The Integumentary System
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Transcript of The Integumentary System
The Integumentary System Skin & Appendages (hair, nails, skin
glands)
Membranes – thin sheet or layer;four major types: fig. 5-1
Cutaneous membrane – skin, primary organ of integumentary system; largest body organ
Serous membranes – line the body cavities that lack opening to the outside and covers the surfaces of organs in those cavities Composed of simple squamous epithelium and
loose connective tissue Types
Parietal – portion that lines walls of body cavity (ex. – parietal pleura, parietal peritoneum)
Visceral – portion which covers organs (ex. – visceral pleura, visceral peritoneum)
Cells of serous membranes secrete watery serous fluid that lubricates membrane surfaces
Membranes
Serous Membranes
Mucous membranes – line cavities and tubes opening directly to the exterior Composed of various types of epithelium &
loose connective tissue Epithelial cells of mucus membranes secrete
mucus Ex. – respiratory, digestive, urinary, &
reproductive tracts.
Membranes
Mucous Membranes
Synovial membrane – organs that line joint cavities Composed of only various connective tissues Cells secrete synovial fluid that lubricates the
ends of bones at joints
Membranes
Synovial Membrane
Skin and it’s tissues – functions as a protective covering, aids in regulating body temperature, houses sensory receptors, synthesizes various chemicals, and excretes wastes. Composed of an epidermis and dermis separated by a basement membrane with a subcutaneous layer beneath. Fig. 5-2, 5-3
Epidermis Outermost layer composed of stratified squamous
epithelium that lacks blood vessels Deepest layer, stratum germinativum, contains cells
undergoing mitosis Epidermal cells undergo keratinization as they are pushed
toward the surface (cytoplasm replaced by the protein keratin – waterproofing)
The outermost layer, stratum corneum, is composed of dead epidermal cells
Production of epidermal cells = rate which they are lost at the surface
Epidermis functions to protect underlying tissues against water loss, mechanical injury, & the effect of harmful chemicals
Melanin – pigment produced by melanocytes, protects underlying cells from the effects of UV light – melanocytes transfer pigment to nearby epidermal cells
Dermis Layer composed largely of fibrous connective
tissue that binds the epidermis to underlying tissues Also contains muscle fibers, blood vessels, & nerve
fibers dermal papillae – parallel rows of peglike
projections (grooves) – fingerprints (unique, pattern never changes, only grows)
Deeper areas of dermis are filled with collagen & elastic fibers; number of Elastic fibers & fat storage decrease with age which leads to wrinkles (Fig. 5-4 )
Dermal blood vessels supply nutrients to all skin cells & help regulate body temp.
Nervous tissue is scattered through the dermis Some carry impulses to muscles & glands of the skin Others are associated with various sensory receptors in
the skin
Subcutaneous (not a part of the skin)
Composed of loose connective tissue & adipose tissue
Adipose tissue helps conserve body heat
Accessory organs of the skin
Hair Follicles – fig. 5-5 Hairs occurs in nearly all regions of the skin;
some exceptions – palms, lips, nipples, penis, soles of feet
Hair growth begins from dermal papillae Hair root lies hidden in follicles & visible part
of hair is called the shaft Arrector pili – smooth muscle that contracts
to cause “goose bumps” – regulated body temperature by “trapping air”
Hair Follicle
Sebaceous glands Secrete sebum – helps keep skin & hair soft
& waterproof Usually found attached to hair follicle but
some open directly to the skin Level of secretion increases during puberty
& amount of secretions is regulated by sex hormones
Inflamed & overactive glands acne (plugged)
Sebaceous Glands
Sweat glands (sudoriferous) Located in nearly all regions of the skin & consist
of a coiled tube Types
Eccrine sweat glands – most numerous; produce sweat to help regulate body temperature; not connected to hair follicles
Apocrine sweat glands (scent glands) Respond to emotional stress Found primarily in axilla & around genitalia & usually
associated with hair follicles Secrete a thicker milky secretion Breakdown of secretion by skin bacteria produces odor
Decrease in activity by both types of glands as a result of aging causes
less able to control body temp. dryness in skin
Sweat gland (sudoriferous) - Eccrine
Eccrine gland
Sweat gland (sudoriferous) - Apocrine
Nails – Fig. 5-6 Protective
covers on the ends of fingers & toes
Produced by epidermal cells that undergo keratinization
Receptors Specialized nerve endings that make it
possible for skin to act as a sense organ Meissner’s corpuscle – capable of detecting
light touch Pacinian corpuscle – detects pressure Other receptors respond to pain, cold, heat,
crude touch, & vibration
Receptors
Regulation of Body Temperature Vital because heat affects the rate of metabolic reactions Heat production & loss
Heat is a byproduct of cellular respiration C6H12O6 + 6CO2 6H2O + 6CO2 + ATP + heat
When body temp increases increase blood flow in dermal vessels
Heat lost to the outside by radiation, conduction, convection, & evaporation
Body temp. decreases decrease blood flow; sweat glands become inactive
Excessive heat loss contraction of skeletal muscles increase cellular
Respiration produces heat
Negative Feedback
Regulation of body temp. Problems in Temperature Regulation
Humid days – sweat doesn’t evaporate Air temp. may be greater than body temp. –
no heat loss by radiation Heat stroke – stop sweating
Burns – most serious & frequent problems that affect skin “Rule of Nines” Fig. 5-8
First degree – sunburn – only surface layers involved, no blistering & minimal tissue damage
Second degree – involved deep epidermal & upper dermal damage, blisters, severe pain
Third degree – complete destruction of epidermal & dermal layers; often underlying muscles & bones are damaged; fluid loss, infection
Rule of Nines
Why are percentagesdifferent in the adultand child?
Categories of Burns
First & Second Degree Burns
Third Degree Burn(OUCH!)
Cancer – uncontrolled cell division; may be caused by UV radiation
Squamous cell carcinoma – slow growing malignant tumor of the epidermis, if caught quickly usually doesn’t metastasize
Basal cell carcinoma – most common type, originates in cells of the lower epidermis, much less likely to metastasize
Malignant melanoma – most serious form of skin cancer, can metastasize and lead to death
Kaposi sarcoma – rare, frequently associated with immune deficiencies
The “ A, B, C, D’s” of Skin Cancer
Malignant Melanoma
Kaposi Sarcoma