Integument
-Largest organ- most visible/accessible organ
-Surface area: 1.5-2m2
-15-20% of total body weight
-First line of defense enviroment
Dead Skin
billions of tons of dust in atmosphere
-Shed about 50,000 cells every minute
Integumentary System: FUNCTIONS
-Protection
-Temperature Regulation
-Excretion
-Vitamin D
-Sensations
Integumentary System:
Functions
Protection
-Protects underlying tissues and organs
-Provides protection against UV coming from the sun
Integumentary System:
Functions
Temperature Regulation:
-Helps regulate body temperature
-Provides insulation to keep heat in
-Evaporative cooling to allow heat out
Integumentary System:
Functions
Excretion
-Removes waster products from the body
e.g. salts, water, and organic wastes by glands
Integument Structure:
Skin (cutaneous layer)= epidermis+dermis
Integument
Quick overview of Structure: SKIN
1. Epidermis: Superficial layer of epithelial tissue 2. Dermis: deep layer of connective tissue. Provides nourishment of epidermis & structural strength. 3. Subcutaneous layer (hypodermis): Not technically part of the skin, it is loose connective tisseue that connects skin to underlying structures & provides insulation
Integument
Quick overview of Structure: SKIN
Accessory structures:
Originate in the dermis extend through the epidermis to skin surface:
1. Hair
2. Nails
3. Glands
What are the two layers of the Dermis?
1. Papillary layer
2. Reticular layer
Epidermis
Avascular: nourished by diffusion from capillaries of the papillary layer of the dermis
Composed of cells arranged into layers or strata
Separated from dermis by basement membrane
Thick vs. Thin skin refers to what skin layer?
EPIDERMIS (the top)
Thin or Thick skin: Most of our body surface?
Thin (4 layers about as thick as a sandwich bag)
Thick skin
5 layers (strata)= 0.5-1mm thick
Covers palms of hands and soles of feet
Deep epidermal ridge patterns
Patterns increase surface area and provide friction
Produce fingerprints
Thin or Thick Skin? Palms of hands
Thick skin (produces our finger prints ....also on soles of feet)
Structure of the Epidermis:
The five strata of KERATIONCYTES in thick skin from basal lamina to free surface:
Stratum germinativum
Stratum spinosum
Stratum granulosum
Stratum lucidum
Stratum corneum
Which of the following is ONLY found in thick skin?
E. Stratum lucidum (clear thick skin covers stratum granulosum)
Easy way to remember the 5 Epidermal layers:
"Can Little Girls Speak German"
from the most superficial to the deepest
Corneum (surface)
Lucidum
Granulosum
Spinosum
Germinativum (deepest layer)
How many days does it take to go from germinativum to the corneum?
15-30 days (bottom to top) keratinized cells stay in corneum for an additional 2 weeks before washing away held togher by desmosomes/shed in sheets
Epidermis Layers: 4-5 Strata
Stratum Corneum (surface)- disposable
15-30 layers of dead keratinocytes
Thicker layer in thick skin
Strong, water resistant barrier
Which of the following is a disposable strata?
D. Stratum corneum (top layer remember CLGSG- top to bottom)
Epidermis layers: 4-5 Strata
Stratum Lucidum (waterproof) "clear"
Thin keratinocyte layer (extra layer in THICK skin)
Epidrmis Layers: 4-5 Strata
Stratum Granulosum (strength) "grainy"
3-5 layers/high keratin fiber and keratohyalin
kh: dense granules / aggregation and crosslinking of keratin
Which of the following has aggregation and crosslinking of keratin?
3. Sensory functions: pain, itch, tickle, temperature, touch and pressure
2 layers of the Dermis?
Papillary
Reticular
Dermis:
Papillary Layer (superficial layer... 1/5)
Consists of Areolar tissue with lots of elastic fibers
Dermal papillae, Capillary beds.
Fingerprints.
Whorls of ridges
Touch receptors (Meissner's)
Free nerve endings sensing pain
Dermis:
Reticular layer (deep<inner> , 4/5)
-Interwoven meshwork of DENSE IRREGULAR connective tissue
-Collagen and elastic fibers
-Also see seome adipose, hair follicles, nerves, oil glands, ducts of sweat glands, heat sensors.
Cleavage <Tension> lines
Elastin and collagen fibers oriented in some directions more than in others
Important in surgery(if incision parallel to lines, there is less gapping, faster healing , less scar tissue)
If skin is overstretched,______________ (stretch marks) occur
striae
Dermal Strength and Elasticity:
Collagen Fibers
Give skin strength and resistance to stretching
Very strong and limit stretching to prevent damage to tissue
Dermal Strength and Elasticity:
Elastin
Elastic fiber that allows skin to stretch and then recoil back to normal length
Stretch marks are a sign that skin has been stretched beyond its capacity and recoil
Stretching of skin due to pregnancy or weight gain can exceed elastic limits of skin by causing damage to the dermis
Dermal Strength and Elasticity:
Sagging and Wrinkles:
Result from permanent reduction in amount of elastin in dermis, mostly caused from aging, hormones, ultraviolet radiation (sun exposure)
What gives skin strength and resistance to stretching?
Collagen Fibers
What allows skin to stretch and then recoild back to normal length?
Elastic Fibers (like a rubberband)
Reduction in amount of ___________ in dermis results in sagging and wrinkles
elastin
What is a derivative of vitamin A that can be applied to the skin as a cream or gel that increases the blood flow to dermis and stimulates repair?
Tretonin (Retin-A) .... decreases the rate of wrinkle formation and existing wrinkles become smaller
SENSORY STRUCTURES OF DEMIS:
MEISSNER'S CORPUSCLE:
egg shaped
Detects light touch (i.e tactile corpuscle)
Located dermal papillae
Populated areas in fingertips, palms, soles, eyelids, tip of tongue & genitalia
SENSORY STRUCTURES OF DEMIS:
PACINIAN CORPUSCLE:
Onion Shaped in cross section; have a lamellated appearance
Located deeper in reticular layer & subcutaneous lare
Detect Pressure
Populated in joints tendons, muscles, mammary glands, & external genitalia
Meisnner's or Pacinian? Populated in joints tendons, muscles, mammary glands, & external genitalia
Pacinian Corpuscle
Meissner's or Pacinian? Detects Pressure
Pacinian Corpuscle
Meissner's or Pacinian? Located in dermal papillae
Messner's Corpuscle
HYPODERMIS:
not technically part of the integument
Located deep in skin (beneath the dermis)-indistinct border
Attaches skin to underlying structures
Consists of loose connective tissue with collagen and elastic fibers
Site of lipid storage and contains about 1/2 of body's fat
Hypodermis
Functions
Energy source
Insulation
Padding
Blood reservoir (can hold 5-8% volume) superficial part has large veins& arteries
Can shunt blood for temperature regulation
Another name for Subcutaneous tissue
Hypodermis/Superficial Fascia
Where is the site of cosmetic liposuction?
Hypodermis (remember it contains 1/2 of the body's fat)
Where is the site of subcutaneous injections with hypodermic needles?
Hypodermis (aka SUBCUTANEOUS TISSUE)
What are the TWO pigments that influence skin color?
Melanin and Carotene
SKIN COLOR:
Carotene
INGESTED
orange-yellow pigment (like a carrot)
found in orange vegetables (carrot)
accumulates in epidermal cells and fatty tissues of the dermis
can be converted to vitamin A
SKIN COLOR:
Melanin
yellow-brown or black pigment
produced by melanocytes in stratum germinativummanufactured from amno acid TYROSINEpackage and store in transport vesicles
melanosomes transferred to keratinocytes
What cells produce melanin?
melanocytes
Melanocytes produce melanin in what layer of the epidermis?
Stratum germinativum
What amino acid manufactures melanin?
tyrosine
Function of Melanocytes:
Melanin protects skin from UV sun damage
Ultraviolet radiation causes DNA mutations and burns that lead to cancer and wrinkles
Skin pigmentation varies on individual based on location
2 times more melanocytes on cheeks, forehead, nipples, genitalia
Can have increased rate of melanin production (eg freckles on light skin mean larger than average production)
People of different races have essentially SAME NUMBER of MELANOCYTES but amount of melanin produced varies
eg Albino individuals have a normal number of melanocytes but can't produce melanin
Abnormal: VITILIGO
loss of melanocytes (like MJ) ... theory is that it is an autoimmune disorder
UV is good for the production of which vitamin?
VITAMIN D!!!!
Vitamin D production: UV (the good)
1. Skin exposed to UV light produces cholecalciferol, which is modified in the liver and then in the kidneys to form calcitriol (active vitmin D)
2. Vitamin D increases blood calcium levels by promoting calcium uptake from the small intestines, calcium released from bone and reduction of calcium loss from the kidneys
3. Calcium functions from bone homeostatis ie. bone formation, growth, repair, and also nerve and muscle formation
Rickets
Abnormal bone development in children & insufficient Vitamin D
Results if low sun exposure and or Vit D3 in diet
Calcitrol can be absorbed through the intestinal walls, what are some of the sources?
Dairy, liver, egg yolks, supplements (yay for ppl who live in cold climates or cover themselves)
Accessory Skin Structures Sebaceous Glands (oil)
Located in Dermis
Holocrine glands (i.e. lysis and death of secretory cells
Sebum:
an oily white substance rich in lipids (+ electrolytes+ proteins)
Most sebaceous glands empty into hair follicles (ie. connected by a duct to upper part of hair follicle.
Sebum lubricates hair and protects eidermis.
It functions to prvent drying (by conditioning skin) and may inhibit bacteria growth
Exceptions to Sebacious Glands:
Some open directly to skin ie those located on lips, glands of eyelid, genitalia
Not associated with hair
T/F Sebaceous Glands are MEROCRINE glands
FALSE (they are holocrine-the secretory cell becomes swollen with vesicles and then ruptures)
Accessory Structures:
Sudoriferous (Sweat Glands) (MEROCRINE)
Merocrine (Eccrine) sweat glands; MOST COMMON
simple, coiled, tubularglands that open directly onto skin surface through sweat pore at surface
Widely distributed on body surface (more numerous than apocrine)
Especially on palms and soles (but absent from parts of lips and certain genital areas)
T/F The skin contains TWO types of sweat (sudoriferous) glands
TRUE (apocrine and merocrine)
Aporcrine or Merocrine? Most common sweat gland
MEROCRINE!!!!
T/F Aprocrine sweat glands rely on merocrine secretion method
TRUE (doesnt make sense I KNOW)
Accessory Structures:
Sudoriferous Sweat Glands (APOCRINE)
Associated with hair
Ducts terminate in hair follicles
Help reduce friction between hair follicles and skin
Respond to stress/ emotions
Begin to function in purberty & continue throughout life
Located in arpits and groin
SMELLY!!!
Aprocrine Sudoriferous Glands
Produce organic substances that when fresh secretions are odorless but when acted upon by bacteria and becomes odiferous (rancid odor stinky)
Merocrine/Apocrine? Produce a nutrient source for bacteria which intensify odor
APOCRINE
Merocrine Suoriferous Glands
Functions
1. Cools skin surface (lowers body temp)
2. Excretes water and elecrolytes
3. Flushes micororganism &(has a peptide w/ antibiotic properites dermicidin) dilutes harmful chemicals from skin
Merocrine Sudoriferous Glands
Sensible Perspiration
Sweat is 99% Water, Salts (NaCl) and organic cmpd
Small amts of ammonia, urea, uric & lactic acid
Quick Accessory Structure (GLANDS) summary:
Merocrine sweat glands widely distributed across the body surface Sebaceous glands are located wherever there are hair follicles Apocrine sweat glands located in relatively restricted areas
Mammary Glands
Modified apocrine sweat glands
Produce milk & function during lactation & pregnancy
Ceruminous Glands
Modified swat glands
Location: external ear canal
Their secretion combines with sebum to produce EAR WAX (aka cerumen)
Function in combination w/ hair to prevent dirt & insects from entry
Also keep eardrum supple/flexible
Hair is composed of keratinized dead cells that have been pushed to the surface
Accessory Skin Structures: HAIR
-Produced by cells @ base of structures called hair follicles
-Hair follicles are tube like pockets of epidermal cells that extend into the dermis
-Individual hairs are actually large colums of dead cells that have filled with keratin
-Rapid growth at the base of the hair follicle in the hair root cause hair to grow longer
-Hair gets its color from melanin
-Hair follicles are in close contact w/ sebaceous glands (conditon hair)
-Hair protects and insulates body
-Most individual hairs grow for several years and then fall out
HAIR
Location: found EVERYWHERE except palms, soles, lips, nipples, & parts of the genitalia
Function: Protects & insulates, Guard openings against particles & insects, sensitive to light touch
Structure: Shaft protudes above skin surface: base of root is the hair bulb (internal matrix is source of hair)
Hair
3 Concentric layers
Medulla- central axis
Cortex- Forms bulk of hair
Cuticle- foms hair surface
GOOSE BUMPS
Arrector pili muscle contracts, pulling on the follicles and forcing the hair to stand erect
Hair Growth
The hair bulb produces the hair in cycles w/ a growth stage and a resting stage
Growth: Cells added at base as hair elongates
Rest: Follicle shortens and holds hair in place
Rest, then hair falls out of follicle, new hair begins.
Why is overheating a greater concern the older you get?
You have decreased sweat gland activity
Decrease vasularity of dermis
Effects of aging
Integument damage, infection, and cancer is a greater concern because:
Epidermal Thinning
Decreased # of langerhans cell
Decreased vitamin D3 production
Decreased glandular activity (oil and sweat)
Decreased melanocytes activity
Reduction in elastic fibers
Reduced blood supply & WBCs and other repair cells less active/responsive
Dermatitis
cause: inflmmation due to allergen or an irritant or toxin or may result from unknown immune problem.
Inflammation of Skin
Primarily involves papillary layer
Typically begins in part of skin exposed to infection or irritation
Maybe no discomfort or itchy or painful
Inflammation can spread amound integument
Eczema (aka ATOPIC Dermatitis)
Allergy: Overactive immune system: Recognizes something on skin as foregin, and immune cels destroy skin (eg pool water may cause a flare up)
Triggers: Temperature changes, fungi, chemical irritants, grease, detergent or stress
Treatment to prevent flare ups:
Create a barrier between skin and enviroment
ANTIhistamines to relieve itch
Hydrocortisone
Antibiots to get rid of bacteria
Emollent (VASELINE) or rich creams
Eczema (aka ATOPIC DERMATITIS)
Chronic Inflammatory Disease that needs to be managed. VERY itchy, known as the MESSY rash b/c its so itchy you SCRATCH.
Up to 40% of all kids in US have eczema at some point
NOT contagious
Keep skin moist because dry skin cause flares
Eczema:
Hereditary or eviromental factors or BOTH
Sebborheic dermatitis/eczema (cradle cap)
Particulary affects the sebum gland rich areas of skin
Dandruff common symptom
Strongest link: allergic response to yeast or other allergen
Corticosteriods inhibit creation of inflammator mediators *prostaglandins
Antihistamine relieve itching
Psoriasis
Chronic skin Disease/Inflammatory Disease
Stem cells in the stratum germinativum are unusually active÷ more frequently that normal
Skin cells multiply so fast (eg skin sheds every 3-4 days)
Strong genetic/hereditary component
Can be aggravated by stress and anxiety
Characterized by inflamed red areas, often develop silvery scales on places like elbows, kness, and lower back (keratinization is abnormal)
Psoriasis
Affects ~5% of ppl in US and ~2% of ppl worldwide
Psoriasis: stem cells divide every 1.5 days
Normal stem cells divide every 20 days
Keritinization is abnormal & typically incomplete by the time outer layers are shed
Affected areas: Red or Pink with losts of small silvery scales that continuously flake off
20-30% of ppl have a genetic predisposition
Dermatitis Psoriasis
Caused by inflammation due to HYPERproliferation (due to Tcells)
Tcells migrate to epidermis
release cytokines (esp Tumor Necrosis Factor TNF)
TNF stimulates proliferation
PSORIASIS / TREATMENT
Goal is to reduce inflammation and slow rapid growth and skin shedding:
Methotrexate: inhibits proliferation of keratinocytes, (anticancer drug that interrupts growth of cells, it is used for severe cases)
Immune suppressing meds such as topical corticosteroids
UV
Coal Tar makes skin more sennsitive to light
SKIN cancer
most common cancer in US
Fastest increasing cancer in US
3 main types:
Basal cell (most common)
Squamous cells
Melanoma (worst b/c mestastasize)
The main difference between melanomas and other skin cancers is that melanoma can MESTASTASIZE (spread) to distant body sites including lungs, liver or brain
Melanoma most common cancer in young adults age 25-20
Among women age 30-35, incidence is exceeded only by breast cancer
Incidence increasing 4% annually, higher than any other cancer
On average, one melanoma death in the US per HOUR
Skin Cancer:
BASAL CELL CARCINOMA
Least malignant
Most common type
Arises from stratum baseal /straum germinativum
2/3 appear areas receive chronic UV exposure
Genetic factors predispose
Skin Cancer:
Squamous cell carcinoma
Less common
Arises from stratum spinosum
Early removal allows a good chance of cure
Squamous Cell Carcinoma
Red or pink scaluy patches
Sometimes wart-like that forms puss in middle
Found on edge of ears, face, lips, mouth and hands
Basal Cell Carcinoma
Small, fleshy bumps
Normally on ears, nose, neck, head
Slow growing, doesnt mestastasize but can penetrate to bony areas that require more invasive surgery
95% of patients with surgical removal live 5 years or LONGER
Which of the following is the most common form of skin cancer?
B. Basal call
Which of the following is the least malignant form of skin cancer?
B. Basal call
Which of the following is the least common form of skin cancer?
A. Squamous cell
Which of the following arises from stratum spinosum?
C. Squamous cell
Malignant Melanoma
Most deadly of skin cancers
Cancer of melanocytes
New cases of melanoma has DOUBLED since 1973
7th most common cancer in US
Begins in melanocytes
Metastasizes rapidly to lymph and blood vessels
Malignant Melanoma
Survival rate after 5 yr: 14% if found after metastasis
99% if detected early
Melanoma ABCDs
Asymmetry- 1/2 doesnt match the other 1/2 (irregular in shape, raised, may ooze or bleed)
Border- edges are ragged, notched, or blurred(border is indistinct&irregular)
Color- pigmentation is not uniform-shades of tan, brown or black are present (a mottled appearance)
Diameter- greater than 1/4 in. Any susdden or continuing increase in size is of special concern. (greater than 55mm isn diamter or area cover by eraser on a pencil is DANGEROUS)
UV radiation can be dived into 2 ranges:
UVA (320-400nm)
UVB (290-320mm)
UVA and UVB are both thought to initiate skin cancer
Tanning salons advertise that UVA is safe (FALSE)
Sunscreen
As sale has risen so has skin cancer (protect again SUNBURN not skin cancer)
Some protection against SCC but not BCC or Malignant Melanoma
Ppl who use it have higher incidence of BCC
Block or absorb UV
