Skin and Appendages

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• Chapter 7
• Skin and Appendages

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Lesson 7-1 Objectives

• List six functions of the skin.
• Define stratum germinativum and stratum corneum.
• Describe the two layers of the skin?epidermis and
  dermis.
• List the two major functions of the subcutaneous
  layer.

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Introduction

• Skin (integument) is bodys largest organ
• Integumentary system describes the skin and its
  appendagesthe hair, nails, and skin glands
• You shed about 1.5 lbs per year

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Skin Perspective

• On average, 1 cm2 of skin contains
• 3,000,000 cells
• 10 hairs
• 15 sebaceous glands
• 3 feet of blood vessels
• 700 sweat glands
• 3000 sensory cells at nerve endings
• 12 feet of nerves
• 200 pain receptors
• 2 cold receptors
• 12 sensors for heat

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Functions of the Skin

• Serves as mechanical barrier
• Protects internal structures
• Participates in the immune response
• Acts as a gland for vitamin D synthesis
• Performs excretory function
• Performs sensory role
• Helps regulate body temperature

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Structure of the Skin

• Layers
• Epidermis
• (lays upon dermis)
• Dermis (skin)
• Subcutaneous
• a.k.a Hypodermis
• Accessory structures
• Hair, nails, glands..etc.

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Overview Structure of the Skin

• Skin classified as cutaneous membrane
• Two primary layersepidermis and dermis joined
  by dermoepidermal junction
• Hypodermis lies beneath dermis
• Thin and thick skin (Figure 7-3)
• Thin skin covers most of body surface (1 to 3
  mm thick) has hair and smooth surface
• Thick skinsoles and palms (4 to 5 mm thick)
  ridged surface with no hair

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Layers of Epidermis

• From deep to Superfical
• Stratum Basale
• A.k.a Stratum Germinativum
• Stratum Spinosum
• Stratum Granulosum
• Stratum Lucidum
• Stratum Corneum
• 2.
• 3. 4.

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Layers uncovered
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Epidermis Outer Layer continued

• Layers of the epidermis
• Stratum corneum (surface layer) composed of
  dead, flattened cells that slough off , our horns
• Stratum germinativum (deepest), a.k.a. stratum
  basale cells continuously dividing and moving
  toward surface
• Keratinization The protein keratin makes skin
  cells hard, flat, and water resistant.
• (Keratinocytescells that actually produce
  protein)

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Epidermal growth and repair

• Shortened turnover time increase thickness of the
  stratum corneum results in callus formation
• Normally 10 to 12 of all cells in stratum
  basale enter mitosis daily

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Structure of the Skin

• Dermopidermal junction (DEJ)
• A basement membrane
• Polysaccharide gel serve to glue the epidermis
  to the dermis below
• Partial barrier to the passage of some cells and
  large molecules

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Dermis

• Our hide, strong and stretchy
• true skin
• Lies under and supports the epidermis
• Gives strength
• Sits on the subcutaneous layer or hypodermis
• Embedded with accessory structures
• Includes blood vessels that nourish epidermis
• Reservoir storage for water and electrolytes

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Dermis continued

• 2 major regions
• Papillary upper/superficial dermal layer
• Pain receptors (free nerve endings)
• Touch receptors Meissners corpuscles
• Allow for grip
• Genetically unique fingerprints
• Arrector pili (goose bumps)
• Reticular Deepest of skin layer
• Blood vessel, sweat glands, oil glands
• Pacinian corpuscles Deep pressure receptors
• Last line of defense
• Leather

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Dermis (cont)

• During wound healing
• fibroblasts begin forming an unusually dense mass
  of new connective fibers
• if not replaced by normal tissue, this mass
  remains a scar
• Cleavage lines (Figure 7-7)patterns formed by
  the collagenous fibers of the reticular layer of
  the dermis
• also called Langers lines

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Langers lines
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Scar formation

• Cleavage lines - patterns formed by the
  collagenous fibers of the reticular layer also

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Subcutaneous Layer Hypodermis

• A.k.a subcutaneous layer
• Connection point to tissue that lies beneath skin
• Highly vascularized
• Two main roles
• Its fat insulates body from extreme temperature
  changes.
• Its connective tissue anchors the skin to
  underlying structures.
• NOT PART OF THE SKIN

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Problems

• Decubitus ulcers Bed sores
• Blood supply is cut off
• Bedridden patients who are not regularly moved
• Pressure of bone on skin eventually cuts off
  supply line

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Real life
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Accessory Structures Hair

• Functions Detect insects, protect eyes, keep
  dust out of lungs
• Hormones affect growth.
• Melanin influences color.
• Hair arises in epidermis.
• Cosmetic role

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Accessory Structures Nails

• Protect tips of fingers and toes from injury
• Condition affected by oxygenation of blood
  supply, trauma, and nutritional deficiencies

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Fingernails

• Scale-like modifications of the epidermis
• Heavily keratinized
• Stratum basale extends beneath the nail bed
• Responsible for growth
• Lack of pigment makes them colorless

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Accessory Structures Glands

• Sebaceous glands
• Oil glands
• Secrete sebum and in fetus vernix caseosa
• Sudoriferous
• Sweat glands

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Sudoriferous Glands

• Apocrine glands Found with hair follicles more
  active at puberty
• Axillary and Genital Regions
• Eccrine glands Everywhere Critical for
  temperature regulation

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• Sweat and Its Function

• Composition
• Mostly water
• Some metabolic waste
• Fatty acids and proteins (apocrine only)
• Function
• Helps dissipate excess heat
• Excretes waste products
• Acidic nature inhibits bacteria growth
• Odor is from associated bacteria

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Sweet Sweat

• Types of modified sweat glands
• Mammary glands Secrete milk
• Ceruminous glands Secrete ear wax (cerumen)
• Pheromones Sex attractants
• Copuline (copulation)

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Skin Color

• Determined by genes, physiology,
  and sometimes pathology
• Dark pigment Melanin
• Melanocyte Make melanin in epidermis(St.Basale)
• Yellow to brown to black
• Melanocyte malfunctions
• Albinism (defect in melanin)
• Vitiligo (loss of brown pigment)

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Skin color continued

• Yellow pigment Carotene
• Orange-yellow (some veggies)
• Presence of melanin overshadows carotenes tint
  in most people
• Hemoglobin
• Red coloring from blood cells in dermis
  capillaries
• Oxygen content determines the extent of red
  coloring

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Skin Color (contd.)

• Physiological changes
• Blushing Blood vessel dilation
• Pallor Blood vessel constriction
• Pathological changes
• Cyanosis or bluish tint Poor oxygenation
• Jaundice or yellowing Bilirubin deposition (Bile
  and Liver products)
• Bronzing Melanin overproduction
• Ecchymosis Black and blue bruising

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Lesson 7-2 Objectives

• Explain four processes by which thebody loses
  heat.
• Describe how the skin helps regulate temperature.

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Body Temperature Key Terms

• Core temperature The inner parts of the body
• Shell temperature The surface areas of the body
• Thermoregulation Balance of heat production and
  heat loss

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Heat Production

• Metabolism basis of body temperature
• Blood disperses heat throughout the body.
• Most heat is produced by muscles, the liver, and
  endocrine glands.
• Affected by food consumption, hormones, disease,
  and physical activity

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Heat Loss

• Sites Skin (80), lungs, and excretory products
  (20)
• Types
• Radiation heat transfer from object to another
  without touching
• Conduction heat transfer through contact
• Convection transfer of heat AWAY from surface by
  movement
• Evaporation heat expended from fluid(liquid)

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Temperature Regulation

• Hypothalamus
• Heat lost by
• Dilation of blood vessels
• Sweating
• Heat conserved by
• Shivering
• Blood vessel constriction
• Less sweat

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Issues in Temperature Regulation

• Hyperthermia Syncope (fainting), cramps, heat
  exhaustion, heat stroke
• Hypothermia Slowed metabolism, fibrillation
  (random heart beat)

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Temperature Regulation Neonates

• Lose more heat than they produce
• Large surface area
• Large bald head
• Less insulation
• Must rely on nonshivering thermogenesis
  metabolism of brown adipose tissue (BAT)
• Have limited capacity to dissipate heat

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Skin Homeostatic Imbalances

• Burns
• Tissue damage and cell death caused by heat,
  electricity, UV radiation, or chemicals
• Associated dangers
• Dehydration
• Electrolyte imbalance
• Circulatory shock

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Burns Classified by Depth

• Partial thickness burns
• First-degree
• Second-degree
• Full-thickness burn
• Third-degree

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• Severity of Burns

• First-degree burns
• Only epidermis is
• damaged
• Skin is red and swollen
• Second degree burns
• Epidermis and upper
• dermis are damaged
• Skin is red with blisters
• Third-degree burns
• Destroys entire skin layer
• Burn is gray-white or black

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Types of Burns

• 1st Degree Burn

• 2nd Degree Burn

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2nd vs. 3rd

• Severe 2nd Degree Burn

• 3rd Degree Burn

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• 3RD Degree Burns

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Critical Burns

• Burns are considered critical if
• Over 25 of body has second degree burns
• Over 10 of the body has third degree burns
• There are third degree burns of the face, hands,
  or feet

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Rules of Nines

• Way to determine the extent of burns
• Body is divided into 11 areas for quick
  estimation
• Each area represents about 9

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Rule of Nines
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Burns Classified by Extent

• Rule of nines
• Eschar (scab)
• Acts like a tourniquet
• Breeds bacteria
• Secretes toxins

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Skin Care

• All ages
• Reduce exposure to UV radiation.
• Especially in older adults
• Skin dries out more easily retain moisture by
  limiting excessive bathing and use of soap.
• Thinner skin bruises more easily and does not
  insulate as well.

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Skin, Drugs, and Chemicals

• Skin can absorb many chemicals.
• Drug delivery systems
• Hypodermic injections
• Transdermal patches
• Intradermal injections (allergy testing)
• Topical applications
• Danger of absorption of toxins