Animal structure and function

          

                                                                                           

Tissues

EpithelialConnectiveMuscleNervous

Epithelial tissue

Epithelial tissue (epithelium):Covers all surfaces of the bodyEpidermis (ectoderm): Outer portion of skinEndoderm:Lining of inner surfaces of digestive tract Mesoderm:Inner surface of body cavities

Epithelial tissue

Closely packedTight junctionsOne/or few cell layers thickSelective absorption in the intestinesRapid gas exchange in lungsProtection from microbes, water loss

Epithelial tissue

Regenerative capabilitiesLiver (gland from epithelial tissues)Epidermis every 2 weeksStomach lining every 2-3 days

Epithelial tissue

TypesBased on cell thicknessShape on exposed surfaceSimpleOne layer thickStratifiedMultiple layers of cells

Epithelial tissue

Shapes of cells Cuboidal:As wide as they are tall (like dice) Columnar:Taller than wide (like bricks on end) Squamous Flat like floor tiles

Epithelial tissues

Epithelial tissue

Simple squamous Lining of lungs, capillary walls and blood vesselsSimple cuboidal Lining of some glandsSimple columnar Lining of stomach, intestines and parts of respiratory tract

Epithelial tissue

Stratified squamous Outer layer of skin and mouthKeratin Water resistant protein

Epithelial tissue

Exocrine glands (duct system)Duct:Connection from gland to tissueSecrete/absorb chemical solutionsSweat and sebaceous glandsLining of intestines & lungs that secrete mucous

Epithelial tissue

Endocrine glands (ductless glands)HormonesSecreted into blood stream

Glands

Connective tissue

Holds tissues & organs togetherDerived from mesodermLoosely packed cellsScattered in an extracellular matrix

Connective tissue

Matrix: Composed of a web of fibers In a foundation of liquid, jellylike or solidFibers (proteins) are collagen, elastic, or reticular

Connective tissue

Collagen:Non-elastic-doesn’t tear easilyElastic:Makes tissue elasticElastin (protein)Reticular:Thin, branched, joins connective tissue to adjacent tissues

Connective tissue

Cells in matrixFibroblasts: Produce & secrete extracellular matrixMacrophages:Engulf foreign bodies & debrisMast cells & heparin

Connective tissue types

1. Loose connective tissueBeneath skin & between organsSupport, insulation, food storageAdipose tissue (fat)Cells become larger when gain weightShrink with weight loss

Connective tissue

2. Dense connective tissueTendons, ligaments, sheath around organs (periosteum), dermis of skinSupport, strong connections3. Special connective tissueCartilage, bone, blood,

Connective tissue

Special connective tissue

Cartilage Consists of chondroitin (glycoprotein) & collagenStrong, flexible tissue, absorb stressJoints, ear pinna, nose, intervertebral discs, larynxChondrocytes: Cartilage cells

Cartilage

Bone

Embryos---more cartilageCartilage is replaced with bone cells or osteocytesMatrix hardens with crystals of calcium phosphate mixed with collagen

Bone

Osteoblasts: Lay down new boneOsteoclasts: Dissolve boneOsteons: Unit of bone structureContains calcified matrix, osteocytes, nerve fibers, blood vessels

Bone

Flat bonesLong bonesSpongy bone: Contains marrowBlood cells formedCompact bone:More dense, gives strength

Bone

Bone

Blood

Plasma (matrix)CellsRBC (erythrocytes)Contain hemoglobin (carries oxygen)WBC (leukocytes)Neutrophils, eosinophils, basophils, lymphocytes, monocytesPlatelets (thrombocytes)

Blood

Blood

Plasma containsWastes, nourishmentHormonesNa+, Ca2+, other ionsFibrinogen, albumin, antibodies

Muscle tissue

MovementOrganization of actin & myosin filamentsSmooth, skeletal & cardiac musclesStriated muscles: skeletal & cardiacSkeletal muscles: voluntary controlSmooth & cardiac muscles: involuntary control

Muscle tissue

Smooth muscle Walls of blood vessels, stomach, intestinesViscera: Internal organsMade of sheets of cells each with a single nucleus

Muscle tissue

Skeletal muscleAttached by tendons to bonesContract move bones

Muscle tissue

Muscle tissue

Cardiac muscleSmall interconnected cellsLinked by gap junctionsOpenings allow small substances & electrical charges to pass between cellsMyocardium Single functioning units

Nerve tissue

NeuronsCell body, dendrites, axon Neuroglia Supporting cellsInsulate neuronsEliminate foreign bodies

Nerve tissue

DentritesThin, branched extensions Receive impulsesAxonsSingle extension of cell bodyCarries impulse awayMyelin sheaths, insulating cover

Neurons

Neurons

Sensory neuronsEye,ears, surface of skinMotor neuronsBrain & spinal cordInterneuronsBrain & spinal cordNeurons within the CNS

Neurons

Summary

Epithelial tissuesSimple or stratifiedCuboidal, columnar, squamousConnective tissuesLoosely packed, tightly packedSpecial (bone, cartilage, blood)Matrix

Summary

Muscle tissuesSmooth, cardiac, skeletalNerve tissues:Neurons (cell body, dentrites, axons)Sensory, motor and interneurons

Coordination

HormonesNervous systemHomeostasis

Homeostasis

Dynamic constancy of internal environmentDynamic because conditions fluctuate Narrow rangepHTempGlucoseOxygen

Regulation

1. Negative feedback loops2. Positive feedback loops

Negative feedback

media\40_08NegativeFeedback_A.html

Positive feedback

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Negative feedback loops

SensorsMeasure internal environmentIntegrating centerReceives information from sensorsCompares to normal rangeResponds

Negative feedback loops

Effectors:Muscles or glandsReceive information from centerResponse

Negative feedback loops

Temperature increaseHypothalamus senses deviationSends signals to relieve heatSweating & vasodilationReach baseline Negative feedback stops response

Negative feedback loops

Temperature decreaseHypothalamus sends signalsShiver, vasoconstrictionTemp to baseline Negative feedback stops response

Thermoregulation

Fig. 40-9

(a) A walrus, an endotherm

(b) A lizard, an ectotherm

Negative feedback loops

Glucose (eat a meal)Elevated blood levelIslets of Langerhans (sensor, center)InsulinLowers blood sugar (uptake in muscle, fat & liver cells)Negative feedback stops insulin release

Positive feedback loops

Uterine contractionsPressure from baby on uterusCauses contractionsCauses more stretchingMore contractionsContinues until birth

Positive feedback loop

Blood clottingClotting factors stimulate the formation of more factorsClot formsMaintain blood volume

Bioenergetics

Overall flow & transformation of energy in an animalDetermines nutritional needsAnimal size, activity and environment

Fig. 40-17

Organic moleculesin foodExternal

environment

Animalbody Digestion and

absorption

Nutrient moleculesin body cells

Carbonskeletons

Cellularrespiration

ATP

Heat

Energy lostin feces

Energy lost innitrogenouswaste

Heat

Biosynthesis

Heat

Heat

Cellularwork

Metabolic rate

Amount of energy an animal uses in a unit of timeTorpor:Physiological state of low activity with low metabolismHibernation:Long term torpor