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Published byAgatha Patience Peters Modified over 9 years ago
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Cells and Tissues Tissue Types
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Body Tissues Tissues are groups of cells with similar structure and function Four primary types Epithelial tissue (epithelium) Connective tissue Muscle tissue Nervous tissue
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Epithelial Tissues Locations o Body coverings o Body linings o Glandular tissue Functions o Protection o Absorption o Filtration o Secretion Characteristics o Cells fit closely together and often form sheets o The apical surface is the free surface of the tissue o The lower surface of the epithelium rests on a basement membrane o Avascular (no blood supply) o Regenerate easily if well nourished
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Classification of Epithelia Number of cell layers o Simple—one layer o Stratified—more than one layer Shape of cells o Squamous flattened o Cuboidal cube-shaped o Columnar column-like
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Simple Epithelia Simple squamous o Single layer of flat cells o Usually forms membranes Lines body cavities Lines lungs and capillaries
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Simple Epithelia Simple cuboidal o Single layer of cube-like cells o Common in glands and their ducts o Forms walls of kidney tubules o Covers the ovaries
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Simple Epithelia Simple columnar o Single layer of tall cells o Often includes mucus-producing goblet cells o Lines digestive tract
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Simple Epithelia Pseudostratified columnar o Single layer, but some cells are shorter than others o Often looks like a double layer of cells o Sometimes ciliated, such as in the respiratory tract o May function in absorption or secretion
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Stratified Epithelia Stratified squamous o Cells at the apical surface are flattened o Found as a protective covering where friction is common o Locations Skin Mouth Esophagus
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Stratified Epithelia Transitional epithelium o Shape of cells depends upon the amount of stretching o Lines organs of the urinary system
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Glandular Epithelium Gland o One or more cells responsible for secreting a particular product Two major gland types o Endocrine gland Ductless since secretions diffuse into blood vessels All secretions are hormones o Exocrine gland Secretions empty through ducts to the epithelial surface Include sweat and oil glands
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Connective Tissue Found everywhere in the body Includes the most abundant and widely distributed tissues Functions o Binds body tissues together o Supports the body o Provides protection
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Connective Tissue Characteristics Variations in blood supply o Some tissue types are well-vascularized o Some have a poor blood supply or are avascular Extracellular matrix o Non-living material that surrounds living cells o Two main elements—produced by the cells Ground substance—mostly water along with adhesion proteins and polysaccharide molecules Fibers
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Connective Tissue Types Bone (osseous tissue) o Composed of Bone cells in lacunae (cavities) Hard matrix of calcium salts Large numbers of collagen fibers o Used to protect and support the body
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Connective Tissue Types Hyaline cartilage o Most common type of cartilage o Composed of Abundant collagen fibers Rubbery matrix o Locations Larynx Entire fetal skeleton prior to birth
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Connective Tissue Types Loose connective tissue types o Areolar tissue Most widely distributed connective tissue Soft, pliable tissue like “cobwebs” Functions as a packing tissue Contains all fiber types Can soak up excess fluid (causes edema)
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Connective Tissue Types Blood (vascular tissue) o Blood cells surrounded by fluid matrix called blood plasma o Fibers are visible during clotting o Functions as the transport vehicle for materials
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Muscle Tissue Types Skeletal muscle o Under voluntary control o Contracts to pull on bones or skin o Produces gross body movements or facial expressions o Characteristics of skeletal muscle cells Striated Multinucleate (more than one nucleus) Long, cylindrical
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Muscle Tissue Types Cardiac muscle o Under involuntary control o Found only in the heart o Function is to pump blood o Characteristics of cardiac muscle cells Cells are attached to other cardiac muscle cells at intercalated disks Striated One nucleus per cell
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Muscle Tissue Types Smooth muscle o Under involuntary muscle o Found in walls of hollow organs such as stomach, uterus, and blood vessels o Characteristics of smooth muscle cells No visible striations One nucleus per cell Spindle-shaped cells
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Nervous Tissue Composed of neurons and nerve support cells Function is to send impulses to other areas of the body o Irritability o Conductivit y
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Wow, that was a lot of information! If you think humans are complex ….
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