2. Structure & Function of the Skin

Question 1

Functions of the skin

Answer 1

Barrier - Water loss, microorganisms (physical), UV radiation

Temp regulation - dilation/constriction of blood vessels

Excretory organ - sweat, salt, toxins, drugs

Vit D synthesis - important for bone growth

Sense organ - touch, pressure, heat, cold, pain

Question 2

Structure of the skin - how many layers?

Answer 2

3 layers:

Epidermis

Dermis

Hypodermis

Question 3

Epidermis - How many zones?

Answer 3

5 Zones:

1. Stratum Basale -
2. Stratum Spinosum -
3. Stratum Granulosum
4. Stratum Lucidum - only present in thick skin
5. Stratum Corneum -

Question 4

Epidermis: Cell types

Answer 4

1. Melanocytes - produce & store melanin
2. Langerhan’s cells - dendritic cells involved in immune response
3. Merkel cells - involved with touch

Question 5

Epidermal proteins

Answer 5

1. Keratin - structural component of outer skin, hair & nails. It forms intermediate filaments which are tough and insoluble, providing strength, protection & waterproofing.
2. Melanin - production occurs after exposure to UV radiation. It is released by melanocytes & taken up be keratinocytes. Protects skin cells from UV radiation damage.

Question 6

Attachment of epidermis to dermis

Answer 6

Epidermis attached to dermis by basement membrane, forming epidermal ridges. Leads to formation of structures such as fingerprints

Question 7

Dermis - how many layers

Answer 7

2 layers:

1. Papillary layer: Loose connective tissue (blood vessels, fibres & macrophages) with open spaces filled with ground substance. This allows movement of immune cells (macrophages) to detect bacteria
2. Reticular layer: Dense irregular connective tissue surrounding hair follicles, blood vessels & glands. This allows movement & absorption of forces in various directions.

Question 8

Dermis: Cell types

Answer 8

1. Fibroblasts - produce collagen & elastin
2. Mast cells - protect against infection, attract immune cells to site of infection (immune response)
3. Macrophages - engulf & remove foreign material, bacteria

Question 9

Dermal proteins

Answer 9

1. Collagen - responsible for skin strength & elasticity. Its degradation leads to wrinkles (ageing)
2. Elastin - Allows skin to return to its original position after stretching/contracting. Ageing leads to loss of elastic fibres.

Question 10

Hypodermis (Subcutaneous layer)

Answer 10

Loose connective tissue & adipocytes (fat cells). Binds skin to underlying tissue, provides padding & thermal insulation

Question 11

Types of skin

Answer 11

Thick skin (Epidermis 400 - 600 μm) - palms of hands inc fingers, soles of feet inc toes

Thin skin (Epidermis 75 - 150 μm) - rest of body

Question 12

Skin derivatives

Answer 12

Extension of the epidermis:

1. Nails
2. Hair
3. Sebaceous glands
4. Sweat glands
   * More on lecture slides/notes*