Transcript skin

CHAPTER 4
Skin & Body Membranes
Body Membranes
 Function of body membranes
 Line or cover body surfaces
 Protect body surfaces
 Lubricate body surfaces
Classification of Body
Membranes
 Epithelial membranes
 * Cutaneous membranes
 Skin or Integumentary
 Mucous membranes
 Serous membranes
 Connective tissue membranes
 Synovial membranes
Epithelial 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
Serous Membranes
 Specific serous membranes
 Peritoneum
 Abdominal cavity
 Pleura
 Surrounds the lungs
 Pericardium
 Surrounds the heart
Connective Tissue
Membranes
 Synovial membranes
 Connective tissue
only
 Line fibrous capsules
surrounding joints
Integumentary System
(Skin)
Would you be enticed by an advertisement for a
coat that is…
Waterproof, stretchable, washable, permanentpress, 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!!
Integumentary System
 Skin (cutaneous membrane)
 Skin derivatives
 Sweat glands
 Oil glands
 Hair
 Nails
Basic Skin Functions
 Protects deeper tissues from:
 Mechanical damage
 Chemical damage
 Bacterial damage
 Thermal damage
 Ultraviolet radiation
 Desiccation
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
Structure of the Skin
 Epidermis
 Outer layer
 Stratified squamous epithelium
 Often keratinized (hardened by keratin)
 Dermis
 Underlying layer
 Dense connective tissue
Skin Structure
Epidermis and dermis are firmly connected
Unless, a burn or friction causes them to
separate
Interstitial fluid accumulates in the cavity
between the layers  Blisters
Skin Structure
 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…
Let’s Label!
Epidermis
 Avascular
 Contains keratinocytes
 Composed of up to 5 layers called strata
 From the outside in
1.
2.
3.
4.
5.
Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinosum
Stratum basale
**Every 25-45 days we have a “new” a epidermis!!
Melanin
 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
Dermis- “Hide”
 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
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 Receptors
Touch 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 Receptors
Temperature 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 Color
3 Pigments Contribute to Skin Color
1. 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.
Appendages of the Skin
 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
 Composition
Sweat
 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 Glands!
Appendages of the Skin
 Hair
 Produced by a
hair follicle
 Consists of hard
keratinized
epithelial cells
 Melanocytes
provide pigment
for hair color
Hair Anatomy
 Central medulla
 Cortex surrounds
medulla
 Cuticle on outside of
cortex
 Most heavily keratinized
Associated Hair Structures
 Hair follicle
 Dermal and epidermal
sheath surround hair root
 Arrector pilli
 Smooth Muscles- “Goose
bumps”!
 Sebaceous gland (oil)
 Sweat gland
Hair Follicles!
Appendages of the Skin
 Nails
 Scale-like modifications of the epidermis
 Heavily keratinized
 Stratum basale extends beneath the nail
bed
 Responsible for growth
 Colorless- Lack of pigment
Nail Structures
 Free edge
 Body
 Root- Embedded
in the skin
 Heavily
keratinized
Homeostatic Imbalances of Skin
 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
Burns
 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
 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 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 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 Burns
 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
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Cross Sectional View
2nd Degree burn: (Note blisters)
McDonalds Coffee Case
Perhaps 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 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 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 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 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 Types
 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
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Malignant Melanoma
ABCDE Rule
 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 & uneven
Skin Cancer Video
Tanning Beds & Melanoma