SKIN AND THE INTEGUMENTARY SYSTEMChapter 6

SKIN IS…

is the largest & heaviest organ in the body.

covered in hair.

vital in maintaining homeostasis.

a protective barrier.

a.k.a. the cutaneous membrane.

SKIN IS…

part of the integumentary system.

divided into three distinct layers:

EPIDERMIS – outer layer

DERMIS – middle layer

SUBCUTANEOUS – bottom layer (Not a true skin layer )

EPIDERMIS

Stratified squamous epithelium

Old cells die are pushed up

Cytoplasm hardens, fills with keratin

KERITINIZATION

Forms tough, waterproof layer - STRATUM CORNEUM

EPIDERMAL LAYERS

Stratum corneum

Stratum lucidum Only in thick skin

Stratum granulosum

Stratum spinosum

Stratum basale

MICROSCOPIC EPIDERMIS

EPIDERMAL PROTECTION

Stratum basale contains MELANOCYTES

Produce MELANIN

Dark pigment in granules that absorbs UV radiation

Granules spread to nearby cells

SKIN COLOR

Everyone has the same # of melanocytes Skin color depends

on amount of melanin produced

Other factors: Blood supply Beta – carotene Bilirubin

Dark Skin

Light Skin

THE KING OF POP

What’s up with M.J.’s skin?

Vitiligo – disorder in which the skin’s melanocytes are destroyed

VITLIGO

Possible causes: Body is allergic to its own melanocytes Cells destroy themselves during pigment

creation

FYI – Cancer patients can develop vitiligo after treatment; the weird thing? The vitiligo actually seems to stop the spread of

the disease!

BACK TO M.J.

Underwent repigmentation Turn white patches dark

again.

Process failed Went through

depigmentation to reverse it

Monobenzene is used to bleach the skin until it’s all the same color

If he stopped the treatments, he would turn back

ALBINISM Body is unable to produce or

distribute melanin due to possible genetic defects

High risk of skin cancer and eye problems

PSORIASIS

Excessive growth and reproduction of keratinocytes followed by inflammation

Caused by the immune system mistakenly reacting

Speeds up creation of new cells and slows loss

WHAT ARE THOSE WHITE SPOTS ON MY FINGERNAILS?

Leukonychia

Can be caused by trauma

Not a calcium deficiency

Zinc deficiency is more pronounced

HOW THICK IS YOUR SKIN?

Epidermis: .5 mm on eyelids Up to 1.5 mm on palms/soles

Dermis: .3mm on eyelids 3 mm on upper back

DERMIS

Directly below epidermis

Dermal papillae project upwards into epidermis Produce fingerprints

Made mostly of dense connective tissue

DERMAL STRUCTURES

BEDSORES

Interference with blood flow to the dermis can kill epidermal cells

Lying in one position too long causes weight of body to block skin’s blood supply

A.k.a. PRESSURE ULCER

Treatment includes shifting the patient frequently and keeping the wound clean

SUBCUTANEOUS LAYER

A.k.a. HYPODERMIS

Loose connective and adipose tissue

Insulation

Major blood supply

SEVERITY OF BURNS

INJECTIONS

SUBCUTANEOUS INJECTION Flu shot, penicillin

INTRADERMAL TB test

INTRAMUSCULAR Epinephrine injection

ACCESSORY ORGANS OF THE SKIN

NAILS

HAIR FOLLICLES

SEBACEOUS GLANDS

SUDORIFEROUS GLANDS

NAILS

Protective coverings

NAIL ROOT & LUNULA contain actively dividing cells

Cells die and become keratinized forming nail body

HAIR FOLLICLES

Hair development

Specialized epidermal tissue Nourished by

dermal blood supply

Cells divide near base and become keratinized

HAIR FOLLICLES Hair color is

determined by melanocytes near root More melanin

produced, darker hair

ARRECTOR PILI- smooth muscles that control “goose bumps”

SEBACEOUS GLAND

Specialized epithelial gland that produces SEBUM

Oily mixture that keeps hair and skin soft, pliable and waterproof

Attached to follicles

SUDORIFEROUS (SWEAT) GLANDS

Tiny tube that is attached to a coil in dermis

ECCRINE GLANDS respond to temperature

Sweat comes out of PORE

Forehead, neck, back

SUDOIFEROUS (SWEAT) GLANDS

APOCRINE GLANDS

Respond to emotions

Active at puberty

Groin, axillary regions

SKIN SENSORY RECEPTORS

The skin has receptors for “touch” Heat Pressure Pain Cold

SKIN TOUCH RECEPTORS

MERKEL’S DISCS Sensitive to vibration

& movement Found in stratum

basale

ROOT HAIR PLEXUS Sensitive to hair

movement

SKIN PRESSURE RECEPTORS

MEISSNER’S CORPUSCLES Light touch – objects

that brush the skin Dermis

PACINIAN CORPUSCLES Heavy pressure Dermis/Subcutaneous

layer

OTHER SKIN RECEPTORS

THERMORECEPTORS KRAUSE CORPUSCLES

Cold RUFFINI CORPUSCLES

Heat

PAIN RECEPTORS Free nerve endings

Hyperhidrosis Overactive sweat glands

Hands Feet Armpits

Caused by overactive nervous system

Treatment:Antiperspirant IontophoresisBotox injections

The Skin’s Role in Homeostasis

Vital in maintaining proper body temperature

Important in the healing of wounds

Aids in production of Vitamin D

VITAMIN D PRODUCTION

Skin cells help produce vitamin D

Dehydrocholesterol made by cells in digestive system

Reaches skin and is changed to vitamin D when exposed to UV light

Regulation of Body Temp During intense heat,

nerve impulses signals the body to release heat

Blood vessels dilate, giving off heat through skin

Eccrine sweat glands become active

Sweat evaporates cooling skin

Regulation of Body Temp

If too much heat is lost:

Muscles in dermal wall contract

Decreases blood flow and heat loss

Sweat glands inactive

Skeletal muscles contract involuntarily Release heat “Shivering”

Healing of Wounds INFLAMMATION – wound and surrounding

areas become swelled Response to injury & stress

4 signs of inflammation: Redness Warmth Swelling Pain

Inflammation Redness - caused

by increased vasodilatation More blood in area

Heat – increased metabolism; WBC’s try to destroy invaders

Inflammation

Swelling – Fluid in area due to change in osmotic pressure Abnormal build up of fluid

called EDEMA

Pain –Pressure on nerve endings from fluid

Healing of Wounds

Shallow wounds (epidermis) Epithelial cells divide and fill in gap

Healing of Wounds

Deep wounds (dermis or subcutaneous layer)

Blood vessels broken

Clot forms and dries into a scab

Fibroblasts lay down collagen fibers forming scar

Phagocytes remove foreign particles