Epithelial Tissue Flashcards Preview

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Flashcards in Epithelial Tissue Deck (32):
1

epithelial tissue
-functions

-protection (barrier against disease)
-slows loss of extracellular fluid and nutrients (burn victims lose this function)
-transcellular transport (active movement across cell)
-absorption of nutrients (selective permeability)
-secretion (glands, choroid plexus)
-sensation
-contractility (glandular secretion; myoepithelium)

2

types of epithelium based on embryology and where are they located?

ectoderm
-epidermis of skin
mesoderm
-endothelial lining of blood vessels
endoderm
-simple epithelial lining of the GI tract

3

what separates the epithelium from all of the tissues that it covers

basement membrane

4

basement membrane
-layers

basal lamina
reticular lamina

5

basal lamina of basement membrane
-secreted by
-layers

secreted by epithelial tissue
layers
-lamina lucida
-lamina densa

6

lamina lucida
-composed of...

glycoprotein
-e.g. Laminin
integrins and dystroglycans (bound by laminin)

7

lamina densa
-composed of...

proteoglycan
-Heparan sulfate
fine fibrils of collagen type IV
-bound by laminin
collagen type VII anchoring fibrils

8

reticular lamina
-secreted by...
-composition

secreted by the fibroblasts of the underlying connective tissue
composition
-collagen fibers types I and III that loop into and bind with anchoring fibrils (collagen type VII)
-anchoring plaques of collagen type IV

9

reticular lamina
-function

anchors basal lamina to underlying connective tissue by way of the extracellular fiber matrix

10

epithelium cell type

polyhedral cell (multi-sided)

11

how are epithelial cells named?
-examples (3)

named by their shape
-squamous (flat)
-cuboidal (centrally located nucleus)
-columnar (apical and basal border with nucleus usually located basally)

12

epithelium cellular arrangements

simple
stratified
transitional
pseudostratified

13

simple epithelium
-location and characteristics

single cell layer
endothelial lining of blood vessel, pulmonary alveoli

14

stratified epithelium
-characteristics and location

more than one layer
may be keratinized (skin) or non-keratinized (moist areas; oral epithelium, vagina, rectum)

15

transitional
-characteristics

looks like multiple unorganized layers

16

pseudostratified
-characteristics

looks like more than one layer when they actually aren't

17

epithelial cellular connections (6)

terminal bars
zonula occludentes (tight junctions)
zonula adherentes
macula adherentes (desmosomes)
gap junctions
hemidesmosomes

18

terminal bars
-location
-functions

location
-attachments surrounding epithelial cells
functions
-provide integrity of the epithelial surface
-provide protection/transport of substances across epithelial membrane

19

zonula occludentes (tight junctions)
-location
-function
-layers

location
-barrier around entire apical end of cells
functions
-prevents material from taking paracellular route in passing from the lumen into the connective tissue
-aka eliminates intercellular space so material must pass through cell
layers
-occludin
-claudins

20

zonula adherentes
-location
-components

location
-cell to cell near the apical border (not always complete around the cell)
-basal to tight junction
components
-cadherins: bind to each other in intercellular space
-transmembrane linker proteins with actin molecules

21

macula adherentes (desmosomes)
-location
-function
-what do they look like

location
-randomly arranged along the lateral cell
disc-shaped plaques that function to attach adjacent cells

22

gap junctions
-function

couple adjacent cells metabolically and electrically by allowing small molecules and ions to pass between cells

23

hemidesmosomes
-function/location

attach epithelial cells to underlying basal lamina

24

cellular specializations of epithelium

microvillus
stereocilia
cilia
glands
flagella
serous glands
-protein-secreting (use rER)
mucous glands
-goblet cells of the gut
-apical end filled with hydrophilic mucin

25

epithelial cell types and their products

ion transport
pinocytosis
neurocrine
paracrine
endocrine
myoepithelial cells

26

ion transport
-what is the function of the cells responsible for this?

magensium dependent Na+/K+ ATPase pump
pushes Na+ against electrochemical gradient

27

pinocytosis
-what is this process

absorption and excretion of small products or compounds by sequestering the particle in cell membrane

28

neurocrine
-what is it

neurotransmitter

29

paracrine
-what is it?

diffusion of compounds into ECF

30

endocrine
-what is this?

steroids or proteins secreted directly into the vascular system

31

myoepithelial cells
-what are they?
-function

contain contractile elements (irregular)
line ducts for active excretion of contents of gland (lie between epithelial cell and basal lamina)

32

regenerative level of epithelial tissue

high