Transcript integ

Chapter 6
Integumentary
System
Organ: 2 or more tissues grouped together
performing a specific function.
Components: Membrane Types
1. Serous membranes
- lines cavities lacking openings to outside
- inner lining of thoracic and
abdominal cavities
- covers the organs in these cavities
- secretes serous fluid
- lubricates and bathes organs
2. Mucus membranes
- line cavities and tracts open to outside
- oral, nasal, digestive, respiratory,
urinary, and reproductive.
- secretes a protective mucus
3. Synovial membranes
- inner linings of joint cavities
- secretes synovial fluid
- thick and colorless
- lubricates joints
4. Cutaneous membrane = skin
Cutaneous Membrane
Skin = largest organ of body
- makes out 15% of total body weight
Functions:
1. *protect underlying tissue (barrier, melanin)
2. stop water loss
3. temperature regulation
4. communication - contains sensory organs
5. make various chemicals (vit. D)
6. excrete water, salts, wastes (oils, etc.)
Skin – 2 Layers
Epidermis
- stratified squamous epithelium
- no blood vessels – nourished by diffusion
- thicker in some areas of body
Layers:
Stratum basale: deepest layer – single
layer of cuboidal cells
- continuous cell division
- receive nourishment from dermis
- 3 different cell types present
Epidermal Cells
*keratin producing
cells – cells which
are dividing
95% of epidermal cells
Produce melanin
Sensitive to touch/
pressure
Melanin = dark pigment capable of absorbing UV rays
- all people have relatively same # of melanocytes
- some just produce more, larger or darker granules
- light also stimulates production of granules
Layers of the Epidermis
S. spinosum: recently produced living
keratinocytes – little keratin production
Langerhans cells – during skin infections
take up and process microbial antigens
S. granulosum: 3-5 row of flattening cells
- high keratin production
Keratinization – process of the cell’s
cytoplasm being replaced by keratin and
hardening
S. lucidum: only found in thickened areas
skin
- extra layer in skin of palms and
soles
- dead keratinized cells
S. corneum: outermost layer of 25-30
rows of dead flattened cells
- constantly being shed
- In the human forearm, for example,
about 1300 cells/cm2/hr are shed (house dust)
- thickness varies by body location
Callus = localized hyperplasia of the stratum
corneum due to pressure or friction
Dermis
• Layer beneath the epidermis
• Dermal papillae – series of ridges and valleys
which help dermis bind to epidermis
Components of Dermis:
• Loose connective tissue
– Collagen and elastic fibers
– Upper portion
• Dense (irregular) tissue
– Lower in dermis
• Glands
– Sweat and sebaceous
• Blood vessels
– Larger lower in dermis
• Sensory receptors
– Pain, pressure, temp.
• Muscle fibers
– Smooth muscle usually associate w/ hair follicles
Accessory organs of skin:
Hair (pili) and hair follicles:
Hair – found on every skin surface except
eyelids, palms, soles, lips, and some
external sex organs
= dead keratinized cells
2 Parts:
1. shaft – portion above skin
2. root - portion in follicle
Melanin also gives hair its’ color
Hair follicle = tubelike depression of epidermal cells into
dermis
Bulb – base of follicle containing dermal blood vessels
and nerves
Arrector pili muscles – smooth muscle attached to follicle
- causes hair to stand upright in response to stimuli
Sebaceous glands – secrete sebum into hair follicle
Sebum = oily secretion
- keeps hair and skin soft
(oily hair results for overactive glands)
- prevent water loss
- antibacterial properties
Hair
Other Glands:
Sweat glands: located in dermis and pass to
surface of skin
• Eccrine sweat glands:
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Simple, coiled tubular glands
function throughout life.
Function in temp. control
Common on skin of palms, soles, forehead, back and neck
• Apocrine sweat glands:
• Simple, branching tubular glands
• located in the axilla, groin, areola, and beard areas.
• Begin functions at puberty – sex hormones stimulate
Ceruminous glands – wax in the ears.
• Protects ear and eardrum for foreign material
Body Temperature Regulation:
- slight changes in body temp. can disrupt metabolic
activities
- normal temp. = 98.6 degrees F (37 degrees C)
- Hypothalamus in midbrain monitors and regulates
temperature control
Too high:
1) dermal blood vessels dilate
2) sweat glands increase secretion
Too low:
1) dermal blood vessels constrict
2) sweat glands shut down
3) involuntary muscle contractions (including
arrector pili muscles)
Fingernails
Subcutaneous layer:
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Layer beneath dermis connecting skin to organs
Composed of loose connective and adipose tissue
Contains major blood vessels
Functions:
1. Insulation
2. Storehouse of fat (energy reserves)
3. Protective layer
4. Pathway for nerves and vessels
Common skin disorders:
Acne: inflammation of sebaceous glands
- usually begins in puberty
- hormones increase size and production of glands
- keratin plugs follicle, secretions accumulate, bacteria in
secretions grow and irritate surrounding skin
Treatment:
- wash with warm soapy water to remove oils and
plugs
- benzyl peroxide in mild cases
- several alternatives for more severe cases
Bed sores (decubitus ulcers): caused by a constant deficiency of
blood to tissues
- overlying a bony projection because of prolonged pressure
- beds, casts, splints
- small cracks become infected and eventually destroys
deeper tissue
Treatment: relieve pressure regularly
- infections can become life threatening
Warts: (common, plantar, genital)
- virus causes epithelial skin cells to proliferate
into uncontrolled cell growth
- generally benign and regress spontaneously
- spread through contact
Cold sores: herpes simplex virus (type 1)
- can lay dormant in few cells for long while
- periodically recurring causing lesions
because of cell destruction
- tend to recur in response to UV light,
hormonal changes, stress
Types of Skin Cancers
• Malignant Melanoma
• Basal Cell Carcinoma
• Squamous Cell Carcinoma
Skin Cancer:
Carcinoma
- light red/pinkish growths
- begins in basal or sqaumous
cells keratinocytes
- grows horizontally over
surface of skin
- common in light skinned
people over 40
- linked to long term sun
exposure
- easily removed or treated
Melanoma
- dark/ multicolored growths
- begins in melanocytes
- grows vertically rapidly
- penetrates into blood vessels
and metastisizes
- deadly when spreads
- can occur at any age
- increased odds w/ severe
sunburns
- look for changes in color, texture,
size, shape, tenderness of moles
or birthmarks
Carcinoma
Melanoma
Skin cancers
Burns:
• Damage to tissue from thermal (heat/cold), electrical,
radioactive, friction or chemical sources.
Direct effect:
tissue in contact with the damaging agent is destroyed
by cell death
Systemic effects = potentially deadly side effects of the
burn
1. severe dehydration
- shock, reduced circulation and urine
production, electrolyte imbalance.
2. bacterial infection
3. loss of temperature regulation
Burn classification:
First degree burn:
- only involves upper layer of epidermis
- mild pain and redness
- heals in 2-3 days
- may result in skin peeling or flaking
Sun burns = most common 1st degree burn
Second degree burn:
- damages deep layers of epidermis and upper level
of dermis (derivatives of dermis are not damaged)
- pain, redness, edema and blister formation
- may take from 7-21 days to heal
- may be some mild scarring or pigmentation
scarring
Third degree burns:
- complete destruction of epidermis, dermis and all
the derivatives (damage reaches subcutaneous layer)
- produce multi-colored, charred wounds
- usually not painful after because of nerve
destruction.
- may not heal on own – skin grafting most times
required
- leaves severe scarring
Burn chart
Epidermal wound healing
Deep wound healing
Words to Know
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Hemangioma
Impetigo
Laceration
Nevus
Pruritis
Wart