• around 1/3 of your blood is found here
• most in the skin on your head
• hat keeps heat in near head
• your skin weighs about 6lbs
• females have more skin

1. Epidermis
2. Dermis
3. Appendages and Glands

• thin outer layer
• mainly stratified squamous epithelium
• has 5 layers

1. Stratum Corneum
2. Stratum Lucidum
3. Stratum Granulosum
4. Stratum Spinosum
5. Stratum Germinativum

5 to 10 layers thick

the cells have spines or extensions coming from them

Cells called melanocytes produce a pigment called melanin

Melanin is the substance that causes the tan, freckle, or darker skin.

• The skin is your radiator
• you make heat in your body, the blood picks up the heat, the heart pumps the blood to the skin and the skin allows the heat to radiate off
• you sweat so the water can evaporate and take heat with it

1. mainly composed of fibrous connective tissue
2. these fibers run in specific directions called lines of tension
3. Blood vessels in the dermis supply nutrients to all skin cells (epidermis and dermis)
4. The blood vessels can dialate or contrict with the temperature
5. Nerves here can sense pressure, light, and temperature
6. The dermis can make Vitamin D. The blood can make Vit D in response to sunlight

1. Hair Follicle
2. Arrector Pili Muscle
3. Sebaceous Glands
4. Nails
5. Sweat Glands

found almost everywhere except soles and palms

hair develops from a tube like depression called a hair follicle

there is epithelial tissue at the base

this tissue reproduces, dies, and is pushed up causing hair growth

Black-a lot of melanin

Brown-less melanin

Blonde-less melanin

Grey-some hairs have melanin, some don't

White- no melanin

Red- iron pigment

when this contracts the hair stands up 

when these contract you get goose bumps

these are caused by temperature change and stress

• a gland in the hair follicle (another name for pores)
• It secretes an oil called sebum

• Emptied into the follicle
• keeps the hair and skin soft and pliant

caused when sebaceous glands in certain areas become over active

the sebum causes the follicle to get plugged 

if bacteria atract then a zit or pimple results

the over production of sebum occurs when hormones are produced

sebum plugging the follicle

if there is pus then bacteria are causing an infection