epi tissue Flashcards
what is called the study of tissues and how they form organs
histology
what are the possible forms of tissues (textures)
solid, semi-solid, soft or liquid
what are the four types of tissues
epithelial, connective, muscular or nervous
what embryonic connective tissue are most body tissues derived from
mesenchyme
what are the 3 embryonic or germ layers and what do they resemble in shape
endoderm, mesoderm and ectoderm
a 3d ball
what is ectoderm
outer covering of the body and nervous tissue
what is endoderm
forms the lining of the body and digestive tract
what is mesoderm
forms everything else like m., lig, cartilage ,b. ,blood, etc.
what is the common purpose of a group of cells
homeostasis
what is epithelial tissue mostly derived from
endoderm but still all 3
what are the four functions of epi tissue
protection, filtration, secretion, excretion
what does protection stand for in epi tissue
epidermis of skin
what does filtration stand for in epi tissue
membranes for nutrient absorption
what does secretion stand for in epi tissue
release mucous, hormones and enzymes
what does excretion stand for in epi tissue
waste products such as CO2, urine
what are the 2 main types of epithelium and where are they located
surface epi; lining and covering
and glandular epi; secretory tissue in glands
what do surface and glandular epi have in common
they are both closely packed cells (cellularity) with hardly any extracellular material (matrix) btw the cells
what is the basement membrane
a non-cellular layer of materials which holds the epithelia to the underlying connective tissue (and gives strength to the epi)
t/f epi tissue is vascular and most connective tissues are avascular
false epi is avascular and most connective tissues are vascular
t/f epi cells have a high ability to divide for repair and renewal
true bc of high wear-and-tear exposure
where does epi tissue lie in order to survive and function
close to tissues that do have blood supply
t/f epi is always covered by another tissue, it never has a free surface
false, its rarely covered by another tissue it always has a free surface
what are the 2 surfaces of epithelium and where is each located
apical surface; faces the body cavity, lumen, ducts, etc.
basal surface; deepest layer, attached to basement mem
what are the 2 layers of the basement mem and what are their main goals
basal lamina (glues epi to the basement mem) and reticular lamina (helps feed to developp new cells and strengthen w collagen)
which layer of the basement mem is closer to the epi cells and contains the proteins laminin (glue) and collagen (strength)
basal lamina
which layer of the basement mem is closer to the underlying connective tissue and contains collagen which is produced by connective tissue cells (fibroblasts)
reticular lamina
what are the possible shapes of epi cells (describe)
squamous; flat and thin
cuboidal; square
columnar; rectangular
transitional; comprised of both squamous and cuboidal cells that form linings of the hollow organs
what is the difference btw simple, stratified and pseudostratified epi
simple; simple row of cells
stratified: 2 or more rows of cells with the name based on the shape of the apical layer
pseudostratified: single row of cells w overlapping sizes but all attached to the basement membrane
whta type of epi cell can be called simple as well
squamous, cuboidal and columnar
whta type of epi cell can be called stratified as well
squamous, cuboidal, columnar and transitional
what are the 2 subclasses of simple squamous epi
endothelium (lines innermost of hollow cavities)
mesothelium (forms epi layer of serous mem)
what are the functions of simple squamous epi
allow rapid passage of substances thru them and lines cardiovascular and lymphatic sys
what are the functions of simple cuboidal epi and simple columnar epi
cuboidal: functions in secretion and absorption
columnar: functions in secretion and absorption, lines digestive tract and forms the ducts of many glands
what is a ciliated and a non-ciliated simple columnar epi
ciliated; the microvilli can move and propel things along
non-ciliated: the microvilli can’t move but their role is to increase surface area
what are the functions of stratified squamous epi (which cells are often dead)
protective layer, cells replace those lost to friction (replaced by cells at the basal layer)
the apical cells (further from the blood so they die)
what is the difference btw keratinized and non-keratinized stratified squamous epi
keratinized: contains protein keratin; tough and water resistant (intended to stay dry like skin)
non-keratinized: found on wet surfaces subject to wear and tear (intended to remain moist)
why are stratified columnar and cuboidal epi rare
because the apical layer is rarely cuboidal or columnar
where is stratified transitional epi found, why is it transitional and what types of epi is it mostly seen as,
found in hollow organs,
bc w the expansion of the organ, the cells slide and flatten
mostly columnar and cuboidal w some squamous
what layers make up an epithelial mem and what two types of epi mem exist
layer of epithelium and a layer of connective tissue
mucous mem (inner lining) and serous mem (outer protective envelope)
what is mucous mem (function, general location, name of connective tissue)
secretes mucous to keep linings moist
found in hollow organs and tracts
connective tissue is the lamina propria
what is serous mem (function, general location, name of 2 sublayers)
secrets fluid for lubrification
line the hollow body cavities mostly in the abdominopelvic cavity, also found in thoracic cavity and covers many of the viscera
visceral and parietal layer
what is glandular epi (function, description, what are the 2 subdivision)
secretion
it is glands developed from specialized epi
exocrine (secreted onto a surface), endocrine (secreted into the blood)
what will endocrine glands always secrete
hormones directly into the blood (the gland’s duct has lost contact with the epithelium)
