1. Dermal Layers
Chapter 6

2. Dermal Layers
Skin is a m________ and is made of e__________ tissue and c_________ tissue. The e______ layer is called the e__________. The c_________ tissue layer is called the d________. Below these two layers is another layer which is not part of the skin, but is still vital to the skin’s function. This layer is called the s_______ ____ layer, or the h___________. This layer consists of adipose tissue.
membrane
epithelial
connective
epithelial
epidermis
connective
dermis
subcutaneous
hypodermis

3. Epidermis Outermost layer of the skin 4 or 5 layers
Stratum corneum
(Stratum lucidum)
Stratum granulosum
Stratum spinosum
Stratum basale
Stratified squamous epithelial tissue
Avascular

4. Epidermis

5. Epidermis
Functions
Prevents water loss (keratinized cells of stratum corneum)
Keeps out disease-causing microorganisms

6. Stratum Basale Deepest epidermal layer Closest to dermis 1-cell thick
Cell division
Pushes older cells toward surface of the skin
Basement membrane is deep to stratum basale

7. Stratum Spinosum Superficial to stratum basale Several cells thick
Less cell divison
Flattened/irregular cells
Spinelike projections from cells

8. Stratum Germinativum
Stratum basale + Stratum spinosum = Stratum germinativum
Growing layers
Where cell division occurs

9. Stratum Granulosum Superficial to stratum spinosum
Very thin, 2-3 cells thick
As cells move up from the stratum basale, they die and become flatter
Keratinization
Older cells harden
Keratin protein

10. Stratum Lucidum
Bonus layer
Thickened skin of palms and soles

11. Stratum Corneum Most superficial layer of epidermis
Many layers of tough, tightly packed dead epidermal cells
Thickest layer of the epidermis (20-30 cells thick)
Dead cells completely filled with keratin
Water resistant
30-40 days from creation in stratum basale until flake off at stratum corneum

12. Epidermis

13. Cells of the Epidermis
Stem cells – undifferentiated cells found only in stratum basale
Keratinocytes – cells that make keratin (most cells in epidermis)
Melanocytes – make melanin, found only in stratum basale
Merkel cells – touch receptors, attached to nerve cells
Dentritic cells (Langerhans cells) – macrophages that guard against foreign microbes/pathogens, alert immune system

14. Dermis Deep to epidermis Binds epidermis to underlying tissues
Blood vessels in the dermis supply nutrients to all layers of the skin
Dense connective tissue
2 layers
Papillary layer
Reticular layer

15. Papillary Layer Areolar connective tissue Lots of blood vessels
Dermal papillae
Capillary loops
Sensory cells
Fingerprints

16. Reticular Layer
Dense connective tissue
Stretch marks
Dermal tearing

17. Hypodermis Subcutaneous layer below Deep to the dermis skin
Adipose, loose connective tissues
Insulation
Major blood vessels
Infants/elderly have less, more sensitive to cold
below
skin

18. HOMEWORK
pg. 116 #1-2
pg. 117 #1-3
Daily Quiz #12 tomorrow!