The skin

• protection 
• sensory perception 
• thermoregulation 
• excretion of small amounts of water and body waste.
• maintenance of bones and teeth (synthesis of vit D) 
• absorbs fat soluble vitamins and drugs through the skin

• Epidermis 
• Dermis 
• Hypodermis (subcutaneous layer)

Epidermis

• Keratin 
• Melanocytes

• tough and fibrous protein 
• contributes to skin colour and protects heat and foreign material

• Produces melanin
• contributes to skin colour and protects against UV rays

• Hair 
• sebaceous glands 
• ducts of sweat glands

attached to dermal layer by upward projections.

Dermis

Strength and pliability

• pain 
• pressure 
• temperature

• Connective tissue 
• elastin
• extracellular matrix

• blood vessels 
• lymphatic vessels 
• nerve fibres 
• hair follicles 
• sweat glands 
• sebaceous glands release sebum

helps regulate body temp

release sebum (oily antimicrobial substance) into the hair follicles to provide moisture and some water proofing for the skin

• helps insulate the body 
• absorbs shock to the skeletal system 
• allows skin to move easily over underlying structures

• subcutaneous fat 
• connective tissue 
• sweat glands

• dermis and epidermis become thinner 
• reduced elasticity 
• efficiency of temp regulation decreases 
• reduced sebum secreted onto the skin resulting in dry skin 
• Vit D production decreases resulting in reduced bone strength
• melanocytes (producing melanin) become less active resulting in increased likelihood of sunburn