Histology Topic 2: Epithelial Tissue Flashcards
What are the general functions of Elithelial Tissue?
- Protection
- Secretion
- Selective
- Absorption
- Excretion
- Trans-cellular
- Transport/diffusion
- Sense organ
What is the general structure of Epithelial Tissue?
- Polarised with an apical surface that faces
the lumen. Basal surface is located interior
-Thin sheets of cells tightly packed
What is Simple Epithelial Tissue?
A single-layered epithelium that is adapted for diffusion
What is Stratified Epithelial Tissue?
A multi-layered epithelium adapted for protection
What resources the shapes of Epithelial Tissue?
- Squamous
- Cuboidal
- Columnar
What is pseudostratified epithelium?
A single layer of epithelium that has a stratified appearance due to the difference in size of the nuclei of the adjacent cells.
What is the Basement Membrane and what is its function?
- Noncellular layer directly beneath epithelial tissue
- Composed of proteins secreted by epithelial cells and
connective tissue - Function: Provides structural support to overlying cells.
Attaches epithelial layer to underlying tissues
Where is Simple Squamous Epithelium found in the body?
▪︎Air sacs of lungs
▪︎lining of heart (mesothelium), blood vessels (endothelium) and lymph vessels
▪︎major cavities
What is the function of Simple Squamous Epithelium?
▪︎To allow materials to pass through by diffusion and filtration
▪︎To secrete lubricating substances
Where is Simple Cuboidal Epithelium found in the body?
▪︎ In ducts and secretary portions of small ducts
▪︎ In the kidney tubules
What is the function of Simple Cuboidal Epithelium?
▪︎ To secrete and absorb
▪︎sensory reception (nose, ears and taste buds)
Where is Simpler Columnar Epithelium found in the body?
▪︎Ciliated: bronchi, uterine tubes, uterus
▪︎Smooth/ Non-ciliated: Digestive tract and bladder
What is the function of Simple Columnar Epithelium?
▪︎Absorbs
▪︎Secretes mucus and enzymes
Where is Pseudostratified Columnar Epithelium found in the body?
Ciliated pseudostratified elithelium lines the trachea and much of the upper respiratory tract
What is the function of Pseudostratified Columnar Epithelium?
▪︎Secretes mucous
▪︎Cilia moves mucous
Where is Stratified Squamous Epithelium found in the body?
▪︎lines esophagus, mouth and vagina
What is the function of Stratified Squamous Epithelium?
▪︎protects against abrasion
Where is Stratified Cuboidal Epithelium found in the body?
▪︎Sweat glands, Salivary glands and Mammary glands
What is the function of Stratified Cuboidal Epithelium?
▪︎protective tissue
What is the function of Stratified Columnar Epithelium?
▪︎Secretes and protects
Where is Stratified Columnar Epithelium found in the body?
▪︎urethra
▪︎ducts of some glands
Where is Transitional Epthelium (Urothelium) found in the body?
▪︎lines bladder, urethra and ureters
What is the function Transitional Epithelium (Urothelium)?
▪︎allows Urinary organs to stretch and expand
What is the difference between Stratified Epithelium and Urothelium?
▪︎Urothelium has less layers than Stratified Epithelium
▪︎Urothelium is more stretchy
What is Keratinized Epithelia?
Epithelia composed of numerous dead squamous cells at the most apical surfaces, adapted to be waterproof and prevent evaporation
How does Keratinized Epithelia arise?
Dead squamous cells at the most apical layers of the Epithelium loses their nuclei and cytoplasms and contain a tough protein, keratin.
What is the structure of Transitional Epithelia?
▪︎stretchy
▪︎looks stratified cuboidal when NOT stretched
▪︎looks stratified squamous when it IS stretched
What is Glandular Epithelium?
▪︎A group of tissues, other than the covering
and lining epithelium that are specialized for the production and
secretion of various macromolecules
▪︎a.k.a secretory epithelium
What is a gland?
▪︎Epithelium that secretes substances into ducts (tubes), onto a surface, or eventually into the blood in the absence of ducts.
What is an Exocrine Gland?
▪︎Glands that secrete their products into ducts that release the secretions onto the surface of organs—>the skin surface
or the lumen of a hollow organ.
▪︎Remain connected to the covering epithelium via tubular ducts —>lined with lining epithelium and carry the
secreted products into the site of action.
What is an Endocrine Gland?
▪︎Group of glands that do not have a duct system—>release their secretions directly into the bloodstream.
▪︎The secretions—>hormones, enter the interstitial fluid and then diffuse into the bloodstream without flowing
through a duct.
▪︎Endocrine secretions have far-reaching effects—>distributed throughout the body by the bloodstream.
Where are Goblet Cells found and what are they function?
▪︎they are found in Columnar Epithelium
▪︎Function:
-Protection and lubrication of epithelial
surfaces (respiratory and digestive tract where it
needs to produce mucus and other substances)
How to identify squamous
▪︎elliptical nucleus
▪︎flat cells
How to identify Cuboidal Epithelium?
▪︎circular nucleus
▪︎cube-shaped cells
How to identify Columnar Epithelium?
- Oval-shaped nucleus
2. Rectangular-shaped cells
How to identify Transitional Epithelium?
▪︎dome-shaped apical cells
How to identify pseudostratified epithelia?
▪︎different shapes of nuclei
▪︎varying height of cells (if visible)
What are the common diseases and disorders relating to Epithelium Tissue?
Acne, dermatitis, impetigo (bacterial skin infection), psoriasis (red, itchy, scaly patches on skin),
sunburn, sweating disorders, yeast infections of the mucous membranes, leprosy
-Sunburn: radiation causes damage to DNA (directly or via free radical excitement)
>Melanocytes produce melanin → distribute to keratinocytes (common type of skin
epithelium).
>When exposed to sun, melanocytes increase production of melanin to
protect cell.
>Once cells are damaged → signal molecules generated → body mounts an
inflammatory response → results in “burn” from sun → blood flows to area to repair
damage.
