1. or the Integumentary System

2. Human Skin Facts Skin is the largest organ of the body.
The skin has a surface area of 1 to 2 square meters and weighs 4 to 5 kilograms

3. Human Skin Facts
You have approximately 19,000,000 skin cells on every square inch of your body.
We keep renewing our skin our entire lives.

5. The Integumentary System is made up of…..
Skin
Sweat Glands
Oil Glands
Hair
Nails
Main Function = Protection

6. The skin varies in thickness from 1. 5 to 4
The skin varies in thickness from 1.5 to 4.0 mm and has 2 distinct regions….
Epidermis – composed of epithelial cells, it is the outermost protective shield
Dermis – the underlying layer composed of fibrous connective tissue, it is tough and leathery

7. Epidermis
It is a keratinized stratified squamous epithelium –the deep layers of the epidermis undergo constant mitosis and the bottom layer cells are pushed toward the surface.
Keratin is the fibrous protein that gives the epidermis its protective quality

9. Dermis
The dermis binds the body together like a body stocking (our hide)
It is richly supplied with nerve fibers, blood vessels, and lymphatic vessels
Hair follicles, oil glands and sweat glands reside in the dermis.

10. What Contributes to Skin Color?
Melanin – a pigment that ranges in color from yellow to reddish-brown to black
Carotene – a yellow to orange pigment
Hemoglobin – pinkish hue of fair skin caused be oxygenated hemoglobin in red blood cells

11. Homeostatic Imbalance
Cyanosis – skin appears blue because of lack of oxygen
Erythema (redness) – fever, hypertension, inflammation, embarrassment
Pallor or blanching – anemia, low blood pressure, fear, or emotional stress

12. Jaundice – yellow cast due to liver disorder
Bronzing – metallic appearance due to Addisons disease (hypofunction of adrenal cortex)
Bruises or hematomas – clotted blood under the skin

13. Sweat Glands 2.5 million per person
Sweat is a filtrate of the blood made up of 99% water, salts, vitamin C, antibodies, dermicidin (a microbe killer), urea, uric acid, ammonia, lactic acid, any ingested drugs
Sweat is usually acidic - pH 4-6

14. Sebaceous (Oil) Glands
Secrete sebum (an oily secretion)
Sebum lubricates hair and skin, slows water loss from skin, and has a bactericidal action
Blocked sebaceous glands form whiteheads, if the blocking material dries it is called a blackhead

15. Nails
-Scalelike
modifications of
epidermis
containing
hard
keratin

16. Hair
Hair follicles make flexible strands consisting of dead cells made of hard keratin

17. Hair Variations……. Kinky hair – a cs. of the shaft is flat
Wavy hair - a cs. of the shaft is oval
Straight hair - a cs. of the shaft is round
Hair color is created by melanin from the base of the hair follicle