1. epithelial – covering & lining 2. connective – support 3. muscle - movement 4. nervous -...
TRANSCRIPT
Tissues
1. Epithelial – covering & lining2. Connective – support 3. Muscle - movement4. Nervous - control
4 Primary Tissue Types
Epithelial Tissue
1. Protection2. Secretion3. Absorption4. Filtration
Functions
1. Composed of sheets of closely packed cells
cells are often strongly connected via tight junctions and desmosomes
Characteristics
• Tight junctions are common in lining of the stomach & intestines. Why?
• Desmosomes are common in the epidermis. Why?
Look at the cartoon below (it represents the epithelium that lines much of your respiratory tract) . Do you see much space between these cells? Now look at the actual slide and notice the same thing.
2. Has polar sides Apical Surface
– side open to exterior or body cavity
Basal surface – rests on a basement membrane of connective tissue
3. Avascular – no blood vessels Depends on diffusion of
nutrients from underlying tissues
4. Has the capacity to regenerate
1. number of cell layers Simple – 1 layer Stratified – more than 1
layer
2. shape of cells in the apical layer
Squamous – flat, scale-like
Cuboidal – cube-like Columnar – column-like
Classification
Locations Alveoli – air sacs of
lungs Kidney Endothelium – lining of
heart and blood vessels
1. Simple Squamous Epithelium
Functions Rapid diffusion FiltrationIn peneumonia, a build-up of
mucous can increase the distance that the gases move. Why does this make it “harder to breathe?”
Locations Liver Pancreas Most glands Kidney tubules
2. Simple Cuboidal Epithelium
Functions Absorption Secretion
Locations Inner linings of:
GI TractGallbladderUterus & uterine
tubes
3. Simple Columnar Epithelium
Functions Absorption & Secretion
Intestines; Microvilli increase S.A. Movement of egg & embryo
Cilia Secretion of mucous
by Goblet cells
Locations Epidermis of skin
Keratinized – filled with keratin
Lining ofOral cavityTongue surfaceEsophagusVagina & anal canal
4. Stratified Squamous Epithelium
Functions Protection
Which is & is not keratinized?
Locations Sweat gland ducts Ovarian follicle – cells
surrounding egg
5. Stratified Cuboidal Epithelium
Functions Secretion
Sweat Ovarian hormones
To the left, we have an oocyte (egg cell) surrounded by stratified cuboidal epithelium. The oocyte is circled in blue
Locations Rare Large ducts of sweat
and salivary glands
6. Stratified Columnar Epithelium
Functions Structure
Locations Respiratory tract from
nasal cavity to bronchiCiliatedGoblet cells
7. Pseudostratified Ciliated Columnar Epithelium
Functions Mucous traps dust &
bacteria Cilia sweep debris
away from lungs
Here, we have pathogens traveling down the pharynx trying to attack the surface cells. How can they be repelled???
The mucosal cells lining the trachea have released a flood of mucus, trapping the pathogens! Now what???
The cilia successfully sweep the pathogens up and away!
Smoking paralyzes the cilia so they have to cough violently to expel mucous
..Then they die!
Why do smokers cough?
Locations Urinary tract
8. Transitional Epithelium
Functions Stretches to allow
filling of urinary organs
Locations Pancreas Stomach Sweat glands Salivary glands Mammary glands Oil glands Goblet cells
9. Exocrine GlandsFunctions Secrete material into
ducts that lead to a tract or body surface
Locations Thyroid Thymus Pituitary Adrenal Testes Ovaries
10. Endocrine GlandsFunctions Secrete hormones into
the bloodstream where they travel to other cells
Easy Epithelium Review