1. Integumentary System
Dermatology – the branch of medicine that specializes in diagnosing and treating skin disorders.
Integumentary system includes – skin, hair and nails. It is the largest organ of the body in surface area and weight! Adults – covers an area of about 2 square meters and weighs about lbs

2. Epidermis Composed of keratinized stratified squamous epithelium.
Outermost region of the skin
4 types of cells
Keratinocytes
Melanocytes
Langerhans cells
Merkel cells

3. Epidermis
1. Keratinocytes – produce keratin, which is a tough, fibrous protein that helps protect the skin and underlying tissues from heat, microbes, and chemicals. They also release a water-repellent sealant. 2. Melanocytes – produce the pigment melanin, which gives us our skin color and absorbs damaging UV light. Melanocytes are particularly susceptible to damage by UV light!

4. Epidermis
Langerhans cells – participate in immune responses against microbes that invade the skin. Langerhans are easily damaged by UV light.
Merkel cells – involved in the process of sensory neurons (nerve cells). They detect touch sensations.

5. Dermis
2nd layer – composed of connective tissue containing collagen and elastic fibers
In the superficial part of the dermis there are papillae that contain tactile receptors called Corpuscles of touch or Meissner corpuscles. These are sensitive to touch!

6. Dermis
In the deeper part of the dermis is adipose cells, hair follicles, nerves, oil glands and sweat glands and blood vessels.
Collagen and elastic fibers give it strength, the ability to stretch, and elasticity (ability for it to return to the original shape.
Extreme stretching may produce tears in the dermis causing stretch marks.

7. Dermis
Albinism – is the inherited inability of a person to produce melanin. Most albinos do not have melanin in their hair, eyes, and skin.
Freckles – accumulation of melanin in patches
Hair
Primary function is protection
Present on most skin surfaces except the palms, fingers, soles of feet and toes.
Hair on your head guards the scalp from injury and the suns rays, eyebrows and eyelashes protect the eyes from foreign particles and hair in the nostrils protects against inhaling particles

8. Dermis Hair continued Shaft – superficial portion
Root – below the surface and penetrates into the dermis
Hair follicle – surrounded by nerve endings, sensitive to touch. At the base of each follicle is the bulb (onion shaped).

9. Dermis
Arrector pili – smooth muscle that is attached to the side of the hair follicle. Under stress, such as cold, or fright, nerves stimulate the muscles to contract, which pulls the hair shafts perpendicular to the skin surface…..creating “goose bumps”.
The color of your hair is due to melanin. Gray hair occurs with a decline in the synthesis of melanin.
Androgenic alopecia or male-pattern baldness – genetically predisposed inhibiting hair growth.

10. Glands
Sebaceous glands – oil glands are connected with hair follicles. They secrete an oily substance called sebum which keeps hair from drying out, prevents excessive evaporation of water from the skin, keeps the skin soft and inhibits the growth of certain bacteria.
When sebaceous glands become enlarged, blackheads develop because the sebum is nutritive to certain bacteria and pimples result. The color is due to melanin and oxidized oil, not dirt! Sebaceous gland activity increases during adolescence. Acne may result.

11. Glands Sudoriferous Glands – sweat glands, produce perspiration
Eccrine sweat glands – distributed throughout the skin, located in the dermis. The sweat produced is mainly to help regulate body temperature through evaporation.
Apocrine sweat glands – mainly in the axilla (armpit), they open to hair follicles, do not begin to function until puberty

12. Nails
Plates of tightly packed, hard, dead, keratinized cells of the epidermis
Nail body – is the portion of the nail that is visible
Lunula – whitish semilunar area near the nail root
The average growth of fingernails is about 1 mm per week

13. Functions of the skin
Body temperature regulation – contributes to the homeostatic regulation of body temperature by liberating sweat and adjusting the flow of blood in the dermis
Protection – protects underlying tissue, microbes, heat, abrasion
Cutaneous sensations – tactile sensations, touch, pressure, warmth, coolness
Synthesis of Vitamin D – exposure to UV radiation activates production of Vitamin D

14. Aging Langerhans cells dwindle – decreasing immune responses
Sebaceous glands decrease – skin and hair more dry
Gray hair – less melanocytes, atypical skin pigmentation
Dermis becomes thinner causing wrinkles
Hair and nails grow slower, nails become brittle

15. Skin cancer Basal cell carcinoma – most common type of skin cancer
Melanoma – can metastasize and spread to other organs
ABCD of skin cancer
A – asymmetry
B – border
C – color
D - diameter

16. Burns 1st degree – involves only the epidermis
2nd degree – destroys a portion of the epidermis and part of the dermis
3rd degree – destroys the epidermis, the underlying dermis, and subcutaneous layer

17. Pressure ulcers
Bed sores – prolonged pressure against an object such as a bed, cast, or splint

18. Terms and conditions
Athletes foot – a superficial fungus infection of the skin of the foot
Cold sore – a lesion, usually in the mouth area, caused by type 1 herpes simplex virus. Can be triggered by UV light, hormonal changes, and emotional stress. Also called a fever blister
Pruritus – itching of the skin
Topical – refers to a medication applied to the skin surface rather than ingested or injected