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