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Cells & Tissues Chapter 3

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Cells & Tissues. Chapter 3. I. The Plasma Membrane Structure. A. Fluid Mosaic Model. Double bilayer of lipids with imbedded, dispersed proteins Bilayer consists of phospholipids, cholesterol, and glycolipids Glycolipids are lipids with bound carbohydrate - PowerPoint PPT Presentation


Cells & Tissues

Cells & TissuesChapter 3I. The Plasma Membrane Structure

A. Fluid Mosaic ModelDouble bilayer of lipids with imbedded, dispersed proteinsBilayer consists of phospholipids, cholesterol, and glycolipidsGlycolipids are lipids with bound carbohydratePhospholipids have hydrophobic tails and hydrophilic headscholesterol: stabilizes lipid membraneintegral proteins: some face outside of membrane, usually receptors for hormones or other chemical messengerstransmembrane proteins span entire width of membrane & protrude on both sidestransport functionsperipheral proteins: not embedded in lipidenzymes

glycocalyx: cell coatstickiness helps bind adjacent cells togetherevery cell has different pattern of sugars & proteins, biological markers for cell recognitionfigure 3.2 p.58B. Specializations of Plasma Membranemicrovilli: fingerlike extensions of plasma membraneincrease cell membrane surface areaabsorption: intestine & kidneyp. 59 figure 3.3Tight junctions: binds cell together into leak proof sheetsIntestines prevent digestive enzymes from seeping into bloodstreamDesmosomes: anchoring junctions for cells subjected to mechanical stressGap junctions: allow communication between cellsTight Junctions



Gap JunctionsII. Cell PhysiologyA. Membrane Transportcells are continuously bathed in extracellular fluid called interstitial fluid largely composed of watercontains nutrients, hormones, salts, & waste products

to stay healthy each cell must extract exact amounts of substances needed from this fluid & reject the restmembrane is selectively permeable: it allows some to pass while excluding othersB. Passive Processessubstances penetrate membrane without any energy input from cell1. simple diffusion2. osmosis3. facilitated diffusion4. filtrationC. Active Transport ProcessesPrimary active transport hydrolysis of ATP phosphorylates the transport protein causing conformational changeSecondary active transport use of an exchange pump (such as the Na+-K+ pump) indirectly to drive the transport of other solutes

substances are too large or have to move against the concentration gradient1. Solute Pumping2. Bulk Transportendocytosis: phagocytosis or pinocytosisexocytosis

ProcessEnergy SourceExampleSimple diffusionKinetic energyMovement of O2 through membraneFacilitated diffusionKinetic energyMovement of glucose into cellsOsmosisKinetic energyMovement of H2O in & out of cellsFiltrationHydrostatic pressureFormation of kidney filtratePassive Membrane Transport ReviewProcessEnergy SourceExampleActive transport of solutesATPMovement of ions across membranesExocytosisATPNeurotransmitter secretionEndocytosisATPWhite blood cell phagocytosisFluid-phase endocytosisATPAbsorption by intestinal cellsReceptor-mediated endocytosisATPHormone and cholesterol uptakeEndocytosis via caveoliATPCholesterol regulationEndocytosis via coatomer vesiclesATPIntracellular trafficking of moleculesActive Membrane Transport ReviewVoltage across a membraneResting membrane potential (RMP) the point where K+ potential is balanced by the membrane potentialRanges from 20 to 200 mV (depends on cell)Results from differential permeability of the plasma membrane to Na+ and K+Steady state potential maintained by active transport of ions

D. Membrane PotentialGeneration and Maintenance of Membrane Potential

E. Cell SignalingContact signaling important in normal development and immunityElectrical signaling voltage-regulated ion gates in nerve and muscle tissueChemical signaling neurotransmitters bind to chemically gated channel-linked receptors in nerve and muscle tissueG protein-linked receptors ligands bind to a receptor which activates a G protein, causing the release of a second messenger, such as cyclic AMP or Tyrosine Kinase.

Hormone AReceptorCatecholaminesACTHFSHLHGlucagonPTHTSHCalcitoninAdenylate cyclaseExtracellular fluidCytoplasmGsFigure 16.2Amino Acid-Based Hormone Action: cAMP Second Messenger

Hormone AReceptorCatecholaminesACTHFSHLHGlucagonPTHTSHCalcitoninAdenylate cyclaseExtracellular fluidCytoplasmGs1Figure 16.2Amino Acid-Based Hormone Action: cAMP Second Messenger

Hormone AReceptorGTPGTPCatecholaminesACTHFSHLHGlucagonPTHTSHCalcitoninAdenylate cyclaseGDPExtracellular fluidCytoplasmGs12Figure 16.2Amino Acid-Based Hormone Action: cAMP Second Messenger

Hormone AReceptorGTPGTPGTPCatecholaminesACTHFSHLHGlucagonPTHTSHCalcitoninAdenylate cyclaseGDPExtracellular fluidCytoplasmGs123Figure 16.2Amino Acid-Based Hormone Action: cAMP Second Messenger

Hormone AReceptorGTPGTPGTPATPcAMPCatecholaminesACTHFSHLHGlucagonPTHTSHCalcitoninAdenylate cyclaseGDPExtracellular fluidCytoplasmGs1234Figure 16.2Amino Acid-Based Hormone Action: cAMP Second Messenger

Hormone AReceptorGTPGTPGTPATPcAMPInactive protein kinase AActive protein kinase ACatecholaminesACTHFSHLHGlucagonPTHTSHCalcitoninTriggers responses of targetcell (activates enzymes,stimulates cellularsecretion, opens ionchannels, etc.)Adenylate cyclaseGDPExtracellular fluidCytoplasmGs12345Figure 16.2Amino Acid-Based Hormone Action: cAMP Second MessengerIII. Body TissuesHistology: study of tissuesgroups of similar cells associated to perform a related functionTYPE1. Epithelial2. Connective3. Muscle4. NervousPURPOSECoveringSupportMovementControlIV. EPITHELIAL TISSUESsheet of cells that covers a body surface or lines a body cavitycells fit so close to make continuous sheetscontains nerve but no blood vesselsquick regenerationA. Classification1. Simple: single layer of cells, used for absorption or filtrationSquamous: lymph system & lines organsCuboidal: exocrine glands and kidneysColumnar: digestive system