1.  Ch 4: Skin and Body Membranes
Integumentary System
P110

2. Skin Structure
Figure 4.4

3. Integumentary System Skin (cutaneous membrane)
Also called the integument
Skin derivatives
Sweat glands
Oil glands
Hairs
Nails

4. Skin Functions Protects deeper tissues from: Mechanical damage (bumps)
Chemical damage (acids & bases)
Bacterial damage (from infection)
Thermal damage (heat or cold)
Ultraviolet radiation (effects of sunlight)
Desiccation (drying out)

5. Skin Functions Aids in heat regulation
Aids in excretion of urea and uric acid
Synthesizes vitamin D

6. Skin Structure
Figure 4.3

7. Skin Structure Epidermis – outer layer Stratified squamous epithelium
Often keratinized (hardened by keratin)
Dermis - inner layer
Dense connective tissue
Found underneath the epidermis
Figure 4.3

8. Skin Structure Deep to dermis is the hypodermis
Also called subcutaneous tissue
Not part of the skin
Anchors skin to underlying organs
Composed mostly of adipose tissue

9. Skin Layers From outermost to inner most layer: Stratum Corneum
Stratum Lucidum
Stratum Granulosum
Stratum Spinosum
Stratum Basale (Germinativum)

10. Layer of Epidermis 1. Stratum basale 2. Stratum spinosum
Also called stratum germinativum
Stratum basale or germinativum is deepest layer
Lies next to dermis
Cells undergoing mitosis
2. Stratum spinosum
3. Stratum granulosum

11. Layer of Epidermis cont’d
4. Stratum lucidum
Occurs only in thick skin
5. Stratum corneum
Outermost layer of the epidermis
Shingle-like dead cells
Flakes off slowly and replaced by new cells

12. Epidermis Facts
Avascular
New epidermis every days

13. Melanin Pigment (melanin) produced by melanocytes
Color is yellow to brown to black
Melanocytes are mostly in the stratum basale
Amount of melanin produced depends upon genetics and exposure to sunlight
Freckles and moles are found where melanin is concentrated to one spot
CROSS OUT THE NEXT LINE

14. Dermis Two layers 1. Papillary layer Outermost layer of dermis
Projections called dermal papillae
Pain receptors
Papillae are arranged in patterns that are genetically determined
This is what allows you to leave fingerprints

15. Dermis
2. Reticular layer
Blood vessels
Glands
Nerve receptors

16. Dermis Facts Vascular and helps maintain body temperature homeostasis
Various fibers are found in the dermis
Collagen fibers are responsible for the toughness and help keep skin hydrated
Elastic fibers gives skin its elasticity
Collagen & elastic fibers decrease as we age