1. Integumentary System
Skin

2. Integumentary system Skin
Adnexal structures (nails, hair, and glands). 

3. Protects against drying
unnecessary loss or addition of water to the body.
Glands produce secretions
Nerve endings
interact with the environment.

4. Glands assist with the elimination of certain body wastes materials.

5. Vitamin D is manufactured in the skin when skin is exposed to ultraviolet radiation.

6. Skin Layers

7. Epidermis most superficial stratified (thick) epithelium
may contain up to one hundred layers of cells. 

8. Epidermis 
All of the cells of the epithelium form near the junction of the epidermis and the dermis. 
As new cells are formed, they push the older cells closer to the skin surface.

9. Epidermis 
The cells in the upper layers of the epidermis are dead. 

10. Epidermis epithelium lacks a direct blood supply
depends upon the underlying connective tissue for nutrients. 

11. Epidermis 
As the thickness of the epithelium increases, the cells move too far from the supply of nutrients to survive. 
The upper layers of dead cells are constantly shed into the environment

12. Epidermis upper epithelium cells contain keratin.
Keratin: waxy material that helps to create the water barrier to keep water in and out of the body
makes the cells a bit more rigid
helps resist penetration by microbes
reduces damage from friction.

13. Dermis lies deep to the epidermis.
contains most of the glands, blood vessels, nerve endings, and hair follicles. 

14. Dermis
Small, finger-like projections from the dermis extend into depressions on the epidermis.  This helps to firmly hold the epidermis and dermis together.

15. Dermis
melanocytes Produce melanin, a yellow-brown pigment, colors the skin and hair. 
They "inject" the melanin into the cells of the epidermis. 
produce melanin in response to exposure to UV-radiation. 

16. Dermis
The lower layer of the dermis is made of strong collagenous connective tissue.  The collagen fibers in this tissue are arranged randomly and in all directions, which help the skin to resist damage due to tearing

17. Subcutaneous layer
actually the junction of the skin to the underlying tissues. 
Mostly made of fat,
insulates the body and prevents heat loss. 
women tend to have a thicker subcutaneous layer than men.

18. Adnexal Structures
hair, nails, and glands of skin

19. Adnexal Structures Hair
produced by a hair follicle and consists of dead, highly keratinized cells.  
produced by cells of the hair bulb

20. Adnexal Structures Hair
As new cells are formed, they push the older cells towards the surface.
The amount of melanin placed into the cells determines hair color

21. Adnexal Structures Nails made of highly keratinized dead cells
The nail is produced by cells of the nail root, which lies near the base of the nail.  As new cells are made, the older cells are pushed towards the end of the finger. 

22. Exocrine glands that have ducts.
Skin glands are like this

23. Types of Exocrine Glands
Merocrine 
very watery secretion. released as it is made. 
can be produced in large volume in a relatively short period of time. 
usually have very little odor to them.

24. Types of Exocrine Glands
Apocrine gland
more viscous (thicker) secretion
has some odor.  (often bacterial action on the secretion)
secretion is surrounded by a small piece of the cell membrane

25. Types of Exocrine Glands
Holocrine gland
Very thick secretion
Often has an odor to it. 
Entire cell is removed during secretion. 
cell ruptures to release the secretion.  Or
cell must leave the gland carrying the secretion along with it.

26. Skin Glands
sudoriferous glands sweat glands. 2 varieties.

27. Skin Glands
First sudoriferous most of the surface of the body / produces a very watery sweat using a merocrine form of secretion used to help cool the body.

28. Skin Glands Second sudoriferous groin and armpit areas
more viscous (thicker) type of sweat. 
an apocrine type of secretion
tends to have an odor to it.

29. Skin Glands Sebaceous gland oily secretion Holocrine method.
usually attached to the hair follicle
root of the hair.  This oily secretion coats the hair and works its way to the skin surface
Keeps skin and hair from drying out. 

30. Skin Glands Ceruminous glands canal of the ear produce the earwax.
holocrine type of secretion
earwax is used to collect debris that enters the ear canal.

31. Mammary gland
produces milk
The breast is a complex structure that contains numerous different glands.  Some of the glands of the breast produce the milk fat.  Others produce the other components of the milk.