2. The Integumentary System
Chapter 6
The Integumentary System

3. Introduction Skin Accessory structures Large waterproof covering
UV light and chemical protection
Accessory structures
Hair, nails, glands

4. The Layers of the Skin

5. Introduction Epidermis: upper layer Dermis: lower layer
Epithelial tissue divided into sublayers
Dermis: lower layer
Dense connective tissue
Connects skin to fat and muscle
Below dermis is subcutaneous layer called hypodermis

6. Introduction (cont’d.)

7. The Epidermis Stratified, squamous, keratinized, epithelium
Keratinization
Cells move to surface, lose water, and nuclei change
Composed of five layers

8. The Epidermis (cont’d.)
Stratum corneum
Outermost layer
Dead, keratinized cells
Barrier to light, heat, chemicals, microorganisms

9. The Epidermis (cont’d.)
Stratum lucidum
One to two cell layers thick
Flat and transparent
Difficult to see

10. The Epidermis (cont’d.)
Stratum granulosum
Two or three layers
Flattened cells
Active keratinization
Lose nuclei
Compact and brittle

11. The Epidermis (cont’d.)
Stratum spinosum
Several layers of spiny-shaped cells
Desmosomes prevalent
Desmosomes: interlocking cellular bridges

12. The Epidermis (cont’d.)
Stratum germinativum
Rests on basement membrane
Lowermost layer called stratum basale
New cells produced here (mitosis)
Melanocytes: produce melanin
Skin color
Albinism

13. The Dermis Also called corium Structures found in dermis
Blood and lymph vessels
Nerves
Muscles
Glands
Hair follicles

14. The Dermis (cont’d.) Divisions Papillary Reticular
Adjacent to the epidermis
Reticular
Between papillary and subcutaneous
Subcutaneous (hypodermis)
Layers of fat below the dermis

15. The Accessory Structures of the Skin

16. Hair Covers most of the surface of the body
Three parts: cuticle, cortex, medulla
Shaft: visible portion
Root: hair follicle
Arrector pili: smooth muscle

17. Hair

18. Hair (cont’d.) Growth Texture: straight, curly, or tightly curly
Hair follicle
Cycles of growth and rest
Texture: straight, curly, or tightly curly
Color: based on complex genetic factors

19. Nails Modified epidermal cells Lunula: white crescent
Body: visible portion
Root: covered by skin
Growth occurs from the nailbed

20. Nails (cont’d.)

21. Sebaceous Glands Produce sebum (oil)
Lubricates skin and hair
Secretion controlled by endocrine system
Increases at puberty
Decreases in later life

22. Sweat Glands Most numerous in palms and soles
Not found on margins of the lips or head of the penis
Each gland has secretory portion and excretory duct
Sweating helps cool the body

23. Functions of the Integumentary System

24. Sensation Temperature receptors Pressure receptors
Hot and cold
Pressure receptors
Excessive pressure as pain
Mild pressure as pleasurable
Combinations produce burning, itching, tickling

25. Protection Prevents passage of harmful physical and chemical agents
Melanin protects from UV rays
Lipid content inhibits water loss
Acid mantle: kills most bacteria
Nails protect ends of our digits
Hair acts as insulation and filter

26. Thermoregulation Normal body temperature: 98.6 degrees F
When external temperatures increase
Blood vessels dilate
Sweat occurs
When external temperatures decrease
Blood vessels first dilate then constrict

27. Secretion Sebum Sweat Vitamin D Cosmetic gloss Moisturizer
Antifungal/antibacterial properties
Sweat
Essential in cooling process
Vitamin D

28. Summary
Discussed the layers of the epidermis and the process of keratinization
Described the structure of the dermis
Discussed the accessory structures of the skin including the hair and nails
Discussed the different functions of the integumentary system