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ANATOMY & PHYSIOLOGY
Mr. Eric Mahinay| 1St^ Semester | BSN – 1B S.Y. 2023 – 2024 ● Integumentary system - includes the skin and its accessory structures including hair, nails, and glands, as well as blood vessels, muscles, and nerves ● Dermatology - a medical specialty of the diagnosis and treatment of disorders of the integumentary system. ● Cutaneous membrane (SKIN) covers the body and is the largest organ of the body by surface area and weight ● Area - 2sqm (22sqft) ● Weight - 4.5 - kg (10-11lbs) ● 16% of body weight ● 0.5 - 4mm thick, thinnest on the eyelids, thickest on the heels; average thickness is 1-2 mm LAYERS OF THE SKIN Epidermis outer, thinner layer consists of epithelial tissue Dermis inner, thicker layer Hypodermis subcutaneous (subQ layer) beneath the dermis attaches the skin to the underlying tissues and organs not a major layer ● composed of keratinized stratified squamous epithelium. ● it contains four principal types of cells: 1.) Keratinocytes - 90% of the cells
- produce keratin (a fibrous protein that provides protection + waterproofs the skin) 2.) Melanocytes - 8% of the cells - produce the pigment melanin - contributes to skin color - absorbs UV light - protects against damage by UV radiation 3.) Langerhan Cells - involved in immune responses - arise from red bone marrow - constitute a small % portion - easily damaged by UV light 4.) Merker Cells - least in number - found in the deepest layer of epidermis - function in the sensation of touch along with tactile discs ● Stratum basale or stratum germinativum ➔ deepest layer ➔ single row of cuboidal or columnal keratinocytes ➔ where new cells are formed ➔ where cell division occurs which produces other layers ● Stratum spinosum ➔ 8-10 layers of keratinocytes ➔ above stratum basale ➔ some cells retain ther ability for cell division ➔ cells have spine-like projections (bundles of filaments of the cytoskeleton) ➔ tightly joins cells to each other ➔ provides strength and flexibility to the skin
STRUCTURES OF THE SKIN
EPIDERMIS
LAYERS OF EPIDERMIS
ANATOMY & PHYSIOLOGY
Mr. Eric Mahinay| 1St^ Semester | BSN – 1B S.Y. 2023 – 2024 ● Stratum granulosum ➔ includes keratohyalin and lamellar granules ➔ above stratum spinosum ➔ 3-5 layers of flattened keratinocytes undergoing apoptosis ➔ organelles begin to disintegrate ➔ becomes non-living cells ➔ transition between deeper metabolicaly active strata and the dead cells of the superficial strata ➔ secretes lipid reach secretion (acts as water sealant) ● Stratum Lucidum ➔ only in thick skin (fingertips, palms, and soles) ➔ 3-5 layers of clear, flat, dead keratinocytes ➔ thick plasma membrane ● Stratum corneum ➔ composed of many sublayers of flat, dead keratinocytes (corneocytes or squames) ➔ constant friction can stimulate formation of callus ➔ 25-30 layers of dead keratinocytes ➔ serves as water, microbe, injury barrier Keratinization - accumulation of more and more protective keratin, occurs as cells move from deepest to the surface layer Dandruff - excess of keratinized cells shed from the scal Growth
- The process takes about 4 weeks
- Rate of cell division in stratum basale increases during injury ● second deepest part of skin ● composed of connective tissues (collagen + elastic fibers) ❖ collagen fibers - 70% of the dermis (gives structural toughness and strength) ❖ elastin fibers - loosely arranged in all directions (gives elasticity) ● blood vessels, nerves, glands, and hair follicles are embedded here ● Papillary region - outer
- consists of areolar connective tissue containing thin collagen + elastic fibers + dermal papillae (including capillary loops ), corpuscles of touch and free neve endings
- superficial portion of the dermis
- surface area is increased due to projections called dermal papillae
- contains capillaries or tactile receptors
- epidermal ridges conforms to the dermal papillae ● Reticular region - deeper portion
- provides skin with strength and elasticity
- consists of dense irregular connective tissue (contains collagen & elastic fibers, adipose cells, hair
DERMIS
LAYERS OF DERMIS
ANATOMY & PHYSIOLOGY
Mr. Eric Mahinay| 1St^ Semester | BSN – 1B S.Y. 2023 – 2024 ● contains areolar connective tissue and adipose tissues ● attaches the skin to underlying organs and tissues ● contains lamellated (pacinian) corpuscles
- detect external pressure applied to the skin ● includes hair, skin glands, and nails A. HAIR (pili)
- composed of dead, keratinized epidermal cells
- consists of ❖ Shaft - mostly projects above the surface of the skin
- straight hair has a round shaft
- curly hair has oval shaft ❖ Root - deep to the shaft that penetrates into the dermis
- has 3 layers: medulla contains granules and air spaces cortex middle layer (main body)
- in dark hair contains pigments
- in gray/white contains air bubbles cuticle outer layer
- heavily keratinized cells that lie like shingles ❖ Epithelial root sheath (Internal) ❖ Dermal root sheath (External) ❖ base of the Hair Follicle
- Bulb : houses the papilla which contains the blood vessels that nourishes the growing hair follicle.
- Matrix : responsible for hair growth and produces new hair ❖ Arrector pili - smooth muscle
- extends from dermis to the side of hair follicle.
- its muscles contract and pull hair straight causing goosebumps. ❖ Hair root plexus - dendrites of neurons that are sensitive to touch
- Different types of hairs: lanugo , vellus, and terminal hairs
- Hair color is determined by the amount and type of melanin, carotene, and blood ➢ Dark hair contains true melanin ➢ Blond and red hair - have variants of melanin in which there are iron/sulfur ➢ Gray hair - decline in tyrosinase ➢ White hair - accumulation of air bubbles in the shaft
- Growth ➢ Every hair follicle goes through a growth cycle consisting of a growth stage and a resting stage. B. SKIN GLANDS ● Sebaceous glands (oil glands)
- sebace = grease
- secrete an oily substance called sebum (prevents hair and skin dehydration)
- inhibits growth of bacteria
- begins to function at puberty
- embedded in the dermis over most of the body
ACCESSORY STRUCTURES OF THE SKIN
FUNCTIONS OF THE HAIR
protection reduction of heat loss sensing light touch
ANATOMY & PHYSIOLOGY
Mr. Eric Mahinay| 1St^ Semester | BSN – 1B S.Y. 2023 – 2024
- absent in palms and soles ● Sudoriferous glands (sweat glands)
- sudori = sweat, ferous = bearing
- 3-4 million glands in your body
- empties onto the skin thru pores or into hair follicles
- there are two main types of sweat glands: Eccrine or Merocrine
- helps cool the body by evaporating
- eliminates small amounts of wastes
- secretes cooling sweat
- secretes directly onto the skin
- began to function soon after birth - sweat - 98% water + 2% dissolved salts an nitrogenous wastes (ex urea & uric acid) Apocrine - located mainly in the skin of axilla, groin, areolae, and bearded facial regions of men
- excretes via hair follicles- secreted during emotional stress and sexual excitement
- began to function at puberty
- slightly more viscous than eccrine secretions
- referred to as cold sweat ● Ceruminous glands
- modified sweat glands in the ear canal
- involved in cerumen (earwax) production (provides a sticky barrier that prevents entry of foreign bodies into the ear canal C. NAILS ● made of hard, keratinized epidermal cells ● located over the dorsal surfaces (ends of finger and toes) ● Each nails consists of: ❖ free edge - part that extends beyond the tip of finger or toe ❖ transparent nail body (plate) - visible portion of the nail ➢ lunula - whitish, moon/crescent shapeat its base ❖ nail root - embedded in a fold of skin ❖ Hyponychium - secures the nail to the fingertip ❖ Eponychium (cuticle) - narrow band of epidermis Shridar Chillal - Indian from Pune, hasn’t cut nails since 1952 -record holder in nail growth -left hand : 242 inches -thumbnail (longest) : 56 inches D. TYPES OF SKIN THIN (HAIRY) THICK (HAIRLESS) covers all parts except palms & soles covers palm & soles lacks stratum lucidum distinct stratum lucidum lacks dermal papillae numerous dermal papillae more sebaceous glands, less sweat glands lacks sebaceous glands, more sweat glands less sensory receptors packed sensory receptors
FUNCTIONS OF THE
NAILS
grasping objects manipulating objects protects ends of digits from trauma scratching
ANATOMY & PHYSIOLOGY
Mr. Eric Mahinay| 1St^ Semester | BSN – 1B S.Y. 2023 – 2024 ● Basal epithelial cells divide and migrate across the wound ● Stop migrating due to contact inhibition ● Thickening of the epidermis ● Extends to the dermis and subcutaneous layers; Scar tissue will form ● Healed tissue loses some of its normal function ● Occurs in 4 stages; Inflammatory - blood clot forms
- enhanced delivery of WBC
- prepares for repair Migratory - clot becomes a scab
- epithelial cells begin to migrate
- fibroblasts synthesizes scar tissue ( fibrosis - scar tissue formation)
- damaged blood vessels repair
- granulation tissue begins to fill the wound Proliferative - extensive growth of epithelial cells
- fibroblasts randomly deposit collagen fibers
- continue blood vessel repair Maturation - scab comes off
- collagen becomes more organized
- fibroblasts decrease in number
- blood vessels restored to normal ● epidermis develops from ectoderm ➢ nails, hair, & skin (epidermal derivatives) ➢ vernix - fatty substance that protects the epidermis of a fetus ● dermis develops from mesoderm A. CANCER ● Cells have a built-in mechanism that causes contact inhibition. Healthy cells stop growing when they come in contact with one another. ● In damaged cells, contact inhibition is lost and therefore the cells continue to grow until they start
DEEP WOUND HEALING
DEVELOPMENT OF THE INTEGUMENTARY
SYSTEM
IMBALANCES OF HOMEOSTASIS
ANATOMY & PHYSIOLOGY
Mr. Eric Mahinay| 1St^ Semester | BSN – 1B S.Y. 2023 – 2024 lumping up on one another. Cancer cells do not exhibit contact inhibition. ● UV radiation, chemicals, or physical trauma are predisposing factors to cancer. Three Forms of Cancer Basal Cell Carcinoma Squamous Cell Carcinoma Melanomas 78% of skin cancers 20% of all skin cancers most dangerous arise from stratum basale arise from squamous cells of the epidermis arise from melanocytes rarely spreads spreads rapidly if not removed spreads rapidly has a pearly elevation with blood vessels in the middle hardened small red growth best chance of full recovery if detected and treated early good chance of recovery if detected and treated early early detection and treatment is key to survival ● Risk factors for cancer: sun exposure, skin type, family history, age, and immunological status ● Warning signs as suggested by American Cancer Society: ABCD rule A: asymmetry , sides do not match B: border , indentations on border C: color, contains various colors D: diameter , larger than 6mm (pencil eraser) E: elevation
B. BURNS
Destroys skin’s contribution to homeostasis : ● Microbial protection ● Prevention of desiccation ● Thermoregulation ● Electrolyte imbalance Graded according to severity First degree epidermis redness, swelling, pain Second degree epidermis + upper part of dermis blisters appear Third degree destroys epidermis, dermis, an dermal structures fluid loss and infection + skin grafting is usually necessary ● Rules of Nines - quick means of estimating burned surface area ❖ Head and neck 4.5% for front, 4.5% for back ❖ Trunk 9% for front, 9% for back ❖ Upper Limbs 4.5% for front, 4.5% for back ❖ Lower Limbs 9% for front, 9% for back ❖ Perineum 1% ● Burns are critical under these conditions: ❖ Over 25% of body has 2nd degree burn ❖ Over 10% of the body has 3rd degree burn
