1. THE INTEGUMENTARY SYSTEM
C14L3
HUMAN SKIN

2. Integumentary System
skin
hair
nails

3. Skin Stats …
Approx. 28 hundred sq. inches (about 18 sq. feet) of skin cover the body
Average thickness is 1/8 inch
Weighs 6-9 pounds (6% of the body weight)
Skin is the largest organ of the human body

4. A piece of skin the size of a quarter contains:
1 yard of blood vessels
4 yards of nerves
25 nerve endings
100 sweat glands
more than 3 million cells

5. FUNCTIONS OF THE SKIN Protection Sensory Response
Temperature Regulator
Excretion
Manufacture
Absorption

6. Protection (a mechanical shield)
Your skin is one of your body’s major defenses. The skin does not permit significant amounts of substances like water in or out of the body. It keeps your body from drying out.
Bacteria, viruses, and many common chemicals that you constantly touch would be very harmful if they penetrated into the body. Skin is an effective barrier to most of them.

7. Protection (a mechanical shield)
Perspiration and oils secreted by the skin provide a form of chemical protection which is acidic and sometimes has enzymes that inhibit the growth of certain microorganisms.

8. Sensory Response
Nerve receptors for pressure, temperature, and pain are in the skin. Communication between your body and the outside world.
The more sensory receptors there are in an area of skin, the more sensitive it is.

9. Temperature Regulator
The amount of blood being carried to the surface of the skin is regulated to control the amount of thermal
energy released. Blood vessels in skin dilate when you need to cool off and constrict when you need to conserve heat. Also evaporation of sweat cools the body.

10. EXCRETION (Secretion)
A small amount of body wastes is excreted with sweat.
sweat glands – move moisture to the surface to cool, also give off certain wastes to help keep the body clean
oil glands (sebaceous) – coat the skin with oils to keep it from drying out.
+The chemical composition of perspiration varies between individuals and also depends on what they have been eating and drinking, why they are sweating, how long they have been perspiring and several other factors. Perspiration consists of water, minerals, lactate and urea.

11. VITAMIN MANUFACTURE
The skin produces small amounts of vitamin D if exposed to sunlight.
Vitamin D helps it absorb calcium and phosphorous to promote bone growth.
As little as minutes of sunlight 2-3 days a week will produce sufficient vitamin D.

12. ABSORPTION
The skin can absorb some chemicals, a few drugs, and a small amount of oxygen.

13. Layers of the Skin
Epidermis (1)
Dermis (2)
Hypodermis (3) 1 2 3

14. Epidermis
the outermost layer of the skin has dead cells at the surface and living cells underneath
contains nerve endings (example: pain receptors)
the older cells of the epidermis fill with a waxy substance called keratin and die
approximately every 25 days (faster for some people and in some areas of the body) a completely new epidermis covers the body

15. Epidermis
The epidermis produces melanin, which is a pigment that protects the body by absorbing some of the Sun’s damaging ultraviolet rays.

16. contains: connective tissues
Dermis
the inner, much thicker layer of the skin; giving skin strength, nourishment, and flexibility.
contains: connective tissues
blood vessels
nerve endings
sweat glands
hair follicles
oil glands

17. Hypodermis layer consists of loosely arranged fat cells and fibers
the fat cells help to cushion and
insulate you body
and store energy

18. Skin

19. Skin Color dark pigment - melanin yellowish pigment - carotene
Pink color of a person's skin is his blood showing through.
Other colors are the results of pigments.
dark pigment - melanin
yellowish pigment - carotene

20. Melanin
Melanin is produced by special cells (melanocytes) in the skin.

21. Freckles
Freckles are clumps of cells that contain more melanin that the rest of the skin.

22. Diseases and Disorders
Albinism
Callus
Blisters
Boils
Acne

23. Albinism
People with albinism do not have the ability to make melanin and thus cannot tan.

24. Callus
a thickened epidermis which helps protect the deeper layers of the skin

25. Blisters
Blisters are not a form of protection, but a response to injury.
Friction causes layers of skin to separate and water collects in the space between the separated layers.

26. Boils
Boils are bacterial infections (the raised portion of skin is filled with pus)

27. Acne
Acne is a skin condition that consists of pimples, deeper lumps (cysts or nodules), and plugged pores (blackheads and whiteheads), that occur on the face, neck, chest, back, shoulders, and even the upper arms.

28. Causes of Acne Acne is caused by three major factors:
Overproduction of oil by enlarged oil glands in the skin.
Blockage of the hair follicles that release oil.
Growth of bacteria, called P. acnes, within the hair follicles.

29. Burns First Degree Second Degree Third Degree
Burns are classified by how deeply they penetrate the skin’s surface.
First Degree
Second Degree
Third Degree

30. involves only the epidermis
First Degree
(superficial)
involves only the epidermis

31. involves the epidermis and some of the dermis
Second Degree
(partial thickness)
involves the epidermis and some of the dermis

32. destroys the epidermis, dermis, and into the subcutaneous tissues
Third Degree
(full thickness)
destroys the epidermis, dermis, and into the subcutaneous tissues

33. Burns
Burns are classified by how deeply they penetrate the skin’s surface.