Epithelial Tissue Flashcards
list the five functions of epithelial tissue
- protection of underlying tissue
- absorption
- secretion
- excretion
- sensation
what are the five characteristics of epithelial tissue?
- distinct cell surfaces
- mostly comprised of cells
- covers body surfaces, lines openings, lines inside of body, inside of heart, lungs, and cavities
- nonvascular
- capable of regeneration
what are the three types of distinct epithelial cell surfaces?
- apical (free) surfaces
- lateral surfaces
- surfaces attached to basement membranes
what are apical or free surfaces?
not attached to any other cells
what are lateral surfaces?
attached to other epithelial cells
what is the basement membrane?
attaches epithelial cells to underlying tissue, produced by epithelium and underlying tissue (usually connective)
are there a lot of extracellular components in epithelial tissue?
not really, it is mostly tightly packed cells
what are the two ways of classifying epithelial tissue?
- by arrangement of layers
2. by cell shape
list and describe the three categories of epithelial classification based on arrangement of layers?
- simple: just one layer of cells, nuclei line up
- pseudostratified: one layer of cells but LOOKS like more than one layer, all cells attached to basement membrane, different heights, always columnar
- stratified: 2 or more cell layers, nuclei stack up
list and describe the three categories of epithelial tissue based on cell shape
- squamous: very thin and plate-like
- cuboidal: square-like, all sides fairly even
- columnar: longer than they are wide
describe simple squamous epithelial tissue
thin layer, not adapted to withstand wear and tear
where is simple squamous epithelial tissue found?
lining blood vessels, the heart, parietal and visceral pleura and peritoneum, the alveoli of the lungs
where is simple cuboidal epithelial tissue found?
in renal tubules, thyroid gland, and ovary surfaces
describe the shape and list the two types of simple columnar epithelial tissue
taller than it is wide, ciliated and non ciliated
state and describe the specialized cells that are found in simple columnar epithelial tissue
goblet cells: secretes mucus for lubrication/moisture/ maintenance/protective function
what are cilia?
hair-like extensions of the apical surface, move particles along in a unidirectional manner in the oviduct and respiratory tract
where is simple columnar epithelial tissue found?
in the uterus, oviduct, lining stomach, small and large intestines, and gallbladder
where is ciliated pseudostratified columnar epithelial tissue found?
nasal cavity, pahrynx, trachea, and bronchi
where is nonciliated pseudostratified columnar epithelial tissue found?
parathryoid
is stratified squamous epithelial tissue thick or thin?
it is typically the thickest epithelial layer
where is stratified squamous epi tissue found?
lining places open to the outside: epidermis (outer layer) of skin, mouth, esophagus, vagina, anus
what is stratified cuboidal and stratified columnar epi associated with?
glands
where is stratified cuboidal epi tissue found?
esophageal glands, sweat glands, salivary glands
where is stratified columnar epi tissue found?
lining mammary glands, lining glands of pharynx and larynx
what is transitional epi tissue?
stratified and highly specialized for stretching and expansion
where is transitional epithelium found?
in urinary tract, lining bladder and ureters
what two things is glandular epi specialized for?
secretion and excretion
define excretion
expulsion of waste products
define secretion, give two examples
release of a substance from a cell that has been synthesized by that cell, and the substance typically affects other cells in the body (hormones, mucus)
what are the two classifications of glandular epithelium?
endocrine and exocrine
define endocrine glandular epi
gland secretes its products into bloodstream for travel around the body
define exocrine glandular epi
empty their products onto an epithelial surface (not the bloodstream) via a duct
how do goblet cells relate to exocrine glandular epi?
they are unicellular glandular epi, that don’t use a duct
how do endocrine and exocrine glandular epi develop
the same until the end stages of development
how does endocrine glandular epi develop at the end stages?
connection to epithelial surface disappears, must secrete into bloodstream
how does exocrine glandular epi develop at the end stages?
connection to epithelial surface remains, forms ducts
list the 3 types of exocrine glands as defined by how the products leaves the cell
merocrine, apocrine, holocrine
describe merocrine cells, give examples
none of the cell is damaged or lost when the product is secreted or excreted, the most common (salivary glands, pancreas in exocrine fashion)
describe apocrine cells, give example
products are released as fragments of gland cells, product accumulates at free end of cell, then pinched off, and any organelles in free end are released, regeneration required (mammary glands)
describe holocrine glands, give example
entire cell is lost with product, least common, needs regeneration (sebacious glands of skin and eyes)
