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Tissues Lecture 8: Epithelial – Proper Connective Tissue Honors Human Biology /TRCC-‐K175 Differentiation & Specialization of Cells Tissues: -an aggregate of particular types of cells -form one of the structural materials of a plant or an animal -all tissue cells are of similar embryonic origin -working together tissue cells perform specific functions -protection, support, circulation, growth, and reproduction Histology -study of tissues Animal Tissue Types 1) Epithelial Tissue 2) Connective Tissue 3) Muscle Tissue 4) Nervous Tissue Animal Tissue Formation Gametes-->Zygote-->Embryo -cells within embryo arranged into 3 tissues 1) Ectoderm -skin & nervous system 2) Mesoderm -muscle, skeleton, & the organs of circulation, reproductive & excretion 3) Endoderm -lining of the gut and associated organs Epithelial Tissue • protection, secretion, & absorption • linked tightly together; one or more layers • one “free” surface (may have cilia) & the other surface adheres to a non-cellular “basement” membrane Types of Epithelial Tissue- (Shape) Three Cell Shapes 1) Squamous - irregular shaped 2) Cuboidal - little boxes or cubes 3) Columnar - tall, rectangular shape Types of Epithelial Tissue (Arrangement) 1) Epithelial -one cell layer thick 2) Stratified Epithelial -several cells thick 3) Pseudostratified Epithelial -appear to be layered but are one layer 4) Transitional Epithelial -layers of closely packed cells -soft & pliable easily stretched Connective Tissue -contain cells & fibers (collagen &/or elastin) -bind structures together, support, protection, store fat, produce blood cells, fill spaces, and act as framework -connective tissue cells are widely separated by a non-cellular matrix Three Major Cell Types in Connective Tissue Three Major Cell Types 1) Fibroblasts - most common - large star-shaped cells - produce collagen (white fibers) & elastin (yellow fibers) 2) Mast Cells - located near blood vessels - contain heparin & histamine 3) Macrophages (histiocytes) - often attached to fibers - play key role in immunity Overview of Connective Tissue in the Human Body Connective Tissue Proper Loose (fibrous) Tissue 1) Areolar Tissue -joins tissue layers together & holds organs in place -mainly composed of fibroblasts (adult stem cells) Areolar connective tissue • Widely distributed; found under skin, around organs, between muscles • Wraps and cushions organs Connective Tissue Proper Loose (fibrous) Tissue 2) Adipose Tissue -specialized loose connective tissue in which fibroblasts enlarge & store fat intercellular matrix is reduced Adipose (fat) tissue • Found under skin, around kidneys and heart • Functions in energy storage and insulation; cushioning for organs -protective cushion for internal organs -insulating layer beneath the skin Connective Tissue Proper Loose (fibrous) Tissue 3) Reticular Tissue -thin delicate fibers -form the framework of liver, spleen, bone marrow, and lymph nodes -give rise to macrophages Connective Tissue Proper Dense (fibrous) Tissue 4) Dense Connective Tissue -close packed fibers, mainly collagen - Found in tendons (connect muscles to bone) and ligaments (connect bone to bone) Dense connective tissue • Found in tendons and ligaments • Forms strong bands that attach bone to muscle or bone to bone - poor blood supply