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HISTOLOGY. THE STUDY OF TISSUES. GENERAL. Tissue = Cells with similar structure & function organized into groups or layers Four major types: Epithelial (Covers or lines surfaces, found in glands) Connective (Bind & support body parts) Muscle (Movement)
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HISTOLOGY THE STUDY OF TISSUES
GENERAL • Tissue = Cells with similar structure & function organized into groups or layers • Four major types: • Epithelial (Covers or lines surfaces, found in glands) • Connective (Bind & support body parts) • Muscle (Movement) • Nervous (Detect changes & transmit info.)
CHARACTERISTICS OF EPITHELIAL TISSUE • Covers all body surfaces inside & out • Many tightly packed cells, usually arranged into layers • Free surface & basement membrane • Functions: protection, absorption, sensation, secretion • High rate of cell division (healing) • Avascular (rely on diffusion)
CLASSIFICATION OF EPITHELIAL TISSUE • Layers • Simple (one layer) • Stratified (>1 layer; Note: only cells at surface have characteristic shape) • Shapes • Squamous • Cuboidal • Columnar • Transitional
CONNECTIVE TISSUE - GENERAL • Few cells widely spaced in non-living matrix • Matrix may be solid, semi-solid, fluid • Largest % of tissue by weight; found in all body parts • Binds, protects, supports • May be vascular
CONNECTIVE TISSUE - GENERAL • Fibroblast • Most common cell • Secretes fibers • Collagen – strong, flexible, structural • Elastic – stretch & recoil • Reticular – highly branched, supportive • Differs in type & amount of fibers in matrix • Loose or dense; regular or irregular
MUSCLE TISSUE • Contract, provide movement • 3 types: • Skeletal (attached to bones) • Smooth (hollow organs) • Cardiac (heart)
NERVOUS TISSUE • Regulate, coordinate, body functions • Brain, spinal cord, nerves • 2 types of cells: • Neuron (nerve cell) • Most specialized cell in body • Conducts (Transmission of nerve impulse) • Neuroglia (“nerve glue”) • Assist neurons (bind, protect, supply)