Tissues Tissues

Chapter 5Chapter 5

Four Major types:Four Major types:

Epithelial: form protective coverings, fxn in Epithelial: form protective coverings, fxn in secretion and absorptionsecretion and absorption

Connective: supports soft body parts and Connective: supports soft body parts and bind structures togetherbind structures together

Muscle: produces body movementsMuscle: produces body movements Nervous: conducts impulses that help Nervous: conducts impulses that help

control and coordinate body activities.control and coordinate body activities.

Epithelial Tissues

• Found throughout the body, covers organs, lines body cavities and lines hollow organs.

• It always has a free (apical) surface (not covered)

• Underside is attached to connective tissue by a thin, nonliving layer called the basement membrane.

• Usually is lacking in blood vessels, receiving nutrients by diffusion from connective tissue

Epithelieal ContinuedEpithelieal Continued

Readily divide, resulting in fast Readily divide, resulting in fast healing injurieshealing injuries

Tightly packed: making good Tightly packed: making good protective barriers to the outsideprotective barriers to the outside

Some invloved in absorption, Some invloved in absorption, excretion, and excretion.excretion, and excretion.

Classified according to shape, Classified according to shape, number of layers of cellsnumber of layers of cells

Classification Of Epithelial CellsClassification Of Epithelial Cells

Squamous: thin, flattened cellsSquamous: thin, flattened cells

Cuboidal: cube shapedCuboidal: cube shaped

Columnar: tall, elongatedColumnar: tall, elongated

Single layers: simpleSingle layers: simple

Stratified: two or more layersStratified: two or more layers

The free surface epithelial cells are The free surface epithelial cells are modified in ways that reflect their modified in ways that reflect their specialized functions.specialized functions.

Simple Squamous Epitheleal Con. Line air sacs (alveoli) of lungs. Forms walls of capillaries Lines the insides of blood and lymph

vessels Covers the membranes that line body

cavities Because they are so thin, they are easily

damaged.

Simple Cuboidal Epithelial Cells

Single Layer

Cube shaped

Covers ovaries and most of the kidney tubules and the ducts of certain glands

Functions in secretion and absorption in glands of the kidneys and secrets glandular products.

Simple Cuboidal EptherliumSimple Cuboidal Eptherlium

Simple Columnar Simple Columnar EpitheliumEpithelium

Elongated: longer than they are wideElongated: longer than they are wide Single layer of cells, with elongated nuclei.Single layer of cells, with elongated nuclei. May be ciliatedMay be ciliated Ciliated cells in the female reproductive tubes Ciliated cells in the female reproductive tubes

cilia aid in movement of the eggcilia aid in movement of the egg Nonciliated SCE cells line the uterus and most Nonciliated SCE cells line the uterus and most

organs of the digestive tract including the organs of the digestive tract including the stomach and both intestines/stomach and both intestines/

SCESCE

The elongation leads to the formation The elongation leads to the formation of thick tissue which provides of thick tissue which provides protection for underlying tissuesprotection for underlying tissues

Some secrete digestive fluids and Some secrete digestive fluids and absorb nutrients from digested foodsabsorb nutrients from digested foods

Those specialized for absorption Those specialized for absorption often have many tiny extensions often have many tiny extensions from their surfaces called microvilli from their surfaces called microvilli to increase surface area for greater to increase surface area for greater absorptionabsorption

SCESCE

►Specialized flask shaped glandular Specialized flask shaped glandular cells (goblet cells) are often scattered cells (goblet cells) are often scattered among them. They secrete a among them. They secrete a protective fluid (mucus) onto the free protective fluid (mucus) onto the free surface of the tissuesurface of the tissue

Simple Columnar Simple Columnar EpithetheliumEpithethelium

CellsCells

Pseudostratified Columnar Pseudostratified Columnar EpitheliumEpithelium

Appear to be stratified/layered but are not.Appear to be stratified/layered but are not. This is due to nuclei of the cells are found This is due to nuclei of the cells are found

in two or more layers. All of the cells share in two or more layers. All of the cells share the same basement membrane. Some of the same basement membrane. Some of them may not contact the free surface.them may not contact the free surface.

Commonly have cilia.Commonly have cilia. Goblet cells in this tissue secrete mucus.Goblet cells in this tissue secrete mucus. Found in passages of respiratory system.Found in passages of respiratory system.

Pseudostratified ColumnarPseudostratified Columnar

Stratified Squamous EpiStratified Squamous Epi Relatively thickRelatively thick Cell division occurs in deeper layers and newer Cell division occurs in deeper layers and newer

cells push older ones to the surface where they cells push older ones to the surface where they flatten. In naming stratified epi tissues, based on flatten. In naming stratified epi tissues, based on cell shape, the appearance of the top layer is used.cell shape, the appearance of the top layer is used.

Forms the outer layer of the skin. As skin cells Forms the outer layer of the skin. As skin cells age, they accumulate a protein called keratin, then age, they accumulate a protein called keratin, then harden and die. Keritinization pr4oduces a harden and die. Keritinization pr4oduces a covering of dry, tough protective material covering of dry, tough protective material preventing water and other substances from preventing water and other substances from escaping and blocking various chemicals and escaping and blocking various chemicals and microorganisms from entereing.microorganisms from entereing.

Stratifired Squ. Epi lines the oral cavity, esophagus, Stratifired Squ. Epi lines the oral cavity, esophagus, vagina and anal canal. Here it is not keratinized, vagina and anal canal. Here it is not keratinized, stays soft and moist and surface cells remain alive.stays soft and moist and surface cells remain alive.

Stratified Squamous epiStratified Squamous epi

Stratified Cuboidal EpiStratified Cuboidal Epi

Two or 3 layers of cuboidal cells Two or 3 layers of cuboidal cells forming a lining of a lumen. Provides forming a lining of a lumen. Provides more protection than a single layer of more protection than a single layer of cells.cells.

Lines larger ducts of the mammary Lines larger ducts of the mammary glands, sweat glands, salivary glands, sweat glands, salivary glands, and pancreas. Also forms the glands, and pancreas. Also forms the lining of developing ovarian follicles lining of developing ovarian follicles and seminiferous tubules.and seminiferous tubules.

Stratified cuboidal EpiStratified cuboidal Epi

Stratified Columnar EpiStratified Columnar Epi

Several layers of cellsSeveral layers of cells Superficial cells are columnar, base Superficial cells are columnar, base

layers are cuboidal. So, look for layers are cuboidal. So, look for layers of cells and a change to layers of cells and a change to columnar in the outer layer.columnar in the outer layer.

Found in male urethra and ductus Found in male urethra and ductus deferens and in parts of pharynxdeferens and in parts of pharynx

Stratified columnar EpiStratified columnar Epi

Transitional EpiTransitional Epi

Specialized to change in response to Specialized to change in response to increased tension. Forms inner lining increased tension. Forms inner lining of bladder and lines ureters.of bladder and lines ureters.

When contracted, there will be several When contracted, there will be several layers of cuboidal cells. Distended, layers of cuboidal cells. Distended, there will be less layers.there will be less layers.

Also helps provide a barrier to prevent Also helps provide a barrier to prevent urinary tract contents from diffusing urinary tract contents from diffusing back in to the internal environment.back in to the internal environment.

Transitional EpiTransitional Epi