Epithelium, Membranes & Fascia Flashcards
tissues
group of cells that are similar in structure that perform a common or related function
histology
study of tissues
what are the primary tissues?
- epithelial tissue
- connective tissue
- muscle tissue
- nerve tissue
epithelial tissue
covering of the body
connective tissue
supports body structure
muscle tissue
provides and produces body movement
nerve tissue
controlling of the body
what are the five characteristics of epithelial tissues?
- polarity
- specialized contacts
- supported by connective tissues
- avascular; but innervated
- can regenerate
what are the epithelial tissue functions?
- protection
- absorption
- filtration
- excretion
- secretion
- sensory reception
polarity
- apical surface: exposed to exterior or cavity–microvilli & cilia
- basal surface: lower and attached—noncellular basal lamina, like a selective filter, and helps in wound repair by scaffolding
specialized contacts
these are specific coverings and linings that cover epithelial tissues –fit closely together
- help bind adjacent cells through tight junctions, desmosomes, and gap junctions
connective tissue support
- reticular lamina & basal lamina (made of connective fibers) –deep to basal lamina
- basement membrane (BM): reinforces epithelial sheets and resists stretching and tearing
avascular but innervated
the epithelial tissue has no blood vessels!
- typically nourished by diffusion from underlying connective tissue
- supplied by nerve fibers
regeneration
- epithelial tissue has a high regenerative capacity
- with enough nutrients - can regenerate
how do we classify epithelia by the number of their cell layers?
simple - one single layer of cells
stratified - multiple layers of cells
pseudostratified - fake cell layers; only single later
how do we classify the shape of epithelial cells?
- squamous - scale-like cells, flattened nucleus
- cuboidal - cube-like shape, round-like nucleus
- columnar - column-shape, elongated nucleus
simple squamous epithelium
- SINGLE layer of FLATTENED squamous cells
- allows material to pass through diffusion and filtration
- can be found in kidney glomeruli, alveoli of lungs, lining of heart, blood vessels, and lymphatic vessels
simple cuboidal epithelium
- SINGLE layer of CUBELIKE cells
- secretes and absorbs material
- can be found in kidney tubules, ducts, and small glands + ovary surfaces
simple columnar epithelium
- SINGLE layer of TALL COLUMN-LIKE cells; can bear cilia and have mucus cells/goblet cells
- helps in the absorption and secretion of mucus or enzymes
- located in various spaces:
- lines ducts of many exocrine glands
- NONCILIATED: the lining of the digestive tracts
- CILIATED: can be found within the bronchi, uterine tubes, some regions of the uterus
pseudostratified columnar epithelium
- SINGLE layer of DIFFERING heights; can also have goblet cells & cilia
- secretes substances (mucus); movement of mucus
- can be found in various places:
- NONCILIATED: male’s sperm carrying ducts/large gland ducts
- CILIATED: the lining of the trachea, upper respiratory tract
stratified squamous epithelium
- MULTIPLE layers of cells [BASAL CELLS - CUBOIDAL CELLS/COLUMNAR CELLS]
[SURFACE CELLS - SQUAMOUS]
*remember keratinized type - these surface cells are dead and full of keratin - protects underlying tissues
- can be found in various locations:
- NONKERATINIZED: moist linings of esophagus, mouth, and vagina
- KERATINIZED: epidermis of the skin
stratified columnar epithelium
- MULTIPLE layers of COLUMNAR (superficial) & CUBOIDAL (basal)
- helps with protection and secretion
- found around the male urethra and large ducts of some glands (typically rare)
stratified cuboidal epithelium
- MULTIPLE layers of CUBOIDAL cells
- also typically rare similar to stratified columnar epithelium
- helps in structural reinforcement
- typically found in sweat and mammary glands
transitional epithelium
- MULTIPLE layer of cells - cell shape varies depending on the function of the organ
- has the ability to change shape and stretch
- located within the urinary bladder, ureters, the superior urethra and prostate gland ducts
