Chapter 4 - Chapter 4 - Types of Tissues...

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Chapter 4 - Types of TissuesTissues are collections of cells and cell products that perform specific, limited functionsTypes of Tissuei.Epithelial tissue:covers exposed surfaces, lines internal passageways & forms glandsii.Connective tissue:fills internal spaces, supports other tissues, transports materials & stores energyiii.Muscle tissue:specialized for contraction; skeletal muscle, heart muscle & walls of hollow organsiv.Neural tissue -carries electrical signals from one part of the body to another1. Epithelial Tissues0.Epithelia - layers of cells covering internal or external surfacesa.Glands - structures that produce secretionsCharacteristics of Epitheliai.Cellularity (cell junctions)ii.Polarity (apical and basal surfaces)iii.Attachment (basal lamina)iv.Avascularity v.RegenerationFunctions of Epithelial Tissuei.Provide physical protectionii.Control permeabilityiii.Provide sensationiv.Produce specialized secretions (glandular epithelium)Specializations of Epithelial Cellsi.Move fluids over the epithelium (protection)ii.Move fluids through the epithelium (permeability)iii.Produce secretions (protection and messengers)Free Surface and Attached Surface -Polarity Apical surfaces: microvilli absorption or secretion & cilia (ciliated epithelium) move fluidBasolateral surfacesMaintaining the Integrity of Epitheliai.Intercellular connectionsii.Attachment to basal laminaiii.Epithelial maintenance and repairA. Intercellular Connectionsv.Support and communication1.CAMs (cell adhesion molecules): transmembrane proteins  2.Intercellular cement: proteoglycans 3.Hyaluronan (hyaluronic acid): glycosaminoglycansvi.Cell junctions - form bonds with other cells or extracellular material:a.occluding (tight) junctionsb.gap junctionsc.macula adherens (desmosomes)i. Occluding (Tight) junctions—between two plasma membranesAdhesion belt attaches to terminal web & prevents passage of water & solutes; isolates wastes in the lumenii. Gap junctions—allow rapid communication4.Held together by channel proteins (junctional proteins, connexons); allow ions to pass and coordinates contractions in heart muscleiii. Macula adherens (Desmosomes)5.CAMs, dense areas, and intercellular cementSpot desmosomes - tie cells together and allow bending and twistingHemidesmosomes - attach cells to the basal laminaAttachment to the Basal Laminai.Clear layer(Lamina lucida) - thin layer, secreted by epithelia and a barrier to proteinsii.

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Term
Fall
Professor
WATSON
Tags
Physiology, Human Anatomy, RNA, cells, Epithelia

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