Epithelial Histology

Question 1

three major morphological characteristics of epithelial tissue types

Answer 1

number of cell layers - simple or stratified

cell shape - flat, square, or rectangular

keratinization - keratinizing or non-keratinizing

Question 2

Name the eight types of epithelial tissue.

Answer 2

simple squamous, simple cuboidal, simple columnar, stratified squamous, transitional, ciliated pseudostratified, stratified cuboidal, stratified columnar

Question 3

simple squamous epithelium

Answer 3

make out intact sheets sittin on a basement membrane, flattened nuclei, used to pass nutrients from two mediums

Question 4

simple cuboidal epithelial cells

Answer 4

usually lines ducts, cells look like squares, nuclei look like perfect circles

Question 5

simple columnar epithelium

Answer 5

cells taller than they are wide, height can vary and nuclei freequency appear elongated in cross-section, commonly found at absorptive surfaces, when occupied by cilia called simple columnar ciliated epithelium

nuclei no longer perfect circle

Question 6

goblet cells

Answer 6

modified columnar epitheliall cells involved in mucous production and secretion

Question 7

non-keratinizing stratified squamous epithelium

Answer 7

found vovering certain internal body surfaces such as the oral cavity, basal cells are cuboidal in form but top outermost layer is squamous

color gets paler because less nutrients near the top

Question 8

keratinizing stratified squamous epithelium

Answer 8

18-30 layers of dead cells compacted on top of each other, prevents dehydration

outermost cells are squamous, filled with hard keratin protein material

dead cells sometimes called corneocytes

Question 9

stratified cuboidal

Answer 9

quite rare, layers of cuboidal cells, outer cells do not flatten out

Question 10

stratified columnar epithelium

Answer 10

rare, in salivary gland, lack of cilia and no basal bodies

Question 11

transitional epithelium

Answer 11

mainly found in bladder, important characteristic is the dome-like appearance of the outer layer of cells, able to stretch out when needed, nuclei start to become larger toward apical side

also has plaque-like structure at the apical end

Question 12

pseudo-stratified epithelium

Answer 12

round nuclei and goblet cells, every cell has a direct connection to the basement membrane

presence of cilia, basal body easy to recognize

found in larger airways of the respiratory system

Question 13

specializations of the apical surface

Answer 13

microvilli, cilia, and stereocilia

Question 14

specialization of the lateral domain

Answer 14

tight junctions, adherens junctions, desmosomes, gap junctions

Question 15

specializations of the basal domain

Answer 15

hemidesmosome

Question 16

microvilli

Answer 16

hard to resolve at the light microscope level, actin-filled extensions from the apical surface of epithelial cells in tissues like the gut

called brush border when cells have a plethora of these structures, important for absorption by increasing apical membrane surface area

Question 17

cilia

Answer 17

mucrotubule based cell surface extension, formed by 9 outer microtubule doublets and 2 inner singlets called the axoneme

used to move materials over the apical surface

non-motile cilia have a distinct 9+0 arrangement

basal body is the large proteniacious mass at the bottom of cilia

Question 18

sterocilia

Answer 18

more closely related to microvilli, very thin, long extensions of the apical surface and contain actin filaments at their core

likely to increase absorptive surface where they are formed

Question 19

terminal bars

Answer 19

apical junctional complexes of simple epithelial cells

poorly resolved group of junctional complexes present at the apical aspect of the lateral membrane domain

Question 20

tight junctions

Answer 20

also known as zonula occludens

act as a barrier or gate to the passage of materials from the lumen into the connective tissue, also has fence function to prevent the free flow of membrane proteins from the apical to the basolateral membrane domain

exist in simple and stratified epithelia (outer layer)

Question 21

adherens junction

Answer 21

also known as zonula adherens

small gap between contacting membranes filled by extracellular domains of adhesion molecules called cadherins

dense cytoplasmic plaque to which actin microfilaments can be found

work to adhere cells together and is involved in tissue morphogenesis as well as cell-cell comunication

Question 22

desmosome

Answer 22

also known as the macula adherens

cadherins in intercellular space bind to each other, connected to a keratin network in the intracellular space

gives stretching ability to cells, main function is adhesion

also have a role in signaling between contacting cells

Question 23

gap junctions

Answer 23

complex provides direct pore between two closely apposed membranes and allows the passage of small molecules between cells

primarily involved in cell-cell communication

six connexin molecules make one connexon and two connexons interact to form a gap junction

allows through molecules less than 1 kDa

Question 24

hemidesmosome

Answer 24

engaged keratin network though molecular organization

link epithelial cells to the BM

transmembrane receptors involved in signaling

Question 25

exocrine gland

Answer 25

secretion onto a body surface via a duct

Question 26

merocrine

Answer 26

cells secrete product via exocytosis

Question 27

apocrine

Answer 27

secretion is surrounded by a thin layer of cytoplasm within vesicles of cell membrane

Question 28

holocrine

Answer 28

cell contents are sloughed off as part of secretion

Question 29

endocrine

Answer 29

secretion into the blood stream via adjacent capillaries, endocrine glands have no ducts

Question 30

paracrine

Answer 30

secretion affects nearby cells, glands are unicellular

Question 31

unicellular glands

Answer 31

gland is made up of one cell such as goblet cells

Question 32

tubular glands

Answer 32

secretory epithelial cells arranged in a tube that also serves as a duct

Question 33

acinar glands

Answer 33

have a duct with a secretory cluster of cells at the end of an acinus, acini are serous (contain a watery section) or mucous

Question 34

three types of gland arrangement

Answer 34

simple tubular, brancehd tubular, compound

Question 35

parenchyma

Answer 35

the functioning epithelial component of glands or organs

Question 36

stroma

Answer 36

the supporting connective tissue framework of glands or organs