1. The Integumentary System

2. Functions Guard the body’s physical and biochemical integrity
Maintain a constant body temperature
Provide sensory information about the surrounding environment.

3. Structure of the Skin 1. Epidermis
Superficial; composed of epithelial tissue
2. Dermis
Deeper layer; composed of connective tissue
3. Subcutaneous layer (Hypodermis) = not part of skin; consists of areolar and adipose tissues

4. Epidermis
Composed of stratified squamous and contains four types of principal cells

5. Epidermal Cells 1. Keratinocytes
Contain keratin which waterproofs cells; protect skin and underlying tissue from heat, microbes, and chemicals
2. Melanocytes
Pigment cells; responsible for skin color and absorbs UV light
3. Langerhans cells
Participates in immune responses
4. Merkel cells
Sensory structure that function in touch

6. 5 Layers of Epidermis 1. Stratum basale 2. Stratum spinosum
Deepest layer of epidermis; contains some stem cells capable of undergoing cell division; when destroyed, new skin cannot regenerate without a skin graft
2. Stratum spinosum
provides strength and flexibility

7. 5 Layers of Epidermis 3. Stratum Granulosum
Transition between deeper, metabolically active strata and the dead cells of the more superficial strata; formation of water repellent sealant between cells
4. Stratum Lucidium
Present in only the fingers, palms, and soles (thick skin)
5. Stratum Corneum
Most superficial layer; consists of dead cells

8. Dermis
Two Regions
Papillary layer
Superficial
Reticular layer
Deep

9. Papillary Layer of Dermis
Areolar Connective Tissue
Contains
Touch receptors
Free nerve endings
heat, cold, pain, tickle, and itch

10. Reticular Layer of Dermis
Deeper region of dermis
Contains
Hair follicles
Sebaceous (oil) glands
Sudoriferous (sweat) glands

11. Structure and Basis of Skin Color
A. Three Pigments: melanin, carotene, and hemoglobin
B. Albinism = inherited inability to produce melanin
C. Vitiligo = complete or partial loss of melanocytes from patches of skin; results in irregular white spots

12. Accessory Structures of Skin (hair, glands, nails)

13. Anatomy of Hair (Pili) Shaft = above the surface
Root = penetrates the dermis
Cuticle = covers hair
Hair follicle = hair grows from here

14. Skin Glands

15. Sebaceous (Oil) Glands
Produce sebum which moistens hair, waterproofs, and softens the skin; inhibits bacterial growth
Acne results when sebaceous glands become inflamed

16. Sudoriferous (Sweat) Glands
Eccrine sweat glands = function to help regulate body temp. through evaporation and eliminate wastes (urea)
Apocrine sweat glands limited in distribution; occur in axillae (armpit) and pubic regions

17. Ceruminous glands
Produce wax (cerumen)
Found in ear

18. Nails Hard, keratinized epidermal cells
Functions: grasping and protection

19. Types of Skin
Thin vs Thick Skin

20. Thin vs Thick Skin Thin Skin Thick Skin
Covers all parts of body except palms, palmar surfaces of digits, and soles
Thick Skin
Covers palms, palmar surfaces of digits, and soles; lacks hair follicles, sebaceous glands, and has more sweat glands

21. Functions of Skin Thermoregulation = regulate body temp Protection
Cutaneous sensations = touch, pressure, vibrations, tickle, heat, cold, and pain
D. Synthesis of Vitamin D