integumentary system ppt
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[SKIN, HAIRS, GLANDS,NAILS]
INTEGUMENTARY SYSTEM
FUNCTIONS1. Protection
– Against abrasion and UV light
– Prevents entry of microorganisms
– Prevents dehydration2. Sensation
– Sensory receptors that can detect heat, cold, touch, pressure, and pain
FUNCTIONS
3. Temperature regulation by controlling
– Blood flow through the skin
– Sweat gland activity4. Vitamin D production5. Excretion of small
amounts of waste products
SKIN SA – 1.2-2.2 m2 and weighs 4-5
kg (9-11 lbs) 2 MAJOR REGIONS:
1. EPIDERMIS2. DERMIS* HYPODERMIS/SUBCUTANEOUS TISSUE (not a part of the skin)
FIG. 5.1
EPIDERMIS Keratinized stratified squamous
epithelium
CELL TYPES:1. Melanocytes 2. Keratinocytes3. Merkel cells4. Langerhans’ cells
5 LAYERS
EPIDERMAL CELLS
Keratinocytes Most abundant cell type Produce the fibrous protein keratin Gives skin its protective properties
Melanocytes Produce the brown pigment melanin Found in the deepest layers of the epidermis
EPIDERMAL CELLS
Langerhans’ cells Epidermal macrophages Help activate the immune system
Merkel cells Touch receptors in association with sensory nerve endings
EPIDERMAL LAYERS STRATUM BASALE/GERMINATIVUM
STRATUM SPINOSUM
STRATUM GRANULOSUM
STRATUM LUCIDUM
STRATUM CORNEUM
EPIDERMAL LAYERS
Stratum Basale (Basal Layer) Deepest epidermal layer firmly
attached to the dermis Structural strength is provided by desmosomes and hemidesmosomes
Consists of a single row of the youngest keratinocytes
Cells undergo mitotic divisions ~every 19 days
10-25% are melanocytes
Stratum Spinosum Melanin granules and Langerhans’ cells
are abundant in this layer Melanin is taken up by the keratinocytes and accumulates on the “sunny side” to protect the nucleus from UV damage
Stratum Granulosum Keratohyaline and lamellated bodies
(waterproofing) accumulate in the cells of this layer
Above this layer the epithelial cells die because they are too far from the dermis
Stratum Lucidum Thin, transparent band superficial to the stratum granulosum
Consists of a few rows of flat, dead keratinocytes
Present only in thick skin
Stratum Corneum Outermost layer of keratinized cells
Accounts for three quarters of the epidermal thickness
20-30 cell layers thick, all dead.
Millions rub off everyday. Totally new every 25-45 days.
FIG. 5.2B
FIG. 5.3
THICK & THIN SKIN Thick skin has all five epithelial strata
Thin skin contains fewer cell layers per stratum Stratum lucidum is usually absent
Hair is found only in thin skin
SKIN COLOR Melanocytes produce melanin inside
melanosomes and then transfer the melanin to keratinocytes
The size and distribution of melanosomes determine skin color
Melanin production is determined genetically but can be influenced by UV light (tanning) and hormones
SKIN COLOR Increased blood flow produces a red
skin color (Erythema), whereas a decreased flow causes pale skin
Decreased oxygen content in the blood results in a bluish color called cyanosis
Carotene, an ingested plant pigment, can cause the skin to appear yellowish
DERMIS Second major skin region
containing strong, flexible connective tissue
Cell types include fibroblasts, a few adipose cells and macrophages
Composed of two layers: papillary and reticular
PAPILLARY LAYER * Areolar connective tissue with collagen and elastic fibers
*Its superior surface contains peg-like projections called dermal papillae Genetically determined Responsible for fingerprints and footprints (films of sweat)
PAPILLARY LAYER Contains blood vessels that supply the overlying epidermis With nutrients Remove waste products Aid in regulating body temperature
RETICULAR LAYER Dense irregular connective tissue Accounts for approximately 80% of
the thickness of the skin Collagen fibers in this layer add
strength and resiliency to the skin Elastin fibers provide stretch-recoil
properties Striae (stretch marks) are caused
when skin is overstretched, the dermis ruptures and leaves visible lines
HYPODERMIS• Deep to the skin• Composed of adipose and areolar
connective tissue• Not really part of the skin• Mostly adipose tissue• Stores fat and connects the skin to the
underlying structures (mainly muscles)• Shock absorber and insulator• Increases greatly as you gain weight
EPIDERMAL APPENDAGES
HAIRS
GLANDS
NAILS
HAIRS Lanugo (fetal hair) is replaced near the time of
birth by terminal hairs (scalp, eyelids, and eyebrows) and vellus hairs
At puberty, vellus hairs can be replaced with terminal hairs
Hairs are columns of dead, keratinized epithelial cells
A shaft above the skin A root below the skin A hair bulb at the site of hair formation
3 CONCENTRIC LAYERS INNER MEDULLA - with pigment granules & air
spaces
MIDDLE CORTEX - pigment granules in dark hair - mostly air in white hair
OUTER CUTICLE - keratinized thin flat cells
FIG. 5.6
HAIRS HAIR FOLLICLE: surrounds hair root HAIR BULB: houses 1. hair papillae: provides
nourishment to growing hairs;
contains blood vessels
2. hair matrix: germinal layer
hair growth & production
GROWTH CYCLE OF HAIRS GROWTH STAGE - cells at the hair matrix differentiate, divide, become keratinized, & die -as new cells are added at the hair root,
hair grows longer
RESTING STAGE - matrix is inactive - hair follicle atrophies
HAIRS Normal hair loss in an adult scalp: 70-100 hairs
Rate of growth/replacement depends on:
Illness Surgery Diet Blood loss High fever Severe emotional stress
HAIR COLOR Melanin in dark-colored hair
Melanin and more of S in blond hair
Melanin and more of Fe in red hair
Gray hair: progressive decline of TYROKINASE
White hair: accumulation of air bubbles in the medullary shaft
SEBACEOUS GLANDS Simple or compound alveolar
glands Found all over the body except
on the palms and soles Soften skin when stimulated
by hormones Secrete an oily secretion called
sebum Acne is an active inflammation
of the sebaceous glands.
FIG. 5.7
SWEAT /SUDORIFEROUS GLANDS
MEROCRINE SWEAT GLANDS: Produce sweat, which cools the body Most numerous in the palms and soles of the
feet
APOCRINE SWEAT GLANDS: Found in axillary and genital areas Ducts empty into hair follicles Produce an organic secretion that can be broken down by bacteria to cause body odor
SWEAT GLANDS
CERUMINOUS GLANDS: Modified merocrine glands in external ear canal that secrete cerumen (ear wax)
MAMMARY GLANDS: Specialized sweat glands that secrete milk
FIG. 5.7
NAIL Stratum Corneum containing hard keratin
PARTS:1. Nail body2. Free edge3. Lunula4. Nail root5. Nail matrix
NAILS Nail growth: 1 mm/week
Slower in toenails
The longer the digit, the faster the nail grows
INTEGUMENTARY SYSTEM FUNCTIONS Protection
Skin Protects against
abrasion and UV light Prevents the entry of
microorganisms Helps regulate body
temperature Prevents water loss
Hair Protects against
abrasion and UV light Acts as a heat insulator
Nails protect the ends of the digits
Sensation Skin contains
sensory receptors for heat cold touch pressure pain
INTEGUMENTARY SYSTEM FUNCTIONS Temperature Regulation Skin
Controls heat loss from the body by dilation and constriction of blood vessels
Sweat glands Produce sweat, which evaporates and lowers body temperature
Vitamin D Production UV light stimulates the
production of a precursor molecule in the skin that is modified by the liver and kidneys into vitamin D
Vitamin D increases calcium uptake in the intestines
Excretion Skin glands remove
small amounts of waste products but are not important in excretion
BASAL CELL CARCINOMA Least malignant and most common skin
cancer Stratum Basale cells proliferate and invade
the dermis and hypodermis Slow growing and do not often metastasize Can be cured by surgical excision in 99% of
the cases
SQUAMOUS CELL CARCINOMA Arises from keratinocytes of Stratum
Spinosum Arise most often on scalp, ears, and lower lip Grows rapidly and metastasizes if not
removed Prognosis is good if treated by radiation
therapy or removed surgically
MELANOMA Cancer of melanocytes is the most
dangerous type of skin cancer because it is: Likely to metastasize Resistant to chemotherapy
MELANOMA Melanomas have the following characteristics
(ABCD rule) A: Asymmetry; the two sides of the pigmented area
do not match B: Border is irregular and exhibits indentations C: Color (pigmented area) is black, brown, tan, and
sometimes red or blue D: Diameter is larger than 6 mm (size of a pencil
eraser)
Treated by wide surgical excision accompanied by immunotherapy
Chance of survival is poor if the lesion is over 4 mm thick
BURNS First-degree: only the epidermis is damaged
Symptoms include localized redness, swelling, and pain
Second-degree: epidermis and upper regions of dermis are damaged
Symptoms mimic first degree burns, but blisters also appear
Third-degree: entire thickness of the skin is damaged
Burned area appears gray-white, cherry red, or black; there is no initial edema or pain (since nerve endings are destroyed)
RULE OF NINES Estimates the
severity of burns Divides body into
areas that are ~ 9%, or multiples of 9%, of the total body area
Younger patients are different
Burns considered critical if: Over 25% of the
body has second-degree burns
Over 10% of the body has third-degree burns
There are third-degree burns on face, hands, or feet
PAGE 115
EFFECTS OF AGING ON THE INTEGUMENTARY
SYSTEM Epidermal replacement of cells slows and skin becomes thinner
Decreased elasticity and loss of subcutaneous tissue leads to wrinkles
Subcutaneous fat layer diminishes, leading to intolerance of cold
Skin becomes dry and itchy Sweat and sebaceous glands
are less active, and the number of melanocytes decreases
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