Chapter 5 Tissues Copyright  The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Know all the tables in this chapter! Introduction Similar cells with a common function are called tissues. The study of tissues is called histology. There are four (4) primary or major tissue types: Epithelial Tissue – protective coverings, secretion, absorption Connective Tissue – support soft body parts, bind structures together Muscle Tissue – produce body movements Nervous Tissue – conduct impulse Know all the tables in this chapter! 5.1 – 5.6

Epithelial Tissue General Characteristics Covers organs and body surface/lines cavities and hollow organs Have a free surface on one side and basement membrane (anchored to connective tissue) on other Usually lack blood vessels, nutrients diffuse to epithelium Cells readily divide so injuries heal quickly Cells are tightly packed Classified according to cell shape and number of cell layers Shapes – squamous (thin, flat), cuboidal (cube shaped), columnar (tall, elongated) Layers – simple (one layer of cells), stratified (more than one layer of cells) Epithelial tissues function in protection, secretion, absorption, excretion, and sensory reception.

Epithelial Tissue Types Simple squamous: Single layer of flat cells Substances pass easily through (diffusion) Nuclei broad and thin Lines air sacs (alveoli) Lines blood vessels Lines lymphatic vessels Easily damaged Simple cuboidal: Single layer of cube-shaped cells Centrally located spherical nuclei Lines kidney tubules Covers ovaries Lines ducts of some glands Secretes, absorbs Free surface of tissue Lumen Connective tissue Simple squamous epithelium Nucleus Basement membrane Basement Free surface of tissue Nucleus Simple cuboidal epithelium Connective tissue (a) (b) (a) (a) (b)

Epithelial Tissue Types Simple columnar: Single layer of elongated cells Nuclei are elongated and usually near the basement Sometimes possesses cilia Sometimes possess microvilli (increase surface area) Thick to protect underlying tissues Often has goblet cells (secrete mucus) Lines uterus, stomach, intestines (protection) Pseudostratified columnar: Although appears layered, really single layer of elongated cells Nuclei at two or more levels, giving the appearance of being stratified Often has cilia Often has goblet cells Lines respiratory passageways Cilia (free surface of tissue) Cytoplasm Goblet cell Nucleus Nucleus Cytoplasm Basement membrane Microvilli (free surface of tissue) Connective tissue (a) (b) Mucus Goblet cell Basement membrane Connective tissue (b) (a)

Epithelial Tissue Types Stratified squamous: Many cell layers Top cells are flat Can accumulate keratin (hard and thick) Outer layer of skin (epidermis) Protects underlying layers Lines oral cavity, esophagus, vagina, and anal canal Stratified cuboidal: 2-3 layers Cube-shaped cells Lines ducts of mammary glands, sweat glands, salivary glands, and the pancreas Cell sloughing off Free surface of tissue Stratified cuboidal epithelium Squamous cells Nucleus Lumen Free surface of tissue Basement membrane Connective tissue (a) (b) Layer of dividing cells Basement membrane Connective tissue (a) (b)

Epithelial Tissue Types Stratified columnar: Top layer of elongated cells Cube-shaped cells in deeper layers Lines part of male urethra and part of pharynx Transitional: Many cell layers Cube-shaped and elongated cells Designed to distend and return to normal size Line urinary bladder, ureters, and part of urethra Free surface of tissue Unstretched transitional epithelium Lumen Free surface of tissue Basement membrane Stratified columnar epithelium Underlying connective tissue (a) (b) Basement membrane Connective tissue Free surface of tissue Stretched transitional epithelium (a) (b) Basement membrane connective tissue Underlying (c) (d)

Glandular Epithelium Composed of cells that are specialized to produce and secrete substances There are two (2) types: Endocrine glands secrete into tissue fluid or blood Exocrine glands secrete into ducts

Types of Glandular Secretions Merocrine Glands Fluid product Salivary glands Pancreas gland Sweat glands Apocrine Glands Cellular product Portions of cells Mammary glands Ceruminous glands Holocrine Glands Secretory products Whole cells Sebaceous glands Pinched off portion of cell (secretion) Disintegrating cell and its contents (secretion) Intact cell Secretion New cell forming by mitosis and cytokinesis (a) Merocrine gland (b) Apocrine gland (c) Holocrine gland

Connective Tissues General characteristics: Most abundant tissue type Many functions: Bind structures Provide support and protection Serve as frameworks Fill spaces Store fat Produce blood cells Protect against infections Help repair tissue damage Have an extracellular matrix made of protein fibers and ground substance Have varying degrees of vascularity Have cells that usually divide

Connective Tissue Major Cell Types Fibroblasts Fixed cell Most common cell Large, star-shaped Produce fibers Mast cells Fixed cell Release heparin Release histamine Macrophages Wandering cell Phagocytic Important in immunity and prevention of infection

Connective Tissue Fibers Collagenous fibers Thick Composed of collagen Great tensile strength Abundant in dense CT Hold structures together Appear white in abundance Elastic fibers Bundles of microfibrils embedded in elastin Fibers branch Elastic Appear yellow in abundance Reticular fibers Very thin collagenous fibers Highly branched Form delicate supportive networks

Connective Tissues Connective Tissue Proper: Loose connective tissue Areolar Adipose Reticular Dense connective tissue Dense regular Dense irregular Elastic Specialized Connective Tissue: Cartilage Bone Blood

Connective Tissue Types Areolar Connective Tissue Mainly fibroblasts Gel-like ground substance Collagenous fibers Elastic fibers Binds skin to structures Beneath most epithelia Blood vessels nourish nearby epithelial cells Adipose Connective Tissue Adipocytes Cushions Insulates Stores fats Beneath skin Behind eyeballs Around kidneys and heart Between muscles Fat droplet Cell membrane Collagenous fiber Fibroblast Nucleus Ground substance Elastic fiber (a) (b) (a) (b)

Connective Tissue Types Reticular Connective Tissue Composed of reticular fibers Supports internal organ walls Walls of liver, spleen Dense Regular Connective Tissue Closely packed collagenous fibers Elastic fibers Fibroblasts Very strong Binds body parts together Tendons, ligaments, dermis Poor blood supply; slow to heal Collagenous fibers Fibroblasts Collagenous fibers White blood cell Fibroblast (a) (b) (a) (b)

Connective Tissue Types Dense Irregular C.T. Randomly organized, thick, interwoven collagenous fibers Dermis of skin Around skeletal muscles Elastic Connective Tissue Abundant in elastic fibers Some collagenous fibers Fibroblasts Attachments between bones Walls of large arteries, airways, heart Stratified squamous epithelium Collagenous fibers Dense irregular connective tissue Fibroblast Elastic fibers (a) (b) Adipose tissue

Connective Tissue Types Hyaline cartilage Most abundant Fine collagenous fibers Ends of bones Nose, respiratory passages Embryonic skeleton Cartilage Rigid matrix containing gel-like ground substance Chondrocytes in lacunae Poor blood supply Covered by perichondrium Three (3) types: Hyaline Cartilage Elastic Cartilage Fibrocartilage Elastic cartilage Flexible…due to elastic fibers External ear, larynx Fibrocartilage Very tough…due to many collagenous fibers Shock absorber Intervertebral discs Pads of knee and pelvic girdle

Connective Tissue Types Three (3) types of cartilage: Elastic fibers Nucleus Nucleus Lacuna Lacuna Chondrocyte Chondrocyte Extracellular matrix Extracellular matrix (a) (b) (a) (b) Hyaline Cartilage Elastic Cartilage Chondrocyte Nucleus Collagenous fiber Extracellular matrix (a) (b) Fibrocartilage

Connective Tissue Types Bone (Osseous Tissue) Solid matrix Supports Protects Forms blood cells Attachment for muscles Skeleton Osteocytes in lacunae Osteon Lamella Central canal Lacuna Canaliculi (a) (b) Lacuna Osteocyte (c)

Connective Tissue Types Blood Fluid matrix called plasma Red blood cells White blood cells Platelets Transports Defends White blood cell Red blood cells Plasma (extracellular matrix of blood) Platelet (a) (b)

There are four (4) types of epithelial membranes: Types of Membranes There are four (4) types of epithelial membranes: Serous Membranes Line body cavities that do not open to the outside Reduce friction Inner lining of thorax and abdomen Cover organs of thorax and abdomen Secrete serous fluid Mucous Membranes Line tubes and organs that open to outside of body Lining of digestive, respiratory, urinary, and reproductive tracts Secrete mucus Cutaneous Membranes Covers body Skin Synovial Membranes Composed entirely of connective tissue Lines joints

Muscle Tissues General characteristics: Skeletal muscle tissue Muscle cells also called muscle fibers Contractile Three (3) types: Skeletal muscle Smooth muscle Cardiac muscle Skeletal muscle tissue Attached to bones Striated Voluntary Smooth muscle tissue Walls of organs Skin Walls of blood vessels Involuntary Non-striated Cardiac muscle tissue Heart wall Involuntary Striated Intercalated discs

Muscle Tissue Smooth Muscle Skeletal Muscle Cardiac Muscle (a) (b) Striations Cytoplasm Nucleus Nuclei Portion of a muscle fiber (a) (b) (a) (b) Smooth Muscle Skeletal Muscle Striations Nucleus Intercalated disc (a) (b) Cardiac Muscle

Nervous Tissue Found in brain, spinal cord, and peripheral nerves Functional cells are neurons Neuroglial cells support and bind nervous tissue components Cellular process Cytoplasm Nucleus Nucleolus Cell membrane Nuclei of neuroglia Sensory reception (a) (b) Conduction of nerve impulses