Epithelial Tissue

Question 1

epithelial tissue

-functions

Answer 1

• 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)

Question 2

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

Answer 2

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

Question 3

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

Answer 3

basement membrane

Question 4

basement membrane

-layers

Answer 4

basal lamina

reticular lamina

Question 5

basal lamina of basement membrane

• secreted by
• layers

Answer 5

secreted by epithelial tissue
layers
-lamina lucida
-lamina densa

Question 6

lamina lucida

-composed of…

Answer 6

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

Question 7

lamina densa

-composed of…

Answer 7

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

Question 8

reticular lamina

• secreted by…
• composition

Answer 8

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

Question 9

reticular lamina

-function

Answer 9

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

Question 10

epithelium cell type

Answer 10

polyhedral cell (multi-sided)

Question 11

how are epithelial cells named?

-examples (3)

Answer 11

named by their shape

• squamous (flat)
• cuboidal (centrally located nucleus)
• columnar (apical and basal border with nucleus usually located basally)

Question 12

epithelium cellular arrangements

Answer 12

simple
stratified
transitional
pseudostratified

Question 13

simple epithelium

-location and characteristics

Answer 13

single cell layer

endothelial lining of blood vessel, pulmonary alveoli

Question 14

stratified epithelium

-characteristics and location

Answer 14

more than one layer

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

Question 15

transitional

-characteristics

Answer 15

looks like multiple unorganized layers

Question 16

pseudostratified

-characteristics

Answer 16

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

Question 17

epithelial cellular connections (6)

Answer 17

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

Question 18

terminal bars

• location
• functions

Answer 18

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

Question 19

zonula occludentes (tight junctions)

• location
• function
• layers

Answer 19

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

Question 20

zonula adherentes

• location
• components

Answer 20

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

Question 21

macula adherentes (desmosomes)

• location
• function
• what do they look like

Answer 21

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

Question 22

gap junctions

-function

Answer 22

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

Question 23

hemidesmosomes

-function/location

Answer 23

attach epithelial cells to underlying basal lamina

Question 24

cellular specializations of epithelium

Answer 24

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

Question 25

epithelial cell types and their products

Answer 25

ion transport
pinocytosis
neurocrine
paracrine
endocrine
myoepithelial cells

Question 26

ion transport

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

Answer 26

magensium dependent Na+/K+ ATPase pump

pushes Na+ against electrochemical gradient

Question 27

pinocytosis

-what is this process

Answer 27

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

Question 28

neurocrine

-what is it

Answer 28

neurotransmitter

Question 29

paracrine

-what is it?

Answer 29

diffusion of compounds into ECF

Question 30

endocrine

-what is this?

Answer 30

steroids or proteins secreted directly into the vascular system

Question 31

myoepithelial cells

• what are they?
• function

Answer 31

contain contractile elements (irregular)

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

Question 32

regenerative level of epithelial tissue

Answer 32

high