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AGRC1041 > epithelium > Flashcards

epithelium Flashcards

1
Q

epithelial tissue arises from what germ layers

A

all 3 but mostly from ectoderm and endoderm

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2
Q

what does epithelia do?

A
  • covered exposed surfaces
  • lines internal tracts
  • line cavities
  • form glands
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3
Q

2 main types of epithelia

A

covering and glandular

(in these flashcards we focus on covering)

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4
Q

cellularity of epithelia

A

continuous layer of cells bound by cell junctions

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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
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6
Q

basal surface of cells attached to a

A

basement membrane; thin layer of mucopolysaccharides and proteins

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7
Q

epithelia are avascular which means

A

they do not contain blood vessels, they obtain nutrients by diffusion or absorption

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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

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9
Q

name 4 roles of epithelia

A

protection, permeability, sensation and secretion

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10
Q

how do we classify epithelial types

A

cell arrangement on the basement membrane and cell shape

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11
Q

simple

A

one cell layer

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12
Q

stratified

A

more than one layer

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13
Q

pseudostratified

A

actually one layer because all cells attached to basement membrane but cells of varying height so it appears stratified

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14
Q

squamous

A

flattened

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15
Q

cuboidal

A

cube shaped

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16
Q

columnar

A

tall cells, rectangle

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17
Q

transitional

A

variable height and shape

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18
Q

8 types of epithelium

A
  • simple squamous
  • simple cuboidal
  • simple columnar
  • pseudostratified columnar
  • stratified squamous
  • stratified cuboidal
  • stratified columnar
  • transitional
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19
Q

where do you find simple squamous epithelium

A

its delicate so found in protected regions

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20
Q

what is simple squamous good for

A

allows for easy exchange of gases, ions and small molecules

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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
Q

what do simple columnar cells tend to have

A

a modified free surface so microvilli, cilia and stereocilia

26
Q

where would you find simple columnar epithelia

A

lining of stomach, intestines, oviduct, collecting ducts of kidneys

27
Q

is pseudostratified columnar what do you call the the tall and short cells

A
  • tall principal cells
  • short pyramidal basal cells
28
Q

in pseudostratified columnar all cells rest on ______ but NOT all cells reach the ______

A

basement membrane, lumen

29
Q

where would you find pseudostratified columnar

A
  • respiratory tract; nasal cavities, trachea, bronchi, with cilia
  • propel mucous and trapped particles to pharynx
  • also in epididymis with sterocilia
30
Q

where is stratified squamous found

A

in regions requiring mechanical protection, such as skin, lining of mouth, esophagus and anus

31
Q

in stratified squamous what where do cells multiply

A
  • 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
Q

2 types of stratified squamous

A

keratinized or non-keratinized

33
Q

non keratinized stratified squamous

A

kept moist by glandular secretions (ex lining of mouth)

34
Q

keratinized stratified squamous

A
  • 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
Q

in stratified squamous the basal cells are

A

cuboidal! they become more squamous as cell mature and progress towards the surface

36
Q

in keratinized stratified squamous describe the 4 major layers (from deepest to most superficial)

A
  • 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
Q

describe stratified cuboidal

A

2-3 layers of cells that are cuboidal or low columnar

38
Q

what is function of stratified cuboidal

A

provides more robust lining than simple cuboidal

39
Q

where would you see stratified cuboidal

A
  • rare
  • ducts of salivary glands, sweat glands, mammary glands
40
Q

describe stratified columnar

A

basal cells are more cuboidal with only apical cells being distinctly columnar

41
Q

where do you see stratified columnar

A
  • rare
  • pharynx, epiglottis, urethra, ducts of salivary glands
42
Q

transitional

A
  • stratified
  • various cell shapes
  • surface cells round
  • basal cells cuboidal
  • intermediate cells polygonal
  • surface cells may be binucleate!!!! 2 nuclei
43
Q

where do you find transitional epithelium

A
  • urinary tract only
  • high degree of stretch
  • accommodates toxicity of urine
44
Q

simple epithelia indicative of

A

absorption or secretion

45
Q

stratified epithelia often provide

A

robust protection

46
Q

example: stratified squamous epithelium provides

A

protection to a surface subjected to wear & tear

47
Q

example; columnar cells with microvilli indicate

A

absorption

48
Q

example; a simple squamous covering suggests

A

passive transport

49
Q

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

A

Epithelia display vascularity in that they have an extensive network of blood vessels that supply nutrients and remove waste products from the cells

50
Q

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

A

Transitional epithelium is found only within the urinary tract and in transverse section can be seen to be a pseudostratified epithelium

51
Q

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

A

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
Q

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

A

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

AGRC1041 (20 decks)

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