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Tissues : The living fabric Chapter 4. Histology = the study of tissues Tissues : groups of cells which are similar in structure and which perform common or related functions. Four Basic Kinds of Tissues. Epithelial Tissue (protection) Connective Tissue (support)

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Tissues the living fabric chapter 4

Tissues : The living fabricChapter 4

  • Histology = the study of tissues

  • Tissues:

    • groups of cells which are similar in structure and which perform common or related functions

Four basic kinds of tissues
Four Basic Kinds of Tissues

  • Epithelial Tissue (protection)

  • Connective Tissue (support)

  • Muscle Tissue (movement)

  • Nervous Tissue (control)

Epithelial tissue
Epithelial Tissue

  • Locations:

    • covers the body

    • lines the cavities, tubes, ducts and blood vessels inside the body

    • covers the organs inside body cavities

  • Epithelial Tissue Functions:

    • Protection from physical & chemical injury

    • Protection against microbial invasion

    • Contains receptors which respond to stimuli

    • Filters, secretes & reabsorbs materials

    • Secretes serous fluids to lubricate structures.

  • SUMMARY: protection, absorption, filtration and secretion

Special characteristics of epithelium
Special characteristics of epithelium

  • Cellularity – cells close together

  • Specialized contacts – tight junctions and desmosomes

  • Polarity – one free surface exposed to body exterior or internal cavity

  • Avascularity – no blood vessels

  • Basement membrane – nonliving, adhesive that reinforces

  • Regeneration – high capacity

Classification of epithelial shapes:

  • squamous – flattened and sac like

  • cuboidal – as tall as they are wide

  • columnar – tall and column shaped

    Classification of epithelial layers present:

  • simple – single layer of cells

  • stratified – multiple cell layers

Simple squamous epithelium
Simple Squamous Epithelium

  • Simple – one cell thick

  • Forms solid layer of cells which line blood vessels, body cavities & cover organs in body cavities

Stratified squamous epithelium
Stratified Squamous Epithelium

  • Stratified – multiple layers

  • Forms epidermis

Simple cuboidal epithelium


Simple Cuboidal Epithelium

Cuboid Cells

  • Simple – one cell thick

  • Roughly cube shaped

  • Line ducts in kidneys, etc, where reabsorption and secretory activities take place.

Stratified cuboidal epithelium


Stratified Cuboidal Epithelium

  • two layers cube like cells

  • Ducts of sweat glands, mammary and salivary glands

Cuboid Cells

Simple columnar epithelium
Simple Columnar Epithelium

  • Simple – one cell thick

  • Column shaped (long & narrow)

  • Line digestive tract where re-absorption & secretion occurs.

Stratified columnar epithelium
Stratified Columnar Epithelium

  • Several cell layers

  • Basal cells usually cuboidal; superficial cells long and columnar; may bear cilia

  • RARE – small amounts at epithelial junctions (stomach-esophagus)

Pseudostratified epithelium
Pseudostratified Epithelium

  • Single layer of cells of differing heights.

  • May bear cilia – found in trachea & upper respiratory tract

  • Non ciliated – ducts of large glands, male urethra

Transitional epithelium
Transitional Epithelium

  • Surface cells dome shaped or squamous

  • Basal cells cuboidal or columnar

  • Stretches readily

  • Location: lines ureters, bladder, urethra


Goblet cells = specialized cells within some epithelial tissues that secrete mucus (example: epithelium lining the digestive and respiratory tracts)

Cilia = hair-like extensions from the cell that beat back and forth uniformly to move mucus along the surface of the epithelium

Microvilli = finger like cell projections that cover the surface of small intestinal epithelium and function to increase surface area for absorption

Classifying epithelia by location
Classifying epithelia by location

  • Endothelium – simple epithelial sheet composed of a single layer of squamous cells attached to a basement membrane

    • Permeable and thin

    • Lines all hollow circulatory system organs: lymphatic vessels, blood vessels, heart

  • Epithelial membranes

    • Continous multi-cellular sheet composed of at least two tissue types: epithelium bound to underlying connective tissue

    • Called “simple organs”

    • 3 types: mucous, cutaneous, serous

Mucous membrane
Mucous membrane

  • Line body cavities that are open to the exterior (digestive, respiratory, urogenital)

  • Contain stratified squamous or simple columnar epithelium

  • Adapted for absorption and secretion

  • Wet or moist membranes

Cutaneous membrane
Cutaneous membrane

  • Your skin

  • Dry membrane, exposed to air

  • Consists of stratified squamous epithelium (epidermis) firmly attached to a thick connective tissue layer (dermis)

Serous membrane
Serous membrane

  • Moist membrane found in closed ventral body cavities

  • Simple squamous epithelium (mesothelium) resting on a tiny amount of loose connective tissue

    • Parietal layer – lines cavity wall

    • Visceral layer – covers outer surface of organ

    • Secrete thin layer of serous fluid – lubricates and prevents organs from sticking together

Serous membrane cont
Serous membrane (cont.)

  • Pleura – encloses lungs

  • Pericardium – encloses heart

  • Peritoneum – abdominopelvic cavity and viscera (internal organs)

Glandular epithelia
Glandular epithelia

  • Gland= one or more cells that produce and secrete a particular product (endocrine or exocrine)

    • the product is called a secretion (water based fluid typically containing proteins)

    • Secretion is also a process – glands take needed substances from the blood and chemically transform them into their secretory product

Endocrine glands
Endocrine glands

  • Eventually lose their ducts

  • Produce hormones which are secreted directly into the extracellular spaceand then enter the blood or lymphatic fluid

  • Covered more in Ch. 17

Exocrine glands
Exocrine glands

  • More numerous than endocrineglands

  • Sweat & oil glands, salivary glands, liver (secretes bile), pancreas (digestive enzymes), mammary glands, mucous glands

Exocrine glands can be:

  • Unicellular– no ducts, produce mucin which forms a slimy coating (mucus) for protection/lubrication; ex: goblet cells found in trachea & digestive tract

  • Multicellular - secrete their products through a duct onto body surfaces or into body cavities

End of e pithelial tissue
End of epithelial tissue

Connective tissue
Connective Tissue

  • Most abundant & widely distributed tissue

  • Functions:

    • Connects, binds and supports structures

      • Tendons, ligaments, etc.

    • Protects & cushions organs and tissues

    • Insulates (fat)

    • Transports substances (blood)

Connective tissue common characteristics:

  • Common origin – all arise from mesenchyme (embryonic tissue)

  • Different degrees of vascularity(avascular to highly vascular)

  • Matrix – composed largely of non-living extracellular matrix, which separates living cells

    • Allows connective tissue to bear weight, withstand tension, endure physical trauma and abrasion

Structural elements
Structural elements

  • Ground substance

    – unstructured material that fills the space between cells and contains fibers

  • Fibers - 3 types

    • collagen (most abundant)

    • elastic

    • reticular

  • Cells – each class has a fundamental cell type

    • Immature form = suffix “-blast”

    • Mature form = suffix “-cyte”

      • Fibroblasts (connective tissue proper)

      • chondroblasts (cartilage)

      • osteoblasts (bone)

      • hemocytoblast (blood)


  • large, irregulary shaped

  • phagocytize both

    foreign matter (immune

    system) and dead tissue


  • May be fixed or migrate freely

  • Not limited to connective tissue

Specific Connective Tissue Types:

  • Mesenchyme

  • Areolar

  • Adipose

  • Reticular

  • Dense regular & irregular

  • Elastic

  • Hyalaine cartilage

  • Fibrocartilage

  • Elastic cartilage

  • Bone

  • Blood

Loose connective tissues

dense connective tissues

Connective tissue proper
Connective tissue proper

  • 2 subclasses

  • Loose connective tissues – areolar, adipose, and reticular

  • Dense connective tissues – dense regular, dense irregular and elastic


  • Found in embryo

  • Gives rise to all other connective tissue


  • Gel-like matrix with fibers (all 3 types) running in random directions and scattered cells of various types

  • distributed under epithelia - in mucous membranes, around organs and capillaries


  • Wraps and cushions organs, role in inflamation, holds and conveys fluid


  • Location: under skin, around kidneys, eyeballs, in bones, w/in abdomen, in breasts

  • Honeycomb or chickenwire appearance

  • Nucleus pushed to the side & large internal fat droplet

  • Function:

    • stores energy (fat) – reserve fuel

    • Insulates against heat loss

    • supports & protects organs


  • Network of reticular fibers in loose ground substance w/reticular cells

  • Location: liver, lymph nodes, bone marrow, spleen

Function: body protection (phagocytic); fibers support other cell types

Dense Regular

  • Primarily parallel collagen fibers; few elastin; fibroblasts

  • Withstands great stress; ligaments and tendons

    Dense Irregular

  • Irregularly arranged collagen/elastic fibers; fibroblasts

  • Dermis of skin, digestive tract, organs and joints

  • Withstands tension in many directions

Elastic connective tissue
Elastic connective tissue

  • Elastin fibers

  • Walls of aorta, parts of trachea & bronchi; forms vocal cords, connects vertebrae

  • Durable & stretches

Hyaline cartilage
Hyaline Cartilage

  • Firm matrix w/ collagen fibers; chondrocytes

  • Forms embryonic skeleton

  • Costal cartilage of ribs

  • Covers ends of bones - absorbs compression between bones in joints

  • Holds open respiratory passages – nose, trachea, larynx

  • Most abundant type of cartilage in body


  • Less firm than hyaline cartilage; thick collagen fibers

  • Location: invertebral disks, pubic symphysis, knee joint

  • Tensile strength, absorbs shock

Elastic cartilage
Elastic Cartilage

  • More elastic fibers

  • Maintains the shape while allowing great flexibility

  • External ear and epiglottis

B one

  • Tree ring-like appearance

  • Hard, calcified matrix, collagen fibers, osteocytes, well vascularized

  • Functions:

    • Supports & protects

    • Mineral storage

    • Fat storage

    • Blood cell production


  • Blood is considered connective tissue because it has living cells.

  • Red & white blood cells in fluid matrix

Function: transport of respiratory gases, nutrients, wastes

Muscle tissue
Muscle Tissue

  • Muscle Tissue:

    • Associated with the bones of the skeleton, the heart and in the walls of the hollow organs of the body.

  • Muscle Tissue Functions:

    • Movement

    • Locomotion

    • Maintains posture

    • Produces heat

    • Facial expressions

    • Pumps blood

    • Peristalsis

Specific Muscle Tissue Types:

  • Skeletal – attached to bones

  • Cardiac – make up the walls of the heart

  • Smooth – in the walls of hollow organs

Muscle skeletal
Muscle - Skeletal

  • Muscle fibers (cells) long, parallel & cylindrical

  • With many nuclei (multinucleate)

  • Striations (cross stripes run perpendicular to the cells

  • Produce voluntary movement

  • Locomotion

  • Heat

Muscle cardiac
Muscle - Cardiac

  • Found only in the walls of the heart

  • Striated, 1 nucleus, involuntary

  • cells branch and are joined to one another via intercalated disks

Muscle smooth
Muscle - Smooth

  • Involuntary, non striated

  • Spindle shaped with one central nucleus

  • Found in the walls of the hollow internal organs

  • Propels substances through organ by contracting and relaxing

Nervous tissue
Nervous Tissue

  • Nervous Tissue:

    • Main component of the nervous system,

      ie., brain, spinal cord & nerves.

  • Nervous Tissue Functions:

    • Regulates & controls body functions

    • Generates & transmits nerve impulses to and from organs

    • Supports, insulates and protects impulse generating neurons (neuroglial cells)

Specific nervous tissue types nervous neuron
Specific Nervous Tissue Types Nervous – Neuron

  • Branching cells with many long processes

  • Large central nucleus

  • Transmit impulses from one area of the body to other areas

  • Regulate activities through neuron impulses

Tissue repair
Tissue Repair

When tissue injury occurs, it stimulates the body’s inflammatory and immune responses.

  • Inflammation represents an offensive action on the part of the body to

    • eliminate the injurious agent,

    • prevent further injury and

    • restore tissue to a health condition

Tissue repair1
Tissue Repair

  • Cells of the immune system mount a vigorous attack against invaders, either by

    • interacting directly with them or

    • by releasing antibodies

Tissue repair2
Tissue Repair

Occurs in two ways:

  • Regeneration – replacement of destroyed tissue by proliferation of the same kind of cells

  • Fibrosis – proliferation of fibrous connective tissue (scar tissue)

  • depends on the type of tissue damaged and the severity of the injury

  • The process of tissue repair
    The process of tissue repair

    • Tissue injury

    • Inflammatory reaction

    • Local blood vessels dilute and become more permeable

      • White blood cells and clotting proteins invade the injured site

    • Clotting – surface dries and forms a scab

      • Stops loss of blood

      • Holds edges of wound together

      • Isolates the area from bacteria

    The process of tissue repair1
    The process of tissue repair

    Organization – the process during which the temporary blood clot is replaced by the ingrowth of granulation tissue

    • Capillary buds invade the clot restoring the vascular supply

    • Fibroblasts invade the region and synthesize new collagen fibers

    • Macrophages phagocytize dead and dying cell debris

    The process of tissue repair2
    The process of tissue repair

    • Surface epithelium begins to regenerate and makes its way across the granulation tissue just beneath the scab, which later detaches

    • Scar tissue matures and contracts and layer of epithelium thickens

    • Final result: fully regenerated epithelial surface with an underlying area of fibrosis (scar) which is invisible or visible as a thin white line (depending upon severity)

    Scar tissue
    Scar tissue

    • The ability of tissue types to regenerate varies widely

    • Scar tissue is very strong, but lacks the flexibility and elasticity of normal tissue

    • Scar tissue on the muscular organs may severly hamper organ function