SKIN and the INTEGUMENTARY SYSTEM—Chapter 6

I. FOUR TYPES OF MEMBRANES THAT FORM ORGANS

A. Serous membranes == ______________________(made of different tissues)
1. Where are they found? --- lining body cavities that do NOT open to the outside
a. examples:



2. What are they made of? --- _________________________________

3. What do they secrete? --- watery serous fluid

B. Mucous membranes == _________________________

1. Where are they found? ---__________________________________
a.examples:


2. What are they made of? -- epithelium + loose connective tissue
3. What do they secrete? --- mucus

C. Synovial membranes == __________________________

1. Where are they found? --- _________________________________
2. What are they made of ? --- a layer of fibrous connective tissue that lies over loose connective tissue & adipose tissue
3. What do they secrete? --- synovial fluid that serves to lubricate the ends of bones at joints

D. Cutaneous membrane == _______________________ == SKIN

II. SKIN (Fig. 6.2)

A. Protective covering that regulates body temp., houses sensory receptors, synthesizes chemicals, & excretes wastes.
B. Made of:
1. epidermis
2. basement membrane
3. dermis
4. subcutaneous layer

C. EPIDERMIS made of:____________________________________(Fig. 6.3)
1. Stratum basal ==
a. Deepest layer; divides & grows == MITOSIS
b. Cells become keratinized as they move toward the surface

c. RATE OF X == __________________________________
d. Blood supply to this layer only

2. Stratum spinosum == thick layer
3. Stratum granulosum == granular layer
4. Stratum lucidum == in thickened skin of palms and soles
5. Stratum corneum == top layer; made of dead epidermal cells

D. Function of the epidermis:
1. PROTECTION –against H₂O loss, mechanical injury, chemicals
2. Contains MELANOCYTES that transfer melanin to epidermal cells to form a protective umbrella (Fig. 6.5); Note Clinical Application 6.1

E. DERMIS (Fig. 6.2)
1. Made of fibrous connective tissue; serves to bind epidermis to underlying tissues

2. Contains lots of ________________________________________
3. Blood fibers serve to supply nutrients & help regulate body temp.
4. Dermal nervous tissue to muscles & glands of skin from sensory receptors

F. SUBCUTANEOUS LAYER (Fig. 6.2)

1. Made of _______________________________________________
2. Conserves body heat
3. Contains blood vessels that bring O₂ & nutrients to skin

III. ACCESSORY ORGANS OF THE SKIN

A. HAIR FOLLICLES, NAILS, SEBACEOUS GLANDS, SWEAT GLANDS
B. Hair follicles (Fig. 6.6, 6.7)
1. Found in ______________________________________________
2. Epidermal cells at base of hair follicle produce the hair--à new cells develop à push older cells toward surface à old cells become keratinized.

3. Hair grows, rests, falls out, replaced by new hair
4. Genes –determine type & amount of pigment in cells
5. Bundle of smooth muscle cells + sebaceous glands attach to each hair follicle. What happens when attached smooth muscle cells contract?

C. Nails (Fig. 6.8)
1. Protection
2. Produced by epidermal cells à become keratinized

D. Sebaceous glands (Fig. 6.11, Clinical application 6.3))

1. Function to keep skin & hair soft & ________________________
2. Open into hair follicle in most areas
3. What stimulates hair to grow?

4. What is electrolysis?

E. Sweat glands (Fig. 6.11)

1. _________________________________ found in most regions of body;
2. produce water + salts + waste products
3. TYPES OF SWEAT GLANDS: ECCRINE APOCRINE

a. Eccrine --- on forehead, neck, back, palms, & soles == respond to ___________________________________________________________
b. Apocrine – axillary region, groin, around nipples; respond to
___________________________________________________________

4. Ceruminous glands –external ear canal
5. Mammary glands- breasts

IV .The skin: a regulator of body temperature. 98.6 ⁰ F 37 ⁰C

A. Fig. 6.12 Skin functions as a homeostatic organ************

B. Heat production & loss. Heat lost == heat produced
1. What is the source of body temperature? Cellular respiration.
2. CELL---> H E A T -> H Y P O T H A L A M U S
3. Increase in temp.
a. More blood enters dermal vesselsà skin reddensà heat lost by
1.)RADIATION - Heat escapes in form of infrared waves that move from warm areas to cool areas
2.) CONDUCTION - Heat moves from body into molecules of cooler objects touching skin
3.) CONVECTION - Heat moves to cool air molecules beside skin; these move away &
more cool air molecules move next to skin
4.) EVAPORATION
a. Sweat evaporates (liquid to gas) and carries heat away
b. Sweat glands increase production

4. Decrease in temperature (Fig. 6.12)
5. Dehydration: electrolyte imbalance == dizziness, headache, muscle cramps, nausea ---give salts + fluids, chick soup, O. J. , gatorade
6. Fever, pyrexia

a. Substances from bacteria or diseased cells cause Phagocytes to release
Interleukin
b. Interleukin travels to brain via blood
c. Interleukin raises set point in hypothalamus
d. Reduced blood flow to skin
e. Skeletal muscles shiver
f. RESULTS : FEVER -- PYREXIA

C.What is hypothermia?

VI. SKIN COLOR(Fig. 6.13)

A. Amount of melanin produced by melanocytes

B. Note that we all have the same # of melanocytes; genes determine how much melanin these cells produce.
What would happen if mutations occur in these cells?

C. What environmental factors influence skin color & make it darker?

1. Sunlight
2. Ultralviolet light
3. X rays

D. What physiological factors affect skin color?
1. Oxygen content
2. Carotene
3. Disease

VII. HOW DO WOUNDS HEAL? (Fig. 6.14) **********

VIII. ESTIMATING EXTENT OF DAMAGE FROM BURNS (Fig. 6.15)

Helpful Activities to do after you finish reading this chapter

Check out the following web sites:
Skin Slides from Lab
Web Sites on the Integument
Hole's Online Learning Center - try Test Yourself