1. Skin and Body Membranes Chapter 4
2 Types of Body Membranes
A. Epithelial and B. Connective
Epithelial Membrane=Skin, Mucous Membrane, Serous Membrane
Connective Membranes=Synovial (areolar connective tissue) that has no Epithelial cells

2. Epithelial Membranes Skin (Integument) Wet Exterior Openings
Interior Linings

3. A. Cutaneous/Integument/Skin
Waterproof-Stretchable-Washable
Self-Repairs: Cuts, Rips, and Burns
Electrical Insulation
Includes: Sweat and Oil Glands, Hairs, and Nails
                        

4. Functions of the Skin Mechanical Damage Physical Barrier
Chemical Damage
Acids and Bases
Bacterial Damage
Unbroken Surface, “Acid Mantle”
Ultraviolet Radiation
Melanin protects from Sun
Thermal Damage
Heat/Cold/Pain Receptors
Desiccation
Waterproofing Surfaces
Heat Loss/Retention
Skin Capillary Access
Urea and Uric Acid Excretion
Perspiration
Vitamin D
Sunlight

5. Skin Structure Epidermis Hypodermis Dermis Stratified Squamous
Keratinizing (hardening)
Dermis
Dense Connective
Contains Blood, Sweat, and Oil Glands
Hypodermis
A.K.A Subcuaneous tissue
Adipose Tissue
Anchor Skin (E&D) to underlying organs
                                      
                        

6. 3 Layers-Actual Picture

7. Epidermis-5 Strata (Layers)
*****OUTSIDE THE BODY*****
EPIDERMI S
Corneum
Lucidum
Granulosum
Spinosum
Basale
*****DERMIS*****

8. Why can we shave (face/legs) and not bleed?
The epidermis is AVASCULAR, meaning it has no blood supply of its own.
Most cells produce keratin (tough, fibrous protein)
Basale (alive with spino- and granulo-) absorbs nutrients, the top 2 (lucid- and corne-) are non-living

9. Then why do you bleed when you shave?
Because you cut too deeply and get into the DERMIS

10. The 5 Strata Layers Corneum:20-30 cells thick
Lucidum: dead, clear cells found only on hands/feet
Granulosum: still living cells
Spinosum:living cells
Basale: absorb nutrients from the dermis to keep them alive, and “float” up to form the above 4 layers

11. New EPIdermis every 25-45 days
Suntans/burns occur in the Basale
Melanin (colored pigment)
Basale cells phagocytize (eat) the melanin
Melanin shields DNA from UV rays

12. Papillary and Reticular
The Dermis
Divided into 2 Layers-
Papillary and Reticular

13. Papillary Layer
Upper projections called papillae containing pain and touch receptors (known as Meissner’s corpuscles)

14. Reticular Layer
Contains blood vessels, sweat and oil glands and deep pressure receptors (Pacinian corpusles)
Many phagocytes to attack bacteria that has passed through Epi-
Collagen fibers and blood vessels