Tissues - Chapter 5 PDF

 TISSUES Tissues are groups of similar cells with similar embryonic origins Four major types of tissues found in the human body. Epithelium, Connective, Nervous, Muscle Epithelium Covering and lining tissue Always has a free surface  Anchored to underlying connecti...

 TISSUES Tissues are groups of similar cells with similar embryonic origins Four major types of tissues found in the human body. Epithelium, Connective, Nervous, Muscle Epithelium Covering and lining tissue Always has a free surface  Anchored to underlying connective tissue by basement membrane Lack blood vessels Cells readily divide Cells are tightly packed with little intercellular space Functions include secretion, absorption, excretion, sensory reception  Cell types Squamous Thin, “roundish”, flattened cells Cuboidal Cube shaped cells Columnar Tall, thin cells  Cell organization Simple A single layer of cells Stratified Several layers of cells Pseudostratified A single layer that looks like several layers All cells attached to basement membrane  Simple squamous epithelium Single layer of thin, flattened cells Common sites of diffusion and filtration Line airsacs of lungs Walls of capillaries Covers membranes that line body cavities  Simple squamous epithelium Single layer of thin, flattened cells Common sites of diffusion and filtration Line airsacs of lungs Walls of capillaries Covers membranes that line body cavities  Simple cuboidal epithelium Single layer of cube shaped cells Covers ovaries Lines kidney tubules Found in ducts of some glands Salivary, thyroid, pancreas Secretes and absorbs  Simple Columnar Epithelium A single layer of elongated cells Lines uterus, stomach, small and large intestines Specialized for absorption Microvilli increase surface area Goblet cells secrete mucus  Ciliated columnar Tall, thin cells with cilia on free end Found in bronchioles, trachea, fallopian tubules Move mucus out of lungs, egg along fallopian tubule  Pseudostratified columnar epithelium Appear layered but are not Cells nuclei are at two or more levels Commonly possess cilia Line passages of respiratory system Mucus traps dust Cilia move mucus upward and out of airways  Stratified squamous epithelium Cells divide in deeper layers and push older cells outward Found in outer layer of skin Cells accumulate keratin as they age Makes them waterproof and bacteria proof Nonkeratinized lines mouth and throat  Stratified cuboidal lines ducts of mammary, sweat, and salivary glands, as well as pancreas Stratified columnar found in male urethra and parts of the pharynx  Transitional epithelium Specialized to change in response to increased tension Forms lining of urinary bladder Consists of several layers of cuboidal cells which can be stretched Forms a barrier which prevents contents of bladder from diffusing back into internal environment  Glandular epithelium Composed of cells specialized to produce and secrete substances Endocrine glands Secrete their products into tissue fluid or blood Adrenal glands, pituitary gland, pancreas  Exocrine glands Secrete their products into ducts that lead to the outside Salivary glands, mammary glands, sweat glands, oil glands, pancreas Classified according to how they release their product  Merocrine glands (most common) Secrete watery, protein rich fluids by exocytosis Salivary, sweat and pancreatic glands Apocrine glands Glands lose small portion of cellular body Mammary, ceruminous glands  Holocrine glands Entire cell is released during secretion Sebaceous glands  CONNECTIVE TISSUE Bind structures, provide support, protection, serve as frameworks, fill space, store fat, produce blood cells, protect against infection, help repair damaged tissue Have lots of extra cellular material called matrix Filled with fibers and ground substance (water-proteins)  Major cell types Fibroblasts Most common cell Large, star shaped Produce fibers Macrophages Also very common Mobile, phagocytic cells  Mast cells Release heparin Prevents blood clotting Release histamine Involved in immune response  Connective tissue fibers Collagenous fibers Made of protein collagen Grouped in parallel bundles Flexible with great tensile strength Found in tendons and ligaments  Elastic fibers Made of protein elastin Can stretch and return to original size and shape Found in vocal cords, skin Reticular fibers Very thin collagenous fibers Form organ frameworks  Loose connective tissue (areolar) Few cells spread amongst a gelatinous matrix Cells are mostly fibroblasts Binds skin to underlying muscles Fills spaces between muscles  Adipose tissue Function in fat storage Found beneath the skin, around kidneys, behind eyeballs, in abdominal membranes Cushions joints Insulates Stores energy  Dense connective tissue Closely packed collagenous fibers Few cells Very strong Binds body parts together Poor blood supply Tendons and ligaments White of eye  Cartilage Provides support, frameworks, protects underlying tissue, forms models for bones Lots of matrix made of collagenous fibers imbedded in gel like ground substance Chondrocytes occupy small chambers called lacunae  Cartilage is surrounded by covering called perichondrium Contains blood vessels Hyaline cartilage Most common Found on ends of bones, nose, trachea  Elastic cartilage Contains dense network of elastic fibers Framework for external ear  Fibrocartilage Very tough, lots of collagenous fibers Intervertebral disks Cushions bones in knees  Bone-osseous tissue It’s hardness is due to mineral salts like calcium carbonate and calcium phosphate Large matrix with lots of collagen Bone is for support and protection Produces blood cells Stores calcium and phosphate  Bone is deposited in thin layers called lamellae These layers form concentric ring around hollow tube called osteonic (Haversian) canals Bone cells (osteocytes) are found in lacunae in these rings Rings, cells, and tubes form a system called an osteon or Haversian system  Osteonic canal contains a blood vessel Canaliculi are small tubes leading from the cells to the blood vessels  Blood (Vascular Tissue) Blood transports materials Nutrients, wastes, proteins, hormones, etc Made of formed elements Red blood cells-erythrocytes White blood cells-leucocytes Platelets-thrombocytes Plasma is liquid part  MUSCLE TISSUE Muscle is contractile There are three types of muscle Skeletal Cardiac Smooth  Skeletal muscle Attached to bones Under conscious control- voluntary Has striations Very large cells, many nuclei  Smooth muscle Lacks striations Smaller cells than striated Spindle shaped Single nucleus Located in stomach, intestines, bladder, walls of blood vessels Involuntary  Cardiac muscle Found only in the heart Cells are striated and joined end to end Have specialized intercellular junction called intercalated disk Cells may be branched Involuntary  NERVOUS TISSUE Found in brain, spinal cord and peripheral nerves Cells are called neurons Respond to changes in the environment by transmitting impulses Nervous tissue includes supporting cells called neuroglial cells