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Chapter 6. Classification of Tissues. Tissues and tissue types. Tissues are: Group of cells similar in structure an function Tissues are organized into organs Histology = study of tissues The four tissue types are: Epithelial Connective Muscular Nervous. Functions of epithelium.
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Chapter 6 Classification of Tissues
Tissues and tissue types • Tissues are: • Group of cells similar in structure an function • Tissues are organized into organs • Histology = study of tissues • The four tissue types are: • Epithelial • Connective • Muscular • Nervous
Functions of epithelium • Physical protection • Secretion • Sensory perception • Absorption • Filtration • Excretion
Epithelial tissue • Includes glands and epithelium • Glands are secretory • Avascular • Polarity • Regeneration • Cellularity • Supported by connective tissue • Attached to a basement membrane
Basement Membrane • Amorphous substance. • Divided in 2 layers: • Lamina lucida (basal) • Secreted by the epithelium • Lamina densa (reticular) • Secreted by the connective tissue
Specializations of epithelium • Ciliated • Microvilli • Stereocilia • Flagella
Classification of epithelia • Number of cell layers • Simple • Stratified • Shape of apical surface cells • Squamous • Cuboidal • Columnar
Cuboidal Epithelia Figure 4.4b
Transitional Epithelium Figure 4.4c
Columnar Epithelia Figure 4.5a
Columnar Epithelia Figure 4.5b
Columnar Epithelia Figure 4.5c
Glandular epithelia • Epithelium that secrete substances • Exocrine glands • Secrete through ducts onto the surface of the gland • Endocrine glands • Release hormones into surrounding fluid. Ductless glands.
Connective tissue functions and classification: • Protects • Supports • Bind tissues together • Classification: • Embryonic • Mesenchime • Loose connective tissue, mucous • Adult
Connective tissues characteristics • No free surface • Vascular • Scanty in tendons • Except cartilage • Supports the body • Maintain body form
Components of the connective tissue 1)Extracellular matrix • Ground substance • Amorphous • Binds cells to fibers • Colorless • Homogeneous • Liquid, semisolid, gel-like, or hard
Matrix • Fibers • Collagen (white) • Most abundant • Brings flexibility and strength to the tissue • Thicker one • Elastic(yellow) • Brings elasticity to the tissues • Can stretch and recoil
Fibers • Reticular • Thinnest one • Found in smooth muscle and framework of the organs • Brings flexibility to organs that need changes in volume
Components of the connective tissue 2) Cells • Fibroblast • most abundant • Synthesis of fibers and ground substance • Macrophage • Phagocytic capacity
Components of the connective tissue • Adipocytes • Closely packed • Signet ring cell • Nucleus eccentric and flat • Mesenchymal cells • Mast cells • Releases histamin • Responsible for allergic reactions • Lymphocytes, etc
Connective tissue proper • Classified as loose or dense • Loose • Areolar tissue • Adipose tissue • Reticular tissue • Rich blood supply
Connective tissue proper • Dense • Dense regular • Dense irregular • Elastic • Poor blood supply
Dense Connective Tissues Figure 4.12a
Dense Connective Tissues Figure 4.12b
Dense Connective Tissues Figure 4.12c
Bone, or osseous tissue • Has osteocytes and osteoblasts • Lacuna • Little ground substance • Dense mineralized matrix • Richly Vascularized