Integumentary System

Learning Objectives

By the end of this section, the learner should be able to:

• Describe the integumentary system and the role it plays in homeostasis
• Describe the layers of the skin and the functions of each layer
• Describe the accessory structures of the skin and the functions of each
• Describe the changes that occur in the integumentary system during the aging process
• Discuss several common diseases, disorders, and injuries that affect the integumentary system
• Explain treatments for some common diseases, disorders, and injuries of the integumentary system

Layers of the Skin

• The skin and its accessory structures (hair, nails, glands, sensory receptors) make up the integumentary system.
• The skin:
  • Largest organ by weight
  • Composed of several tissue types
  • Also called the cutaneous membrane
  • Contains 2 layers: epithelial tissue overlying connective tissue
    • Epidermis: Outer layer
    • Dermis: Inner layer

Epidermis:                                                    

• Outer layer, composed of stratified squamous epithelium
• Basement membrane between epidermis and dermis

Dermis:

• Inner layer, thicker than epidermis
• Connective tissue, with collagenous and elastic fibers, muscle, blood, nervous tissue

Subcutaneous layer (hypodermis):

• Beneath dermis; insulating layer
• Areolar and adipose connective tissue.
• Not considered part of the skin
• Contains blood vessels that supply skin

Skin and Subcutaneous Layer

Epidermis

• Stratified squamous epithelium
• Lacks blood vessels
• Deepest layer, stratum basale, nourished by blood vessels in dermis
• As cells grow, they migrate toward free surface, away from nutrient supply
• As they migrate, older cells, keratinocytes, begin to flatten and die
• Keratinization: Process of hardening, dehydration, and keratin accumulation that occurs in epidermal cells as they migrate outward
• Keratin: Tough, fibrous, waterproof protein made and stored in the cells
• As cells reach outer surface, become tightly packed, develop desmosomes, form outermost layer, stratum corneum
• Stratum corneum cells are eventually shed from skin surface
• Thickest on palms and soles (0.8 through 1.4 mm)
• Most of body has thinner epidermis, 0.07 through 0.12 mm
• Functions:  Protects against water loss, harmful chemicals, mechanical injury, pathogens

Skin Color

Skin color results mainly from melanin pigment:

• Eumelanin:  Brownish-black pigment of epidermis
• Pheomelanin:  Reddish yellow pigment, found in certain areas

• of carotene pigment from diet
• Jaundice

Dermis

• Inner layer of skin
• Average of 1 to 2 mm thick
• Contains projections called dermal papillae between epidermal ridges
• Binds epidermis to underlying tissues
• Connective tissue layer, containing muscle fibers, nerve cell processes
• Dermal blood vessels supply nutrients to all skin cells
• Contains hair follicles, sweat and sebaceous glands
• Contains sensory receptors: Lamellated (Pacinian) corpuscles for pressure, Tactile (Meissner’s) corpuscles for light touch

Dermis Lies Deep to Epidermis

Glands of the Skin

Skin Functions

Skin is versatile, and vital for homeostasis

Functions of the skin:

• Protective barrier:  Protects against harmful substances, UV radiation, microorganisms, water loss
• Sensation:  Contains sensory receptors for touch, pressure, temperature changes, pain
• Excretion of some wastes
• Production of Vitamin D:  Starts in skin; when produced and activated, helps with calcium absorption
• Regulation of body temperature:  Helps cool body by sweating and blood flow changes

Body Temperature Regulation Mechanisms

When body temperature rises:

• Thermoreceptors signal hypothalamus
• Vasodilation of dermal blood vessels
• Vasoconstriction of deep blood vessels
• Sweat glands are activated

When body temperature falls:

• Thermoreceptors signal hypothalamus
• Vasoconstriction of dermal blood vessels
• Vasodilation of deep blood vessels
• Sweat glands are inactive
• Muscles contract involuntarily (shivering)

Problems in Temperature Regulation

Hyperthermia: abnormally high body temperature

• Can occur on hot, humid day, when sweat cannot evaporate
• When air temperature is high, radiation is less effective
• Body may gain heat from hotter air
• Skin becomes dry, person gets weak, dizzy, nauseous, with headache, rapid pulse

Hypothermia: abnormally low body temperature

• Can result from prolonged exposure to cold, or illness
• Shivering is involuntary skeletal muscle contraction, caused by hypothalamus
• Progresses to confusion, lethargy, loss of reflexes and consciousness
• Without treatment, organs shut down

Learning Objectives

By the end of this section, the learner should be able to:

• Describe the integumentary system and the role it plays in homeostasis
• Describe the layers of the skin and the functions of each layer
• Describe the accessory structures of the skin and the functions of each
• Describe the changes that occur in the integumentary system during the aging process
• Discuss several common diseases, disorders, and injuries that affect the integumentary system
• Explain treatments for some common diseases, disorders, and injuries of the integumentary system

Layers of the Skin

• The skin and its accessory structures (hair, nails, glands, sensory receptors) make up the integumentary system.
• The skin:
  • Largest organ by weight
  • Composed of several tissue types
  • Also called the cutaneous membrane
  • Contains 2 layers: epithelial tissue overlying connective tissue
    • Epidermis: Outer layer
    • Dermis: Inner layer

Epidermis:                                                    

• Outer layer, composed of stratified squamous epithelium
• Basement membrane between epidermis and dermis

Dermis:

• Inner layer, thicker than epidermis
• Connective tissue, with collagenous and elastic fibers, muscle, blood, nervous tissue

Subcutaneous layer (hypodermis):

• Beneath dermis; insulating layer
• Areolar and adipose connective tissue.
• Not considered part of the skin
• Contains blood vessels that supply skin

Skin and Subcutaneous Layer

Epidermis

• Stratified squamous epithelium
• Lacks blood vessels
• Deepest layer, stratum basale, nourished by blood vessels in dermis
• As cells grow, they migrate toward free surface, away from nutrient supply
• As they migrate, older cells, keratinocytes, begin to flatten and die
• Keratinization: Process of hardening, dehydration, and keratin accumulation that occurs in epidermal cells as they migrate outward
• Keratin: Tough, fibrous, waterproof protein made and stored in the cells
• As cells reach outer surface, become tightly packed, develop desmosomes, form outermost layer, stratum corneum
• Stratum corneum cells are eventually shed from skin surface
• Thickest on palms and soles (0.8 through 1.4 mm)
• Most of body has thinner epidermis, 0.07 through 0.12 mm
• Functions:  Protects against water loss, harmful chemicals, mechanical injury, pathogens

Skin Color

Skin color results mainly from melanin pigment:

• Eumelanin:  Brownish-black pigment of epidermis
• Pheomelanin:  Reddish yellow pigment, found in certain areas

• of carotene pigment from diet
• Jaundice

Dermis

• Inner layer of skin
• Average of 1 to 2 mm thick
• Contains projections called dermal papillae between epidermal ridges
• Binds epidermis to underlying tissues
• Connective tissue layer, containing muscle fibers, nerve cell processes
• Dermal blood vessels supply nutrients to all skin cells
• Contains hair follicles, sweat and sebaceous glands
• Contains sensory receptors: Lamellated (Pacinian) corpuscles for pressure, Tactile (Meissner’s) corpuscles for light touch

Dermis Lies Deep to Epidermis

Glands of the Skin

Skin Functions

Skin is versatile, and vital for homeostasis

Functions of the skin:

• Protective barrier:  Protects against harmful substances, UV radiation, microorganisms, water loss
• Sensation:  Contains sensory receptors for touch, pressure, temperature changes, pain
• Excretion of some wastes
• Production of Vitamin D:  Starts in skin; when produced and activated, helps with calcium absorption
• Regulation of body temperature:  Helps cool body by sweating and blood flow changes

Body Temperature Regulation Mechanisms

When body temperature rises:

• Thermoreceptors signal hypothalamus
• Vasodilation of dermal blood vessels
• Vasoconstriction of deep blood vessels
• Sweat glands are activated

When body temperature falls:

• Thermoreceptors signal hypothalamus
• Vasoconstriction of dermal blood vessels
• Vasodilation of deep blood vessels
• Sweat glands are inactive
• Muscles contract involuntarily (shivering)

Problems in Temperature Regulation

Hyperthermia: abnormally high body temperature

• Can occur on hot, humid day, when sweat cannot evaporate
• When air temperature is high, radiation is less effective
• Body may gain heat from hotter air
• Skin becomes dry, person gets weak, dizzy, nauseous, with headache, rapid pulse

Hypothermia: abnormally low body temperature

• Can result from prolonged exposure to cold, or illness
• Shivering is involuntary skeletal muscle contraction, caused by hypothalamus
• Progresses to confusion, lethargy, loss of reflexes and consciousness
• Without treatment, organs shut down

Learning Objectives

By the end of this section, the learner should be able to:

• Describe the integumentary system and the role it plays in homeostasis
• Describe the layers of the skin and the functions of each layer
• Describe the accessory structures of the skin and the functions of each
• Describe the changes that occur in the integumentary system during the aging process
• Discuss several common diseases, disorders, and injuries that affect the integumentary system
• Explain treatments for some common diseases, disorders, and injuries of the integumentary system

Layers of the Skin

• The skin and its accessory structures (hair, nails, glands, sensory receptors) make up the integumentary system.
• The skin:
  • Largest organ by weight
  • Composed of several tissue types
  • Also called the cutaneous membrane
  • Contains 2 layers: epithelial tissue overlying connective tissue
    • Epidermis: Outer layer
    • Dermis: Inner layer

Epidermis:                                                    

• Outer layer, composed of stratified squamous epithelium
• Basement membrane between epidermis and dermis

Dermis:

• Inner layer, thicker than epidermis
• Connective tissue, with collagenous and elastic fibers, muscle, blood, nervous tissue

Subcutaneous layer (hypodermis):

• Beneath dermis; insulating layer
• Areolar and adipose connective tissue.
• Not considered part of the skin
• Contains blood vessels that supply skin

Skin and Subcutaneous Layer

Epidermis

• Stratified squamous epithelium
• Lacks blood vessels
• Deepest layer, stratum basale, nourished by blood vessels in dermis
• As cells grow, they migrate toward free surface, away from nutrient supply
• As they migrate, older cells, keratinocytes, begin to flatten and die
• Keratinization: Process of hardening, dehydration, and keratin accumulation that occurs in epidermal cells as they migrate outward
• Keratin: Tough, fibrous, waterproof protein made and stored in the cells
• As cells reach outer surface, become tightly packed, develop desmosomes, form outermost layer, stratum corneum
• Stratum corneum cells are eventually shed from skin surface
• Thickest on palms and soles (0.8 through 1.4 mm)
• Most of body has thinner epidermis, 0.07 through 0.12 mm
• Functions:  Protects against water loss, harmful chemicals, mechanical injury, pathogens

Skin Color

Skin color results mainly from melanin pigment:

• Eumelanin:  Brownish-black pigment of epidermis
• Pheomelanin:  Reddish yellow pigment, found in certain areas

• of carotene pigment from diet
• Jaundice

Dermis

• Inner layer of skin
• Average of 1 to 2 mm thick
• Contains projections called dermal papillae between epidermal ridges
• Binds epidermis to underlying tissues
• Connective tissue layer, containing muscle fibers, nerve cell processes
• Dermal blood vessels supply nutrients to all skin cells
• Contains hair follicles, sweat and sebaceous glands
• Contains sensory receptors: Lamellated (Pacinian) corpuscles for pressure, Tactile (Meissner’s) corpuscles for light touch

Dermis Lies Deep to Epidermis

Glands of the Skin

Skin Functions

Skin is versatile, and vital for homeostasis

Functions of the skin:

• Protective barrier:  Protects against harmful substances, UV radiation, microorganisms, water loss
• Sensation:  Contains sensory receptors for touch, pressure, temperature changes, pain
• Excretion of some wastes
• Production of Vitamin D:  Starts in skin; when produced and activated, helps with calcium absorption
• Regulation of body temperature:  Helps cool body by sweating and blood flow changes

Body Temperature Regulation Mechanisms

When body temperature rises:

• Thermoreceptors signal hypothalamus
• Vasodilation of dermal blood vessels
• Vasoconstriction of deep blood vessels
• Sweat glands are activated

When body temperature falls:

• Thermoreceptors signal hypothalamus
• Vasoconstriction of dermal blood vessels
• Vasodilation of deep blood vessels
• Sweat glands are inactive
• Muscles contract involuntarily (shivering)

Problems in Temperature Regulation

Hyperthermia: abnormally high body temperature

• Can occur on hot, humid day, when sweat cannot evaporate
• When air temperature is high, radiation is less effective
• Body may gain heat from hotter air
• Skin becomes dry, person gets weak, dizzy, nauseous, with headache, rapid pulse

Hypothermia: abnormally low body temperature

• Can result from prolonged exposure to cold, or illness
• Shivering is involuntary skeletal muscle contraction, caused by hypothalamus
• Progresses to confusion, lethargy, loss of reflexes and consciousness
• Without treatment, organs shut down

Learning Objectives

By the end of this section, the learner should be able to:

• Describe the integumentary system and the role it plays in homeostasis
• Describe the layers of the skin and the functions of each layer
• Describe the accessory structures of the skin and the functions of each
• Describe the changes that occur in the integumentary system during the aging process
• Discuss several common diseases, disorders, and injuries that affect the integumentary system
• Explain treatments for some common diseases, disorders, and injuries of the integumentary system

Layers of the Skin

• The skin and its accessory structures (hair, nails, glands, sensory receptors) make up the integumentary system.
• The skin:
  • Largest organ by weight
  • Composed of several tissue types
  • Also called the cutaneous membrane
  • Contains 2 layers: epithelial tissue overlying connective tissue
    • Epidermis: Outer layer
    • Dermis: Inner layer

Epidermis:                                                    

• Outer layer, composed of stratified squamous epithelium
• Basement membrane between epidermis and dermis

Dermis:

• Inner layer, thicker than epidermis
• Connective tissue, with collagenous and elastic fibers, muscle, blood, nervous tissue

Subcutaneous layer (hypodermis):

• Beneath dermis; insulating layer
• Areolar and adipose connective tissue.
• Not considered part of the skin
• Contains blood vessels that supply skin

Skin and Subcutaneous Layer

Epidermis

• Stratified squamous epithelium
• Lacks blood vessels
• Deepest layer, stratum basale, nourished by blood vessels in dermis
• As cells grow, they migrate toward free surface, away from nutrient supply
• As they migrate, older cells, keratinocytes, begin to flatten and die
• Keratinization: Process of hardening, dehydration, and keratin accumulation that occurs in epidermal cells as they migrate outward
• Keratin: Tough, fibrous, waterproof protein made and stored in the cells
• As cells reach outer surface, become tightly packed, develop desmosomes, form outermost layer, stratum corneum
• Stratum corneum cells are eventually shed from skin surface
• Thickest on palms and soles (0.8 through 1.4 mm)
• Most of body has thinner epidermis, 0.07 through 0.12 mm
• Functions:  Protects against water loss, harmful chemicals, mechanical injury, pathogens

Skin Color

Skin color results mainly from melanin pigment:

• Eumelanin:  Brownish-black pigment of epidermis
• Pheomelanin:  Reddish yellow pigment, found in certain areas

• of carotene pigment from diet
• Jaundice

Dermis

• Inner layer of skin
• Average of 1 to 2 mm thick
• Contains projections called dermal papillae between epidermal ridges
• Binds epidermis to underlying tissues
• Connective tissue layer, containing muscle fibers, nerve cell processes
• Dermal blood vessels supply nutrients to all skin cells
• Contains hair follicles, sweat and sebaceous glands
• Contains sensory receptors: Lamellated (Pacinian) corpuscles for pressure, Tactile (Meissner’s) corpuscles for light touch

Dermis Lies Deep to Epidermis

Glands of the Skin

Skin Functions

Skin is versatile, and vital for homeostasis

Functions of the skin:

• Protective barrier:  Protects against harmful substances, UV radiation, microorganisms, water loss
• Sensation:  Contains sensory receptors for touch, pressure, temperature changes, pain
• Excretion of some wastes
• Production of Vitamin D:  Starts in skin; when produced and activated, helps with calcium absorption
• Regulation of body temperature:  Helps cool body by sweating and blood flow changes

Body Temperature Regulation Mechanisms

When body temperature rises:

• Thermoreceptors signal hypothalamus
• Vasodilation of dermal blood vessels
• Vasoconstriction of deep blood vessels
• Sweat glands are activated

When body temperature falls:

• Thermoreceptors signal hypothalamus
• Vasoconstriction of dermal blood vessels
• Vasodilation of deep blood vessels
• Sweat glands are inactive
• Muscles contract involuntarily (shivering)

Problems in Temperature Regulation

Hyperthermia: abnormally high body temperature

• Can occur on hot, humid day, when sweat cannot evaporate
• When air temperature is high, radiation is less effective
• Body may gain heat from hotter air
• Skin becomes dry, person gets weak, dizzy, nauseous, with headache, rapid pulse

Hypothermia: abnormally low body temperature

• Can result from prolonged exposure to cold, or illness
• Shivering is involuntary skeletal muscle contraction, caused by hypothalamus
• Progresses to confusion, lethargy, loss of reflexes and consciousness
• Without treatment, organs shut down