os 203 06262013 integumentary system

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INTEGUMENTARY SYSTEMOS 203: Skin, Muscles and BonesDr. Rowena Genuino

26 June 2013

Arcilla, Arguilla, Azucena 1

SKIN Largest organ of the body Higher Surface area to Volume ratio in children

o Children are more prone to dehydrationand hypothermia

LAYERSEPIDERMIS

Thin but tough epithelial Function:

o Protective barrier against environment Appearance:

o

Paper thin and brownDERMIS

With thick vascularized connective tissue Function:

o Makes the skin pliableo Nutritiveo Elasticityo Tensile and strong

Appearanceo Thick and white

When cut, there is moderate bleeding due tovascularization

Gritty feelingHYPODERMIS

Composed of modified loose connective tissue Function:

o Insulationo Shock absorptiono Energy storage

Appearance:o Thin and white (superficial fascia)o Thick and yellow (subcutaneous fat)

Soft and least resistant to infection

MAIN FUNCTIONS OF THE SKINSKIN AS ORGAN FOR PROTECTION

Stratum Corneum

End product of keratinization or the differentiationof keratinocytes

Process of keratinization (takes 1 month):o Flatten and Stack up: cuboidal to

polyhedralo There is a loss of nuclei and organelleso Keratin bundles + Matrix fill up cello Thickening of plasma membrane

(envelope protein)

Waterproof barrier that decreases the bodyswater loss

Toughest layer due to Brick-Mortar Model:o Keratin-filled squames = Bricko Intercellular liquid = Mortaro Cornified cell envelope- reinforces CM,

adds to toughness

Two compartments:o Proliferating layer: the basement

membrane which produces cells(mitosis)

o Differentiating layer: the outer layers(stratum corneum is the mostdifferentiated layer)

Stratum Granulosum

Composed of Keratohyalin granuleso Filaggrinn- binds keratin bundles

Stratum Spinosum

Has many layers

Desmosomesfor intercellular junction Lamellar granules produces ceramide for

intercellular junctionStratum Basale

Single mitotic layer with stem cells

OutlineI. Skin

a. Layersi. Epidermisii. Dermisiii. Hypodermis

b. Main Functionsi. Skin as Organ for Protectionii. Skin as Immunologic Organiii. Skin as Organ for Supportiv. Skin as Organ for

Homeostasis & Secretion

v. Skin as Sensory OrganII. Skin Appendages

a. Eccrine Glandb. Hairc. Pilosebaceous Unit

i. Hair Follicleii. Sebaceous Glandiii. Apocrine glandiv. Arrector Pili


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OTHER EPIDERMAL CELLSMelanocyte

Serves as UV barrier Distributed to the apex of the basal cells Dendritic Derived from neural crest Appearance: clear, rounded cells Types of melanin:

o Phenomelanin(fair skin)o Eumelanin (dark skin)

SKIN AS IMMUNOLOGIC ORGANLangerhans Cell

For immune surveillance; antigen presentingcells

Found in the mid-epidermis Dendritic Derived from bone marrow Part of Mononuclear Phagocytic System

**Disease note: Allergic contact dermatitis

Due to malfunction of Langerhans cellsSKIN AS ORGAN FOR SUPPORT

Elasticity and tensile strength due to connectivetissues:

o Fiberso Ground Substanceo Connective Tissue cells

Dermis provides nutrients due to highvascularization

Epidermal-dermal Attachmento Peg and socket Interdigitation

Epidermal rete ridges(downward)

Dermal Papillae (upward) Basal lamina (found in between

the two other layers, serves forattachment)

o Produces pattern of fingerprints

Skin tension lineso Shows what orientation the collagen

fibers are directed towardso Useful in knowing where to make a cut

to prevent scaring


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Dermatoglyphic patternso parallel epidermal ridges (containing

sweat pores)o grooves, form whorls, arches or loops

form unique fingerprints

SKIN AS ORGAN FOR HOMEOSTASIS & SECRETIONVascular Network of skin

Provides nutritiondue to vascularization:o To appendages in the dermis and

hypodermiso To epidermis

Provides thermoregulationo Diverts arterial blood directly into veins

without passing capillaries for heatconservation

o Tips of fingers, toes, earsGlomus bodies

Atrio-ventricular shunts Conserves heat by diverting blood from arteries

directly to vein without passing through capillaries

Causes tips of fingers and toes and ears to go bluefirst

SKIN AS SENSORY ORGANMerkel Cell-neurite complexes

For touch With dense core granules Abundant in finger tips

Free nerve endings

Pain, itch, temperatureEncapsulated nerve receptors

Meissner corpuscleo Also for toucho Small; found in dermal papillaeo With Spirally coursing axon surrounded

by lamellaeo Abundant in lips and finger tips

Pacinian corpuscleo Large; found deep in dermiso With central axon surrounded by

concentric lamellaeo Abundant in fingertips and joints

**Disease note: Leprosy

Attacks nerves of skin Makes the skin dry, rough and edematous Autonomic nerve dysfunction (nerve cells

dont function properly)

SKIN APPENDAGES

ECCRINE GLANDS

Most abundant skin gland Thermoregulation Excretory function:

o Heavy metalso Organic compoundso Macromolecules

Single coiled tubular: sweat glands

Single duct with 3 segments:o Intraepidermalo Straight dermalo Coiled dermal


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Ductal portiono Darkly stainingo Stratified cuboidal; highly eosinophilic cells

Secretory portiono Single layer of slightly eosinophilic pyramidal

cells

Sweato Clear and odorless

Mainly composed of NaClHAIR

Keratinized cells Sheds of in cycles which determines the

maximum length the hair can grow

Absent in palm of the hands, soles of the feet,and mucocutaneous junction

Velus: barely visiblehair found all over the body Terminal: thicker hair of the eyebrows, head,

pubic region, etc.

Functions of hair:

Protection and thermoregulation

Sensation Immune reserve/epidermal cell reserve via cell

regeneration

PILOSEBACEOUS UNITHAIR FOLLICLE

Parts of Hair Follicle

Infundibulumo Opens into skino Where the sebaceous gland emptieso Bulge stem cell

Inferior segmento Present only during growth stage

Hair bulbo With hair matric with melanocyte to

provide hair coloro With hair papilla

Concentric layers of hair follicle

Hair shafto Composed of hard keratino Takes longer to shed due to sulfur rich,

closely packed keratin bundles

o Interlocking cuticles of hair shaft andinner root sheath

Makes hair difficult to pull


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Internal root sheath External root sheath

o Continues with surface Fibrous sheath

Stages in growth

Growing (Anagen):o Longest stageo 8/10 hair follicles are at this stageo Duration of Anagen determines hair

length (ex. eyelash: 6 weeks, scalp: 3years)

Regressing (Catagen)o Shortest stageo Where separation happenso Club hair

Resting (Telogen)o Stage right before follicle gets shed off

**Disease note: Andorgenic Alopecia Male pattern baldness Caused by excess androgen plus genetic

predisposition

SEBACEOUS GLAND

Simple branched alveolar Holocrine Produces sebum- a triglyceride that softens thin

skin and in charge of hair flexibilityDisease note: Acnecaused by increased production of

sebum due to hormonal changes

APOCRINE GLAND

Not present in all units

Simple coiled With merocrine secretions Has larger lumen Eosinophilic

ARRECTOR PILI

Hair movement, causes hair to stand up whenstimulated

Hi sa mga intarmed! Labyu!Jules

Smile always (well need it)! -Jasmine

Hey friends! Nagdagdag ako ng mga pictures para masma-imagine nyo yung mga structures :>Join UP-MSS Because at MSS, We Can!Join MSSR-IPPNW for socially responsible fun!- Carlos

os 203 06262013 integumentary system

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