Tissues
Tissues Group of cells that are similar in structure and function 4 primary types Epithelium (covering) Connective (support) Nervous(control)
Epithelial tissue (epithelium) Lining, covering, and glandular tissue of the body Functions: protection, absorption, filtration, and secretion
Special characteristics of epithelium - Cells fit closely together to form continuous sheets - Membranes have one free surface (apical surface) which is exposed to body s exterior or cavity - Lower surface of epithelium rests on a basement membrane (structureless material secreted by cells) - No blood supply of their own (avascular) and depend on diffusion from capillaries in the
Classification of epithelium Simple epithelium- one layer of cells- most concerned with absorption, secretion, and filtration (not protection) Stratified epithelium- more than one layer of cells- function primarily to protect
shapes Squamous cells- flattened cells like fish scales Cuboidal cells- cube-shaped like dice Columnar cells- shaped like columns Combine these with simple and stratified to describe the epithelium fully
Simple epithelium Simple squamous epitheliumsingle layer of thin squamous cells resting on a basement membrane- usually forms membranes where filtration or exchange occurs by rapid diffusionalso forms serous membranes that line ventral body cavity and cover the organs in that cavity
Simple epithelium Simple cuboidal epithelium- 1 layer of cuboidal cells resting on a basement membrane- common in glands or ducts- forms walls of kidney tubules and surface of ovaries
Mucosae (mucous membranes)- epithelial membrane that line body cavities open to exterior Simple epithelia Simple columnar epitheliumsingle layer of tall cells that fit closely together- lines entire length of the digestive tract Goblet cells- produce lubricating mucus are often seen here
Simple epithelia Pseudostratified columnar epithelium- all cells rest on basement membrane but some are shorter than others giving it the false appearance that it is stratified- main function is absorption
Stratified epithelia Stratified squamous- most common stratified in the body- several layers of cells- at the free edge are squamous but at basement are cuboidal or columnar - found where abuse or friction occurs (mouth, esophagus, skin)
Stratified epithelia Stratified cuboidal- usually has just 2 cell layers with at least the surface cells being cuboidal in shape Stratified columnar- columnar cells but base cells vary in size or shape Both are fairly rare in body being found mainly in ducts of large glands
Stratified epithelia Transitional epithelium- highly modified squamous epithelium that forms the lining of only a few organs (bladder, ureters, and part of urethra due to considerable stretching)- cells of the basal layer are cuboidal or columnar; near free surface vary in appearance- when organ is stretched the cells become squamous like
Glandular epithelium Gland- consists of one or more cells that make and secrete particular products Secretion- product secreted that typically contain protein molecules in an aqueous (water-based) fluid
2 major types of glands Both develop from epithelial sheets Endocrine glands- lose their connection the surface (duct)- secretions (hormones) diffuse directly into the blood vessels that weave through the gland- (thyroid, adrenals, pituitary) Exocrine glands- retain ducts and secretions empty through ducts into epithelial surface- (sweat and oil, liver)
Connective tissue Connects body parts Found everywhere in the body Most abundant and widely distributed of the tissue types
Common characteristics of connective tissue Variations in blood supply Most are well vascularized Exceptions: tendons and ligaments have poor blood supply, cartilages are avascular Consequently takes longer to heal
Common characteristics Extracellular matrix- many different types of cells plus varying amounts of a nonliving substance found outside the cells Produced by the connective tissue cells then secreted to their exterior Can be liquid, semi-solid/gel-like, or solid Because of this connective tissue is able to bear weight to withstand stretching or other abuses
characteristics Fibers- various types and amounts are deposited in and form part of the matrix material Collagen (White) fibers Elastic (yellow) fibers Reticular (fine collagen) fibers
characteristics Performs many functions: Protecting Supporting Binding together other body tissues
Types of connective tissue Bone- (osseous) composed of bone cells siting in cavities (lacunae) and surrounded by layers of very hard matrix that contains calcium salts in addition to large numbers of collagen fibers Exceptional ability to protect and support
Forms supporting structures of the larynx, attaches ribs to breast bone, covers ends of bones where they form joints cartilage less hard and more flexible than bone Found only a few places in the body Hyaline- most widespread and has abundant collagen fibers hidden in a matrix with a bluewhite appearance
cartilage Elastic- found where structure with elasticity is desired Supports the external ear Fibrocartilage- highly compressible- between the vertebrae of the spinal column
Dense connective tissue (Dense fibrous tissue) Collagen fibers are in matrix element- between collagen are rows of fibroblasts Forms strong, ropelike structures such as tendons and ligaments; also lower layers of the skin Tendons- attach skeletal muscles to bones Ligaments- connect bones to bones at joints- more stretchy and contain more elastic fibers
Loose connective tissue Softer and have more cells/fewer fibers than any other connective tissue except blood Areolar tissue- wraps organs and protects them edema= body region is inflamed areolar tissue soaks up the excess fluid and swells
Loose connective tissue Adipose tissue- commonly called fat- tissue where cells predominate- cells filled with oil Forms subcutaneous tissue beneath the skin to insulate the body- also surrounds some organs
Reticular connective tissue Consists of a delicate network of reticular fibers with reticular cells Limited at certain sites Forms the stroma- internal supporting framework which supports many free blood cells in lymphoid organs
blood Vascular tissue Consists of blood cells surrounded by nonliving, fluid matrix called blood plasma Fibers are soluble protein molecules that are visible only when blood clotting
Muscle tissue Highly specialized to contract or shorten to produce movement Types: Skeletal- striated, voluntary, multinucleate Cardiac- only in heart, striated, uninucleate, involuntary Smooth- no striations- uninucleate, stomach,
Nervous tissue Commonly called neurons- receive and conduct impulses from one part to another (irritability and conductivity are the 2 major functional characteristics) Make up the nervous system (brain, spinal cord, and nerves)
Name these structures!
A: Fibroblas ts B: Collagen fibers C: Elastin Fibers
Tendon
Stratified Squamous
Adipose tissue
Transitional epithelium
Simple columnar
Reticular fibers
Bone tissue osseous
Hyaline cartilage
Simple cuboidal
blood
Skeletal muscle tissue
Elastic cartilage
Pseudostratified columnar epithelium
Nervous tisse
Smoothe muscle tissue
Stratified cuboidal epithelium
Reticular tissue
fibrocartilage
ligament
Simple squamous
Cardiac muscle
Stratified columnar
Areolar tissue