unit = neuron (nerve cell)Muscle TissueComposed of long cells called muscle fibers that can contractMade of actin and myosin proteinsMost abundant tissue in most animals3 types of muscle tissues:SkeletalAttached to bones by tendonsResponsible for voluntary movementsDon’t increase in number, just enlarge (lifting)Striated (overlapping filaments)CardiacStriated and branchedForms contractile wall of the heartSmoothLacks striationsWalls of digestive tract, bladder, arteries, etcCells contract more slowly than skeletal but can stay contracted longerOrgan systems are interdependentOrgans are separated by sheets of connective tissue called mesenteriesEx. diaphragm separates thorasic cavity from abdominal cavityPhysical laws constrain animal formEx. SA: volume ratio → constrains sizeEx. Laws of thermodynamics → constrains shape Cells need to be in contact with external environment or bathed in a solutionSimple organisms = body wall is only 2 layers thick; both sides are exposed to the environment for nutrient exchangeComplex animals = need highly folded internal structures; organ system can control internal solutionsREGULATING THE INTERNAL ENVIRONMENTInterstitial Fluid → internal environment of vertebrates; fills spaces between cells; exchanges nutrients and waste with bloodHelps keep homeostasis, which is a balanced dynamic stateHomeostasis3 functional control units:Receptor → detects changes (ex. body temperature)Control Center → processes information from the receptor and directs a response to the effectorEffector → makes the change; see Ex. pg. 843Negative FeedbackA change triggers the control mechanism to counteract further change in that directionEx. body temp is high = sweat = body temp decreasesPositive FeedbackA change triggers the control mechanism to amplify the changeEx. hormones during childbirth signal MORE hormones to start laborInternal regulation is EXPENSIVE! Much of the energy obtained from food is used to balance the internal environmentBIOENERGETICS OF ANIMALSProduction and use of ATP generates heat; therefore, an animal constantly loses heat to the environmentFlow of energy through an animal sets limits on the animals behaviorMetabolic rate → amount of energy an animal uses in a unit of timeMeasured in calories or kilocalories (kcal)Can be measured by monitoring rate of heat lossMost energy from food goes to ATP production; little goes to growth an development Endothermic → body is warmed by heat generated by metabolism; high energy strategyEctothermic → metabolic heat production is not enough to effect body temperature; requires less energyMetabolic rate is inversely related to body size; Ex. 1 gram of a mouse uses 20 times more calories than 1 gram of an elephant → NOT sure why!?!Animals adjust metabolic rates as conditions change:BMR (basal metabolic rate) → metabolic rate of an endotherm at rest, with an empty stomach, experiencing no stressSMR (standard metabolic rate) → metabolic rate of an ectotherm (resting/ fasting/ non-stressed)Activity has a large effect on metabolic rateMaximal metabolic rate (highest rate of ATP utilization) occurs during peak activitiesNeither endotherms or ectotherms can sustain this rate over a long period of timeOnly endotherms can do long-duration activities (long distance running) → their cell respiration rate is 10x greater than in ectotherms ................
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