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Tissues. Chapter 4. Tissues. groups of cells with common role 4 basic types: Epithelial Connective Muscular Nervous. Epithelial Tissue. Cells close together – continuous sheets Cover surfaces & line cavities- always a free surface = Apical surface
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Tissues Chapter 4
Tissues • groups of cells with common role • 4 basic types: • Epithelial • Connective • Muscular • Nervous
Epithelial Tissue • Cells close together – continuous sheets • Cover surfaces & line cavities- always a free surface =Apical surface • Basement membrane of connective tissue • No blood vessels- avascular • Have a nerve supply • High capacity for cell division.
Categories- Table 4.1 • Simple epithelium = • 1 layer of cells • Stratified Epithelium= • more than 1 layer of cells • Cell Shapes = • squamous, cuboidal, columnar, transitional (change shape)
Simple Epithelium • Squamous= single layer of flat cells. • Important for filtration (kidneys) or diffusion (lungs & capillaries) • Called endothelium when lining heart, blood and lymphatic vessels • Called mesothelium when in serous membranes
Pseudostratified Columnar appears stratified: nuclei at various levels
Pseudostratified Columnar appears stratified: nuclei at various levels
Stratified Squamous Epithelium • Apical layer cells are flat • Deep layers vary from cuboidal to columnar • Cells in the basal layer divide and move upward toward apical surface • Found in areas of surface wear & tear
Transitional Epitheliumvariable in appearance—cells can stretch
Transitional Epitheliumvariable in appearance—cells can stretch
Connective Tissue • Most abundant tissue type • small cells far apart • large amount of extracellular material (matrix) • Often good blood supply • Found between other tissues • Classified using matrix characteristics
Connective Tissue Cellsvary with tissue type • Fibroblasts- present in several tissues • secrete fibers & ground substance • Macrophages- from monocytes • Engulf bacteria & cell debris by phagocytosis • Plasma cells- develop from B lymphocytes • Make antibodies
Connective Tissue Cells • Mast cells- near blood cells • part of reaction to injury- histamine • Adipocytes= fat cells or adipose cells • Store triglycerides (fat)
Extracellular Matrix • Fluid, gel or solid plus protein fibers • Ground substance-between cells and fibers • Fibers- 3 types • Collagen fibers: very strong & flexible • Elastic fibers: smaller stretch and return to original length • Reticular fibers: provide support & strength • found in basement membranes & organ support
Loose Connective Tissue • Areolar • Adipose • Reticular
Classification • Dense Connective tissue • Dense regular • Dense irregular • Elastic
Cartilage • Dense network of collagen & elastic fibers embedded in chondroitin sulfate • stronger than dense fibrous • Cells = chondrocytes • Occur singly or in groups • Found in spaces called lacunae • Surrounded by perichondrium • No blood vessels or nerves
Classification - Cartilage • 3 types • Hyaline- fibers not easily visible • Fibrocartilage- fibers visible • Strongest type. E.g. in vertebral discs • Elastic- chondrocytes in threadlike network e.g. ear cartilage