Cells to TissuesCells to Tissues
As human body develops from singleAs human body develops from single
to multicellular, cells specialize.to multicellular, cells specialize.
Body is interdependent system,Body is interdependent system,
malfunction of one group of cells ismalfunction of one group of cells is
Cells specialize into types of tissues,Cells specialize into types of tissues,
then interspersed into organs.then interspersed into organs.
Tissues = groups of cells that areTissues = groups of cells that are
similar in structure and function.similar in structure and function.
Linings of surfacesLinings of surfaces
Bone, ligaments,Bone, ligaments,
Brain, nerves,Brain, nerves,
spinal cordspinal cord
Function of Epithelial TissueFunction of Epithelial Tissue
Skin protects from sunlight & bacteria & physicalSkin protects from sunlight & bacteria & physical
Lining of small intestine, absorbing nutrients intoLining of small intestine, absorbing nutrients into
Lining of Kidney tubules filtering wastes from bloodLining of Kidney tubules filtering wastes from blood
Different glands produce perspiration, oil, digestiveDifferent glands produce perspiration, oil, digestive
enzymes and mucusenzymes and mucus
Characteristics of Epithelial TissueCharacteristics of Epithelial Tissue
Form continuous sheets (fit like tiles)Form continuous sheets (fit like tiles)
Apical SurfaceApical Surface
All epithelial cells have a top surface thatAll epithelial cells have a top surface that
borders an open space – known as aborders an open space – known as a lumenlumen
Basement MembraneBasement Membrane
Underside ofUnderside of allall epithelial cells which anchorsepithelial cells which anchors
them to connective tissuethem to connective tissue
Avascularity (a = without)Avascularity (a = without)
Lacks blood vesselsLacks blood vessels
Nourished by connective tissueNourished by connective tissue
Regenerate & repair quicklyRegenerate & repair quickly
Classification ofClassification of
Epithelial TissueEpithelial Tissue
Cell ShapeCell Shape
Squamous – flattened likeSquamous – flattened like
fish scalesfish scales
Cuboidal - cubesCuboidal - cubes
Columnar - columnsColumnar - columns
Cell LayersCell Layers
Simple (one layer)Simple (one layer)
Stratified (many layers)Stratified (many layers)
Named for the type of cell atNamed for the type of cell at
the apical surface.the apical surface.
Simple Squamous EpitheliumSimple Squamous Epithelium
Single Layer of flattened cellsSingle Layer of flattened cells
Absorption, and filtrationAbsorption, and filtration
Not effective protection – single layer of cells.Not effective protection – single layer of cells.
Walls of capillaries, air sacs in lungsWalls of capillaries, air sacs in lungs
Form serous membranes in body cavityForm serous membranes in body cavity
Simple Cuboidal EpitheliumSimple Cuboidal Epithelium
Single layer of cube shaped cellsSingle layer of cube shaped cells
Secretion and transportation in glands,Secretion and transportation in glands,
filtration in kidneysfiltration in kidneys
Glands and ducts (pancreas & salivary),Glands and ducts (pancreas & salivary),
kidney tubules, covers ovarieskidney tubules, covers ovaries
Simple Columnar EpitheliumSimple Columnar Epithelium
Elongated layer of cells with nuclei at same levelElongated layer of cells with nuclei at same level
Absorption, Protection & SecretionAbsorption, Protection & Secretion
When open to body cavities – called mucousWhen open to body cavities – called mucous
Special FeaturesSpecial Features
MicrovillMicrovilli, bumpy extension of apical surface, increasei, bumpy extension of apical surface, increase
surface area and absorption rate.surface area and absorption rate.
Goblet cellsGoblet cells, single cell glands, produce protective, single cell glands, produce protective
Linings of entire digestive tractLinings of entire digestive tract
Pseudostratified EpitheliumPseudostratified Epithelium
Irregularly shaped cells with nuclei at differentIrregularly shaped cells with nuclei at different
levels – appear stratified, but aren’t.levels – appear stratified, but aren’t.
All cells reach basement membraneAll cells reach basement membrane
Absorption and SecretionAbsorption and Secretion
Goblet cells produce mucusGoblet cells produce mucus
Cilia (larger than microvilli) sweep mucusCilia (larger than microvilli) sweep mucus
Respiratory Linings & Reproductive tractRespiratory Linings & Reproductive tract
Stratified Squamous EpitheliumStratified Squamous Epithelium
Many layers (usually cubodial/columnar atMany layers (usually cubodial/columnar at
bottom and squamous at top)bottom and squamous at top)
Keratin (protein) is accumulated in older cellsKeratin (protein) is accumulated in older cells
near the surface – waterproofs and toughensnear the surface – waterproofs and toughens
Skin (keratinized), mouth & throatSkin (keratinized), mouth & throat
of cubodial only)
Transitional EpitheliumTransitional Epithelium
Many layersMany layers
Very specialized – cells at base are cuboidalVery specialized – cells at base are cuboidal
or columnar, at surface will vary.or columnar, at surface will vary.
Change between stratified & simple as tissueChange between stratified & simple as tissue
is stretched out.is stretched out.
Allows stretching (change size)Allows stretching (change size)
Urinary bladder, ureters & urethraUrinary bladder, ureters & urethra
One or more cells that make and secrete aOne or more cells that make and secrete a
Secretion = protein in aqueous solution:Secretion = protein in aqueous solution:
hormones, acids, oils.hormones, acids, oils.
Endocrine glandsEndocrine glands
No duct, release secretion into blood vesselsNo duct, release secretion into blood vessels
Often hormonesOften hormones
Thyroid, adrenal and pituitary glandsThyroid, adrenal and pituitary glands
Exocrine glandsExocrine glands
Contain ducts, empty onto epithelial surfaceContain ducts, empty onto epithelial surface
Sweat, Oil glands, Salivary glands, Mammary glands.Sweat, Oil glands, Salivary glands, Mammary glands.
Shapes of Exocrine glandsShapes of Exocrine glands
Simple – single, unbranched duct
Compound – branched.
Shape: tubular or alveolar
Tubular – shaped like a tube
Alveolar – shaped like flasks or sacs
Tubuloalveolar – has both tubes and
sacs in gland
Modes of SecretionModes of Secretion
(How the gland’s product is released)(How the gland’s product is released)
Just released by exocytosis without alteringJust released by exocytosis without altering
the gland at all.the gland at all.
Ex: Sweat glands and salivary glandsEx: Sweat glands and salivary glands
The gland ruptures and releases secretionThe gland ruptures and releases secretion
and dead cells as well.and dead cells as well.
Sebaceous (oil glands on the face) onlySebaceous (oil glands on the face) only