Integumentary System
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Integumentary System
• Composed of several tissues
• Maintains homeostasis
• Protective covering
• Retards water loss
• Regulates body temperature
• Houses sensory receptors
• Contains immune system cells
• Synthesizes chemicals
• Excretes small amounts of waste
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Skin Cells
• help produce Vitamin D needed for
normal bone and tooth development
• some cells (keratinocytes) produce
substances that simulate development of
some white blood cells
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Layers of Skin
• Skin is one of the
largest organs of the
body
• Epidermis
• Dermis - “true skin”
• Subcutaneous layer
• beneath dermis
• not part of skin
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Epidermis
• lacks blood vessels
• keratinized
• thickest on palms and soles (0.8-1.4mm)
• contains melanocytes which provide melanin
• rests on basement membrane
• made of stratified squamous
• as cells are pushed from the deeper portion, they tend to die
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Dermis
• on average 1.0-2.0 mm thick
• contains dermal papillae
• binds epidermis to underlying
tissues
• made of irregular dense
connective tissue
• contains muscle cells,
nerve cell processes,
specialized sensory receptors,
blood vessels, hair follicles, and
glands
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Subcutaneous Layer
• Called “hypodermis”
• Made of loose
connective tissue and
adipose tissue
• insulates
• Contains
major blood vessels
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Hair Follicles
• epidermal cells
• tube-like depression
• extends into dermis
• hair root
• hair shaft
• hair papilla
• dead epidermal cells
• melanin
• arrector pili muscle –
when the muscle
contracts, hair is pulled
into an upright position (cold temp. or fright activates them)
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(nerve receptor)
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Nails
• protective coverings
• nail plate
• nail bed
• lunula – actively
dividing region in the
fingernail
• cuticle – fold of
skin over the nail
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Sebaceous Glands
• usually associated with hair
follicles
• holocrine glands
• secrete sebum – prevents the
skin from drying out
• absent on palms and soles
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Sweat Glands
• sudoriferous glands – activated by heat, pain, fever and nervousness
• widespread in skin
• originates in deeper dermis
or hypodermis
• eccrine glands – respond to
elevated body temperature
• apocrine glands – respond to
emotional stress and begin to function during puberty
•Causes body odor
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Regulation of Body
Temperature
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Heat Production and Loss
•Radiation
•Primary source of heat loss
•Infrared heat rays escape from warmer surfaces to cooler
surroundings.
•Conduction
•Heat moves from the body into the molecules of cooler
objects in contact with its surface
•Ex. Sitting on a cold desk
•Evaporation
•Sweat glands secrete sweat to the surface of the skin. As
the sweat evaporates, it carries heat away from the surface
cooling the skin.
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Problems in Temperature
Regulation
Hyperthermia – abnormally high body temperature
Hypothermia – abnormally low body temperature
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Skin Color
Genetic Factors
(greatest impact on skin color)
• varying amounts of melanin
• varying size of melanin
granules
• albinos lack melanin
Physiological Factors
• dilation of dermal blood vessels
• constriction of dermal blood
vessels
• accumulation of carotene
• jaundice - indicator of liver
malfunction
Environmental Factors
• sunlight (melanocytes help to protect deeper cells from sunlight)
• UV light from sunlamps
• X-rays
• All of the above factors darkens melanin
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Healing of Cuts
•Blood escapes
from the dermal
blood vessels.
Platelets begin
sticking together
to form a clot. The
blood clot and
dried tissue fluid
form a scab.
Fibroblasts
migrate to the
injury site and
produces new
connective tissue.
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Healing of Burns
First degree burn – superficial partial-thickness
Second degree burn – deep partial-thickness
Third degree burn – full-thickness
• autograft - using burn victims own skin that hasn’t
been damaged
• homograft - using cadaver skin from a skin bank
• various skin substitutes
•Amniotic membrane
•Artificial membranes of silicone, polyurethane, or nylon
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Healing of Burns
•First degree
•Superficial, skin red and dry
•Involves only epidermis
• Rx – cold water
•Heals in one week (example: sunburn)
•Second degree
•Epidermis and dermis
•Pain, swelling, redness, and blistering
•Subject to infection
•Rx – pain medication, dry sterile dressing
•Healing within two weeks
•Third degree
•Epidermis, dermis, and
subcutaneous layers (full thickness)
•Loss of skin, blackened skin
•May be life threatening
•Rx – prevention of infection, fluid replacement, skin grafting
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Rule of Nines
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Don’t forget about Stems Test 2
Tomorrow and your Skin Quiz
Wednesday!
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Common Skin Disorders
• Acne
– Disorder of sebaceous glands
– Sebum plugs pores and area fills with leukocytes (white blood cell)
– Also, blackheads, cysts, pimples, and scarring
• Albinism – absence of melanin
• Alopecia – baldness
• Athlete’s foot
– Contagious fungal infection
– Usually contracted in public baths and showers
– Rx – antifungal agents
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Common Skin Disorders
Acne
Albinism
Alopecia
Athlete’s Foot
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Common Skin Disorders
• Boils (carbuncles)
– Painful, bacterial infection of hair follicle or sebaceous glands
– Rx – antibiotics, excision, and drainage of affected area
• Dermatitis
– Non-specific skin inflammation
– Rash – reaction to soap, plants, etc.
– Skin blotches – caused by stress
• Eczema
– Acute or chronic inflammatory skin disease
– Skin dry, red, itchy, and scaly
– Rx – remove cause, hydrocortisone to help alleviate symptoms
• Excoriation - abrasion
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Common Skin Disorders
Eczema
Boil
Excoriation
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Dermatitis
Common Skin Disorders
• Herpes
– Herpes simplex I
• Viral
• Fever blister or cold sore
– Shingles (herpes zoster)
• Viral infections of nerve endings
• On chest or abdomen, accompanied by severe pain
• Impetigo
–
–
–
–
Acute, inflammatory and contagious
Seen in babies and young children
Caused by staphylococcus or streptococcus
Vesicles that rupture and develop distinct yellow crusts
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Common Skin Disorders
Herpes Simplex I
Shingles
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Impetigo
Common Skin Disorders
• Pruritis - itching
• Psoriasis
– Chronic inflammatory skin disease
– Dry reddish patches covered with silvery-white scales
• Ringworm
– Contagious fungal infection
– Raised, itchy circular patches with crusts
• Scabies
– Communicable – transmit from one person to another
– Severe itching
– Mite burrows in skin, lays eggs, eggs hatch
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Common Skin Disorders
Pruritis
Ringworm
Psoriasis
Scabies
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Common Skin Disorders
• Skin cancer
– Associated with exposure to sun (UV rays)
– Most common type of cancer in people
– Skin cancer cells are most likely to occur from nonpigmented epithelial
cells
• Basal cell carcinoma (Cutaneous carcinoma)
– Occurs mostly in middle-aged people who have a light complexion and
work or plays outdoors
– Most common, least malignant
– Usually on face
– Rx – surgical removal or radiation
• Squamous cell carcinoma
–
–
–
–
Mostly scalp and lower lip
Grows rapidly, metastasizes to lymph nodes
Rx – surgical removal or radiation
Prognosis good with early diagnosis
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Common Skin Disorders
Basal Cell Carcinoma
Squamous Cell Carcinoma
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Common Skin Disorders
• Melanoma
–
–
–
–
Malignant
Occurs in melanocytes
Metastasizes to other areas quickly
Brown or black irregular patch that occurs
suddenly
– Change in existing wart or mole may indicate
melanoma
– Rx – surgical removal of melanoma and
surrounding area and chemotherapy
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Common Skin Disorders
Melanoma
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Common Skin Disorders
• Skin lesions
–
–
–
–
Pustule – small collection of pus in the top layer of skin
Tumor
Ulcer (superficial and decubitus – lying down)
Vesicle
• Urticaria (hives)
– Itchy wheals or welts
– Usually allergic reaction to drugs, food, etc.
– Rx – avoid allergen
• Warts (verrucae)
– Caused by virus
– Some disappear spontaneously, others removed with
liquid nitrogen, chemicals, or laser
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Common Skin Disorders
Urticaria
Warts
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Life Span Changes
• Skin becomes scaly
• Age spots appear
• Epidermis thins
• Dermis becomes reduced
• Loss of fat
• Wrinkling
• Sagging
• Sebaceous glands secrete
less oil
• Melanin production slows
• Hair thins
• Number of hair follicles
decrease
• Nail growth becomes impaired
• Sensory receptors decline
• Body temperature unable to be
controlled
• Diminished ability to activate
Vitamin D
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Clinical Application
Acne Vulgaris
•most common skin disorder
•sebum and epithelial cells clog glands
•produces whiteheads and blackheads (comedones)
•anaerobic bacteria trigger inflammation (pimple)
•largely hormonally induced
•Androgens (hormone) stimulate sebum production
•treatments include antibiotics, topical creams, birth control pills
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