Tissues(info & epithelial) 4

Tissues(info & epithelial) 4

1. Cell junctions

   • Anchoring Junctions
     • Adherens junctions: keeps tissues from separating as they stretch and contract -Cadherin: glycoprotein that forms belt-like plaque
     • Desmosmes: act as "spot welds" btwn cells -uses cadherin and *intermediate filament* to hook to cytoplasm -common in skin and muscle
     • Hemidesmosomes: half-welds that join cells to a basement memebrane
   • Communicating Junctions
     • Gap Junctions: small passageways that allow substances to pass btwn cells -Ions can pas btwn these -In cardiac and smooth muscle If a cell gets sick or dies, these seal like a safety hatch so the chemical reactions don't spread
   • Occluding Junctions
     • Tight Junctions: provides a leak-proof seal btwn adjacent cells -located in stomach and bladder

2. Four Basic Tissues

   • Epithelial
     • Covers body surfaces, forms glands, and lines hollow organs,  body cavities, and ducts Characteristics -supported by connective tissue -avascular but innervated -typically regenerates
     • Characteristics
       • Used to line surfaces and form protective barriers; also used to secrete mucous, hormones, and various substances
   • Connective Tissues
     • Functions in protection, support, and binding of organs Fat(adipose) is a type of C.T. that stores energy RBCs, WBCs, and platelets are part of the C.T. of blood
   • Muscle Tissue
     • Generates physical force to produce movement. Also, generates heat.
   • Nervous Tissue
     • -internal communication -detect body changes -provide means for a quick response to stimuli
   • Germ Layers
     • Endoderm, mesoderm, and ectoderm
     • Endoderm
       • Inner lining of the digestive tract -epithelial
     • Mesoderm
       • Muscle and connective tissue are derived from this -epithelial
     • Ectoderm
       • Nervous tissue -epithelial

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