Cells and Tissues Tissue Types Body Tissues Tissues are groups of cells with similar structure and function Four primary types Epithelial tissue (epithelium) Connective tissue Muscle tissue Nervous tissue 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 Classification of Epithelia Number of cell layers o Simpleone layer o Stratifiedmore than one layer Shape of cells o Squamous flattened o Cuboidal cube-shaped o Columnar column-like Simple Epithelia Simple squamous o Single layer of flat cells o Usually forms membranes Lines body cavities Lines lungs and capillaries 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 Simple Epithelia Simple columnar o Single layer of tall cells o Often includes mucus-producing goblet cells o Lines digestive tract 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 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 Stratified Epithelia Transitional epithelium o Shape of cells depends upon the amount of stretching o Lines organs of the urinary system 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 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 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 elementsproduced by the cells Ground substancemostly water along with adhesion proteins and polysaccharide molecules Fibers 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 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 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) 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 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 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 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 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 Wow, that was a lot of information! If you think humans are complex .