Skin

Question 1

Describe skin as an organ

Answer 1

The skin is a combination of tissues. It has its own blood supply and accounts for 16% of the total body weight. It is the largest organ in the body and acts as a major compartment separator. It also helps with body homeostasis, sensory reception, and protects us from the external enviroment.

Question 2

Name the layers of the skin?

Answer 2

Epidermis
Dermis
Hypodermis

Question 3

Describe the epidermis?

Answer 3

Epithelium

Forms boundary between internal and external compartments

Question 4

Describe the Dermis?

Answer 4

Connective tissue

Gives structural strength

Question 5

Describe the Hypodermis?

Answer 5

Fat

Question 6

How many layers are present in the epidermis?

Answer 6

5

Question 7

Name the 5 layers of the epidermis?

Answer 7

Stratum Germinativum 
Stratum Spinosum
Stratum Granulosum
Stratum Lucidum 
Stratum Corneum

Question 8

What is stratum germinativum?

Answer 8

Bound to basement membrane by hemidesmosomes
Bound to other cells by desmosomes
Regular assortment of organelles
stem cells

Question 9

What are stratum spinosum

Answer 9

Spinous layer
Created after cell death
Cells shrink but desmosome junctions create “spines”

Question 10

What is stratum granulosm

Answer 10

Defined by the presence of keratohyalin granules

Accumulations of protein around keratin intermediate filaments

Question 11

What is Stratum Lucidum (Stratum corneum)

Answer 11

Stratum lucidum are difficult to identify
Keratohylin converted to keratin
disulphide linkage gives strength 
No organelle
Desmosomes bind cells
30 day turnover

Question 12

Describe the organization of connective tissue in the dermis?

Answer 12

The dermis is composed of 2 layers

Papillary Layer 
- Loose connective tissue
- Irregular interface with epidermis
- Cellular e.g macrophages
- Blood vessels
Nerve endings

Reticular Layer

• Dense irregular connective tissue
• Collagen bundles in 3 planes
• Elastic fibers