06 Integumentary System

8/14/2019 06 Integumentary System

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INTEGUMENTARY SYSTEMSKIN

BODYS LARGEST ORGAN

APPROXIMATELY 7% ADULT BODY WEIGHT


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Main Concepts

Functions

Holds it all together

Protection

Water Resistant

Temperature Reg.

BP Regulation

Excretion Sensory Perception

Metabolic Function

Anatomy

Epidermis

4 cell types

Dermis 2 layers

Hypodermis

(not part ofintegument)


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FUNCTIONS OF SKIN KEEPS EVERYTHING IN!!!

PROTECTION AGAINST INFECTION

RESISTANT TO INVASION

LOW pH OF SKIN SECRETIONS (ACID MANTLE) KEEPSBACTERIA FROM MULTIPLYING

NATURAL ANTIBIOTIC SECRETION

CONTAINS MACROPHAGES AND LANGERHANS CELLS FORCASES OF A BREAK IN THE SKIN

PHYSICAL HARM CONTINUITY OF SKIN

HARDNESS OF KERATINIZED CELLS

WATER RESISTANT (NOT WATERPROOF) GLYCOLIPIDS OF SKIN FORMS BARRIER TO WATER LOSE APPX. 500 ml OF WATER/ DAY ON AVERAGE

(WITHOUT VIGOROUS EXERCISE)


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FUNCTIONS OF SKIN

TEMPERATURE REGULATION SWEATING (EVAPORATION) VASODILATION/ VASOCONSTRICTION (8x INCREASE IN

HEAT CONDUCTANCE THROUGH SKIN WHENVASODILATED)

INSULATION, ESPECIALLY SUBCUTANEOUS FAT GOOSEBUMPS (WELL, NOT REALLY, BUT GOOD TRY!)


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FUNCTION

BLOOD PRESSURE REGULATION VASOCONSTRICTION/ VASODILATION

EXCRETION OF WASTES UREA, AMMONIA, URIC ACID, SALT

SENSORY PAIN RECEPTORS TOUCH RECEPTORS TEMPERATURE RECEPTORS PRESSURE RECEPTORS VIBRATION RECEPTORS

METABOLIC FUNCTION ABLE TO PRODUCE VITAMIN D FROM CHOLESTEROL IN

BLOOD VESSELS WHEN EXPOSED TO SUNLIGHT


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SKIN ANATOMY

EPIDERMIS STRATIFIED SQUAMOUS

EPITHELIAL CELLS NONVASCULAR

DERMIS TOUGH, FIBROUS

CONNECTIVE TISSUE VASCULAR

HYPODERMIS : NOT PARTOF THE INTEGUMENT

(SUBCUTANEOUS) SUPERFICIAL FASCIA MOSTLY ADIPOSE ANCHORS SKIN LOOSELY TO

UNDERLYING STRUCTURES


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EPIDERMIS: 4-5 LAYERSTOP

5: STRATUM CORNEUM: KERATIN FILLED DEAD CELLS GLYCOLIPIDS B/T CELLS DURABLE OVERCOAT

4: (STRATUM LUCIDUM) ONLY IN THICK SKIN

NUCLEI DISINTEGRATE, CELLSDIE

3: STRATUM GRANULOSUM FLATTENED CELLS ACCUMULATION OF GRANULES

2: STRATUM SPINOSUM

1: STRATUM BASALE SINGLE ROW YOUNG CELLS (KERATINOCYTES) RAPID DIVISION MELANOCYTES

BOTTOM


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EPIDERMIS: CELL TYPES Keratinocytes:

majority of epidermal cells

produce keratin (tough fibrousprotein)

Melanocytes: in stratum basale (10-25% of

basal cells)

produce melanin (pigment)

which is then taken in bykeratinocyes (uv protection)


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EPIDERMIS: CELL TYPES

Langerhans cells:

macrophages(protection frominvasion)

Merkel cells:

epidermal/ dermal

junction assists with sensory

nerve ending


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DERMIS (YOUR HIDE) Strong and flexible (collagen, elastin, reticular

fibers) Contains nerves, bvs, lymph

Houses glands and hair follicles (but does not

create these) 2 layers papillary

reticular


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DERMIS: PAPILLARY LAYER Loose Areolar CT

Ridges in contact withepidermis epidermal ridges form

fingerprints friction

Contains:

capillary plexes free nerve endings

(pain sensation)

meissners corpuscles(soft touch)


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DERMIS: RETICULAR LAYER

80% of dermis

Dense Irregular CT

Collagen: stregnth

binds h2o

Elastin: flexibility


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BLISTERS AND CALLOUSES

Blister: friction, burn, or pathology

separation between epidermisand dermis filled with fluid

Callous: overgrowth of epidermis

over time

protection


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More Concepts

Pigments

melanin

carotene

hemoglobin

Appendages

nails

hair

hair follicles

sweat glands

oil glands


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SKIN COLOR Due to 3 pigments

melanin carotene

hemoglobin

Range of colors

reds, yellows, browns


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MELANIN

Two types brown/ black

yellow to reddish brown

All humans have same # of melanocytes secrete different amounts, types, and sizes of granules to create

different skin colors

freckles are uneven accumulations of melanin

Stimulation of melanocytes by sunlight protects keratinocytes from uv radiation

absorbs light and dissipates energy as heat.


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SKIN COLOR:HEMOGLOBIN AND CAROTENE

Carotene: yellow/orange pigment

accumulates in stratum corneum and fattytissue

especially notable in palms and soles(when eating many carotene rich foods)

Hemoglobin:

pinkish

hemoglobin in RBC's circulating throughcapillaries

transparency of epidermis in caucasiansallows this color to show through


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ABNORMAL SKIN COLORS

Redness: blushing; fever; hypertension;

inflammation; allergy

Pallor:

fear; anger; stress; anemia Jaundice:

liver disorder causes bilepigments to accumulate intissues including whites ofthe eyes


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ABNORMAL SKIN COLORS BRONZING:

ADDISONS DISEASE BRUISING:

BLOOD BLEEDING UNDERINTACT SKIN, LEADS TO

CLOTTING (HEMATOMA) CYANOSIS:

POORLY OXYGENATEDHEMOGLOBIN, SKIN APPEARS

BLUE


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Moles


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Skin Tags

Usually caused byfriction

Over growth of

epidermal cells Have blood supply

Mostly benign


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SKIN APPENDAGES

Nails Hair

Hair follicles

Sweat glands

Sebaceous glands


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HAIR Functions:

insulation trap heat (though not as much in humans) protection

nose hairs trap foreign substances eyelashes, eyebrows, and head hair protects

from sunlight sensation

(ie. whiskers) social/ communication

Hair accessories erector pili muscles sebaceous glands (oil)


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HAIR Composed ofkeratin

Hairshaft (above skin) Hair root (inside the skin)

Hairfollicle

in dermis, but made from

epidermal pocket surrounding follicle is knot

of sensory nerve endings

expanded bulb is dermal

papilla capillary plexus w/

nutrients and growthsignals


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HAIR SHAPE AND COLOR

Shape of follicle: oval: curly hair c shape: wavy hair round: straight hair

Hair color: melanocytes produce the melanin which is then

picked up by the cortical cells gray/ white hair: decreased melanin production


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HAIR GROWTH

Cycles of growth lasting 6-10 yrs in scalp (3-4months in eyebrows)

2-5 mm per week (varies)

We lose appx. 50-100 hairs per day

Stimulated by testosterone though testosterone is also what leads to male pattern

baldness

INTERESTING HAIR FACTS: HAIR GROWS FASTER IN THE SUMMERTHAN IN WINTER: CUTTING HAIR HAS NO EFFECT ON GROWTH: HAIRGROWS FASTEST BETWEEN 16-24 YEARS OF AGE


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HAIR GROWTH


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NAILS

Function help in grasping

and manipulation ofsmall objects

protection for endsof digits

Scale-like

modification ofepidermis

Made of hard keratin


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GLANDS

Derived fromepithelial tissue;reside in dermis

Sweat glands:

everywhere exceptnipples andexternal genitalia

two types: Eccrine Apocrine

Sebaceous (oil)glands


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SWEAT GLANDS Eccrine

Most of our sweat glands

Temperature regulation

Ducts empty into pores

Apocrine

Axillary and anogenitalregions only

Odorless untildecomposed by bacteria

on skin

Ducts empty into hairfollicles

Sweat, fat and protein


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Sweat 99% water

Dermicidin

Lactic acid

Acidic (pH 4-6)

NaCl

Vit C Metabolic wastes

Antibodies


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SEBACEOUS GLANDS

Everywhere exceptpalms/ soles

Produce sebum (lipid)

softens and lubricates skinand hair

slows water loss

bactericidal

secreted into hair follicles

Pimples and acne


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PIMPLES

WHITEHEAD: PLUGGED

SEBACEOUS GLAND

BLACKHEAD(COMEDONE): PLUGGED

SEBACEOUS GLAND

WHERE SEBUMUNDERGOESOXIDATION


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CUTANEOUS RECEPTORS

Exteroreceptors Two types (sensitive to stimuliarising outside the body) encapsulated nerve endings

Vibration

Deep Pressure

Light touch

free nerve endings

Pain

Temperature

Pressure

Stretch

Touch


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ENCAPSULATED NERVEENDINGS

End of the nerve is wrapped ina thin layer of connectivetissue

Mechanoreceptors Meissners corpuscles

just beneath epidermis light touch

Pacinian corpuscles deep in dermis

Vibration, pressure Ruffini corpuscles

dermis and sub-q Skin stretch, finger position


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FREE NERVE ENDINGS Naked nerve endings of sensory neurons

Found everywhere in the body (many in connective andepithelial tissue)

Nociceptors Pain

Thermoreceptors (cold/ heat)

Mechanoreceptors merkel discs

deep in epidermis light touch receptor

hair follicle receptors wrap around hair follicles detect bending of hair

TWO POINT DISCRIMINATION


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TWO POINT DISCRIMINATION Receptor fields

Receptor density

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06 Integumentary System