04_LectureOutline

04_LectureOutline - Four Types of Tissues Tissues are...

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Four Types of Tissues Tissues are collections of cells and cell products that perform specific, limited functions Types of tissue Epithelial tissue Covers exposed surfaces Lines internal passageways Forms glands Connective tissue Fills internal spaces Supports other tissues Transports materials Stores energy Muscle tissue Specialized for contraction Skeletal muscle, heart muscle, and walls of hollow organs Neural tissue Carries electrical signals from one part of the body to another Epithelial Tissues Epithelia Layers of cells covering internal or external surfaces Glands Structures that produce secretions Characteristics of Epithelia Cellularity (cell junctions) Polarity (apical and basal surfaces) Attachment (basal lamina) Avascularity Regeneration Functions of Epithelial Tissue Provide physical protection Control permeability Provide sensation Produce specialized secretions (glandular epithelium)
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Specializations of Epithelial Cells Move fluids over the epithelium (protection) Move fluids through the epithelium (permeability) Produce secretions (protection and messengers) Free Surface and Attached Surface Polarity Apical surfaces: microvilli increase absorption or secretion cilia (ciliated epithelium) move fluid Basolateral surfaces Maintaining the Integrity of Epithelia Intercellular connections Attachment to basal lamina Epithelial maintenance and repair Intercellular Connections Support and communication CAMs (cell adhesion molecules): transmembrane proteins Intercellular cement: proteoglycans Hyaluronan (hyaluronic acid): glycosaminoglycans Cell junctions Form bonds with other cells or extracellular material: occluding (tight) junctions gap junctions macula adherens (desmosomes) [Insert Animation: Intercellular Connections] Occluding (Tight) junctions— between two plasma membranes Adhesion belt attaches to terminal web Prevents passage of water and solutes Isolates wastes in the lumen Gap junctions— allow rapid communication Held together by channel proteins (junctional proteins, connexons) Allow ions to pass Coordinate contractions in heart muscle Macula adherens (Desmosomes) CAMs, dense areas, and intercellular cement Spot desmosomes tie cells together allow bending and twisting Hemidesmosomes attach cells to the basal lamina
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Attachment to the Basal Lamina Clear layer (Lamina lucida) Thin layer Secreted by epithelia Barrier to proteins Dense layer (Lamina densa) Thick fibers Produced by connective tissue Strength and filtration Epithelial Maintenance and Repair Epithelia are replaced by division of germinative cells (stem cells) Near basal lamina Classification of Epithelia Singular epithelium; plural epithelia
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This note was uploaded on 12/29/2011 for the course BIOLOGY 24011 taught by Professor Pan during the Fall '11 term at HCCS.

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04_LectureOutline - Four Types of Tissues Tissues are...

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