Lectures 4-5: Epithelial Tissue Flashcards by Morgan Reich

functions of epithelial tissue (5)

-sensory detection
-absorption
-secretion
-transport
-protection

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epithelial structure: rules (4)

-avascular
-covers body surfaces
-lines internal, closed body cavities and tubes (like blood vessels)
-constitutes glands

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how do epithelial cells exhibit polarity

-cells closely positioned and attached to one another
-attached basally to basement membrane
-face into a lumen or to outside world

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3 domains of epithelial cells

-apical
-lateral
-basal

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apical domain definition

borders on the lumen

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lateral domain definition

borders on neighboring cells

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basal domain definition

borders on basement membrane, related to underlying connective tissue

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microvilli function

extend into lumen to increase surface area for absorption

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where are microvilli found

intenstines and kidney tubules

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microvilli aka

brush border or striated border

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microvilli structure (4)

-villin at top
-actin core
-terminal web
-intermediate filaments

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function of glycocalyx

increase surface area for absorption

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glycocalyx structure

carbohydrate chains linked to membrane proteins or lipids

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cilia definition

mobile, hair like structures extending from dark basal bodies

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is glycocalyx associated with cilia? why

no, no absorption

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how do cilia move and why

all in same direction for a specific purpose

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how is core of cilia different from microvilli

cilia have core of microtubules

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microtubules arrangement

9 + 2 (9 peripheral doublets and 2 central singlets )

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function of basal bodies

anchor cilia

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arrangement of basal bodies (2 different ways)

-9 triplets (9 groups of 3)
-turn into 9+2 as they extend into cilium

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3 functions of lateral domain

-form selective barrier for things to go through or between
-adherence
-communication between cells

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absorption takes place in which domains

apical mostly, some in lateral

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3 parts of junctional complex: epithelial cells (list both names)

-zonula occludens (tight junction)
-zonula adherens (intermediate junction)
-macula adherens (desmosome/spot junction)

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list junctions from most apical to basal

-zonula occludens is most apical
-desmosome is most basal

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main functions of zonula occuldens/tight junction (2)

-form protective barrier between epithelial cells (first line of defense) -separate luminal space from intercellular space and connective tissue

how can the tight junction change

can be really tight or leaky depending on tissue type (would want it to be very tight in blood brain barrier to prevent substances from entering)

zonula occludens: how does it work

-plasma membranes of 2 neighboring epithelial cells are joined together intermittently -will separate and come back together for contact before separating again

leakiness of zonula occludens is related to what

number of ridges and grooves

after zonula occludens, do cells every come back together

zonula adherens main function

cell to cell adhesion, but cells do not contact each other directly

2 components found in zonula adherens

-actin -intermediate filaments

what joins cell cytoskeletons together: epithelial cells

linking proteins

main function of desmosomes

cell to cell adhesion, but cells don't touch

macula adherens/desmosome structure

-attachment plaques -intermediate filaments -linking proteins

attachment plaques function

-associate with intermediate filaments to provide more structure and stability for desmosome

what are spot welds in desmosome/macula adherens

small dot of adhesion attached to intermediate filaments

are gap junctions part of the junctional complex

gap junction definition

-specialized lateral domain

main function of gap junction

exchange or signaling between adjacent cells

how do gap junctions work

-2 cells approach each other and get very close (2 nm wide gap) -allows for direct passage of signaling molecules from one cell to another

where are gap junctions found (what kind of tissues)

-tissues that accomplish coordinated functions -cardiac muscle, neurons, rods and cones

gap junction structure (2)

-2 cell membranes -communicating connexons

connexons can be ______ or __________

open, closed

how connexons work

connexons come together between 2 cell membranes -substances pass through connexons

what substances can't enter the connexon

substances in intracellular space

can substances in the connexon can't leak into the intracellular space

what is the lateral domain composed of

junctional complex and gap junctions

which way does the basal domain face

towards basement membrane

what is basement membrane stained with

periodic acid schiff

2 components of basement membrane

-basal lamina -reticular lamina

2 ways epithelial cell attaches to basal lamina

-hemidesmosomes -focal adhesions

hemidesmosome means

1/2 desmosome

hemidesmosomes are associated with

attachment plaques and intermediate filaments

function of attachment plaque

attach cell to basal lamina

attachment plaques are associated directly with

intermediate filaments

focal adhesions are important for

mechanoreception and propioception

focal adhesions are associated with

actin filaments

classification of covering epithelium: 2 main ways (general)

-number of cell layers -shape of cell closest to lumen or outside world (apical)

in terms of number of cell layers, epithelial cells can be __________ or ______________

simple, stratified

simple epithelium definition

-one layer -every single cell touches the basement membrane

3 epithelial cell shapes

-squamous -cuboidal -columna

stratified epithelium definition

more than 1 layer

how are stratified epithelium named

for shape of cells in apical layer

2 types of stratified epithelium

-keratinized -non keratinized

keratinized stratified epithelium

-not alive, no nuclei -toughest -makes up most skin

pseudostratified epithelium are always what shape

columnar

is pseudostratified epithelium simple or stratified

simple

feature of simple epithelium

basal cells which don't go up all the way to lumen but still touch basement membrane

transitional epithelium is a subtype of which kind of epithelium

stratified

transitional epithelium unique feature

rounded surface cells gives epithelial cells distensible property

transitional epithelium is only found in which organ

urinary bladder

transitional epithelium aka

urothelium

apical cells of transitional epithelium are rounded when

no urine is in bladder

glands are created partially from

epithelial tissue

2 types of subtissue that create glands

-parenchyma -stroma

parenchyma: origination and function

-created from epithelial cells -working cells -secrete mucous, sweat, etc

stroma: origination and functions

-created from connective tissue -supporting tissue

2 kinds of glands: general

endocrine and exocrine

endocrine glands: function

secrete hormones into blood or lymphatic vessels located in connective tissue

exocrine glands function

secrete into ducts

where does secretion take place normally (apical or basal)

apical

endocrine glands exhibit what unique features (2)

-ductless, no lumen -polarized towards basement membrane instead of apical surface (reverse polarity)

where do endocrine secretions go

into blood vessels (capillaries) in stroma

2 types of endocrine secretion

-regulated -constitutive

constitutive endocrine secretion

endocrine cells that secrete steroid hormones

in endocrine cells, which organelle is likely in abundance

smooth ER

regulated endocrine secretion

secretion is regulated by stimulus

2 ways exocrine glands are classified

-structure -type of secretion

structure of exocrine glands can be divided into 2 parts:

-branching of ducts -shape of secretory unit

2 types of branching: exocrine glands

-simple (little to no branching) -compound (multiple layers)

2 shapes of secretory unit: exocrine glands

-tubular -acinar (berry shaped)

2 types of secretion: exocrine glands

-serous (watery) -mucous

serous secreting compound glands: structure/appearance

-cells are apical to duct -nucleus is always basal -secretion is apical -pyramidal shape

under light EM, are mucous cells or serous cells darker

serous cells

what organelle is abundant in basal portion of cell of serous secreting glands

rough ER

where is golgi complex located in serous secreting compound glands

above nucleus, near secretory granules

where are secretory vesicles located in cell of serous secreting glands

apical cytoplasm near lumen

how are mucous secreting glands classified as epithelium

pseudostratified columnar epithelium

example of mucous secreting gland

goblet cells

what do goblet cells secrete specifically

mucins (hydrophilic glycoproteins)

organelles present and orientation difference between serous and mucous cells?

how to tell serous and mucous cells apart

-mucous: lumen tend to be larger, nuclei look compressed because mucous is heavy

Lectures 4-5: Epithelial Tissue Flashcards

(103 cards)