Upload
phebe-mccormick
View
223
Download
2
Tags:
Embed Size (px)
Citation preview
Identify the type of junction with its purpose:
forms an impermeable junction; prevents molecules from passing between cells
Let small molecules move directly between neighboring cells
reduces tearing, twisting, stretching
helps form the tight junction around apical lateral borders
Do Now:
Location:Covers body SurfacesLines body cavitiesForms glands
Functions:SecretionSelective absorptionProtectionTranscellular supportDetection of sensation
Epithelial Function
SecretionWhen a cell produces substances and releases
those substances into the environment.Ie. Digestive tract has high secretion
Selective AbsorptionEpithelial tissue is in direct contact with the
outer environment so it selects what materials come into and out of the cell
ProtectionTissue in contact with the external
environment has to have a protective function to protect internal tissue Ie. Skin
Function
Transcellular TransportAble to help substances travel through a
certain distance
Detection of SensationAssociated with nerve cells because epithelium
can be found on the external part of the body; nerve cells receive stimuli
Function
Cells are usually joined by specialized cell-to-cell junctions
Little or no intercellular materialDon’t have a lot of extracellular material
around them
Epithelial Festures
First the name of tissue indicates # of layers (3 types)1. Simple – one layer of cells (extends from
basement membrane to the apical surface)
2. Stratified – more than one layer of cells
Classifications of Epithelia
Classification of Epithelia3. Pseudostratified- tissue appears to be
stratified, but all cells contact basement membrane so it is in fact simple
Classifications of EpitheliaLast name of tissue describes shape of cells
(3 types)1. Squamous – cells wider than
tall (plate or “scale” like)
2. Cuboidal – cells are as wide as tall, as in cubes
3. Columnar – cells are taller than they are wide, like columns
Naming EpitheliaNaming the epithelia includes the layers
(first) and the shape of the cells (second)i.e. stratified cuboidal epithelium
The name may also include any accessory structuresGoblet cells, cilia, keratin, etc.
Special epithelial tissues (don’t follow naming convention)PsuedostratifiedTransitional
How do you go about naming epithelial tissue?
Do Now:
Simple Squamous EpitheliumDescription
single layer of flat cells with disc-shaped nuclei
Special types Endothelium (inner covering)
slick lining of hollow organsMesothelium (middle covering)
Lines peritoneal (abdomen), pleural (lungs), and pericardial (heart) cavities
Covers visceral (internal) organs of those cavities (ie. pancreas, stomach, lung, etc.)
Simple Squamous EpitheliumFunction:
Passage of materials by passive diffusion and filtration
Secretes lubricating substances reducing friction from muscle in serous membranes
Location:Renal corpuscles (blood filtering component in kidneys)
Alveoli of lungs
Lining of heart, blood and lymphatic vessels
Lining of ventral body cavity Pericardium- membrane covering the heart
Pleura- membrane covering the lung
Peritoneum- membrane covering the abdominopelvic cavity
Simple Squamous Epithelium
Simple squamous lining the
walls of the capillary
Simple Cuboidal EpitheliumDescription
single layer of cube-like cells with large, spherical central nuclei
Function secretion and absorption
Location kidney tubules, secretory portions of
small glands, ovary surface
Simple Cuboidal Epithelium
Simple Columnar EpitheliumDescription
single layer of column-shaped (rectangular) cells with oval nucleiSome have cilia at their apical surfaceMay contain goblet cells (secrete
mucus)Function
Absorption; secretion of mucus, enzymes, and other substances
Ciliated type propels mucus or reproductive cells by ciliary action
Simple Columnar EpitheliumLocation
Non-ciliated form Lines digestive
tract, gallbladder, ducts of some glands
Ciliated form Lines small
bronchi, uterine tubes, and uterus
Identify a location where simple squamous, cuboidal
or columnar tissue is found?
Do Now:
Stratified EpitheliaLayers: contain two or more layers of cellsRegeneration: from Basal membraneFunction: protectionNaming: according to the shape of cells at
apical layer
Stratified Squamous EpitheliumDescription
Many layers of cells – squamous in shape
Deeper layers of cells appear cuboidal or columnar
Thickest epithelial tissue – adapted for protection
Stratified Squamous Epithelium
Specific types Keratinized – contain the protective protein
keratinSurface cells are dead and full of keratin
Non-keratinized – forms moist lining of body openings
FunctionProtects underlying tissues in areas subject to
abrasionLocation
Keratinized – forms epidermisNon-keratinized – forms lining of esophagus,
mouth, and vagina
Stratified Squamous Epithelium
Non-keratinized vs. Keratinized
Stratified Cuboidal EpitheliumDescription
generally two layers of cube-shaped cells
Functionprotection
LocationForms largest
ducts of sweat glands
Forms ducts of mammary glands and salivary glands
Stratified Columnar Epithelium
Descriptionseveral layers;
basal cells usually cuboidal; superficial cells elongated
Functionprotection and
secretionLocation
Rare tissue typeFound in male
urethra and vas deferens, largest ducts of salivary glands, nasopharynx
Pseudostratified Columnar EpitheliumDescription
All cells originate at basement membraneOnly tall cells reach the apical surfaceMay contain goblet cells and bear ciliaNuclei lie at varying heights within cells
Gives false impression of stratification
Function secretion of mucus; propulsion of mucus by
cilia
Pseudostratified Columnar EpitheliumLocations
Non-ciliated type Ducts of male
reproductive tubes
Ducts of large glands
Ciliated variety Lines trachea and
most of upper respiratory tract
Transitional EpitheliumDescription
Basal cells usually cuboidal or columnarSuperficial cells dome-shaped or
squamousFunction
stretches and permits distension of urinary bladder
Location Lines ureters, urinary bladder and part
of urethra
Transitional EpitheliumRelaxed state
Stretched state
Name three types of tissue, what they look at and a place where they can be
found.
Do Now:
Glandular EpitheliumDucts carry products of exocrine
glands to epithelial surfaceInclude the following diverse glands
Mucus-secreting glands Sweat and oil glandsSalivary glandsLiver and pancreas
May be: unicellular or multicellular
Unicellular Exocrine Glands (The Goblet Cell)
Goblet cells produce mucin
Mucin + water mucus
Protects and lubricates many internal body surfaces
Types of Multicellular Exocrine Glands
What are the two types of stratified squamous
epithelial? Where can they be found?
Do Now:
Where can simple cuboidal and stratified cuboidal be
found? What is the difference in the function
of each?
Do Now: