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The Tissue Level of Organization
 

The Tissue Level of Organization

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    The Tissue Level of Organization The Tissue Level of Organization Presentation Transcript

    • Chapter 4 The Tissue Level of Organization Copyright 2009, John Wiley & Sons, Inc.
    • What is a Tissue?
      • A tissue is a group of cells
        • Common embryonic origin
        • Function together to carry out specialized activities
      • Hard (bone), semisolid (fat), or liquid (blood)
      • Histology is the science that deals with the study of tissues.
      • Pathologist specialized in laboratory studies of cells and tissue for diagnoses
      Copyright 2009, John Wiley & Sons, Inc.
    • 4 Types of Tissues
        • Epithelial
          • Covers body surfaces and lines hollow organs, body cavities, duct, and forms glands
        • Connective
          • Protects, supports, and binds organs.
          • Stores energy as fat, provides immunity
        • Muscular
          • Generates the physical force needed to make body structures move and generate body heat
        • Nervous
          • Detect changes in body and responds by generating nerve impulses
      Copyright 2009, John Wiley & Sons, Inc.
    • Development of Tissues
      • Tissues of the body develop from three primary germ layers:
          • Ectoderm, Endoderm, and Mesoderm
        • Epithelial tissues develop from all three germ layers
        • All connective tissue and most muscle tissues drive from mesoderm
        • Nervous tissue develops from ectoderm
      Copyright 2009, John Wiley & Sons, Inc.
    • Cell Junctions
      • Contact points between the plasma membranes of tissue cells
        • 5 most common types:
          • Tight junctions
          • Adherens junctions
          • Desmosomes
          • Hemidesmosomes
          • Gap junctions
      Copyright 2009, John Wiley & Sons, Inc.
    • Tight Junctions
      • Web-like strands of transmembrane proteins
        • Fuse cells together
        • Seal off passageways between adjacent cells
          • Common in epithelial tissues of the stomach, intestines, and urinary bladder
          • Help to retard the passage of substances between cells and leaking into the blood or surrounding tissues
      Copyright 2009, John Wiley & Sons, Inc.
    • Adherens Junctions
      • Dense layer of proteins called plaque
        • Resist separation of cells during contractile activities
        • Located inside of the plasma membrane attached to both membrane proteins and microfilaments of the cytoskeleton
        • Transmembrane glycoproteins called cadherins insert into the plaque and join cells
        • In epithelial cells, adhesion belts encircle the cell
      Copyright 2009, John Wiley & Sons, Inc.
    • Desmosomes
      • Contain plaque and cadherins that extends into the intercellular space to attach adjacent cells together
        • Desmosome plaque attaches to intermediate filaments that contain protein keratin
        • Prevent epidermal cells from separating under tension and cardiac muscles cells from pulling apart during contraction
      Copyright 2009, John Wiley & Sons, Inc.
    • Hemidesmosomes
      • Resemble half of a desmosome
        • Do not link adjacent cells but anchor cells to the basement membrane
        • Contains transmembrane glycoprotein integrin
        • Integrins attach to intermediate filaments and the protein laminin present in the basement membrane
      Copyright 2009, John Wiley & Sons, Inc.
    • Gap Junctions
      • Connect neighboring cells via tiny fluid-filled tunnels called connexons
        • Contain membrane proteins called connexins
        • Plasma membranes of gap junctions are separated by a very narrow intercellular gap (space)
          • Communication of cells within a tissue
          • Ions, nutrients, waste, chemical and electrical signals travel through the connexons from one cell to another
      Copyright 2009, John Wiley & Sons, Inc.
    • Epithelial Tissues
      • Epithelial tissue consists of cells arranged in continuous sheets, in either single or multiple layers
        • Closely packed and held tightly together
        • Covering and lining of the body
        • Free surface
      • 3 major functions:
        • Selective barrier that regulates the movement of materials in and out of the body
        • Secretory surfaces that release products onto the free surface
        • Protective surfaces against the environment
      Copyright 2009, John Wiley & Sons, Inc.
    • General Features of Epithelial Cells
      • Surfaces of epithelial cells differ in structure and have specialized functions
        • Apical (free) surface
          • Faces the body surface, body cavity, lumen, or duct
        • Lateral surfaces
          • Faces adjacent cells
        • Basal surface
          • Opposite of apical layer and adhere to extracellular materials
      Copyright 2009, John Wiley & Sons, Inc.
    • General Features of Epithelial Cells
      • Basement membrane
        • Thin double extracellular layer that serves as the point of attachment and support for overlying epithelial tissue
        • Basal lamina
          • Closer to and secreted by the epithelial cells
          • Contains laminin, collagen, glycoproteins, and proteoglycans
        • Reticular lamina
          • Closer to the underlying connective tissue
          • Contains collagen secreted by the connective tissue cells
      Copyright 2009, John Wiley & Sons, Inc.
    • Epithelial Cells Copyright 2009, John Wiley & Sons, Inc.
    • Epithelial Tissues
        • Own nerve supply
        • Avascular or lacks its own blood supply
        • Blood vessels in the connective tissue bring in nutrients and eliminate waste
        • High rate of cell division for renew and repair
        • Numerous roles in the body (i.e. protection and filtration)
      • Covering and lining epithelium
          • Outer covering of skin and some internal organs
      • Glandular epithelium
          • Secreting portion of glands (thyroid, adrenal, and sweat glands)
      Copyright 2009, John Wiley & Sons, Inc.
    • Covering and Lining Epithelium
      • Normally classified according to:
        • Arrangement of cells into layers
        • Shapes of cells
      Copyright 2009, John Wiley & Sons, Inc.
    • Covering and Lining Epithelium
      • Arrangement of cells in layers
        • Consist of one or more layers depending on function
        • Simple epithelium
          • Single layer of cells that function in diffusion, osmosis, filtration, secretion, or absorption
        • Pseudostratified epithelium
          • Appear to have multiple layers because cell nuclei at different levels
          • All cells do not reach the apical surface
        • Stratified epithelium
          • Two or more layers of cells that protect underlying tissues in areas of wear and tear
      Copyright 2009, John Wiley & Sons, Inc.
    • Different Types of Covering and Lining Epithelium
      • Cells vary in shape depending on their function
        • Squamous
          • Thin cells, arranged like floor tiles
          • Allows for rapid passage of substances
        • Cuboidal
          • As tall as they are wide, shaped like cubes or hexagons
          • May have microvilli
          • Function in secretion or absorption
      Copyright 2009, John Wiley & Sons, Inc.
    • Different Types of Covering and Lining Epithelium
        • Columnar
          • Much taller than they are wide, like columns
          • May have cilia or microvilli
          • Specialized function for secretion and absorption
        • Transitional
          • Cells change shape, transition for flat to cuboidal
          • Organs such as urinary bladder stretch to larger size and collapse to a smaller size
      Copyright 2009, John Wiley & Sons, Inc.
    • Simple Epithelium
        • Simple squamous epithelium
        • Simple cuboidal epithelium
        • Simple columnar epithelium (nonciliated and ciliated)
        • Pseudostratified columnar epithelium (nonciliated and cilated)
      Copyright 2009, John Wiley & Sons, Inc.
    • Simple squamous epithelium
        • Single layer of cells that resembles a tiled floor on the surface
          • Nucleus is centrally located and appears flattened oval or sphere
        • Found at sites for filtration or diffusion
      Copyright 2009, John Wiley & Sons, Inc.
    • Covering and Lining Epithelium
      • Endothelium
        • The type of simple squamous that lines the heart, blood vessels, and lymphatic vessels
      • Mesothelium
        • The type of epithelial layer of serous membranes such as the pericardium, pleura, or peritoneum
      • Unlike other epithelial tissue, Both are derived from embryonic mesoderm
      Copyright 2009, John Wiley & Sons, Inc.
    • Simple cuboidal epithelium
        • Cuboidal shaped cells
        • Cell nuclei round and centrally located
        • Found in thyroid gland and kidneys
        • Functions in secretion and absorption
      Copyright 2009, John Wiley & Sons, Inc.
    • Simple columnar epithelium
        • Column shaped cells
        • Oval nuclei at near base
        • Nonciliated and ciliated
      Copyright 2009, John Wiley & Sons, Inc.
    • Nonciliated simple columnar epithelium
        • Contains columnar cells with microvilli at their apical surface and goblet cells
            • Secreted mucus serves as lubricant for the lining of digestive, respiratory, reproductive and urinary tracts
            • Also prevents the destruction of the stomach lining by acidic gastric juices
      Copyright 2009, John Wiley & Sons, Inc.
    • Ciliated simple columnar epithelium
        • Columnar epithelial cells with cilia at the apical surface
          • In respiratory tract, goblet cells are interspersed among ciliated columnar epithelia
          • Secreted mucus on the surface traps inhaled foreign particles. Beating cilia moves particles to the throat for removal by coughing, swallowing, or sneezing
          • Cilia also moves oocytes to the uterine tubes
      Copyright 2009, John Wiley & Sons, Inc.
    • Covering and Lining Epithelium
      • Pseudostratified columnar epithelium
        • Appears to have several layers due to nuclei are various depths
        • All cells are attached to the basement membrane in a single layer but some do not extend to the apical surface
        • Ciliated cells secrete mucus and bear cilia
        • Nonciliated cells lack cilia and goblet cells
      Copyright 2009, John Wiley & Sons, Inc.
    • Covering and Lining Epithelium Copyright 2009, John Wiley & Sons, Inc.
    • Stratified Epithelium
      • Two or more layers of cells
      • Specific kind of stratified epithelium depends on the shape of cells in the apical layer
        • Stratified squamous epithelium
        • Stratified cuboidal epithelium
        • Stratified columunar epithelium
        • Transitional epithelium
      Copyright 2009, John Wiley & Sons, Inc.
    • Stratified Squamous Epithelium
        • Several layers of cells that are flat in the apical layer
          • New cells are pushed up toward apical layer
          • As cells move further from the blood supply they dehydrate, harden, and die
        • Keratinized form contain the fibrous protein keratin
          • Found in superficial layers of the skin
        • Nonkeratinized form does not contain keratin
          • Found in mouth and esophagus
      Copyright 2009, John Wiley & Sons, Inc.
    • Stratified Cuboidal Epithelium
        • Fairly rare type of epithelium
        • Apical layers are cuboidal
        • Functions in protection
      Copyright 2009, John Wiley & Sons, Inc.
    • Stratified columnar epithelium
        • Also very uncommon
        • Columnar cells in apical layer only
        • Basal layers has shorten, irregular shaped cells
        • Functions in protection and secretion
      Copyright 2009, John Wiley & Sons, Inc.
    • Transitional Epithelium
        • Found only in the urinary system
        • Variable appearance
        • In relaxed state, cells appear cuboidal
        • Upon stretching, cells become flattened and appear squamous
        • Ideal for hollow structure subjected to expansion
      Copyright 2009, John Wiley & Sons, Inc.
    • Glandular Epithelium: Endocrine Glands
        • Secretions, called hormones, diffuse directly into the bloodstream
        • Function in maintaining homeostasis
      Copyright 2009, John Wiley & Sons, Inc.
    • Glandular Epithelium: Exocrine Glands
        • Secrete products into ducts that empty onto the surfaces of epithelium
        • Skin surface or lumen of a hollow organ
        • Secretions of the exocrine gland include mucus, sweat, oil, earwax, saliva, and digestive enzymes
        • Examples of glands include sudoriferous (sweat) glands
      Copyright 2009, John Wiley & Sons, Inc.
    • Structural Classification of Exocrine Glands
      • Multicellular glands are categorized according to two criteria:
        • Ducts are branched or unbranched
        • Shape of the secretory portion of the gland
          • Simple gland duct does not branch
          • Compound gland duct branches
          • Tubular glands have tubular secretory parts
          • Acinar glands have rounded secretory parts
          • Tubuloacinar glands have both tubular and rounded secretory parts
      Copyright 2009, John Wiley & Sons, Inc.
    • Structural Classification of Exocrine Glands Copyright 2009, John Wiley & Sons, Inc.
    • Functional Classification of Exocrine Glands Copyright 2009, John Wiley & Sons, Inc.
    • Connective Tissue
      • Most abundant and widely distributed tissues in the body
      • Numerous functions
        • Binds tissues together
        • Supports and strengthen tissue
        • Protects and insulates internal organs
        • Compartmentalize and transport
        • Energy reserves and immune responses
      Copyright 2009, John Wiley & Sons, Inc.
    • Characteristics of Connective Tissue
      • Three characteristics of Connective Tissue
        • Extra cellular matrix
        • Fibers
        • Cells of various types
      Copyright 2009, John Wiley & Sons, Inc.
    • Extracellular matrix of Connective Tissue
      • Extracellular matrix is the material located between the cells
        • Consist of protein fibers and ground substance
      • Connective tissue is highly vascular
      • Supplied with nerves
        • Exception is cartilage and tendon. Both have little or no blood supply and no nerves
      Copyright 2009, John Wiley & Sons, Inc.
    • Cells and Fibers in Connective Tissue Copyright 2009, John Wiley & Sons, Inc.
    • Connective Tissue Cells
      • Fibroblasts
        • Secrete fibers and components of ground substance
      • Adipocytes (fat cells)
        • Store triglycerides (fat)
      • Mast cells
        • Produce histamine
      • White blood cells
        • Immune response
        • Neutrophil and Eosinophils
      • Macrophages
        • Engulf bacteria and cellular debris by phagocytosis
      • Plasma cells
        • Secrete antibodies
      Copyright 2009, John Wiley & Sons, Inc.
    • Connective Tissue Extracellular Matrix
      • Ground substance
        • Between cells and fibers
          • Fluid, semifluid, gelatinous, or calcified
        • Functions to support and bind cells, store water, and allow exchange between blood and cells
        • Complex combination of proteins and polysaccharides
      • Fibers
        • Collagen fibers
        • Elastic fibers
        • Reticular fibers
      Copyright 2009, John Wiley & Sons, Inc.
    • Classification of Connective Tissues
      • Embryonic connective tissue
        • Mesenchyme and mucous connective tissue
      • Mature connective tissue
        • Loose connective tissue
          • Areolar, adipose, and reticular
        • Dense connective tissue
          • Dense regular, dense irregular, and elastic
        • Cartilage
          • Hyaline, fibrocartilage, and elastic cartilage
        • Bone tissue
        • Liquid connective tissue
          • Blood and lymph
      Copyright 2009, John Wiley & Sons, Inc.
    • Embryonic Connective Tissue
        • Mesenchyme
          • Gives rise to all other connective tissues
        • Mucous (Wharton’s Jelly)
          • Found in umbilical cord of the fetus
      Copyright 2009, John Wiley & Sons, Inc.
    • Loose Connective Tissue: Areolar Connective Tissue
        • Most widely distributed in the body
        • Contains several types of cells and all three fibers
      Copyright 2009, John Wiley & Sons, Inc.
    • Loose Connective Tissue: Adipose Tissue
        • Contains adipocytes
        • Good for insulation and energy reserves
        • White (common) and brown adipose tissue
      Copyright 2009, John Wiley & Sons, Inc.
    • Loose Connective Tissue: Reticular Connective Tissue
        • Fine interlacing reticular fibers and cells
        • Forms the stroma of liver, spleen, and lymph nodes
      Copyright 2009, John Wiley & Sons, Inc.
    • Dense Connective Tissue
      • Dense connective tissue
        • Contains numerous, thicker, and denser fibers
        • Packed closely with fewer cells than loose connective tissue
      • Dense regular connective tissue
        • Bundles of collagen fibers are regularly arranged in parallel patterns for strength
        • Tendons and most ligaments
      Copyright 2009, John Wiley & Sons, Inc.
    • Types of Mature Connective Tissue: Dense Irregular Connective Tissue
        • Collagen fibers are usually irregularly arranged
        • Found where pulling forces are exerted in many directions
        • Dermis of skin and heart
      Copyright 2009, John Wiley & Sons, Inc.
    • Dense Connective Tissue: Elastic Connective Tissue
        • Contain branching elastic fibers
        • Strong and can recoil to original shape after stretching
        • Lung tissue and arteries
      Copyright 2009, John Wiley & Sons, Inc.
    • Types of Mature Connective Tissue: Cartilage
      • Cartilage is a dense network of collagen fibers and elastic fibers firmly embedded in chondroitin sulfate
        • Chrondrocytes
          • Cartilage cells found in the spaces called lacunae
        • Pericondrium
          • Covering of dense irregular connective tissue that surrounds the cartilage
          • Two layers: outer fibrous layer and inner cellular layer
        • No blood vessels or nerves, except pericondrium
      Copyright 2009, John Wiley & Sons, Inc.
    • Hyaline cartilage
        • Most abundant cartilage in the body
        • Surrounding by perichondrium (some exceptions like articular cartilage)
        • Provide flexibility and support. Reduces friction
      Copyright 2009, John Wiley & Sons, Inc.
    • Fibrocartilage
        • Chondrocytes are scattered among bundles of collagen fibers within the extracellular matrix
        • Lack a perchondrium
        • Strongest type of cartilage
        • Found in intervertebral disc (between vertebrae)
      Copyright 2009, John Wiley & Sons, Inc.
    • Elastic Cartilage
        • Chrondrocytes are located within a threadlike network of elastic fibers
        • Pericondrium is present
        • Provides strength and elasticity
      Copyright 2009, John Wiley & Sons, Inc.
    • Repair and Growth of Cartilage
      • Cartilage grows slowly
      • When injured or inflamed, repairs is slow due to its avascular nature.
      • Two patterns of cartilage growth:
        • Interstitial growth
          • Growth from within the tissue
        • Appositional growth
          • Growth at the outer surface of the tissue
      Copyright 2009, John Wiley & Sons, Inc.
    • Bone tissue
      • Bones are organs composed of several different connective tissues: bone (osseous) tissue, periosteum, and endosteum.
      • Compact or spongy
      • Osteon or haversian system
        • Spongy bone lacks osteons. They have columns called trabeculae
      Copyright 2009, John Wiley & Sons, Inc.
    • Liquid Connective Tissue
      • Blood tissue
        • Connective tissue with liquid extracellular matrix called blood plasma
      • Lymph
      Copyright 2009, John Wiley & Sons, Inc.
    • Membranes Copyright 2009, John Wiley & Sons, Inc.
    • Epithelial Membranes
      • Mucous membranes
        • Lines a body cavity that opens directly to the exterior
        • Epithelial layer is important for the body’s defense against pathogens
        • Connective tissue layer is areolar connective tissue and is called lamina propria
      Copyright 2009, John Wiley & Sons, Inc.
    • Epithelial Membranes
      • Serous membranes or serosa
        • Lines a body cavity that does not open directly to the exterior. Also covers the organs that lie within the cavity
        • Consist of areolar connective tissue covered by mesothelium (simple squamous epithelium) that secrete a serous fluid for lubrication
      Copyright 2009, John Wiley & Sons, Inc.
    • Epithelial membranes: Mucous Membranes
      • Membranes are flat sheets of pliable tissue that cover or line a part of the body
      • Epithelial membranes are a combination of an epithelial layer and an underlying connective tissue layer
        • Mucous, Serous, and Cutaneous membranes
      • Synovial membranes
        • Lines joints and contains connective tissue but not epithelium
      Copyright 2009, John Wiley & Sons, Inc.
    • Muscular Tissue
      • Consists of elongated cells called muscle fibers or myocytes
        • Cells use ATP to generate force
        • Several functions of muscle tissue
        • Classified into 3 types: skeletal, cardiac, and smooth muscular tissue
      Copyright 2009, John Wiley & Sons, Inc.
    • Skeletal Muscle Tissue
        • Attached to bones of the skeleton
        • Have striations
        • Voluntary movement or contractions by conscious control
        • Vary in length (up to 40 cm) and are roughly cylindrical in shape
      Copyright 2009, John Wiley & Sons, Inc.
    • Muscular Tissue
      • Cardiac muscle tissue
        • Have striations
        • Involuntary movement or contraction is not consciously controlled
        • Intercalated disc unique to cardiac muscle tissue
      Copyright 2009, John Wiley & Sons, Inc.
    • Smooth Muscle Tissue
        • Walls of hollow internal structures
          • Blood vessels, airways of lungs, stomach, and intestines
        • Nonstriated
        • Usually involuntary control
      Copyright 2009, John Wiley & Sons, Inc.
    • Nervous Tissue
      • Consists of two principle types of cells
        • Neurons or nerve cells
        • Neuroglia
      Copyright 2009, John Wiley & Sons, Inc.
    • Excitable Cells
      • Neurons and muscle fibers
      • Exhibit electrical excitability
        • The ability to respond to certain stimuli by producing electrical signals such as action potentials
        • Actions potentials propagate along a nerve or muscle plasma membrane to cause a response
          • Release of neurotransmitters
          • Muscle contraction
      Copyright 2009, John Wiley & Sons, Inc.
    • Tissue Repair: Restoring Homeostasis
      • When tissue damage is extensive both stroma and parenchymal cells are active in repair
        • Fibroblast divide rapidly
        • New collagen fibers are manufactured
        • New blood capillaries supply materials for healing
      • All of these process create an actively growing connective tissue called granulation tissue
      Copyright 2009, John Wiley & Sons, Inc.
    • Aging and Tissues
      • Tissue heal faster in young adults
      • Surgery of a fetus normally leaves no scars
      • Young tissues have a better nutritional state, blood supply, and higher metabolic rate
      • Extracellular components also changes with age
      • Changes in the body’s use of glucose, collagen, and elastic fibers contribute to the aging process
      Copyright 2009, John Wiley & Sons, Inc.