Skin

Question 1

What is the skin?

Answer 1

Combination of tissues with its own blood supply, accounts for 16% total body weight

• largest organ in the body
• acts as major compartment separator
• helps with homeostasis, sensory reception and protection from external environment

Question 2

What are the three 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

What are the five layers of the epidermis?

Answer 6

• stratum germinativum
• stratum spinosum
• stratum granulosum
• stratum lucidum
• stratum corneum

Question 7

Describe the stratum germinativum

Answer 7

• bound to basement membrane by hemidesmosomes
• bound to other cells by desmosomes
• regular assortment of organelles
• stem cells

Question 8

Describe the stratum spinosum

Answer 8

• spinous layer
• created after cell death
• cells shrink bu desmosome junctions create spines

Question 9

Describe the stratum granulosum

Answer 9

• defined by presence of keratohyalin granules

- accumulations of protein around keratin intermediate filaments

Question 10

Describe the stratum corneum

Answer 10

• keratohyalin converted to keratin
• disulphide linkages give strength
• no organelles
• desmosomes bind cells
• 30 day turnover

Question 11

What two layers compose the dermis?

Answer 11

• papillary layer

- reticular layer

Question 12

Describe the papillary layer

Answer 12

• loose connective tissue
• irregular interface with epidermis
• cellular e.g. macrophages
• blood vessels
• nerve endings

Question 13

Describe the reticular layer

Answer 13

• dense irregular connective tissue
• collagen bundles in 3 planes
• elastic fibres