Trans 2 Epithelium Flashcards
What are the characteristics of an epithelium?
- Avascular tissue
- Covers internal closed cavities and body tubes that communicate with the exterior
- lining or surface epithelium
- Self-renewing
- With functional and morphological polarity
- Can form glands
What are the functions of an epithelium
Selective barrier Absorption Secretion Protection Others (sensation, contractility, transport of nutrients and other elements, waterproofing)
Classification of epithelium based on morphological characteristics
Simple
Compound
Classifications of epithelium based on cell shape
Squamous
Cuboidal
Columnar
Type of squamous epithelium
Single later of flattened cells
Simple squamous epithelium
Function of simple squamous epithelium
exchange and barrier
The endothelium and mesothelium are examples of what kind of epithelium
Simple squamous
Type of simple epithelium in wc the height and width of the cells are almost equal
Simple cuboidal
Function of simple cuboidal cell
Secretion and absorption
The kidney tubule is an example of what epithelium
Simple cuboidal
Type of simple epithelium with the width smaller than the height of the cell
Simple columnar
What is the function of simple columnar cells
Secretion and absorption
The lining of the gallbladder is an example of what epithelium
Simple columnar
Type of epithelium consisting of a single layer which appears to be stratified due to different levels of the nuclei
Pseudostratified
Where can you find pseudostratified epithelium?
respiratory (lining of trachea, bronchi and nasal cavity)
Male reproductive tract (epididymis)
True or false
For compound epithelium, you describe the epithelium based on which type of cell is present in larger amounts
False, you described based on the MOST SUPERFICIAL layer
Several layers of flattened cells
Stratified squamous epithelium
Can be keratinized or non-keratinized
Function of keratinized stratified squamous epithelium
Waterproofing layer (skin)
Where to find non-keratinizing stratified squamous epithelium
Mucus-rich regions with glandular tissue underneath
Function of stratified squamous epithelium
Barrier and protection
Consists of 2-3 layers of cuboidal cells
Stratified cuboidal
Function of stratified cuboidal cells
barrier and conduit
The large excretory duct of salivary glands are made up of what kind of epithelium?
Stratified cuboidal
Usually consists of 2-3 layers of columnar cells
Stratified columnar cells
Function of stratified columnar cells
Barrier and conduit
The large excretory ducts of exocrine are made up of what type of compound epithelial cells?
Stratified columnar
Other name of transitional epithelium
Uroepithelium
Surface cells of transitional epithelium
Dome cells or umbrella cells
Cells in the transitional epithelium that allow changes in the volume without changes in the pressure of the organ
Dome cells / umbrella cells
Match the following (Transitional epithelium)
- Dome shaped
- Flattened
A. Contracted
B. Distended
Dome-shaped (contracted) -> flattened (distended)
Function of the uroepithelium
Barrier with a distensible property
True or false:
The height of the cells often reflects the level of secretory or absorptive activity
True
Three domains/surfaces of an epithelial cell
Apical
Lateral
Basal
What are the surface modifications of the apical part of the epithelial cell
Microvilli
Cilia
Stereocilia
What are the surface modifications in the lateral domain of the epithelial cell?
Tight junction
Intermediate junction
Desmosomes
Gap junctions
Surface modification of the basal domain
Hemidesmosomes
Functions of the apical cell
Increase the surface area for absorption
Move substances along the epithelial surface
Domain of epithelial cells that face the organs lumen and often have specialized projecting structures
Apical domain
Shortest non-motile projection, closely packed with upright array of fingerlike evaginations from the plasma membrane of the cell
Microvilli
Microvilli are composed of what kind of filaments
ACTIN filaments
Horizontal network of filaments which lies just below the base of microvilli, where the actin filaments are attached for RIGIDITY
Terminal web
Microvilli have this on their surfaces which serves as surface for adsorption and release of digestive enzymes
Glycocalyx
What are the functions of microvilli
Increases absorptive surface of a cell
Facilitates movement of materials
Motile surface modifications used to move mucus/ovum across surface (respiratory tract/oviduct)
Cilia
The cilia has a core of microtubules called what? And where is it attached?
Axoneme, attached to the basal body
How many peripheral doubles and central singlets does an axoneme have?
9 peripheral doubles, 2 central singlets (9:2)
How many peripheral doubles and central singlets does a basal body have?
9 peripheral doubles, 0 singlets (9:0)
Where does the cilia come from?
Centriole
What causes cilia to move?
Adjacent axoneme interaction via DYNEIN links
What are the functions of non-motile cilia
Detection of light, odors, motion and flow of liquid
Only found in cuboidal or columnar epithelia, type of cilia with rapid beating patterns of movement that propel a current of fluid and suspended matter in one direction over the epithelium
Motile cilia
Movement of motile cilia
Metachronous
Non-motile, bigger and more elevated microvili which is long, thin and clumped at the ends
Stereocilia
Functions of stereocilia
absorption for ductus deferens and epididymis in male repro tract
Sensory hearing for Organ of Corti
Epithelial cells that strongly adhere to neighboring cells
Lateral
Collective term used to refer to the specific structural components that make up the barrier and attachment devices between adjacent cells
Junctional complex
Transmembrane proteins present in anchoring junctions
Cell adhesion molecules
CAMs for cell to cell adhesion
Cadherins
Immunoglobulin superfamilies
Selectins
Ca 2+ dependent, for same cell types
Cadherins
CAMs for same cell types
Immunoglobulin superfamilies
CAM attaching different cell types
Selectins
Found at the most apicolateral portion, most adhesive portion, fused plasma membrane of adjacent cells
Tight junction (Zonula Occludens)
Fusion of the tight junction (sealing intercellular space and maintaining polarity) was brought about by what transmembrane protein?
occludins
Junction that is medial in position with a wider intercellular space
Intermediate Junction (Zonula Adherens)
Plasma membrane of adjacent cells are linked by what complexes
E-cadherin and catenin complexes
Why is the intermediate junction not present in squamous cells
Squamous cells are too thin and flat
Lowermost junctional complex
Desmosomes (Macula adherens)
Major transmembrane link proteins
Desmocollin and desmoglein
Part of the cytplasm which counters wear and tear and holds the shape of the skin
Cytoplasmic attachment plaque
Allows faster communication
Gap Junctions (Nexus)
Gap junctions are made up of what
Connexons
Functions of connexons
Allows the transmission of ions, basically transmembrane channels
Differentiate connexon from connexin
Connexon: channels
Connexin: transmembrane proteins that surrounds the connexons
Found in actively transporting epithelia of smooth muscle, cardiac muscle and nerves
Gap junctions
TRUE OR FALSE: epithelial cells strongly adhere to basal lamina esp those subject to friction and other mechanical forces
True
Specialized structure located next to the basal domain of epithelial cells and the underlying connective tissue stroma
Basement membrane
Increase cell surface area and facilitate interactions between adjacent cells and ECM proteins
Basal cell membrane infoldings
Main cell adhesion molecules
Integrins
The basement membrane is made up of what
Basal lamina + reticular lamina
Single later, one of the main characteristics of epithelium
Basal lamina
Basal lamina collagen type
Type IV collagen
The basal lamina [collagen] is coated with what and why
PROTEOGLYCANS with negatively charged SULFATE groups, allowing it to become an electrostatic barrier
Two layers of the basal lamina
Lamina lucida
Lamina densa
Thinner portion of the basal lamina, with laminin only
Lamina lucida
Made up of laminin, type IV collagen, sulfated proteoglycans, glycoproteins (Fibronectin)
Lamina densa
NOTE: laminin makes up the backbone/scaffold
Functions of the basal lamina
Attachment, selective barrier, polarity, tissue-scaffolding for would healing and repair
Made up of reticular fibers of underlying connective tissue
Reticular lamina
Reticular fibers collagen type
Type III
Anchoring fibrils collagen type
Type VII collagen
Why is reticular lamina thickened in the trachea
To support airway from collapsing
Type of cell-ecm junction, one half of the desmosome
Hemidesmosome
Where is the hemidesmosome connected
To the basal lamina
Desmosome vs hemidesmosome
Clustered transmembrane proteins that link to cytokeratin intermediate filaments are integrins in hemidesmosome, cadherins in desmosome
Where can you find hemidesmosomes
Abrasive and shearing forces
Group of epithelial cells specialized for sevretion
Glands
Types of glands depending on method of delivery
Exocrine gland
Endocrine gland
Has a ductal system, decretes products onto a surface directly or through epithelial ducts or tubes connected to a surface
Exocrine glands
Classification of exocrine glands based on number of cells
Unicellular
Multicellular
Classification of exocrine glands based on branching
Simple
Compound
Classification of exocrine glands based on secretory portion
Tubular
Acinar
Tubulo-acinar
Classification of exocrine glands based on secretion
Mucous
Serous
Mexed seromucous acini called SEROUS DEMILUNE
Classification of exocrine glands based on method of secretion
Merocrine
Holocrine
Apocrine
Tubular vs acinar vs tubulo-acinar
Elongated - rounded - mixed
[exocrine gland based on type of secretion] produces mucin, have a pale cytoplasm and a flat nucleus
Mucous
[exocrine gland based on type of secretion] with watery, enzyme rich secretion
Serous
[exocrine gland based on type of secretion] with a half moon appearance
Serous demilune
Merocrine vs holocrine vs apocrine
Cell is intact - Suicidal secretion - Part of cell is destroyed
Components of exocrine glands
Stroma
Parenchyma
Supportive portion of exocrine glands
Stroma
Secretory portion of exocrine gland, epithelial component
Parenchyma
[stroma] condensation of connective tissue
Capsule
[stroma] extemds omward from the capsule to divide the gland into lobes and lobules
Septa (thinner septa to divide into lobules)
[stroma] delicate network which surrounds acini
Reticular fibers
Ductal system arrangement:
Intercalated duct -> striated duct -> intralobular duct -> interlobular duct -> lobar duct -> main duct
Gland that lacks a duct system, they decrete their products into the connective tissue to the blood stream tor each their target cells
Endocrine glands
What do you call the products of endocrine glands
Hormone
How are cells in endocrine gland arranged
Cords and columns
Except thyroid gland, cells are in rounded units
True or false: endocrine glands are avascular
False, they are HIGHLY VASCULAR