CHAPTER 4Skin & Body Membranes

Function of body membranes Line or cover body surfaces

Protect body surfaces

Lubricate body surfaces

Body Membranes

Epithelial membranes

* Cutaneous membranes

Skin or Integumentary

Mucous membranes

Serous membranes

Connective tissue membranes

Synovial membranes

Classification of Body Membranes

#1: Cutaneous membrane = SKIN Dry membrane

Outermost protective boundary

Superficial epidermis Keratinizing stratified

squamous epithelium

Underlying dermis Mostly dense

connective tissue

Epithelial Membranes

#2: Mucous Membranes

Surface epithelium

Type depends on site

Underlying loose connective tissue lamina propria

Lines all body cavities that open to the exterior body surface

Often adapted for absorption or secretion

Epithelial Membranes

#3: Serous Membranes

Simple squamous surface epithelium

Underlying areolar connective tissue

Line open body cavities that are closed to the exterior of the body

Serous layers separated by serous fluid

Epithelial Membranes

Specific serous membranes Peritoneum

Abdominal cavity

Pleura Surrounds the lungs

Pericardium Surrounds the heart

Serous Membranes

Synovial membranes

Connective tissue only

Line fibrous capsules surrounding joints

Connective Tissue Membranes

Integumentary System (Skin)

Would you be enticed by an advertisement for a coat that is…

Waterproof, stretchable, washable, permanent-press, that invisibly repairs small cuts, rips and burns, and that is guaranteed to last a life-time with reasonable care?

You already have such a coat…

Your cutaneous membrane SKIN!!

Skin (cutaneous membrane)

Skin derivatives

Sweat glands

Oil glands

Hair

Nails

Integumentary System

Protects deeper tissues from:

Mechanical damage

Chemical damage

Bacterial damage

Thermal damage

Ultraviolet radiation

Desiccation

Basic Skin Functions

Aids in heat regulation

Aids in excretion of urea and uric acid

Synthesizes Vitamin D

Linked now to cancer protection HOMEWORK- VITAMIN D ARTICLES & CORRESPONDING QUESTIONS

* Need to know Table 4.1 (pg 111)- Functions of skin and how those functions are accomplished

Skin Functions

Epidermis

Outer layer

Stratified squamous epithelium

Often keratinized (hardened by keratin)

Dermis

Underlying layer

Dense connective tissue

Structure of the Skin

Skin Structure

Epidermis and dermis are firmly connectedUnless, a burn or friction causes them to separate

Interstitial fluid accumulates in the cavity between the layers Blisters

Deep to the dermis is the hypodermis

Subcutaneous tissue

Essentially adipose tissue

Not considered part of the skin

Anchors skin to underlying organs

Skin Structure

Skin Structure… Let’s Label!

Avascular

Contains keratinocytes

Composed of up to 5 layers called strata

From the outside in

1. Stratum corneum2. Stratum lucidum3. Stratum granulosum4. Stratum spinosum5. Stratum basale

**Every 25-45 days we have a “new” a epidermis!!

Epidermis

Melanocytes

Cells found mostly within the stratum basale of the epidermis

Produce melanin (pigment)

Ranges in color from yellow to brown to black

Acts as a natural sunscreen

Amount of melanin produced depends upon genetics and exposure to sunlight

Melanin

Dense Connective Tissue Consists of two major regions

Papillary layer- Upper dermal region Projections called dermal papillae

Fingerprints Houses pain & touch receptors Capillary loops

Reticular layer- Deepest skin layer

Blood vessels Sweat & oil glands Pressure & nerve receptors

Dermis- “Hide”

Fingerprint Activity!

Put on a latex free glove

Get your hand nice and sweaty

Carefully look under the dissecting microscope at the ridges of your fingertips

** The ridges of your fingertips are lined with sweat pores that leave unique, identifying films of sweat FINGERPRINTS!!

Touch & Temperature ReceptorsTouch Receptors

There are more touch receptors in some areas of our bodies compared to other areas

Size and density of receptors varies in different areas of the body

2-point threshold will be smaller for areas that are more sensitive

Temperature ReceptorsTemperature sensitivity is not uniform

Cold receptors are unevenly distributed throughout the dermis and subcutaneous layer of the skin

Warmth receptors are deeper & less numerous.

Temperature Receptors

• Temperature receptors show adaptation over time as the body adjusts (acclimation / habituation)

• Cutaneous thermoreceptors • Free nerve endings that respond to particular ranges of

temperatures and changes within those ranges• Separate locations on the skin are sensitive to hot or to cold,

or are not sensitive to temperature at all

Skin & Sensory Perception

Many receptor sites for cutaneous sensations to stimuli such as touch, pressure, temperature, and pain

A receptive field is the area on the skin that activates a sensory neuron

Receptive fields may be small and numerous or large and overlapping

Skin Color3 Pigments Contribute to Skin Color1. Melanin – Yellow, reddish-brown, or black pigment

2. Carotene – Orange-yellow pigment found in carotene-rich foods• Carrots and other orange, deep yellow or leafy green

vegetables• Yellow Babies??

• Jaundice Yellowish cast; Signifies a liver disorder

3. Hemoglobin – Red coloring from the blood cells in the dermis capillaries• Oxygen content determines extent of red coloring

• Cyanosis

Did Veggies Turn My Baby's Skin Yellow?

The other night, when I removed my toddler's socks, I was shocked to see that her feet were a

yellowish color. My pediatrician said that she is eating too many orange veggies. However, she

only eats one form of these vegetables per day and the other vegetables she eats are green.

Carotenemia- Accumulation of the yellow coloring that the body converts to Vitamin A

Consuming a lot of vegetables that contain carotene

Green vegetables (broccoli/spinach), carrots, sweet potatoes and squash

Not harmful – it’s just not pretty!!

It will go away if you reduce the amount of carotene in her diet. Your baby will get all

the Vitamin A she needs if you give high-carotene vegetables every other day, or

every two days.

Did Veggies Turn My Baby's Skin Yellow?

CAROTENEMIA- Can also happen in adults. I will never forget my high school friend who went

on a diet, and ate bags of carrots in an attempt to quiet her hunger. Her skin turned a pale

shade of yellow and the palms of her hands and bottoms of her feet were of much greater

intensity! Needless to say, when this started to happen, she changed her diet strategy.

Skin Appendages

Include…

Cutaneous Glands (Exocrine)

Sweat & sebaceous glands

Hair & hair follicles

Nails

Arise from the epidermis

Role in maintaining homeostasis

Appendages of the Skin

Sebaceous (oil) glands

All over the skin, except palms of hands & soles of feet

Produce sebum (oily substance)

Lubricant for skin & hair

Kills bacteria

Ducts usually empty into a hair follicle

Glands are activated at puberty

Acne

Active infection of sebaceous glands

Appendages of the Skin

Sweat glands (Sudoriferous glands Sudor = sweat)

Widely distributed in the skin Two types

Eccrine Glands All over the body Sweat reaches the skin via a duct that opens

externally as a pore on the skin surface Apocrine Glands

Confined to axillary & genital areas Ducts empty into hair follicles

Appendages of the Skin

Composition Mostly water; some salts (NaCl) Some metabolic waste (Urea, ammonia, uric acid) Fatty acids & proteins (Apocrine glands only)

Function Helps dissipate excess heat Excretes waste products Acidic nature inhibits bacteria growth

Odor is from associated bacteria…

Sweat

Sweat Glands!

Hair

Produced by a hair follicle

Consists of hard keratinized epithelial cells

Melanocytes provide pigment for hair color

Appendages of the Skin

Central medulla

Cortex surrounds medulla

Cuticle on outside of cortex

Most heavily keratinized

Hair Anatomy

Hair follicle

Dermal and epidermal sheath surround hair root

Arrector pilli

Smooth Muscles- “Goose bumps”!

Sebaceous gland (oil)

Sweat gland

Associated Hair Structures

Hair Follicles!

Nails Scale-like modifications of the epidermis

Heavily keratinized

Stratum basale extends beneath the nail bed

Responsible for growth

Colorless- Lack of pigment

Appendages of the Skin

Free edge

Body

Root- Embedded in the skin

Heavily keratinized

Nail Structures

Infections & Allergies Athletes foot

Caused by fungal infection Tinea pedis

Itchy, red, peeling condition

Homeostatic Imbalances of Skin

Infections & Allergies Boils and carbuncles

Inflammation of the hair follicles & sebaceous glands

Common on the dorsal neck Caused by bacterial infection

Staphylococcus aureus

Homeostatic Imbalances of Skin

Infections & Allergies Cold sores (fever blisters)

Small, fluid filled blisters on or around the lips Itch and sting

Caused by the herpes simplex virus Remains dormant until activated by emotional stress,

fever, or UV radiation

Homeostatic Imbalances of Skin

Infections & Allergies Contact Dermatitis

Itching, redness, swelling of the skin, progressing to blistering

Caused by exposure of the skin to chemicals Poison Ivy

Homeostatic Imbalances of Skin

Infections & Allergies Impetigo

Pink, water filled raised lesions Commonly around the mouth and nose Develop a yellow crust eventually rupture Caused by highly contagious bacterial infection

Staphylococcus Common in elementary school-aged children

Homeostatic Imbalances of Skin

Infections & Allergies Psoriasis

Chronic condition Overproduction of skin cells that results in reddened

epidermal lesions covered with dry, silvery scales Can be disfiguring, if severe

Autoimmune disorder Immune system attacks a person’s own tissues Triggered by trauma, infection, stress, hormonal changes

Homeostatic Imbalances of Skin

BurnsBurns

Tissue damage and cell death caused by intense heat, electricity, UV radiation (sunburn), or chemicals (acids)

Associated life-threatening dangers Body loses fluids containing proteins & electrolytes as

these seep from the burned surfaces Dehydration & Electrolyte imbalance Kidneys shut down Circulatory shock

Infection Burned skin is sterile for 24 hours but after that bacteria &

fungi invade the nutrient rich environment of dead tissue 1-2 days after a severe burn – immune system is depressed

Rule of Nines Rule of Nines

Volume of fluid lost can be estimated indirectly by determining the extent of the burn by using the Rule of Nines

Body is divided into 11 areas Each area represents about 9% of the total body surface See page 122 textbook

Severity of BurnsSeverity of Burns First-degree burns

Only epidermis is damaged Skin is red and swollen Heal within 2-3 days, without special attention

Sunburn

Second-degree burns Epidermis and upper dermis region are damaged Skin is red & painful with blisters No permanent scars result if care is taken to prevent

infection

Severity of BurnsSeverity of Burns Third-degree burns

Destroy the entire skin layer Burn is gray-white or black Nerve endings are destroyed Not painful Regeneration is not possible

Skin grafting must be done to cover the underlying exposed tissue

Critical BurnsCritical Burns

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Burns are considered critical if:

Over 25% of body has second degree burns

Over 10% of the body has third degree burns

There are third degree burns of the face, hands, or feet

Cross Sectional View

2nd Degree burn: (Note

blisters)

McDonalds Coffee CasePerhaps the most well-known, "frivolous lawsuit”, is the story of Stella Liebeck - the woman who was burned by hot coffee from McDonalds. Here are the facts about the McDonald's lawsuit; decide for yourself if the suit was frivolous:

• Stella Liebeck was a 79-year-old grandmother who was the passenger in her grandson's car• McDonalds served the coffee at roughly 190 degrees. (190 Degree liquid will cause third-degree burns within 2-7 seconds of contact with the skin.)• Stella was wearing cotton jogging pants, and the 190 degree liquid soaked into the pants.

Skin CancerSkin Cancer Neoplasm = Tumor Cancer – abnormal cell growth

Two types of Skin Cancer Benign

Does not spread (encapsulated) Malignant or cancerous

Metastasizes (invade) other parts of the body

Skin CancerSkin Cancer Skin cancer is the most common type of cancer

Cause is unknown Risk Factor

Overexposure to UV radiation Predisposing Factors

Frequent irritation of the skin by Infections, chemicals, or physical trauma

Skin Cancer TypesSkin Cancer Types

Basal Cell Carcinoma Least malignant

Most common type

Slow-growing

Cells of the stratum basale (epidermis) no longer form keratin & they start to invade the dermis & subcutaneous tissue

Lesions often occur on sun-exposed areas of the face

Shiny, domed shaped nodules that may have a central ulcer

Skin Cancer TypesSkin Cancer Types

Squamous Cell Carcinoma Arises from stratum spinosum (epidermis)

Lesion:

Scaly, reddened papule (small rounded elevation)

Gradually forms a shallow ulcer with a firm, raised border

Most often on the scalp, ears, dorsum of the hands, lower lip

Grows rapidly & metastasizes to lymph nodes

Early removal allows a good chance of cure

Basal Cell Carcinoma

Skin Cancer TypesSkin Cancer Types

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Malignant Melanoma Most deadly of the skin cancers

Cancer of melanocytes

Arises from accumulated DNA damage in a skin cell and usually appears as a spreading brown, black patch

Metastasizes rapidly to lymph and blood vessels

Detect using the ABCDE rule

Malignant Melanoma

A = Asymmetry

Two sides of pigmented mole do not match

B = Border irregularity

Borders of mole are not smooth; exhibit indentations

C = Color

Different colors in pigmented area (blacks, browns, tans, blues, reds)

D = Diameter

Spot is larger then 6 mm in diameter (pencil eraser)

E = Elevation

Mole is raised above the surface & unevenSkin Cancer Video

Tanning Beds & Melanoma

ABCDE Rule