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Integumentary System Integumentary System collagen


Integumentary System Integumentary System collagen

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									                                    Integumentary System

•Largest organ
•Average adult skin is 2 square meters
•From birth to adulthood will increase in size 7-fold
•Weights approx. 6 lbs.
•Receives 1/3 of circulating blood
•Varies in thickness from 0.5 mm (tympanic membrane) to 6 mm (soles of feet and palms of
•One centimeter of skin contains:
        15 sebaceous glands;
        3 yards of blood vessels;
        100 sweat glands;
        3000 sensory cells;
        4 yards of nerves;
        300,000 epidermal cells; and
        10 hair follicles

Functions of the Skin:

•Protection – physical barrier against trauma, bacterial invasion, excessive loss of fluids and
proteins, skin cells provide immunity protection, skin pigmentation protects against UVR
•Sensation – feel pain, pressure and temp (nerve endings)
•Thermoregulation – regulates body temperature , involving the nerves, blood vessels and
glands. Cold body leads to decrease in temperature leads to vasoconstriction leads to decrease
blood flow to conserve body heat; if too hot leads to increase body temperature arteries in the
skin dilate, blood flow and sweat production increases allowing body to cool.
•Metabolism – when exposed to sunlight – synthesizes Vitamin D – mineralization of bones and
•Communication/Social interaction – body image, physical attraction; damage can lead to
functional/physiologic consequences – impact on self-esteem.
                                       Layers of The Skin

         o Cells in Epidermis:
                Squamous cells
                Melanocytes- synthesize and excrete melanin with exposure to sunlight-
                   Vit D- melanin stimulating hormone (MSH); shields against ultraviolet
                Langerhans- from bone marrow; initiate immune response with exposure
                   to environmental antigens
                Merkel Cells- associated with touch receptors; slowly adapt when
         o Barrier to water loss, protection, washing sheds the outer most layer
         o Formed from 5 layers (Memory Neumonic: C-ozy L-ayers G-enerating S-kin B-
           arriers) ; each layer is at a progressive stage of cell differentiation as it is growing
           (30 day average turnover)

               •Stratum  Corneum – outer tough/cornified layer composed of squamous cells
               without nuclei or organelles and keratinocytes which produce keratin
               (scleroprotein); prevents dehydration to the lower layers
               •Stratum Luciderm – found on thicker parts of skin only (I.E. Soles of feet and
               palms of hands), clear eleidin which becomes keratin when it moves up to the
               corneum layer
               •Stratum Granulosum – Langerhans cells and squamous cells with obvious
               keratohylin granules
               •Stratum Spinosum –spinelike structures forming the thickest layer of new
               keratinocytes composed of tightly bound squamous cells by intercellular junctions
               •Stratum Basalis, or stratum germinativum – reproductive layer of the
               epidermis where keratinocytes divide and move up to replace the surface cells

Epidermal-Dermal Junction/Basement membrane zone
 Separates epidermis from the dermis
 Layer affected in blister formation
 Rete ridges (basal epidermis) linked to dermal papillae of papillary dermis – prevents
Dermis (Mesenchymal layer)

       o Cells in Dermis
              Fibroblasts- secrete connective tissue matrix
                     Collagen gives tensile strength
                     Elastin provides recoil and prevents permanent reshaping
              Mast cells- release histamine
              Machrophages- phagocytic; part of immune response
              Endothelial cells- lining of blood vessels
       o Thickest layer, supplies and support and nutrition to the epidermis, regulates heat ,
         immune responses, receptors for heat and cold sensation.
       o Consists of hair follicles, sebaceous glands, sweat glands, blood vessels, lymph
         vessels, and nerves
        2 layers
         •Papillary dermis – thinner collagen fibers
         •Reticular dermis – thicker collagen fibers
Hypodermis (Superficial fascia- Adipose layer)

       o Cells in the Hypodermis
             o Macrophages
             o Fibroblast
             o Adipose
       o Attaches dermis to underlying structures
       o Provides insulation for the body, ready reserve of energy, additional cushioning, adds
         to the mobility of the skin over underlying structures.
Skin Immune System (SIS)

Cells that provide immune protection:
       •Langerhan’s cells – found in the stratum granulosom layer of the epidermis
       •Tissue macrophages – found in the dermis, most important cell of the SIS
       •Mast cells – found in the papillary dermis, epidermal appendages, blood vessels, nerves,
       fat tissue

Dermal Appendages:

       •Nails – tightly packed keratin (“hard keratin”) plates at the end of fingers and toes
                 * Continuously grow throughout life. FYI- I have actually witnessed a nail
               continuing to grow on a dry gangrenous finger!
       •Hair follicles and sebaceous glands are integrated units.
                    * Growth is cyclic with periods of growth and rest over different body structures
       •Glands - originate in the dermis but are actually appendages of the epidermis.
               Sebaceous – sac-like gland that opens onto the surface through a canal. Secrete
               sebum – lipid-rich oily substance, lubricates the skin, contributes to ph of skin.
               Growth of sebaceous glands is dependent on testosterone; enlargement is one sign
               of puberty
       •       Sweat – tightly coiled tubular gland –2 types
       •                 Apocrine – Located in axilla, scalp, abdomen and genital area:
                         puberty, contains proteins/fatty acids (B.O)
       •                 Eccrine – greatest in number in palms of hands, soles of feet, and
                         forehead. At birth, most important – regulates body temperature
                         lacks protein/fatty acids – through evaporation.

Blood Supply And Innervation:

       Blood to skin is limited to papillary capillaries/ plexus at the dermis. There are only
alpha adrenergic receptors in the skin.

Age Alters Skin Characteristics:
Barrier functions of the stratum corneum is reduced: thinner, drier, wrinkled, and changes in
    Flattening of dermo-epidermal borders
    Shortening and decrease in capillary loops
    Decrease in number of melanocytes (grey hair)
    Decrease in Langerhan cells
    Loss of rete pegs leads to smooth, shiny appearance
    Decrease in vasculature leads to atrophy of glands and in turn the skin is drier.
    Loss of elastin fibers leads to wrinkles
                                  Integumentary Dysfunctions

•Don’t Forget to Review Content Material for this Unit in Web CT! There is a great list of
dermatology definitions.

•In our text, there are pictures of different skin lesions.
Clinical Manifestations:

Leisons- observable and easily assessed for distribution and structure:

Pressure Ulcers- ischemic ulcers r/t shearing force and pressure (Use the Braden Score!)

               I-     Nonblanchable erythema of intact skin
               II-    Partial thickness- Shallow wounds involving epidermis and possibly
                      partial loss of the dermal layer= Epidermal and Dermal Repair
               III-   Full thickness- Loss of the epidermal and dermal layers, extending at least
                      to the SQ layer and possibly into the fascia-muscle layer and the bone=
               IV-    Full thickness w/ extensive destruction (May be unstagable)

                                    Dysfunctions of the Skin

Impentigo Contagiosa- bacterial infection characterized by reddish macules that become vesicles
and easily rupture. Often seen around nose and mouth. Dry and form honey-brown crusts and
pruitis is common. (Contact Precautions)

Folliculitis- Staphylococcal infection of hair follicle. Papules and pustuals found around hair
shaft. A furnuncle (boil) is a deeper form of folliculitis. Starts as a pimple and forms a boil w/
yellow or black center. A curbuncle is a more invasive form often found on the neck and
buttocks area. Accompanied by fever, pain, increased WBC count and possible sepsis.- (Do Not
Squeeze boils!)

Cellulitis- Skin infection extending into the dermis and subcutaneous layers often r/t strep
infection. Characterized as intense redness, swelling and streaking. Lymph node involvement
often common. Monitor for sepsis.

Psoriasis- Noninfectious inflammatory disease of skin where epidermal cells grow at faster rate
than normal (often 9 times faster). Aggrevated by stress, trauma, infection and seasonal change.
Characterized by red patches of skin covered with scales and is normally bilateral. Often seen on
scalp, knees, shin and elbows. May benefit from UV light because the inhibits epidermal
Tinea Capitis- Fungal infection transmitted from person to person. Characterized by pruitic
circular lesions at the scalp leaving bald patches.

Tinea Corporis- Fungal infection usually contacted from pets. Characterized by pruitic,
unilateral, circular lesions.

Tinea Cruris (jock itch)- Don’t share towels!
Tinea Pedis (Athletes foot)- Wear clean dry socks!

Candidiasis (Candida albicans)- Fungal infection resulting in an inflamed area with white
material that peels easily and bleeds. Grows in moist areas. (Swish and swallow!)

Scabies- Skin disruption caused by pregnant itch mite which burrows under the skin to lay eggs.
The burrow leaves a trail that is grayish-brown and commonly found between the fingers and on
the wrist. It itches more at night. * Highly contagious. Treat the whole family.

Pediculosis capitis (head lice)- The female lies her eggs close to the scalp. This appears as tiny
white specks that firmly attach. Nits hatch in 10 days. – NIX or RID.

Contact dermatitis- Not contagious. Associated with allergens or familial history. Characterized
by itching, redness, oozing vesicles and crusting.

Acne- predominantly in adolescence. Has some hereditary components and is aggrevated by
stress, hot, humid weather, and premenstrual periods in women. Closed comedones (white head)
and open comedones (black heads) and pustules vary in severity. Benzoyl peroxide and Vit A
depress sebum production.
                                    Physiology of Skin Repair

Two mechanisms of repair – determined by the tissue layer or layers involved and their capacity
to regenerate.

Regeneration – replacement with more of the same (epidermal and superficial dermal layers)
Connective tissue repair – scar formation (full thickness that extends through dermis)

Types of Healing:
•Primary intention- Healing ridge
•Secondary- Heal by scar formation
•Tertiary (delayed primary)- Example= Complicated abdominal wounds
Normal Integument Healing Response
•Inflammatory phase- last usually 1 - 4 days
       Hemostasis – initiates the entire wound healing cascade
•Proliferative phase- 4 – 20 days
       Matrix deposition/collagen   synthesis
•Remodeling phase- 21 days to 2 years
     •Strengthening and reorganizing of collagen fibers
Regulation of Wound Healing
•Growth factors- Attract needed cells to the wound bed, stimulate cell division, and stimulate
specific cellular activities
•Cytokines- Regulate cellular function and wound repair – “fine tune” repair process
•MMP’s and TIMP’s- MMP’s degrade the matrix, TIMP’s inhibit MMP’s
•Hormones – insulin deficiency, excess levels of cortisol
•Interplay of Regulatory Factors- Concentration/Combination of substances, Specificity of
receptors, Cell Activation
Factors Affecting Skin Characteristics

Age – newborn skin is almost as thick as adults, difference is transcutaneous water loss,
adolescence – increased activity of sebaceous glands due to hormonal stimulation, mature adult –
dermis decreases in thickness by 20% , epidermal turnover is increased leads to slower healing
times – young adult 21 days, 35+ 42 days, decrease in barrier function leads to friction, decrease
in UVR protection due to decrease in melanocytes, dryness leads to wrinkles, decrease in sensory
receptors leads to burns/trauma, decrease in Vit. D production, decrease in mast cells, decrease in
inflammatory responses. UGH!!
skin elasticity decreases related to age and solar damage – collagen unwinds and elastin lysis –
starts at age 30.

Sun – excessive exposure to UVR; dermotokelosis – dryness, tough leathery texture, wrinkling,
irregular pigmentation; Ca; if more than 6 serious sunburns have increase risk of melanoma

Hydration – provided by sebum and intact s. corneum, factors affecting – humidity, sebum prod.
decrease and age

Soaps – excessive use of alkaline soap, detergents decrease thickness # of cell layers, interferes
with water-holding capacity of skin and impair bacterial resistance. Ordinary handwashing –
takes 45 mins. to restore ph. Avoid alcohol and acetone.

Nutrition – if with damaged skin – increase Vit. C – collagen formation; increase protein –
supply amino acids for protein synthesis; CHO – for cell metabolism

Nutritional status- Increased caloric needs:
        Protein 0.8 g/kg/day for avg. adult, with wound increases to 1.25 to 2.0 g/kg/day
        Vitamin A needs increase, Vitamin C 100 to 1000mg, 15 –30 mg of zinc and 200% of
        RDA of Vit. B, 20 –30 mg of iron

Medications - corticosteroids – interfere with collagen formation; skin flora changed by antx,
oral steroids, and hormones; NSAIDS, analgesics, antihistamines alter inflammatory reactions.

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