epithelium Flashcards
1
Q
epithelial tissue arises from what germ layers
A
all 3 but mostly from ectoderm and endoderm
2
Q
what does epithelia do?
A
- covered exposed surfaces
- lines internal tracts
- line cavities
- form glands
3
Q
2 main types of epithelia
A
covering and glandular
(in these flashcards we focus on covering)
4
Q
cellularity of epithelia
A
continuous layer of cells bound by cell junctions
5
Q
polarity of epithelia; apical and basal surfaces
A
- apical; external environment or internal space, specializations; cilia, microvilli, sterocilia
- basal surface; attached to basement membrane, surfaces differ in structure and function
6
Q
basal surface of cells attached to a
A
basement membrane; thin layer of mucopolysaccharides and proteins
7
Q
epithelia are avascular which means
A
they do not contain blood vessels, they obtain nutrients by diffusion or absorption
8
Q
regeneration of epithelia
A
cells that are damaged or lost at exposed surface are replenished from basal stem cells
high rate or cell division = high mitotic index
9
Q
name 4 roles of epithelia
A
protection, permeability, sensation and secretion
10
Q
how do we classify epithelial types
A
cell arrangement on the basement membrane and cell shape
11
Q
simple
A
one cell layer
12
Q
stratified
A
more than one layer
13
Q
pseudostratified
A
actually one layer because all cells attached to basement membrane but cells of varying height so it appears stratified
14
Q
squamous
A
flattened
15
Q
cuboidal
A
cube shaped
16
Q
columnar
A
tall cells, rectangle
17
Q
transitional
A
variable height and shape
18
Q
8 types of epithelium
A
- simple squamous
- simple cuboidal
- simple columnar
- pseudostratified columnar
- stratified squamous
- stratified cuboidal
- stratified columnar
- transitional
19
Q
where do you find simple squamous epithelium
A
its delicate so found in protected regions
20
Q
what is simple squamous good for
A
allows for easy exchange of gases, ions and small molecules
21
Q
give some examples of where you would find simple squamous
A
lung alveoli, lining of body cavities, heart and blood vessels
22
Q
what may simple cuboidal be involved in
A
secretion, absorption (microvilli) and excretion
23
Q
where do you find simple cuboidal
A
glands, ducts, parts of kidney tubules, thyroid glands
24
Q
what is simple columnar function
A
protection absorption and secretion
25
what do simple columnar cells tend to have
a modified free surface so microvilli, cilia and stereocilia
26
where would you find simple columnar epithelia
lining of stomach, intestines, oviduct, collecting ducts of kidneys
27
is pseudostratified columnar what do you call the the tall and short cells
- tall principal cells
- short pyramidal basal cells
28
in pseudostratified columnar all cells rest on ______ but NOT all cells reach the ______
basement membrane, lumen
29
where would you find pseudostratified columnar
- respiratory tract; nasal cavities, trachea, bronchi, with cilia
- propel mucous and trapped particles to pharynx
- also in epididymis with sterocilia
30
where is stratified squamous found
in regions requiring mechanical protection, such as skin, lining of mouth, esophagus and anus
31
in stratified squamous what where do cells multiply
- the basal cells multiply and move up towards surface, flattening and degenerating as they reach the superficial layers
- basal cells divide continously
- daughter cells pushed to surface as they mature and then degenerate
- the most mature cells are without a nucleus (they are dead)
- eventually shed from surface
32
2 types of stratified squamous
keratinized or non-keratinized
33
non keratinized stratified squamous
kept moist by glandular secretions (ex lining of mouth)
34
keratinized stratified squamous
- keratinized tissue forms where mechanical stress and dehydration are problems (ex skin)
- keratin is a protein
- deposited within cells as they mature
- forms a tough, acellular surface layer as cells die
35
in stratified squamous the basal cells are
cuboidal! they become more squamous as cell mature and progress towards the surface
36
in keratinized stratified squamous describe the 4 major layers (from deepest to most superficial)
- stratum germinativum: germinal layer where new cells form (very bottom layer)
- stratum spinosum; prickle cell layer, many desmosomes (layers that look like normal cuboidal)
- stratum granulosum; granular layer, keratin granules forming (top layer under keratin where looks more squamous and don't see nuclei as clearly)
- stratum corneum; cornfield layer, dead keratinized cells (looks completely different, can't see cells)
37
describe stratified cuboidal
2-3 layers of cells that are cuboidal or low columnar
38
what is function of stratified cuboidal
provides more robust lining than simple cuboidal
39
where would you see stratified cuboidal
- rare
- ducts of salivary glands, sweat glands, mammary glands
40
describe stratified columnar
basal cells are more cuboidal with only apical cells being distinctly columnar
41
where do you see stratified columnar
- rare
- pharynx, epiglottis, urethra, ducts of salivary glands
42
transitional
- stratified
- various cell shapes
- surface cells round
- basal cells cuboidal
- intermediate cells polygonal
- surface cells may be binucleate!!!! 2 nuclei
43
where do you find transitional epithelium
- urinary tract only
- high degree of stretch
- accommodates toxicity of urine
44
simple epithelia indicative of
absorption or secretion
45
stratified epithelia often provide
robust protection
46
example: stratified squamous epithelium provides
protection to a surface subjected to wear & tear
47
example; columnar cells with microvilli indicate
absorption
48
example; a simple squamous covering suggests
passive transport
49
Which of the following statements about epithelia is INCORRECT?
Epithelia display cellularity in that they are a continuous layer of cells bound by cell junctions
Epithelia display polarity in that they have an apical surface that is exposed to the external environment or internal space, and a basal surface that is attached to a basement membrane
Epithelia display regeneration in that they have a high rate of cell division that replaces cells that are lost or damaged at the exposed surface
Epithelia display vascularity in that they have an extensive network of blood vessels that supply nutrients and remove waste products from the cells
Epithelia display vascularity in that they have an extensive network of blood vessels that supply nutrients and remove waste products from the cells
50
Which of the following statements about epithelia is INCORRECT?
Transitional epithelium is found only within the urinary tract and in transverse section can be seen to be a pseudostratified epithelium
Simple cuboidal epithelia may be involved in secretion or absorption and are found in the ducts of glands and the follicles of the thyroid
Simple columnar epithelia function in absorption and secretion, and so often have an apical surface modified with microvilli or cilia
Keratinised stratified squamous epithelium is located in areas of the body where mechanical abrasion and dehydration may occur; consequently, the stratum corneum forms a protective layer that is acellular
Transitional epithelium is found only within the urinary tract and in transverse section can be seen to be a pseudostratified epithelium
51
Which of the following statements about epithelia is INCORRECT?
Epithelia display avascularity in that they lack a blood supply and so obtain nutrients by diffusion or absorption
Epithelia display cellularity in that they are a continuous layer of cells bound by cell junctions and where the basal surface of all cells is attached to a basement membrane
Epithelia display polarity in that they have a basal surface and an apical surface that may possess specialisations such as cilia, microvilli, and stereocilia
Epithelia display regeneration in that they have a high rate of cell division that replaces cells that are lost or damaged at the exposed surface
Epithelia display cellularity in that they are a continuous layer of cells bound by cell junctions and where the basal surface of all cells is attached to a basement membrane
52
Which of the following statements about epithelia is INCORRECT?
Transitional epithelium is stratified, has a high degree of stretch, and is found only within the urinary tract
Simple cuboidal epithelia may be involved in secretion or absorption and are found in the ducts of glands and the follicles of the thyroid
Pseudostratified columnar epithelium lines the nasal cavities, trachea, and bronchi, where the cilia on its apical surface trap particles and propel mucous
Keratinised stratified squamous epithelium is characterised by 4 strata of cells, with the stratum granulosum forming the upper-most layer of dead, heavily keratinised cells
Keratinised stratified squamous epithelium is characterised by 4 strata of cells, with the stratum granulosum forming the upper-most layer of dead, heavily keratinised cells
