L1/L2 Epithelium & Glands

Question 1

What are the four basic tissue types?

Answer 1

Epithelium, connective, muscle and nervous

Question 2

Origin of ectoderm epithelia

Answer 2

skin; sweat glands; oral cavity; vagina; anus

Question 3

Origin of mesoderm epithelia

Answer 3

endothelium; mesothelium (lining of body cavities); genital and urinary systems

Question 4

Origin of endoderm epithelia

Answer 4

Esophagus, GI tract; liver; pancreas; respiratory system

Question 5

Primary functions of epithelia

Answer 5

provide a boundary layer through which movement of substances can be regulated; cover or line all body surfaces, except joint cavities (line all passages that connect directly or indirectly to exterior)

Question 6

Diverse functions of epithelia

Answer 6

protection, lining, absorption, secretion, sensation, contractility

Question 7

How long does it take for intestinal epithelia to renew? Epidermal epithelia?

Answer 7

Intestines: 2-3 days; Epidermis: 28 days

Question 8

What does epithelia contain that allows for self renewal?

Answer 8

stem cells, pluripotent cells w/ the capacity to divide asymmetrically, producing copies of itself and more differentiated daughter cells

Question 9

What are the 5 morphological characteristics of epithelia?

Answer 9

1. Continuous sheets, solid organs or glands held together by specialized junctions with little to no intercellular material (closely apposed)
2. avascular
3. basal surface sits on basal lamina
4. polarized
5. numerous apical PM modifications

Question 10

What kinds of junctions exist in epithelia?

Answer 10

Zonula occludens, zonula adherens, desmosomes, and gap junctions

Question 11

Function of zonula occludens

Answer 11

barrier

Question 12

Which epithelial junctions function to provide adhesion?

Answer 12

zonula adherens & desmosomes

Question 13

Function of gap junctions

Answer 13

communication

Question 14

functionality of cytokeratins

Answer 14

insert into desmosomes and confer strength to the tissue

Question 15

What must nutrients do as a result of epithelia’s avascular property?

Answer 15

pass from blood vessels through underlying connective tissue or lamina propria

Question 16

What is the basal lamina

Answer 16

extracellular structure that underlies epithelia and is visible only by EM

Question 17

What is the composition of basal lamina

Answer 17

either lamina desna alone or lamina desna AND lamina lucida; electron dense & 20 to 100mm thick

Question 18

Where are the proteins that make up Basal Lamina? Where are they secreted from?

Answer 18

Type IV collagen, laminin, entactin & proteoglycans; the epithelial cell

Question 19

How do epithelia attach to basal lamina?

Answer 19

via actin-integrin-laminin-type IV collagen connections

Question 20

Why is it important that hemidesmosomes are strengthened? What are they strengthened by?

Answer 20

They are exposed to high levels of stress (ex. skin); cytokeratin-integrin-laminin-type IV collagen connections.

Question 21

Where and how to basal lamina attach?

Answer 21

Reticular lamina va anchoring fibrils composed of type VII collagen

Question 22

What are the (5) functions of basal lamina?

Answer 22

structural support; filter for molecules and cells; req. for cells to maintain polarity & organize mem. proteins; bind growth factors to promote differentiation and proliferation; pathway for cell migration (ex. wound healing)