The Integumentary System Chapter 6

4 Major Types of Membranes within the Human Body

SerousMucousSynovialCutaneous

Serous Membranes

Line body cavities that lack outside openings

Covers organs within cavitiesConsists of a layer of simple

squamous epithelium and thin layer of loose connective

Secrete serous fluid for lubrication

Mucous MembranesLine cavities and tubules that open to

the outside oral and nasal cavities digestive, respiratory, urinary, and

reproductive systems

Epithelium overlying loose connectiveSecrete mucus

Synovial Membranes

Inner linings of freely moving jointsFibrous connective tissue overlying

loose and adiposeSecrete thick, colorless synovial

fluid for lubrication at the end of bones

Cutaneous Membrane

SkinOrgan of the integumentary

system

Skin Intro.

Key Characteristics of the Skin

Largest organ in the body (SA)

Maintains homeostasis

Functions of the SkinProtection

Chemical barrier (secretions, pigments) Biological barrier (macrophages) Mechanical barrier (epidermis)

Regulation of body temperatureRetards water lossSensory reception

Temperature, pain, light pressure, deep pressureExcretionSynthesis of various chemicals

Vitamin D from cholesterol and UV light

Layers of the SkinEpidermisstratified squamous

Dermisconnective, epithelial, smooth muscle, nervous tissue,

blood

Subcutaneous Layer (hypodermis)loose connective, adiposebind skin to underlying organs

Subcutaneous Injection

Administered to layer beneath the skin

Absorbed rapidly because more blood vessels are present

AKA - hypodermic

Intradermal Injections

Injected into layers of tissues within skin

Not absorbed as quickly because of few blood vessels being present

Epidermis - CharacteristicsHair and nails extend from this layerOuter Layer

Stratum corneum consisting of stratified squamous Contains carotene Mostly dead cells

Lacks blood vessels Contain keratinocytes Inner layer

stratum basale nourished by dermal blood vessels; rapid cell division; site of melanin formation

Balance of mitosis and stratum corneum Calluses

Stratum lucidumMostly dead cellsMade of translucent, keratin containing cells

EpidermisShields tissues from excessive water loss, mechanical

injury, and harmful chemicalsProtection from microorganismsFetus/Newborn

Milia• Small white bumps due to accumulations of sebaceous gland secretions

Lanugo• Covers a child when he/she is born• Like a hairy covering

Vernix caseosa• White cheesy like covering that provides protection in utero

Melanin and Skin ColorProduced by melanocytesAbsorbs UV light (natural sunscreen)

Skin colorDue to presence of melanin

Responsible for dark skin color

About same # of melanocytes in all humansDiffer in amount of melanin & size of granulesInfluenced by environmental and physiological factors (pinkish v. bluish

skin) Cyanosis – lack of oxygen; bluish skin

Other Skin PigmentsCarotene

Orange pigment Present in stratum corneum Converted to vitamin A which maintains and

repairs epithelial tissue

Hemoglobin Part of a red blood cell that carries oxygen Responsible for skin color of caucasians

Dermis - Key CharacteristicsThicker than epidermisContain a variety of tissues - mainly fibrous

connectiveSeparated from epidermis by the basement

membraneSensory fibers (nerve fibers) presentContains hair follicles, sebaceous glands, and sweat

glandsBlood vessels present

Dermis - FunctionsNourish epidermis and connects epidermis to bodyRegulates body temperature

Blood vessels and arrector pili muscleProduction of Vitamin D

Utilizes UV rays to convert cholesterolRole in production of T-lymphocytesBed Sores

Skin cells deprived of oxygen Decubitus ulcer

Subcutaneous Layer - Characteristics

Beneath dermisLoose connective and adipose tissuesNo distinct boundary with the dermisContains major blood vessels Cold intolerance

Loss of insulating subcutaneous tissue with age

Subcutaneous Layer - FunctionsInsulation

adipose tissueNutrient supplier

supply upper layers of skin with nutrients through blood vessels

Binds upper layers

HairPresent on most body surfacesDevelop from hair follicleFollicle extends from surface

down to the dermisRoot located in dermisComposed of dead epidermal

cellsDelayed action gene

Cause of graying hair

HairBase of root (follicle) receives nourishment

supplied by dermal blood vessels Formed by epithelial and connective tissues

Old cells pushed to surface keratinization

Shaft dead epidermal cells

Arrector pili muscle smooth muscle responsible for goosebumps

Hair color

Sebaceous GlandsGroup of specialized epithelial cellsAssociated with the hair follicleHolocrine glands

secrete sebum• Contains lipids cholesterol, cell fragments• healthy hair and soft, pliable, waterproof skin

secretes vernix caseosa

Acne overactive glands due to hormones blackheads vs. whiteheads

Skin with Acne

Whitehead Blackhead

NailsKeratinized stratified squamousForm from the nail root

proximal endGrowing region marked by the

lunulaNail bed attaches the nail

layer of epithelium Often called the matrix If damaged, doesn’t grow

Cuticle

Sweat GlandsExocrine glandsFound all over body

palms and soles especially2 main types

apocrine eccrine

Apocrine GlandsRespond to

emotional stressArmpits and groinBegin to function at

onset of puberty stimulated by

hormonesUsually associated

with hair follicles

Eccrine GlandsNot associated with

hair folliclesMost numerousFunction all the timeRespond to

temperatureForehead, neck, back

Body Temperature RegulationMetabolism is temperature sensitiveResult of cellular metabolism Most active

skeletal, cardiac, liverCooling mechanism

dermal vessels relax sweat

Heating mechanism shivering

Healing of WoundsInflammation

response to injury or stressInflamed skin

red, swollen, warm, painfulDilation

blood vessels dilate causing redness and supplying nutrients

Skin CancerCutaneous carcinoma

epithelial cells slow growing

Prevention sunblock avoid high intensity sunlight examine skin and watch for changes in lesions

- Cells of lower part of epidermis invade the lower levels- Exposed areas develop ulcers- Slow to metastasize

Basal Cell Carcinoma

Squamous Cell Carcinoma

-Epithelial cells not in contact with b.m. develop lesions-Metastasize easily

Result of epithelial studies:

If you receive more than 2 blistering burns before the

age of 20 ... You have a greater risk of developing a

melanoma.

Normal Mole

Atypical Mole Raised Atypical Mole Flat

Atypical Mole on the Scalp

Early Melanoma-Rare-Deadly cancer of melanocytes

Skin Cancer – ABCD RuleA

asymmetricalB

irregular bordersC

Color – not uniformD

diameter

Treatment and RecoveryRule of NinesEstimation of extent

of burn to determine how much fluid will be needed for replacement

Dependent upon Total area of

burn Severity of burn

Burns - Causes

FireContact with a hot surfaceUV lightAcid/Base

Classification of Burns1st degree2nd degree3rd degreeInfection is the main problem

associated with burn Loss of water, electrolytes, and proteins Circulatory collapse Renal shutdown (kidneys stop working)

First Degree BurnsMinor discomfort

Usually brief

Skin reddens - no blisters Just epidermal damage

Destruction of tissue is minimal May peel

A typical sunburn Inhibits the immune response by depressing

the activity of macrophages

Second Degree BurnsDeep epidermal layers and upper layer of dermis

Blisters formHair follicles, sweat glands, and sebaceous glands are

damagedPain – more than 1st Swelling and fluid lossScarring is commonRegeneration is possible

Third Degree BurnsEpidermis and dermis completely destroyed

Full thickness burn

Muscles and bones affectedInsensitive to pain

Nerve endings are destroyed

Fluid loss (a serious problem)InfectionRegeneration impossible

Result of epithelial studies:

If you receive more than 2 blistering burns before the

age of 20 ... You have a greater risk of developing a

melanoma.

True or False?Sunscreens labeled 15 and higher

don’t protect you against all the sun’s rays.

Suntans are a sign of skin damage. Sunscreens should be used on cloudy

days.

True or False?Infants shouldn’t be in the sun at

all. Some medications can make your

skin sensitive to the sun.

All are true

SPF 15Most people benefit from sunscreens

with sun protection factor (SPF) numbers of 15 or more.

The SPF number gives you some idea of how long you can stay in the sun without burning.

SPF 15 (15 = rating of UV protection)

For example, if you burn in 10 minutes without sunscreen and you apply a liberal dose with a SPF number of 15, you should be protected from sunburn for 150 minutes.

Why do we tan?

The penetration of UV rays to the skin’s inner layers results in the production of more melanin.

The melanin eventually moves towards the outer layers of the skin and becomes visible as a tan.

How do sunscreens work?

Most sun protection products work by absorbing, reflecting, or scattering the sun's rays.

Absorbers of UV radiation (PABA) para-amino benzoic acid

Reflectors of UV Radiation (zinc oxide)