epithelial tissue histology: –the study of tissues. tissues: –simply groups of similar cells...
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Epithelial Epithelial TissueTissue
Histology:Histology:
– the study of tissues.the study of tissues.
Tissues:Tissues:
– Simply groups of similar cells that work Simply groups of similar cells that work together performing the same tasktogether performing the same task
– Greatest form of teamwork in the bodyGreatest form of teamwork in the body
Where are epithelial tissues found?Where are epithelial tissues found?
With few exceptions, organs are With few exceptions, organs are composed of four basic tissue types:composed of four basic tissue types:
– – Epithelial TissueEpithelial Tissue
– – Connective TissueConnective Tissue
– – Muscular TissueMuscular Tissue
– – Nervous TissueNervous Tissue
Why Study Histology?Why Study Histology?
Knowing the difference between normal and abnormal tissue is the first step in diagnosis and
treatment of patients.
Skin, our largest and heaviest organSkin, our largest and heaviest organ
made of all four tissue types
Epithelial Tissue
Muscular Tissue
Nervous Tissue
Connective Tissue
Epithelial TissueEpithelial TissueMakes up 3% of your body weightMakes up 3% of your body weight
Cells don’t moveCells don’t move
They don’t send messagesThey don’t send messages
Their cells are all touching one anotherTheir cells are all touching one another
Of all tissues, they are the most widely varied in Of all tissues, they are the most widely varied in structure and functionstructure and function
Locations of Epithelial TissuesLocations of Epithelial TissuesCovers the body Covers the body
Found on the inside of Found on the inside of hollow organs and the hollow organs and the outside of outside of all all organsorgans
Found above a Found above a connective tissue layer connective tissue layer
Lines the cavities, Lines the cavities, tubes, ducts, and blood tubes, ducts, and blood vessels inside the bodyvessels inside the body
Epithelial AnatomyEpithelial AnatomyApical surfaceApical surface – upper surface that is free or – upper surface that is free or exposed to the “exterior”exposed to the “exterior”
Basal surfaceBasal surface – attached surface (below) – attached surface (below)
MicrovilliMicrovilli – small fingerlike extensions that – small fingerlike extensions that increase the surface area allowing for more work increase the surface area allowing for more work to be doneto be done
Functions of Epithelial TissueFunctions of Epithelial Tissue– Protects from physical & chemical injuryProtects from physical & chemical injury– Protects against microbial infectionProtects against microbial infection– Contains nerve endings which respond to Contains nerve endings which respond to
stimulistimuli– Filters, secretes & reabsorbs materialsFilters, secretes & reabsorbs materials– Secretes fluids to lubricate jointsSecretes fluids to lubricate joints
Three Basic ShapesThree Basic ShapesSquamousSquamous – like – like scales, or pancakes scales, or pancakes (“being (“being squashedsquashed like like a a pancakepancake”)”)
CuboidalCuboidal – looks like – looks like cubescubes
ColumnarColumnar – longer – longer and look like columnsand look like columns
Cell OrganizationCell OrganizationSimpleSimple – single layer of cells; typically found where – single layer of cells; typically found where absorption and filtration occur absorption and filtration occur
simple squamoussimple squamous
simple cuboidalsimple cuboidal
simple columnarsimple columnar
StratifiedStratified – layers of cells; common in areas where – layers of cells; common in areas where protection is needed like the skinprotection is needed like the skin
stratified squamousstratified squamous
Two Types of Stratified ColumnarTwo Types of Stratified Columnar
CiliatedCiliated
UnciliatedUnciliated
cilia
No cilia
Squamous EpitheliumSquamous EpitheliumSimple SquamousSimple Squamous
Forms solid, single layer of Forms solid, single layer of cells cells
lines blood vessels, body lines blood vessels, body cavities and covers organscavities and covers organs
Stratified SquamousStratified Squamous Forms epidermis and is Forms epidermis and is
mostly for protection mostly for protection
Found in areas of high Found in areas of high friction friction
Cuboidal EpitheliumCuboidal Epithelium
Simple CuboidalSimple Cuboidal
Roughly cube shapedRoughly cube shaped
Line ducts in kidneys where Line ducts in kidneys where absorption and secretion absorption and secretion activities take place.activities take place.
Very, very rare to have Very, very rare to have stratified cuboidalstratified cuboidal
Columnar EpitheliumColumnar EpitheliumSimple columnar– one cell Simple columnar– one cell thickthick
rectangular shaped rectangular shaped (long and narrow)(long and narrow)
Lines digestive tract where Lines digestive tract where absorption & secretion absorption & secretion occurs.occurs.
White spots are White spots are goblet cells goblet cells which secrete mucous which secrete mucous
No stratified columnarNo stratified columnar
Confusing Epithelial TissueConfusing Epithelial Tissue
Transitional Epithelium – Numerous layers of Transitional Epithelium – Numerous layers of cells of varying and often irregular shape cells of varying and often irregular shape
Shape of cells depends upon the amount of Shape of cells depends upon the amount of stretching (ex: bladder)stretching (ex: bladder)
Confusing Epithelial Tissue Continued…Confusing Epithelial Tissue Continued…““Pseudostratified Columnar Epithelium”Pseudostratified Columnar Epithelium”
Tall rectangular cells, with Tall rectangular cells, with multiple irregular rows multiple irregular rows of nucleiof nuclei. Nuclei are positioned at differing levels. Nuclei are positioned at differing levels
Cells narrow in the area without the nucleusCells narrow in the area without the nucleus
Located in the trachea; secrete & move mucousLocated in the trachea; secrete & move mucous
Goblet cells secret mucous to aid cilia
in moving substances across the cells’ surface
Epithelial Tissue in Review…Epithelial Tissue in Review…
Epithelial tissues can be found in three types of membranes: Cutaneous, Serous, and mucous membranes.
Mucosa Mucosa MembranesMembranes
Mucus-secreting membranes line tubes; moistens and Mucus-secreting membranes line tubes; moistens and protects from enzymes and acid (i.e., stomach, trachea, protects from enzymes and acid (i.e., stomach, trachea, mouth, and vagina)mouth, and vagina)
Membranes are involved in absorption and secretion.Membranes are involved in absorption and secretion.
Serous MembranesSerous Membranes
SerousSerous membranes line membranes line body cavities that do not body cavities that do not open directly to the outsideopen directly to the outside
They cover the organs They cover the organs located in those cavities. located in those cavities.
Fluid lubricates the Fluid lubricates the membrane and reduces membrane and reduces friction and abrasion when friction and abrasion when organs move against each organs move against each other.other.
Cutaneous MembranesCutaneous Membranes
Cutaneous Cutaneous membranesmembranes cover the cover the surface of the body. surface of the body.
Consists of stratified Consists of stratified squamous epithelium squamous epithelium
Cutaneous Cutaneous membranes are thick, membranes are thick, relatively waterproof, relatively waterproof, and dry. and dry.
Function = protectionFunction = protection
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