Transcript Integumentary System

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Integumentary System Components
 Cutaneous membrane (skin)
▪ Epidermis
▪ Dermis
▪ Accessory structures
 Subcutaneous layer (hypodermis)
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Main Functions of the Integument
 Protection
 Temperature maintenance
 Synthesis and storage of nutrients
 Sensory reception
 Excretion and secretion
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 5-1
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The Epidermis
 Stratified squamous epithelium
 Several distinct cell layers
▪ Thick skin—five layers
▪ On palms and soles
▪ Thin skin—four layers
▪ On rest of body
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
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The Epidermis
 Keratinocytes
▪ 90% of epithelial cells
 Melanocytes
▪ 8% of epithelial cells
▪ Produce pigment melanin
▪ Pigments skin (brown)
▪ Absorbs UV
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The Epidermis
 Langerhans cells
▪ Participate in immune responses
 Merkel cells
▪ Located in the deepest layer of epidermis
▪ Contact tactile (Merkel disk) of sensory neurons
▪ Help to detect touch sensations
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Cell Layers of The Epidermis
 Stratum germinativum (basale)
 Stratum spinosum
 Stratum granulosum
 Stratum lucidum (in thick skin)
 Stratum corneum
▪ Dying superficial layer
▪ Keratin accumulation
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
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The Structure of the Epidermis
Figure 5-2
Melanocytes
Figure 5-3
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Effects of UV Radiation
 Beneficial effect
▪ Activates synthesis of vitamin D3
 Harmful effects
▪ Sun burn
▪ Wrinkles, premature aging
▪ Malignant melanoma
▪ Basal cell carcinoma
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 5-4
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Types of Skin
Thin skin
▪Covers all of body except for palms, soles, and
fingertips
▪Lacks stratum lucidum
▪Thin stratum spinosum and stratum corneum
▪Lacks epidermal ridges
▪Fewer sweat glands than thick skin
▪Sparser distribution of sensory receptors
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Types of Skin
 Thick Skin
▪ Covers palms, soles, fingertips
▪ Has stratum lucidum
▪ Thicker stratum spinosum and stratum corneum
▪ Lacks hair follicles, arrector pili muscles, and sebaceous
glands
▪ Has a greater number of sweat glands
▪ Sensory receptors more densely clustered
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Epidermal Ridges
 Palms, fingers, soles, toes
 Ridges and grooves
 Develop during 3rd and 4th months of fetal
development
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Skin Color
 Melanin
▪ Causes colors from pale yellow to tan to black
▪ Melanocytes
▪ More in areas of darker color (ex. Penis, nipples, areolae, face,
limbs)
▪ Color determined by amount of pigment produced
▪ Accumulation of pigment = freckles or liver spots (age spots)
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Skin Color
 Carotene
▪ Yellow-orange pigment
▪ Precursor of vitamin A
▪ Used to synthesize pigments needed for vision
▪ Found in stratum corneum and fatty areas of dermis and
subcutaneous layer
 Hemoglobin
▪ Oxygen carrying pigment
▪ Red
▪ Causes pink skin when little carotene or melanin are
present
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Albinism
 Inherited
 Inability to produce melanin
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Vitiligo
 Partial or incomplete loss of melanocytes
 Produces white patches
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Skin Color
 Cyanotic
▪ Bluish
▪ Appears in mucous membranes, nail beds, skin
▪ Sign of lack of oxygen
 Jaundice
▪ Yellowish coloration
▪ Caused by buildup of bilirubin in the blood
▪ Can indicate liver disease
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Skin color
 Erythema
▪ Redness of the skin
▪ engorgement of capillaries in the dermis with blood
▪ Caused by injury, exposure to heat, infection,
inflammation, or allergic reactions
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Hair
 Function = protection
▪ Scalp – from sun’s rays & injury
▪ Also decreases heat loss
▪ Eyebrows & eyelashes – protect eyes from foreign objects
▪ Nostrils – protect from foreign objects
▪ Ear canal – protect from foreign objects
 Function = touch
▪ Touch receptors associated with hair follicles (root hair plexus)
▪ Activated when hair is moved
Hair Follicles
Figure 5-5(b)
Hair Follicles
Figure 5-5(c)
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Hair growth cycle
 Each follicle goes through a growth cycle
▪ Growth stage
▪ Scalp: 2-6 years growth
▪ 0.3 mm/day growth rate
▪ Resting stage
▪ Growth of hair stops
▪ Scalp: 3 months
▪ After resting stage
▪ Hair replaced
▪ New growth stage
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
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Rate of growth & replacement altered by:
 Illness
 Radiation therapy
 Chemotherapy
 Age
 Genetics
 Gender
 Severe emotional stress
 Rapid weight loss (reduction of calories and/or protein)
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Hair loss
 Normal = 100 per day (from scalp)
 Rate of hair shedding increases 3-4 months after
childbirth
 Alopecia
▪ Partial or complete loss of hair
▪ May result from genetic factors, aging, endocrine
disorders, chemotherapy, or skin disease
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Types of hair
 Lanugo
▪ Very fine, nonpigmented hairs
▪ Produced by the 5th month of fetal development
▪ Cover body of fetus
▪ Usually shed before birth (except scalp, eyebrows, eyelashes)
 Vellus hairs
▪ “peach fuzz”
▪ Replace lanugo
▪ Short, fine hairs
▪ Slightly thicker than lanugo
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Terminal hairs
 Head
 Eyebrows
 Eyelashes
 Coarse pigmented hairs
▪ Develop in presence of androgens
▪ During puberty
▪ In axillae (armpits) and pubic regions
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Male = 95% terminal hair:5% vellus hair
Female =65% terminal hair:35% vellus hair
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Hair color
 amount and type of melanin in keritinized cells
▪ melanocytes found in the matrix of bulb
 Dark hair = pure melanin
 Blond or red hair = variants of melanin
▪ More sulfur or iron
 Graying = decline of tyrosinase
▪ Enzyme that catalyzes production of melanin
 White = accumulation of air in medullary shaft
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Sebaceous Glands - Oil glands
 In dermis
 Usually open into the neck of hair follicle
▪ Except in lips, glans penis, labia minora, and tarsal glands
 Absent in palms and soles
 Small on trunk and limbs
 Large on breasts, face, neck and upper chest
 Secrete sebum
▪ Oily substance - triglycerides, cholesterol, proteins, and inorganic salts
▪ Coats surface of hairs - Prevents drying and becoming brittle
▪ Prevents excessive evaporation from skin
▪ Keeps skin soft & Inhibits growth of certain bacteria
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Acne
 Inflammation of sebaceous glands
 Usually begins during puberty
▪ Infected by bacteria
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Sudoriferous glands - Sweat glands
 3 to 4 million
 Secrete through exocytosis into hair follicles or
onto skin surface through pores
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Sudoriferous glands (continued)
 Eccrine sweat glands
▪ Simple, coiled tubular
▪ More common type
▪ Distributed throughout skin, except:
▪ Lips, nail beds, glans penis, glans clitoris, labia minora, eardrums
▪ Most numerous on forehead, palms, soles
▪ Sweat consists of water, ions, urea, uric acid, ammonia, amino acids,
glucose, and lactic acid
▪ Function = regulate body temperature
▪ Insensible perspiration – sweat that evaporates before perceived as
moisture
▪ Sensible perspiration – sweat seen as moisture
▪ Function = eliminate waste
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Sudoriferous glands (continued)
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Apocrine sweat glands
▪ Simple, coiled tubular
▪ Found in axilla (armpit), groin, areolae, and bearded
regions of face
▪ Secretions through exocytosis
▪ These are actually merocrine glands
 They used to be thought to be apocrine
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Sudoriferous Glands (continued)
 Ceruminous glands
▪ Sweat glands of the external ear
▪ waxy secretion
▪ Combined secretion of ceruminous and sebaceous
glands in the ear is called earwax
▪ In combinations with hairs – impedes entrance of
foreign objects
Figure 5-7
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Accessory Structure
 Nails
▪ Plate of tightly packed, hard, keratinized epidermal cells
 Average growth = 1mm /week
 Function = grasp small objects, protection, scratching
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 5-8
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Deep Wound Healing
 Occurs when injury extends into the dermis and
hypodermis
 4 phases:
▪ Inflammatory phase
▪ Blood clot forms; inflammation
▪ Migratory phase
▪ Clot becomes scab; granulation tissue forms
▪ Proliferative phase
▪ Extensive growth of epithelial cells in random patterns
▪ Maturation phase
▪ Scab sloughs off
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Deep Wound Healing
 Fibrosis
▪ Scar tissue formation
▪ Hypertrophic scar
▪ Scar remaining within boundaries of wound
▪ Keloid scar
▪ Scar extending beyond boundaries of wound
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Skin Grafts
 Covering a wound with healthy skin taken from a
donor site
▪ Transplanted skin taken from:
▪ Self = autograft
▪ Identical twin = isograft
▪ Analogous skin transplantation
 Especially with burn patients
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Major Age-Related Changes
 Injury and infection increase
 Immune cells decrease
 Sun protection diminishes
 Skin becomes dry, scaly
 Hair thins, grays
 Sagging, wrinkles occur
 Heat loss decreases
 Repair slows
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings