Epithelium-Leture 9/13/21

Question 1

Epithelium

Answer 1

Form continuous sheet lining free surface

Question 2

Characteristics of epithelial (3)

Answer 2

• Polarized, free spiral surface and basal surface
• Express keratin intermediate filaments
• All avascular

Question 3

Apical surface

Answer 3

Faces towards the lumen of the cell

Question 4

Basal surface

Answer 4

Attached to basal lamina or basement membrane

Question 5

Epithelial function (8)

Answer 5

• Protection
• Surface transport (cilia)
• Absorption
• Secretion
• transepithelial transport
• reproductive
• Special sensory
• Contraction

Question 6

Epithelial cell types (6)

Answer 6

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

Question 7

Simple squamous

Answer 7

One layer of thin cells flat irregular shape

Question 8

Simple cuboidal

Answer 8

One layer of cubed epithelium

Question 9

Simple columnar

Answer 9

One level of long, column like epithelium

Question 10

Stratified columnar

Answer 10

Cells closest to the lumen have columnar shape, more than one layer

Question 11

SSKE

Answer 11

Stratified squamous keratinizing epithelium, has dead protecting layer like skin

Question 12

SSNKE

Answer 12

Stratified squamous non-karatinizing epithelium, cells go all the way to the lumen

Question 13

Pseudostratified

Answer 13

Looks stratified, but all cells attach to basal lamina but don’t necessarily span the whole layer, typically have cilia

Question 14

Transitional

Answer 14

Only found in urinary tract, umbrella cells large top layer (often bind cleave)

Question 15

Characteristics of apical surface (4)

Answer 15

• Microvilli
• Glycocalyx
• Cilia
• Stereocilia

Question 16

Characteristics of Basal Surface

Answer 16

• Hemidesmosomes
  Basal lamina
  Basal invaginations
  Basal evaginations

Question 17

Characteristics of the Lateral surface

Answer 17

• Zonula occludens
• Zona adherins
• Macula adherins (desmosomes)
• Gap junctions

Question 18

Zonular junctional complexes

Answer 18

Unites epithelial cells and form apical barrier, includes zonula occludens and zonula adherins

Question 19

Zonula Occludens

Answer 19

Aka tight junctions, regulate apical border seal and create apical and basso lateral domains

Question 20

Proteins involved in tight junctions

Answer 20

Occludin, Claudin (transmembrane proteins)

Actin (anchors to cells)

Question 21

Zonula adherens

Answer 21

Also called Cadherins, Ca2+ dependent intercellular linkages continuous with the actin cytoskeleton, resists mechanical stress and sends signals

Question 22

Macula communicans

Answer 22

Gap junctions that form a channel for ions and other stuff to pass through

Question 23

Proteins of gap junctions

Answer 23

Cluster of 6 connexins form one connexon

Question 24

Structure of basal lamina

Answer 24

Mainly comprised of a chicken wire complex made of collagen type IV and laminitis connected by nidogen

Question 25

Reticulum lamina

Answer 25

Under basal lamina, made up of collagen type III

Question 26

Roles of basal lamina (5)

Answer 26

- Physical support for epithelial - Roles in development, morphogenetic, and differentiation - Role in cell migration following injury - Filtration barrier - May be discontinuous

Question 27

Types of epithelial glands

Answer 27

- Unicellular - Multicellular, simple (unbranched duct) - Multicellular, compound (branched duct)

Question 28

Exocrine glands

Answer 28

Maintain contract with surface epithelium, secretes into lumen

Question 29

Endocrine glands

Answer 29

Lose contact with surface epithelium, secrete to interstitial space

Question 30

Modes of secretion (3)

Answer 30

- Merocrine - Apocrine - Holocrine

Question 31

Merocrine

Answer 31

Exocytosis, only the product is released

Question 32

Typical secretion from Merocrine glands

Answer 32

- Zymogens - Sweat - Mucus - Lysozyme

Question 33

Apocrine

Answer 33

Aka decapitation secretion, a portion of the apical cytoplasm is released along with product

Question 34

Holocrine

Answer 34

The entire cell and its contents (sebum) become the secretory product, cell borders disappeared, nucleus degenerates, cytoplasmic droplets coalesce

Question 35

Serous glands

Answer 35

- Watery secretion - Abundant RER - Round nucleus - Cells well stained

Question 36

Mucous glands

Answer 36

- Thick secretion - Clear cytoplasm - Flat nucleus - Cells poorly stained

Question 37

Myoepithelial cells

Answer 37

Aka basket cells, contract in order to help expel secretory products