chapter 4 skin & body membranes. function of body membranes line or cover body surfaces ...
TRANSCRIPT
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