1. The Skin & Integumentary System
Chapter 6

2. Cutaneous Membrane (skin)
body covering
helps prevent water loss
helps regulate body temperature
helps produce vit. D needed for normal bone and tooth development
2 layers: epidermis & dermis
Hypodermis or subcutaneous layer (below the dermis)

4. Epidermis made of keratinized stratified squamous epithelium
layers (from bottom to top): 1. stratum basale (germinativum)-mitotic, contains melanocytes which produce the brown pigment melanin (protects underlying tissues from UV light) 2. stratum spinosum 3. stratum granulosum 4. stratum lucidum –palm and sole only 5. stratum corneum- flat, dead cells filled with the waterproofing protein called keratin

9. Dermis main tissue is dense irregular fibrous connective tissue
contains blood vessels, nerve fibers, accessory organs

10. Subcutaneous Layer made of adipose tissue and loose connective tissue
has major blood vessels that supply the skin

12. Hair follicles-tubelike depression of epidermis-mitosis occurs at base, and old cells become part of the hair itself (shaft) as they die and become filled with keratin; hair color is due to distribution and amount of melanin; red color is due to iron containing pigment
Sweat glands-2 types: 1) Eccrine sweat glands-empty onto surface of skin; “odorless”; usu. respond to rise in temp. 2)Apocrine sweat glands-empty into hair follicle; “odor”; usu. respond to emotions

13. Sebaceous glands-produce oily secretion (sebum): usu
Sebaceous glands-produce oily secretion (sebum): usu. empty into hair follicles; everywhere except palms and soles
Arrector pili muscles-bands of smooth muscle attached to base of hair follicles: contraction causes goose bumps
Nails-dead keratinized cells; produced at nail bed; area of most active growth is lunula

16. Figure 06.10

17. Figure 06.07

18. Regulation of Body Temperature
Skin’s role in promoting heat loss- blood vessels leading to skin dilate; blood vessels leading to internal organs constrict---more blood flows to dermis and heat is lost through skin
Skin’s role in conserving heat-blood vessels leading to skin constrict; blood vessels leading to internal organs dilate---more blood flows to organs, and less heat is lost through skin

19. Types of Heat Loss
radiation-heat escapes from a warm area to cooler area
conduction-heat moves from body directly into molecules of cooler object in contact with the body surface
convection-as cool air circulates over skin, heat flows to it

20. evaporation-fluid (sweat, water, etc
evaporation-fluid (sweat, water, etc.)on surface of skin evaporates, carrying heat with it
High humidity in the air interferes with evaporation because the air already is saturated with water vapor, so less water can enter the air through evaporation from the skin---the body is not able to lose heat as well

21. In hot and humid environments, the body can overheat because there is less evaporation, and the air temperature may be close to or greater than body temperature (radiation of heat from the skin decreases) ---person may suffer from heat exhaustion.
If excessive heat loss occurs, the brain triggers the skeletal muscles to contract slightly, generating some heat----then may shiver, generating even more heat. Also, sweat gland activity decreases.

22. In elderly people, sweat glands become replaced by fibrous tissue

23. Factors affecting skin color
Genetics-most influential
Environmental-sunlight, UV light, X-Rays
Physiological-whether blood is oxygenated or deoxygenated; presence of abnormal pigments, such as carotene (orange) and bilirubin(yellow)

24. Inflammation
blood vessels in injured area dilate and become more permeable, causing blood to flow to the area and some of the liquid part of the blood to enter the tissue (tissue becomes reddened, warmed, and swollen)