Lecture 2: Epithelium

Question 1

What germ layers is epithelial derived from?

Answer 1

mesoderm, ectoderm, endoderm (All of them)

Question 2

Skin is derived from what germ layer?

Answer 2

ectoderm

Question 3

blood vessels are derived from what germ layer?

Answer 3

mesoderm

Question 4

Gut is derived from what germ layer endoderm?

Answer 4

endoderm

Question 5

What are the 6 functions of epithelium?

Answer 5

1. Protection
2. Distention
3. Secretion/excretion
4. Absorption
5. filtration
6. Contraction

Question 6

What are 5 characteristics of epithelia?

Answer 6

1. strong apical - basal polarity
2. avascular
3. littler intercellular space
4. Rests on basement membrane (LM) or basal lamina (EM)
5. Has a high rate of turnover and mitosis after injury (except glands)

Question 7

Describe the apical domain of the epithelium (location and cell specializations)

Answer 7

It is adjacent to lumen / external environment. *Microvili

• sterocilia
• cilia (motile and non motile)

Question 8

Describe the lateral domain (location and cell specializations)

Answer 8

Adjacent to other epithelial cells.

• Occluding (tight) junctions
• Adhering junctions (belt and spot desmosomes), *Communicating (gap) juntions

Question 9

Describe the basal domain of the epithelium (location and cell specializations)

Answer 9

Adjacent to underlying CT

• Basement membrane / basal lamina
• Hemi- desomosomes
• focal contacts

Question 10

What is a brush border where is it found?

Answer 10

Formed by microvilli, it is in intestine and striated border in kidney tubules –> increase surface area

Question 11

What is at the core of microvilli

Answer 11

Have core of actin filaments

Question 12

Where is sterocilia found?

Answer 12

epididymal duct and vas deferens also sensory epithelium of the ear

Question 13

Describe primary ciliary diskinesia

Answer 13

AKA immotile cilia syndrome –> nonfunctional/ absent dynein arms

Question 14

What is the arrangement of non-motile cilia (primary cilia) and function?

Answer 14

9+0 –> sensor of fluid flow (mechanoreceptors) in kidney tubules

Question 15

Tight juntions AKA

Answer 15

zonula occludens- regulates movement of materials between cells, contains occludin and claudins

Question 16

Belt desmosomes AKA

Answer 16

zonula adherens - E-cadherin rich –> lateral adhesion between cells
FASCIA ADHERENS- cardiac muscle cells

Question 17

Spot desmosomes AKA

Answer 17

macula adherens - localized spot attachments between cells.
Plaques - desmoplakins and plakoglobins
Crosslinkers- desmocollin and desmoglein

Question 18

Communicating / Gap Junctions AKA

Answer 18

zonula communicantes -

connexons formed by connexins that can open and close.

Question 19

What is the function of a hemi desmosome?

Answer 19

Anchors intermediate filaments of cytoskeleton into basal lamina

Question 20

What is the function of focal contacts?

Answer 20

anchors actin filaments of cytoskeleton into extracellular matrix

Question 21

What are the two components of basal lamina?

Answer 21

lamina densa and lamina rara

Question 22

What is lamina densa composed of?

Answer 22

Type 4 collagen, entactin, nidogen, perlecan

Question 23

What is lamina rara?

Answer 23

laminin anchored to integrin receptors

Question 24

What forms the glomerular filtration barrier?

Answer 24

Basal lamina of endothelial cell of capillary in glomerulus fusing with basal lamina of kidney podocyte

Question 25

Describe the nucleas shape in squamous, cuboidal, and columnar cells.

Answer 25

Squamous- flattened cuboidal- rounded columnar - elongate nucleus

Question 26

What is the classification of respiratory epithelium?

Answer 26

Pseudostratified ciliated columnar

Question 27

What does transitional epithelium line? (4)

Answer 27

Kidneys, ureters, blader, urethra (AKA urothelium)

Question 28

What type of epithelium lines blood vessels and serous membranes?

Answer 28

Simple squamous epithelium

Question 29

What type of epithelium lines ducts of glands, walls of kidney tubules, and the covering of ovary?

Answer 29

Simple cuboidal epithelium

Question 30

What type of epithelium lines the intestine and gallbladder?

Answer 30

Simple columnar epithelium

Question 31

Stratified squamous nonkeratinized epithelium lines what structures? (5)

Answer 31

oral cavity, esophagus, rectum, anal canal, vagina

Question 32

What type of epithelium forms the epidermis of the skin?

Answer 32

Stratified squamous keratinized epithelium

Question 33

What kind of epithelium lines the ducts of sweat glands?

Answer 33

stratified cuboidal or columnar epithelium

Question 34

What is characteristic of urothelium?

Answer 34

umbrella cells, numerous tight junctions and discoidal vesicles (infolding of cell membrane that allow for distention)

Question 35

Describe the two types of glands.

Answer 35

Exocrine (ducts) | Endocrine (ductless-- secrete into blood vessels)

Question 36

What are unicellular exocrine glands called what do they secrete?

Answer 36

goblet cells --> hydrophilic glycoproteins (mucus)

Question 37

What are 4 mechanisms of secretion in glandular epithelium?

Answer 37

1. Merocrine 2. Apocrine 3. Holocrine 4. Cytocrine

Question 38

Merocrine

Answer 38

exocytosis off apical surface in vesicles (proteins in milk)

Question 39

Apocrine

Answer 39

Part of cytoplasm extruded with secretion (lipids in milk)

Question 40

Holocrine

Answer 40

Cell dies --> part of secretion (Sebaceous gland)

Question 41

Cytocrine

Answer 41

Transfers secretion to another cell (melanocyte transfers melanin into keratinocytes