1. The Integumentary System

2.  Integument means covering.  Skin and its appendages make up the integument system  It covers about 3,000 square inches of the surface.  It is made up of hair, nails, sebaceous (oil) glands, and Sudoferious (sweat) glands.

3. Functions of skin  Skin is covering for the underlying, deeper, tissue, protecting them from dehydrations, injury, and germ invasions.  Skin helps regulate body temperature by controlling the amount of heat loss.Evaporation of the water from the skin, in the form of perspiration, rids the body of excess heat.  Skin helps manufacture vitamin D. The ultra violet light on the skin is necessary for the first stages of vitamin D formation.

4. Functions of The Skin Continuation….  Skin is the sight of many nerve endings. A square inch of skin contains about 72 feet of nerves and hundreds of receptors.  Skin has tissues for the temporary storage of fat, glucose, water, and salts such as sodium chloride. Most of the substances are later contained observed and transferred to other parts of the body.  Skin is designed to screen out harmful ultraviolet contained by sunlight.  Skin has special properties to absorb drugs and bad toxins.

5. Structure of the Skin  The skin consists of two basic layers: o The epidermis or outermost or outermost covering made of epithelial cells with no blood vessels present o The dermis or true skin is made of connective tissue and is vascular o ***The hypodermis isn’t really considered but since its in the diagram I’ll go over it.

6. Epidermis  Keratinized stratified squamous epithelium  Four types of cells  Keratinocytes – deepest, produces keratin (tough fibrous protein)  Melanocytes - make dark skin pigment melanin  Merkel cells – sensory receptors for touch  Langerhans cells – macrophage which are effective in the defense  Layers (from deep to superficial)  Stratum basale or germinativum – single row of cells attached to dermis; youngest cells  Stratum spinosum – spinyness is artifactual; tonofilaments (bundles of protein) resist tension  Stratum granulosum – layers of flattened keratinocytes producing keratin (hair and nails made of it also)  Stratum lucidum (only on palms and soles)  Stratum corneum – horny layer (cells dead, many layers thick)

7. Epithelium: layers (on left) and cell types (on right)

8. Dermis  Corium, is the thicker, inner layer if the skin.  It contains masses of connective tissues, collagen tissue bands, elastic fibers, nerve endings, muscles, hair follicles, oil and sweat glands, and fat cells.  The thickness of the dermis varies over different parts of the body for instance, the dermis is thicker over the soles of the feet and the palms of the hands.  There are many nerve receptor of different types of the dermal layer.  Blood vessels in the dermis aid in the regulation of body temperature to maintain homeostasis.

9. * Dermis layers * * * Dermal papillae

10. Hypodermis  Not considered apart of the Integumentary system.  It lies under the dermis and called superficial fascia.  It consists of loose connective tissues and contains about ½ of the bodies stored half.

12. Hair and hair follicles: complex Derived from epidermis and dermis Everywhere but palms, soles, nipples, parts of genitalia * “arrector pili” is smooth muscle * Hair papilla is connective tissue ________________ Hair bulb: epithelial cells surrounding papilla

13. Skin appendages  Derived from epidermis but extend into dermis.  Include:  Hair and hair follicles  Sebaceous (oil) glands  Sweat (sudoiferous) glands  Nails

14.  Functions of hair  Warmth – less in man than other mammals  Sense light touch of the skin  Protection - scalp  Parts  Root imbedded in skin  Shaft projecting above skin surface  Make up of hair – hard keratin  Three concentric layers  Medulla (core)  Cortex (surrounds medulla)  Cuticle (single layers, overlapping)

15.  Types of hair  Vellus: fine, short hairs  Intermediate hairs  Terminal: longer, courser hair  Hair growth: averages 2 mm/week  Active: growing  Resting phase then shed  Hair loss  Thinning – age related  Male pattern baldness  Hair color  Amount of melanin for black or brown; distinct form of melanin for red  White: decreased melanin and air bubbles in the medulla  Genetically determined though influenced by hormones and environment

16. Sebaceous (oil) glands  Entire body except palms and soles  Produce sebum by holocrine secretion  Oils and lubricates

17. Sweat glands  Entire skin surface except nipples and part of external genitalia  Prevent overheating  500 cc to 12 l/day! (is mostly water)  Humans most efficient (only mammals have)  Produced in response to stress as well as heat

18. Types of sweat glands  Eccrine or merocrine  Most numerous  True sweat: 99% water, some salts, traces of waste  Open through pores  Apocrine  Axillary, anal and genital areas only  Ducts open into hair follices  The organic molecules in it decompose with time - odor  Modified apocrine glands  Ceruminous – secrete earwax  Mammary – secrete milk

19. Nails  Of hard keratin  Corresponds to hooves and claws  Grows from nail matrix

20. Careers Associated with Integumentary System  Dermatologist- Annual salary of 279,000, Dermatologists are medical doctors who deal with skin and skin aliments, the conduct skin evaluations in order to determine how to best treat and prevent conditions and diseases. Education: Undergraduate, 4 years of medical school, residency programs (3-4 years)  Plastic surgeon- Doctors who deal with replacing, repairing or reconstructing various parts of the body, mostly facial features. Annual salary of 300,000 to 791,510, Education: Complete up to medical school requirements and then must complete residencies which takes longer than other normal residencies.  Allergist- Annual salary: 332,450, Specialist in diagnosis and treatment of allergic diseases. Education: The first step towards becoming an allergist is earning a medical degree, then two more years for specialization; the final step is to earn certification from the board of allergy and immunology.

21. Disorders of the Integumentary system  Burns  Threat to life  Catastrophic loss of body fluids  Dehydration and fatal circulatory shock  Infection  Types  First degree – epidermis: redness (e.g. sunburn)  Second degree – epidermis and upper dermis: blister  Third degree - full thickness  Infections  Skin cancer

22. Burns First-degree (epidermis only; redness) Second-degree (epidermis and dermis, with blistering) Third-degree (full thickness, destroying epidermis, dermis, often part of hypodermis)

23. Critical burns  Over 10% of the body has third- degree burns  25 % of the body has second-degree burns  Third-degree burns on face, hands, or feet Estimate by “rule of 9’s”

24. Tumors of the skin  Benign, e.g. warts  Cancer – associated with UV exposure (also skin aging)  Aktinic keratosis - premalignant  Basal cell - cells of stratum basale  Squamous cell - keratinocytes  Melanoma – melanocytes: most dangerous; recognition:  A - Asymmetry  B - Border irregularity  C - Colors  D - Diameter larger than 6 mm

25. Basal cell carcinoma Sqaumous cell carcinoma Melanoma Skin Cancer