1. THE INTEGUMENT

2. INTEGUMENTARY SYSTEM Most visible organ system of the human body
Makes about 16% of your body weight
The skin is an organ system because it is composed of many different types of tissues and organs
Accessory organs (Oil-, wax-, and sweat-producing glands, hair, and nails)
Sensory organs for touch
Blood/lymphatic vessels
Seals the body in a protective barrier that is flexible yet resistant to abrasion
Our first line of defense against an often hostile environment
Coordination of immune response to pathogens

3. EPIDERMIS Superficial, stratified squamous epithelium
Protects the dermis, prevents water loss and pathogen entry
Synthesize vitamin D3
Sensory receptors: detect touch, pressure, pain, and temperature
Immune cells – Langerhans cells
Organized into many layers called strata of cells
Thin skin vs. Thick skin (palms and soles of feet)
Melanocytes – produce melanin / pigment
Keratinocytes are cells produced deep in the epidermis
Resistant to dehydration and friction
Cells produce keratin, until they reach the surface of the cell and then get sloughed off
Most abundant epithelial cells
Production regulated by epidermal growth factor

4. LAYERS OF EPIDERMIS

5. Thick layer or irregularly arranged connective tissue
Dermis
Thick layer or irregularly arranged connective tissue
Supports and nourishes the epidermis
Papillary layer – dermal papillae
Reticular layer
Vascularized irregular tissue
Pressure receptors
Sweat glands/sebaceous glands

6. “Goosebumps” AND HOMEOSTASIS

7. What the skin can tell us

8. Hypodermis AKA Subcutaneous layer
Composed mainly of adipose tissue and areolar tissue
Important in stabilizing the position of the skin in relation to underneath tissues
During early life, subcutaneous fat serves as energy reserve and shock absorber
During puberty, sex hormones cause accumulation of fat
Only the superficial region has large arteries and veins
Deeper region have limited number of capillaries and no vital organs
This makes drug administration via subcutaneous injection a useful method

9. Sebaceous glands & follicles

10. Sweat Glands

11. Apocrine to blame!