Epithelial Tissue Flashcards
Avascular tissue is composed of cells that: (4)
o cover the exterior body surfaces
o line the internal closed cavities including the vascular system
o line body tubes that communicate with the exterior (GIT, urogenital and respiratory tracts)
o form secretory portions and ducts of glands
What are the defining characteristics of epithelial tissue?
- Cells are in close apposition and have little extracellular matrix
- Functional and morphologic polarity
o Cells have 3 domains- apical domain, lateral domain and basal domain - Cells adhere strongly by specialized cell junctions
- Cell basal surface attaches to basement membrane
What is epithelioid tissue? (2)
o Cells that are closely apposed and have a basement membrane but lack a free surface
o Present as most endocrine glands
How does epithelium function as a selective barrier?
Epithelia covering and lining surfaces form a sheet-like cellular investment that separates underlying connective tissue from the external environment, internal cavities or fluid connective tissue (blood or lymph)
What are the functions of epithelia? (5)
How does the classification of epithelial tissue take place?
Simple squamous:
Image
Locations
Functions
Simple cuboidal:
Image
Locations
Functions
Simple columnar:
Image
Locations
Functions
Pseudostratified columnar:
Image
Locations
Functions
Stratified squamous:
Image
Locations
Functions
Stratified cuboidal:
Image
Locations
Functions
Transitional (urothelium):
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Locations
Functions
- Epithelia may also be classified according to its _____ specialisations if present
- Some exocrine glands have cells that are _____ in shape
- These cells are still classified as either columnar or cuboidal
apical
pyramidal
In stratified epithelium:
o The cell ____ and ____ vary from layer to layer
o Only the shape of the cells that form the surface layer is used in classification.
height
shape
What are the SPECIAL classifications of epithelia? (2)
- Pseudostratified epithelium
o Nuclei are at different levels and some cells do not reach the free surface
o Since all cells rest on the basement membrane, it is regarded as a simple epithelium - Transitional epithelium (urothelium)
o Stratified epithelium with special
Simple squamous epithelia in specific locations:
1. Endothelium-
2. Endocardium-
3. Mesothelium-
lining of the blood and lymphatic vessels
lining of the ventricles and atria of the heart
lining of the walls of the abdominal, pericardial and pleural cavities
- Specific _____ characteristics are associated with each cell surface
- The free apical domain is always directed toward the exterior surface of the lumen of an enclosed cavity or tube
- The lateral domain ________ with adjacent cells and has specialised attachment areas
- The basal domain rests on the ______ _____ anchoring the cell to underlying connective tissue
biochemical
communicates
basal lamina
What are the Apical Domain Specializations? (3)
- Microvilli
- Stereocilia (stereovilli)
- Cilia
What are microvilli? (5)
- Cytoplasmic processes containing a core of actin filaments
- Functions in increasing surface area for absorption
- In kidney tubules- brush border
- In GIT- striated border
- Also located in brain ependyma
What are Stereocilia (stereovilli)? (3)
- Microvilli of unusual length (very long)
- Functions in facilitating absorption and mechanoreception
- Limited to male reproductive system and sensory hair cells in the ear
What are cilia? (4)
- Motile cytoplasmic processes
- Contains the motor protein dynein
- Core of microtubules in 9+2 pattern
- Functions in transportation
Where are cilia found? (4)
o Oviducts
o Trachea and bronchi
o Brain ependyma
o Olfactory epithelium
Zonula Occludens (tight junction):
Image
Cytoskeleton Component
Functions
