1. The Integumentary System
Chapter 5

2. General Characteristics
Composed of all four types of tissues… epithelial, connective, muscle and nervous tissue.
Largest organ- surface area is 20 ft2
Very versatile organ
Vital to maintaining homeostasis
Also called the cutaneous membrane
Consists of two distinct layers
Epidermis
Dermis
*Hypodermis*

3. Epidermis Superficial layer (Epi- means above)
Thinner layer: mm thick
Composed of epithelial tissue-keratinized stratified squamous
Composed of 4-5 strata/cell layers
Stratum Corneum
Stratum Lucidum
Stratum Granulosum
Stratum Spinosum
Stratum Basale

4. Stratum Corneum Many cell layers (15-30) Squamous dead cells
Keratinized
Cells at free surface are there for no more then 2 weeks
Stratum Corneum

5. Stratum Lucidum (clear layer)
2-3 cell layers
Cells are receiving final keratin
Appears clear
In thick skin areas-palms and soles of feet
Stratum Lucidum

6. Stratum Granulosum (grainy layer)
4-5 cells thick
Becoming squamous
Start filling with keratin-protein for strength & water resistance
Stratum Granulosum

7. Stratum Spinosum (spiny layer)
Polyhedral shape
8-10 cells thick
Resulting daughter cells from stratum basale layer.
Stratum Spinosum

8. Stratum Basale (base) Stratum Germativum (to start growing)
1 cell layer
Cuboidal/columnar
Able to divide
Contains pigment cells called melanocytes which produce melanin
Epidermal ridges-dermal papillae (nipple-shaped mound)
Increase diffusion
Stratum Basale

9. Dermis Deepest portion of the skin
Thickest portion of the skin ( mm)
Contains all 4 types of tissues
Epithelial: glands & duct structures, blood vessels
Connective: dense irregular CT & loose CT make up the majority of the dermis.
Muscle: walls of blood vessels, hair follicle muscles called erector pilli
Nervous: sensory receptors (temperature, pain & pressure)
Composed of 2 layers/strata
Papillary
Reticular

10. Papillary Layer
Contains papillae, ridges that extend superficially into the epidermal area.
They form the distinct pattern in the epidermis known as “prints”
Areolar tissue that supports & nourishes the epidermis
Contains capillaries & nerves

11. Reticular Layer Anchors skin to deeper tissue
Reticular connective tissue & dense irregular CT present

12. Hypodermis Deep to the dermis
Not technically a part of the skin, but closely associated with it
Mostly composed of adipose tissue and areolar connective tissue where fat storage occurs in the
Also referred to as the subcutaneous layer since the skin is the cutaneous layer