510-5 Epithelia Flashcards
Epithelia is sensitive and doesn’t bleed. How do we describe this?
Highly innervated and Avascular
What are the two general layers of the basement membrane?
The Basal Lamina and the Reticular Lamina
What type of collagen is found in basal lamina and what are its properties?
Type IV Collagen
a loose, gel-like collagen
What are the two layers of Basal Lamina?
Lamina Lucida
Lamina Densa
Where is Laminin found and what does it do?
Found in the Lamina Lucida
It’s a glycoprotein that binds the type IV collagen in the Lamina Densa
What is the Lamina Densa largely compose of?
Type IV collagen
How are the Basal Lamina and Reticular Lamina joined together?
Loops of type VII Collagen anchoring fibrils.
Name the 3 types of Collagen found in the basement membrane.
Type I - Largest fibrils found deepest in Reticular Lamina
Type VII - loops found in the Reticular lamina anchoring into the Lamina Densa of the Basal Lamina.
Type IV - gel like collagen found in the Lamina Densa portion of the Basal Lamina
Drawn correctly, is Transitional Epithelium (as in the lining of the bladder) Stratified or Psuedo-stratified?
Psuedo Stratified
What’s the advantage to a simple squamous epithelium?
Rapid Diffusion
What might staggering of cell nuclei in columnar epithelium suggest?
pseudo-stratification
found in upper respiratory tract (trachea, nasal cavities)
What are the 3 layers of a mucous membrane?
Epithelial Cells Lamina Propria (vascular connective tissue) Musculara Mucosae (thin layer of smooth muscle)
Name a difference between non-keratinized and keratinized epithelium.
Nucleated (non-keratinized)
Non-nucleated (keratinized)
Where is non-keratinized, stratified, squamous epithelium found?
Oral mucosa, esophagus, vagina
Where do you find keratinized stratified squamous epithelium?
Skin
some Oral Epithelia
Where do you find stratified cuboidal and stratified columnar epithelia?
Certain ducts (pancreas, salivary, sweat glands - uncommon)
Where would you find Domed surface epithelium with protein plaques on the free surface?
Bladder.
Pseudostratified transitional epithelium
look for: pseudostratified, dark plaques on free surface
What’s the only cell that lacks an intercellular junction?
Erythrocytes (red blood cells)
What is the function of a tight junction?
Waterproofing
think caulking / magnets zipping up toward the apical end
AKA - Zona Occludens
What is the function of an adhesive junction?
What role does Ca++ play?
Cell binding
think velcro or glue (uses actin filaments)
AKA - Zona Adherens
Ca++ allows binding of actin. Kelating inhibits Calcium from doing this
What is the function of a Desmosome?
Very tight junction
think bolts (joins intermediate filaments)
Hold cells together against mechanical stresses
What is the function of a hemi-desmosome?
Connects the cell to underlying connective tissue via intermediate filaments (in the cell), various collagen and proteins, and ultimately to the type VII collagen loops in the Reticular Lamina
How many connexin = one connexon
Six
What is a primary structural difference between exocrine and endocrine glands?
Exocrine glands have ducts, Endocrine glands don’t
Name two mixed (endocrine/exocrine) glands.
Pancreas (endocrine hormones without ducts, exocrine products via ducts)
Liver
Two structural types of exocrine glands
Simple and Compound (branched)
Describe a tubuloacinar gland.
A compound gland with secretory cells at both bulged acinar regions AND throughout duct (tubed) regions.
I.e. Breast ducts
What kind of gland releases whole cells into ducts?
Cytogenetic glands
What is the mechanism of merocrine secretion?
Exocytosis at the apical end of the cell.
(Releases into a duct)
(Most common type of secretion)
Sebaceous glands secrete by what process?
Holocrine
The cell swells then lyses, releasing contents.
Name two surfaces of epithelia.
Basal surface and free surface
