1. The Integumentary System
Chapter 5

2. Integumentary System The Body Covering Includes: skin, nails & hairs
Skin = cutaneous membrane

3. Structure Two main parts = Epidermis- surface epithelial layer
Dermis -deeper connective tissue layer
Deep dermis not part of the skin = subcutaneous layer or Hypodermis

4. Figure 5.1

5. Epidermis Keratinized stratified squamous epithelium 4 cell types:
Keratinocytes
Melanocytes
Langerhans cells
Merkel cells

6. Epidermal Cells Keratinocytes 90% of epidermal cells 4-5 layers
Produce keratin
Protect skin
Waterproof skin

7. Epidermal Cells Melanocytes - produce melanin
Transfer pigment to keratinocytes
8% of epidermal cells

8. Epidermal Cells Langerhans Cells- immune response
Merkel cells – sensory
Include tactile disc and neuron
= touch sensation

9. Epidermal Layers Generally 4 strata (layers)
Stratum basale –includes stem cells
Stratum spinosum – 8-10 cell layer
Cells beginning to look flattened
Stratum granulosum –keratin
Losing cell organelles and nuclei
Include lamellar granules = waterproofing lipid
Stratum corneum – flattened dead cells
Cells shed and are replaced from below- mostly keratin-filled

10. Skin Color Melanin- dark color Carotene- yellow orange
Darkness depends on amount of melanin produced.
gives some protection against UV
Carotene- yellow orange
In stratum corneum and adipose layers-
Hemoglobin in blood- pink-red
Depends on blood flow

11. Accessory Structures
Hair
Skin glands
Nails

12. Hair Found on most skin surfaces Made of fused keratinized cells
Not on palmar surfaces of hand and fingers or plantar surfaces of feet
Made of fused keratinized cells
Consists of shaft & root
Surrounded by hair follicle
Base is bulb which includes growing matrix producing cells
Nerves- hair root plexuses
Muscle- arrector pili

13. Figure 5.3

14. Glands sebaceous gland- secrete oily sebum sudoriferous or sweat gland
Connected to hair follicles
sudoriferous or sweat gland
Eccrine sweat gland
Wide distribution- thermoregulation
apocrine sweat gland
Axilla, groin, areolae, beard
Contain other cell material and produce pheromes
Ceruminous Glands- external auditory canal
Combine with sebum to produce earwax

15. Nails Plates of packed hard dead keratinized cells
Nail body- major visible portion
Free edge- part extending past finger or toe
Root – part not visible

16. Figure 5.4a

17. Figure 5.4b

18. Functions Temperature Regulation Protection Sensory reception
Excretion & Absorption -small
Vitamin D synthesis

19. Aging Adolescence- can develop acne Mostly dermis- visible ~ age 40
Loss of collagen fibers
Loss of elasticity
Loss of immune responses
Decreased melanocyte functions-
gray hair, blotches
Thinning