Epithelial Tissue

Question 1

What are the functions of the skin?

Answer 1

1. Protect body from foreign material and pathogens
2. Prevents loss of body fluid
3. Thermorégulation through heat retention and dissipation
4. Protects body from predators (frog’s poisonous skin)
5. Sensory abilities like touch
6. Communication through visual and pheromonal signals
7. Appendages: hair, nails, sebaceous glands, sweat glands

Question 2

How would you classify skin?

Answer 2

Stratified squamous keratinized epithelium

Question 3

What are the three main layers of the skin?

Answer 3

Epidermis, dermis, hypodermis

Question 4

What are the layers of the epidermis?

Answer 4

Basement membrane
Stratum germinativum
Stratum spinosum
Stratum granulosum
Stratum corneum

Question 5

Is the basement membrane stained?

Answer 5

No

Question 6

Describe the cells in the stratum germinativum

Answer 6

Singular layer of columnar cells

Question 7

What do the cells in the stratum germinativum do?

Answer 7

Either divides and creates copy of itself in the same layer or differentiates

Question 8

Describe the cells in the stratum spinosum

Answer 8

Polygonal shape, has spines between cells

Question 9

What is special about the cells in the stratum granulosum?

Answer 9

They have keratohyalin granules

Question 10

What is the function of keratohyalin granules?

Answer 10

Makes skin waterproof

Question 11

Describe the cells in the stratum corneum?

Answer 11

Flat cells (dead because they burst and released granules)

Question 12

What are the different types of simple epithelia?

Answer 12

Simple squamous (flat)
Simple cuboidal (cube)
Simple columnar (column)

Question 13

What are the types of stratified epithelia?

Answer 13

Stratified squamous (keratinized and non-keratinized)
Transitional

Question 14

What is transitional epithelium?

Answer 14

Tissue changes when expanding

Question 15

What type of epithelia looks stratified but is only one layer?

Answer 15

Pseudostratified columnar

Question 16

What is the basement membrane made of?

Answer 16

Proteoglycans, glycoproteins and collagen

Question 17

What is under the basement membrane?

Answer 17

Reticular fibers

Question 18

What is the proteoglycan made of?

Answer 18

50% sugar and 50% protein

Question 19

What is the function of proteoglycan?

Answer 19

The glycosaminoglycan are negatively charged and hold water

Question 20

What is a glycoprotein made of?

Answer 20

10% sugar and 90% protein

Question 21

How many sugars are there in a proteoglycan?

Answer 21

3 (link trisaccharide)

Question 22

What are the three types of glycoproteins?

Answer 22

Laminin
Nidogen
Fibronectin

Question 23

What is laminin?

Answer 23

Cross shaped glycoprotein
Links surface of epithelial cells to the basement membrane

Question 24

What is nidogen-1?

Answer 24

A small glycoprotein
Essential components for basement membranes

Question 25

What is fibronectin

Answer 25

Adhesive glycoprotein Binds plasma membrane of the epithelial cells to heparan sulfate

Question 26

What types of collagens can be found in the basement membrane?

Answer 26

Type IV: synthesized by epithelial cells Type VII: anchoring filaments Type III: Reticular fibers

Question 27

What is another name for basement membrane

Answer 27

Basal lamina

Question 28

What are the functions of the basement membrane?

Answer 28

1. Structural attachment of epithelial cells to connective tissue. 2. Compartmentalization 3. Filtration: movement of molecules is regulated by ionic charges 4. Helps maintain polarity of epithelial tissues 5. Tissue scaffolding: helps to scaffold regeneration

Question 29

What are the characteristics of all epithelial tissues?

Answer 29

1. Cells are closely associated with little extracellular space 2. Cells are strongly attached via intracellulaire junctions. 3. Line body surfaces and body cavities 4. Specialization: absorption, secretion, sensation, contractility 5. Cells are polarized 6. Epithelial tissues rest on a basement membrane

Question 30

What can be found in the stratum germinativum (or basale)?

Answer 30

Stem cells

Question 31

What can be found in the stratum spinosum?

Answer 31

Desmosomes

Question 32

Where can melanocytes be found?

Answer 32

Between basement membrane and stratum germinativum

Question 33

What do melanocytes do?

Answer 33

Sends melanin granules through finger-like projections and gets phagocytosed by stratum spinosum. Melanin protects the nucleus of the cells

Question 34

What are the two types of melanin?

Answer 34

Eumelanin (brown) Pheomelanin (red)

Question 35

What are the two layers of the dermis?

Answer 35

Papillary layer Reticular layer