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Chapter 4. Tissue: The Living Fabric G.R. Pitts, Ph.D, J.R. Schiller, Ph.D. & James F. Thompson, Ph.D. General. Tissues - groups of cells with similar basic structures which cooperate to perform a related function Four basic types of tissues

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Chapter 4

Chapter 4

Tissue: The Living Fabric

G.R. Pitts, Ph.D,J.R. Schiller, Ph.D. &James F. Thompson, Ph.D.


General
General

  • Tissues - groups of cells with similar basic structures which cooperate to perform a related function

  • Four basic types of tissues

    • Epithelial – linings for protection, coordination, synthesis, absorption, elimination

    • Connective – support

    • Muscle – for movement

      • muscle tissue is a highly specialized connective tissue

    • Nervous – for control and coordination

      • nervous tissue is a highly specialized epithelial tissue


Epithelial tissue characteristics
Epithelial Tissue Characteristics

  • Cellularity - densely packed

  • Polarity

    • apical surface

    • basal surface (or basolateral)

  • Specialized contacts - tight junctions and desmosomes

  • Supported by connective tissue

    • basal lamina (epithelial “glue”)

    • reticular lamina (connective tissue “glue”)

    • basement membrane - reticular and basal laminae together

  • Innervated but avascular (no direct blood supply)

  • Regeneration – high capacity for regeneration


  • Classifying epithelial tissues
    Classifying Epithelial Tissues

    Simple

    Stratified

    • By number of cell layers

    Pseudostratified epithelium (from the respiratory tree) appears stratified, but actually is a single layer of cells of varying heights; each cell touches the basement membrane


    Classifying epithelial tissues1
    Classifying Epithelial Tissues

    Squamous

    Transitional

    Cuboidal

    Columnar

    • By cell shape


    Glandular epithelial tissues
    Glandular Epithelial Tissues

    • functions in secretion – a gland may be one cell or a group of specialized cells

    • two major types

      • exocrine glands have ducts leading to body surfaces

        • various products are synthesized and stored for release

        • secretions are secreted into the duct system

        • e.g., sweat glands, salivary glands, etc.

      • endocrine glands are ductless

        • hormones are synthesized and stored for release

        • hormones are secreted into the tissue fluid and then diffuse into the blood stream

        • e.g., thyroid and parathyroid glands


    Exocrine gland classification
    Exocrine Gland Classification

    • Unicellular glands

      • single cell glands

      • goblet cells


    Exocrine gland classification1
    Exocrine Gland Classification

    • Multicellular glands

      • Structurally classified by duct configuration and by the shape of the secretory units

        • simple glands have a single duct

        • compound glands have branched ducts

      • Merocrine glands

        • Exocytosis

      • Holocrine glands

        • Cell rupture


    Connective tissue characteristics
    Connective Tissue Characteristics

    • Two basic components

      • Cells – fewer, rarely touching, surrounded by a matrix

        • immature forms (-blasts) secrete the matrix and can still divide

        • once the matrix is secreted, the cells mature into -cytes which have decreased cell divisions and secrete less matrix material

        • chondro- cartilage, osteo- bone, fibro – connective, etc.

      • Extracellular Matrix

        • ground substance (gelatinous glycoproteins)

        • structural fibers (fibrous proteins, e.g., collagen, elastin, reticulin)

    • Common embryological origin (from mesoderm)

    • Innervated and Vascular (direct blood supply)

      • Cartilage is the one exception with no capillary beds


    Connective tissue matrix
    Connective Tissue Matrix

    • Ground Substance

      • supports cells, binds them together

      • may be solid, fluid, or gel

      • interstitial fluid

      • Glycoproteins called proteoglycans - large polysaccharide molecules bound to a protein core (like a bottle brush)

        • Hyaluronic acid – gelatinous, separates cells, traps extracellular fluid; lubricates joints; gives shape to eyeballs; fills body spaces

        • Chondroitin sulfate – capable of being mineralized; cartilage, bones, skin, blood vessels

        • Dermatin sulfate – harder; skin, tendons, blood vessels, heart valves

        • Keratin sulfate - still harder; bone, cartilage, cornea of the eyes


    Connective tissue matrix1
    Connective Tissue Matrix

    • Protein fibers are embedded in the ground substance

      • Used for structural support, adhesion, and to connect cells

    • Provide strength and support

      • Collagen fibers

        • highly polymerized, gigantic molecules

        • tough, moderate flexibility

        • protein collagen - parallel bundles of fibers

        • bone, cartilage, tendons, ligaments

      • Elastic fibers (elastin)

        • branched; smaller, thinner fibers than collagen

        • Very flexible and elastic but also strong

        • can be stretched to 150% of its original length

        • require special stains to be seen

      • Reticular fibers

        • thin, less polymerized collagen fibers

        • require special stains to be seen


    Types of connective tissues
    Types of Connective Tissues

    • Connective Tissue Proper

      • areolar (loose fibrous) connective tissue

      • adipose tissue

      • reticular connective tissue

      • dense (fibrous) regular connective tissue

      • dense (fibrous) irregular connective tissue

    • Cartilage

      • hyaline cartilage

      • elastic cartilage

      • fibrocartilage

    • Bone

    • Blood


    Connective tissue types
    Connective Tissue Types

    Classified by the characteristics of the matrix

    Also see Table 4.1

    Details covered in lab


    Connective tissue diseases
    Connective Tissue Diseases

    • Many diseases

    • Most of them very rare

    • They may involve the joints but primarily affect other organs

    • Cause(s) of these diseases unknown

    • But in all of them, the immune system seems to be activated and causes damage to different organs in the body


    Systemic lupus erythematosus
    Systemic Lupus Erythematosus

    http://www.niehs.nih.gov/health/topics/conditions/lupus/index.cfm

    • Symptoms: skin rash, mild arthritis, and generalized weakness or tiredness

    • Rarer symptoms: hair loss, mouth ulcers, headaches and poor circulation in the fingers

    • Serious complications of kidney, heart, and brain inflammation

    • 9 times more likely in women

    • 4 times more likely in African-Americans


    Marfan syndrome
    Marfan Syndrome

    • Genetic defect on chromosome 15 that encodes the fibrilin protein


    Nervous tissue
    Nervous Tissue

    • Highly specialized epithelial cells

    • Convert stimuli into electro-chemical signals for transfer of information

    • Structure

      • cell body (soma) and extensions

      • dendrites (highly branched) – carry incoming signal

      • axon (long, usually single strand) – carry outgoing signal


    Muscle tissue characteristics
    Muscle Tissue Characteristics

    • a high degree of cellularity

    • cells contain contractile proteins

    • well vascularized

    • a highly specialized type of connective tissue


    Classification of muscle tissues
    Classification of Muscle Tissues

    • two types are Striated:

      • Skeletal muscle

        • attached to bones

        • multinucleate

        • voluntary

        • fibers are parallel and cylindrical

      • Cardiac muscle

        • most of the heart wall

        • single nucleus (usually)

        • involuntary

        • branched cylinders connected by intercalated discs


    Classification of muscle tissues1
    Classification of Muscle Tissues

    • One type is non-striated

      • Smooth muscle

        • located in the walls of hollow organs:

          • blood vessels

          • digestive tract

          • airways

          • bladder

        • involuntary

        • single nucleus

        • spindle shaped


    Epithelial membranes
    Epithelial Membranes

    A particular Epithelium and its underlying Connective Tissue support

    trachea

    skin



    Mucous membranes
    Mucous Membranes

    • Line body structures which open directly to the exterior

    • Viscous mucus secretions lubricate surfaces and provide a defensive barrier that traps particles and microbes


    Serous membranes
    Serous Membranes

    • Line closed body cavities and their organs

    • Watery serous fluid lubricates the cavity and its organs

      • pleura – lungs

      • pericardium - heart

      • peritoneum - abdominal organs

        • parietal

        • visceral


    Tissue injury repair
    Tissue Injury & Repair

    • Inflammation

      • redness

      • swelling

      • heat

      • pain

      • loss of function

    • Organization restores blood supply

      • Blood clot replaced by granulation tissue

    • Regeneration and Fibrosis

      • Epithelium regenerates

      • Fibrous conn. tissue matures and contracts


    Tissue repair
    Tissue Repair

    • During development some cells lose their ability to divide with specialization

    • Some cells maintain the ability to replace others

      • Stem cells

        • immature, undifferentiated cells

        • hide in protected areas in skin/GI tract to replace cells

      • Tissue repair

        • new cells come from parenchyma (functioning portion) or stroma (connective tissue)

        • if parenchyma cells proliferate then repair nearly complete; if not, then we get scar tissue formation

        • fibroblasts will produce collagen and other matrix materials during fibrosis – a less functional tissue


    Conditions affecting repair
    Conditions Affecting Repair

    • Nutrition

      • adequate protein in the diet for repair

      • necessary vitamins and other nutrients

    • Blood circulation

      • transport oxygen, nutrients, antibodies and other defensive molecules and cells to the site

      • WBCs remove debris which would otherwise interfere with healing

    • Age

      • young people heal faster and have less obvious scars

      • young people have a better nutritional status, a better blood supply, and a higher metabolism


    Embryonic germ layers
    Embryonic Germ Layers

    We’ll see the embryonic tissues again in Chapter 28 next semester


    End chapter 4

    End Chapter 4

    Exam 1 covers Chapters 1-4




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