EPITHELIUM Flashcards
four basic types of tissue
epithelial, connective, muscular, nervous
Most organs can be divided into __________, which is composed of the cells responsible for the organ’s specialized functions
parenchyma
what is stroma?
cells of which have a supporting role in the organ; always CT except in brain and spinal cord
What are possible shapes of epithelial cells?
columnar, cuboidal, squamous; c ells size and morphology are generally dictated by their function
What is lamina propria
the connective tissue that underlies the epithelia lining the organs of the digestive, respiratory, and urinary systems
what is papillae?
area of contact between the epithelium and connective tissue maybe increased by irregularities at the interface in the form of small evaginations; occur most frequently in epithelial tissues subject to friction (skin and tongue)
what is Basal Pole/ domaine
region of the cell contacting the connective tissue
have specializations include the basal lamina, plasma membrane infoldings, and hemidesmosomes
what is Apical Pole
the opposite end of the basal pole, usually facing a space.
Rich in: ion channels, carrier proteins, glycoproteins, and hydrolytic enzymes, and aquaporins
what is lateral surfaces
regions of cuboidal or columnar cells that adjoin the neighboring cells
Basement membrane
All epithelial cells in contact with subjacent connective tissue have at their basal surfaces a specialized, feltlike sheet of extracellular material referred to as this
Basement membrane
All epithelial cells in contact with subjacent connective tissue have at their basal surfaces a specialized, feltlike sheet of extracellular material referred to as this It has two parts: basal lamina and reticular lamina
What is epitelial tissues?
Are cells which cover surfaces, line body cavities or form glands
What is connective tissue?
Cells that produe an extracellular matrix and serve to link or support other specialized tissues by forming tendons, bone or fatty tissue.
What is connective tissue?
Cells that produe an extracellular matrix and serve to link or support other specialized tissues by forming tendons, bone or fatty tissue.
reticular lamina
layer beneath the basal lamina, this one is more fibrous than basal lamina contains Type III collagen bound by anchoring fibrils of type VII collagen (produced by connective tissue)
Laminin
large glycoproteins that self assemble as a lacelike network immediately below the cells’ basal poles where they are held in place by the transmembrane integrins
The macromolecules in the basal lamina come from the _______
epithelial tissues
The molecules in the basal lamina are:
Type IV collagen laminin nodigen and perlecan
What are the functions of epithelial tissue?
Protection Transcellular transport Secretion Absoption Selective permeability Detection of sensations
Identify the type of cell in the image
Simple squamous epithelium
Identify the type of cell in the image
simple squamous epithelium
Identify the type of cell in the image
simple squamous epithelium
What are the functions of simple squamous epithelium?
- infiltration
- diffusion- lungs
- transport- cardiovascular system
- secretion
- reduction of friction - peritoneal cavity
Types of simple squamous epithelium:
endothelium
mesothelium
endocardium
type of epithelial lining found in blood and lymphatic vessels which form a semipermeable barrier between blood and lymphatic vessels. It can secrete factors for roles.
endothelium
What is mesothelium?
The mesothelium is the epithelium that lines the wall and covers the contents of the closed cavities of the body
Epithelial lining of ventricles and atria of the hear
Endocardium
Simple Epithelia
contain one cell layer; cell shape classification: squamous, cuboidal, or columnar
Stratified Squamous Nonkeratinized Epithelium
Lines wet cavities (mouth, esophagus, and vagina) where water loss is not a problem; the flattened cells of the surface layer contain much less keratin, retaining their nuclei and metabolic function
Stratified Squamous Keratinized Epithelium
- epithelium that gives more protection
- Layers of cells composing the free surface are dead, non nucleated, filled with keratin.
Ex. skin
Stratified squamous parakeratinized epithelium
Very similar to keratinized but many cells at the surface retain thei nuclei
Ex. hard palate and gingiva
Identify the type of epithelium cell in the image and its functions
Simple cuboidal epithelium
This cells present a centrally placed nucleus. They made uo ducts of many glands of the body, covering the ovary, composed many kidney tubules.
Identify the type of epithelium and describe
Stratified cuboidal epithelium
contains only two layers of cuboidal cells, lines the duct of cellsof glands
this epithelium are usually specialized for absorption, with apical cilia or microvilvi
simple columnar epithelium
identify type of epithelium and explain
Stratified columnar epithelium
Can be found in the conjunctiva lining the eyelids where is it both protective and mucus secreting. Large ducts in glands.
Identify epithelium and describe
Transitional epitehlium
Its compsed of layers of cells that are either squamous or cuboidal. Its located EXCLUSIVELY in the urinary system
The polarity of the cell are determined
by the properties of each domain (apical, basal, basolateral surface of cell) , which are determined by specific lipids and integral membrane proteins
examples of Modifications on apical surface
microvilli, stereocilia and flagella
Lateral domain or pole
Lateral side of the cell and has structures link the lindividual cells together into a functional unit
Junctional complexes
cell adhesion molecules (CAMs)
What are CAMs?
Cell adhesion molecules
What is the CAM’s function?
- control and regulate diverse intracellular processes
- Cell adhesion
- cell proliferation
- cell migration
- intercellular communications
- cell recognition
- regulation of intercellular diffusion barrier
- generation of inmune responses
- apoptosis
Types of cell juntions/junctional complexes:
- occluding junctions
- anchoring junctions
- communicating junctions
Name the type of junction and function
Tight junctions/ occluding junction
mostly apical
- prevents diffusion of molecules between adjacent cells
- prevents lateral migration of specialized cell memebrane proteins
How the small bowel prevents macromolecules from passing the cells?
Tight junctions in epithelial cells lining
Trasmembrane protein responsible for seal between cells:
occludin and claudin, makes sure substances go THROUGH the membrane and not between them
Transmembrane proteins in tight junctions:
- occludings
- claudins
- nectins
- junctional adhesive molecules (JAMs)
Identify ZO1, ZO2, ZO3, actin, claudin. occludin, and JAM
What are anchoring junctions?
provide mechanical stability to epithelial cells so that they can function as a cohesive unit
What are the types of anchoring junctions?
- adherens junctions
- desmosome
- hemodesmosome
Adherent junction/ zonula adherens
LOCATION: located basal to zonulae occludentes
FUNCTION: joins cell membranes and links cytoskeleton of two cells via transmembrane linker proteins
Which proteins are important for adherens junctions?
cadherins y catenins
cadherin
transmembrane glycoproteins of each cell that interact in the presence of Ca2+
catenin
protein to whom cytoplasmic cadherins binds, these link to actin filaments (cytoskeleton) with actin binding proteins
How actine filaments of adjacent cells are attached?
are attached by e-cadherine- catenine complex by actinin and vinculin
What are desmosomes or macula adherens?
resembles a single spot weld and does not form a belt around the cell; are discshaped structures at the surface of one cell that are matched
with identical structures at an adjacent cell surface.
Epithelial desmosomes attach to —
cable like filaments of cytokeratin
What type of cadherins are found in desmosomes?
desmogleins and desmocollins
How desmosomes anchore the cell?
cytoplasmic part of proteins Desmogleins and desmocollins bind to plakoglobins, these link desmoplakina. Desmoplakins bind to intermediate filaments rather than actin.
Type of communication junction
gap junction
Name cell junctions
what are gap junctions?
cell structures that permit direct passage of signaling molecules, small molecules, from one to another
Explain gap junction structure
six closely packed transmembrane channel-forming proteins (connexins) that assember form channel structures called connexons (hemochannels)
Two connexons, one in each cell form the gap junction
_____ attach the basal cellmembrane to the underlying basal lamina; they have strong adhesive properties
type of hemisdosome found in stratified squamous and pseudostratified epithelium
Type 1
How hemidesmosomes commit adhesion?
The half desmosome , structurally, the integrins are the ones which binds to intermediate filaments. Integrins bind primarily to laminin in basal lamina.
Which type of hemisdosomes are present in plama membranes of simple columnar epithelial lining of small and large intestines?
Type 2
Proteins present in type 2 hemidesmosomas
plectin, filamentos de keratina y integrinas
Proteins present in type1 hemidesmosomas
integrina, tonofilamentos, plakin proteins, erbin and CD151
microvilli
in epithelial cells specialized for absorption, the apical surfaces present an array of projections
(it looks like a brush)
brush or striated border
apical surfaces are densely covered with uniform microvilli
stereocilia
restricted to absorptive epithetlial cells lining the the epididymis and the proximal part of ductus deferens in the male reproductive system and on the sensory hair cells of the cochlea (inner ear)
cilia
long projecting structures, larger than microvilli, which contain internal array sof microtubules. most cell types have at least one cilium of variable length usually called a primary cilium which is not motile but is enriched with receptors and signal transduction complexes for detection of light, odors, motion, and flow of liquid past the cells
what is the assembly of each cilium
9 doubles form an array around two central microtubules
what the 9+2 assembly of microtubules is called, cilia?
axoneme
relatively weak and transcient attachments in the basal cell membranes of epithelial cells are called ____
focal adhesion
Focal adhesion structures
Although resembling hemidesmosomes superficially, focal adhesions are smaller, more numerous, and consist of integrins linked indirectly to bundled actin filaments
integrins of focal adhesions are also linked _______________
via paxillin to focal adhesion kinase
What is focal adhesion kinase?
signaling protein which upon integrin binding to laminin or other specific ECM proteins initiates a cascade of intracellular protein phosphorylation affecting cell adhesion, mobility, and gene expression.
Are formed by clusters of α and β integrins that form weak interactions with laminin, type IV collagen, and fibronectin molecules of the basal lamina.
Focal Adhesion
The 9 +2 arrangement of cillia is made of —–, whereas arms composed of the protein ——.
The 9 +2 arrangement of cillia is made of -microtubules-, whereas arms composed of the protein -dynein-
IDENTIFY PARTS AND WHAT IT IS
axonema
Kartagener syndrome
results from hereditary defects in the ciliary dynein that would normally provide the energy for ciliary bending
It can cause:
Lung infections.•Immotile sperm
Structure of Microvillus
Each microvillus contains a core of 25 to 30 actin filament bundle, cross-linked to each other by a number of actin-binding proteins, such asespin,fascin,villin, andfimbrin
What is the function of the terminal web?
Provides support and give rigidity to the microvilli
What is the terminal web?
Is a complex of actin and spectrin molecules as well as intermediate filaments located at the cortex of the epithelial cells.
Structure of stereocilia
Are supported by internal bundles of actin filaments that are cross linked by fimbrin and espin
ezrin: anchors the actin filament to the plasma membrane
Identify structure
erzin
fimbrin
erzin
actin filament
Identify type of epithelium
Simple squamous epithelium
Identify the epithelium
Simple squamous epithelium
Identify the epithelium
Simple columnar epithelium
Identify epithelium
Pseudostratified epithelium,
identify epithelium
simple columnar epithelium
identify epithelium
stratified columnar cells
identify epithelium
simple cuboidal epithelium
identify epithelium
simple cuboidal epithelium
identify epithelium
stratified squamous epithelium
identify the epithelium
squamous non keratinized
identify the epithelium
transitional epithelium
identify the epithelium
