The Integumentary SystemSkin, Hair, and Nails, How to tell the difference.

Chapter 6, pg 191

•First line of defense•Social implications• Care and feeding of your skin•Skin Hair Shaft with Sebaceous Glands

Objectives

• Describe histology: Epidermis, dermis, and subcutaneous tissue

• Discuss color and markings

Thick vs. Thin skin

• Avg skin depth: 1-2 mm• Thick skin: palms, soles

– Has sweet glands, I mean sweat glands

• Thin skin: everywhere else– Has sweat glands, hair follicles,

and sebaceous glands

hypothenar eminence

• the elongated, fleshy bulge at the base of the little finger.

• Hypothenar hammer syndrome is a condition of the hand in which the blood flow to the fingers is reduced.

• occurs when workers repeatedly use the palm of the hand as a hammer to push and twist objects.

• damage certain blood vessels of the hand especially the ulnar artery. The following slide is shows surgery to repair this.

• The faint of stomach should avert their eyes

Hypothenar hammer syndrome

Epidermis: squamous epithelium

• No blood vessels, gets nutrients through diffusion

• Tough• Keratinocytes• Melanocytes• Tactile receptors• The stratum corneum is the

layer that we see.

Keratin

• Structural protein found in hair, nails, turtle shells

• Lots of cysteine

• Lots of collagen

Dermis

• Boundary between epidermis and dermis is wavy.• Dermal Papillae are dermis waves going up into epidermis.

– What benefit might this give?

• More nerve endings & blood vessels• Sweat glands & Hair follicles begin here

Layers of skin

Hypodermis: fat stores

• Adipose tissue deposits of subcutaneous fats

• Binds the skin to underlying tissues

• Pads the body, and an energy resevoir

• Less fat makes infants and the elderly more sensitive to cold

• Women’s layer is 8% thicker than mens

Skin color

• 3 pigments responsible– Hemoglobin: makes it

redder

– Melanin: determines pale vs. dark

– Carotene: yellow pigment from yellow & orange vegetables: most notable in heel

Suntan, burn, and lotion

• In caucasians UV light stimulates melanin production. It takes 5-7 days to get a layer that is protective

• Other races have continual melanin production; leads to a lower level of skin cancer

Sun burn

• MSH, a hormone comes from the pituitary.

• The pituitary is connected to the optic nerve.

• When you see more light you make more melanin.

• The flip side; sunglasses can lead to sunburn.

• Sunlight arrives on earth in three forms: infrared (heat), visible light and ultraviolet. Ultraviolet light is classified into three categories:

• UVA (315 to 400 nm), also known as black light, which causes tanning

• UVB (280 to 315 nm), which causes damage in the form of sunburn

• UVC (100 to 280 nm), which is filtered out by the

atmosphere and never reaches us.

• Note that UV light can be reflected off of water, snow, even sand can reflect 20% of the UV light that hits it

• when you get a sunburn, what you are really getting is cellular damage from ultraviolet radiation.

• The body responds with increased bloodflow to the capillary bed, bringing in cells to repair the damage.

• extra blood causes the redness

Protect yourself from the sun.

• Sunscreen works by absorbing UV rays

• Eye black is used to reduce glare when playing sports

• Many animals have evolved similar structures

Final thoughts

• Many variations exist• Cyanosis: blue skin from lack of

blood• Erythema: abnormal redness• Jaundice: when too much hemoglobin

is breaking down• Albinism• Hematoma: bruising• But remember its not what’s on the

outside, but on the inside that counts.