Lecture 4 - Epithelium and Glands Flashcards
The Seven Functions of Epithelium
Protection Absorption Transcellular Transport Selective Permeability Surface Transport Secretion Sensation
Two Forms of Epithelia
In Epithelia As Sheets
In Glands Derived
Mesothelia
Membrane lining outer surface of cavity or organ
Serosa
Lines many regions of intestines CONSISTS OF MESOTHELIUM AND CONNECTIVE TISSUE
Endothelium
Lining internal surface of heart lymph, or blood vessels
Epithelium Always has
Basement Membrane
Characterisistics of Epithelium
Surface Sheet Avascular Decreased ECM Dynamic Polarized (oriented) Cell Surface specialized
Free Vs Attached Epithelial
for a sheet the free is free on the lumen, and the attached is attached
Luminal and Abluminal Epithelial
Luminal is on the lumen and abluminal base
Apical, Lateral, and Basal, on a epithelial Cell
Apical is on the luminal side
Basal is on the basement membrane
Lateral is middle
Apical Surface Specializations (Name 3)
Microvilli, Cilia, Steriocilia
Microvilli
Increase SA, Function in Absorption, covered in glycolyx rich in Carbohydrates
How To Stain for Microvilli
PAS Stain (rich in carbohydrates)
Cilia
Longer than microvilli, help in moving substances across the surface
Steriocilia
Very long processes
only in male reproductive system and inner ear
Lateral junctional complexes (List the three)
Tight Junctions
Adhering Junctions
Gap Junctions
Tight Junctions
Seals Adjacent Cells
Keep transmembrane proteins from floating from the side they are on
Adhering Junctions (Two TypeS)
Generally mechanical stability and unity
Zonula Adherens - formed by transcellular proteins
Macula Adherens - formed by plaques and specialized filaments
Difference of Tight Junctions and Adherens
Tight Junctions cut the lumen away from the rest, and keep specializations in that area
Adherens hold things tight together
Gap Junctions
Specialized Area Allows Cell Cell Communication, passage of small molecules
Basement Membrane (two Parts)
Basal Lamina
lamina reticularis
Basal Lamina (produced by and what collagen)
Made by Epithelia has type IV collagen
Hemidesmosomes
Anchor the basal lamina to the epithelia
Lamina Reticularis (produced by and what collagen)
Like the pad of the rug
manufactured by connective tissue
type III Collagen
Basal Infoldings
Infolding of the basal region of the cell
Increases Surface Area
Seen in places of transport
Site of pumps and mitochondria
visually looks like striations with mitochondria
The Two Basal Cell surface specializations
Basal Infoldings and Basement membrane
Pseudostratified Epithelium
Appears Stratified but is really one later, and they all attach to the basement membrane
Simple Squamus (two Examples)
Cells so flat, any thickness is nucleus bulging into the lumen
ex// endothelium and mesothelium
Simple Cuboidal
Seen in ducts of glands for secretion and absorption
Simple Columnar
Used for absorption and Secretion
Often with microvilli
located in the GI
Stratified Squamous Non-keratinized
See nucleus in outer most layer
not hardened by karatin so maintains moist surface and protects underlying
Stratified Squamous Keratinized
Cytoplasm filled with keratin. Make rougher surface adds layer of protection
no nuclei (shed)
ex// Skin and tongue
Pseudostratified
Often ciliated
found in respiratory system
only columnar reach surface
Transitional Epithelium
Located Exclusive in urinary tract
when relaxed its cuboidal, when stretched its squamous
walls of bladder
Metaplasia
Reversible change of epithelia type to other
Dysplasia
Disordered growth leading to neoplasm
Neoplasia
New Growth of tissue and increase in number of cells
carcinoma
malignant tumor of epithlelium tissue
Adenocarcinoma
malignant tumor of glandular epithelial tissue
Gland Formation
Originally were epithelial tissue and then becomes gland through invagination. Can be unicellular or multicellular
Exocrine Gland
Maintains contact with epithelial and secrete through duct
Endocrine Gland
Ducltess secrete hormones usually
distribute thorugh the blood
removes contact with epithelial
gets invaded by blood vessels
Exocrine and Endocrine where it secretes
Exocrine - secrete apically
Endocrine Secrete basally
Merocrine
Secretion from Exocrine via exocytosis
Apocrine
Small Portions of cytoplasm release with product
Holocrine
Secretory cell is destroyed, whole cell becomes part of product
Serous vs Mucous Secretion
Serous is watery and often enzymes
Mucous is viscous with glycoprotein content
