Integumentary System
the skin, complex set of organs that protects body
The Skin
1.5-4.0 millimeters (mm), composed of two distinct regions, the epidermis and dermis
Epidermis
composed of epithelial cells, is the outermost protective shield of the body. A keratinized stratified squamous epithelium consisting of 4 distinct cell types and 4 or 5 distinct layers
Dermis
makes up the bulk of the skin, is a tough leathery layer composed mostly of fibrous connective tissue. Only the dermis is vascularized
Hypodermis (Superficial Fascia)
the subcutaneous tissue deep to the skin. It is not part of the skin, but it shares some of the skins protective functions. It is superficial to the tough connective tissue wrapping (fascia) of the skeletal muscles, consists mostly of adipose tissue. Func
Cells of the Epidermis
keratinocytes, melanocytes, epidermal dendritic cells, and tactile cells
Keratinocytes
main role is to produce keratin, the fibrous protein that helps give the epidermis its protective properties
Melanocytes
the spider-shaped epithelial cells that synthesize the pigment melanin, are found in the deepest layer of the epidermis. As melanin is made it is accumulated in membrane bound granules called melanosomes, that are moved along actin filaments by motor prot
Epidermal Dendritic Cells
arise from bone marrow and migrate to the epidermis. Also called Langerhans cells.
Functions: they imgest foreign substances and are key activators of pur immune system
Tactile Cells
are present at the epidermal-dermal junction. Shaped like a spiky hemisphere. Each cell is associated with a disclike sensory nerve ending. (touch receptors)
Layers of the Epidermis (a)
thick skin which covers the palms, fingertips, and soles of feet; Epidermis consists of 5 layers , or strata (bed sheets); deep to superficial: Stratum Basale, Stratum Spinosum, Stratum Granulosum, Stratum Lucidum, and Stratum Corneum.
Stratum Basale (Basale Layer)
Deepest epidermal layer firmly attached to the dermis, Single row of stem cells, Also called stratum germinativum: cells undergo rapid division, Journey from basal layer to surface
Takes 25-45 days, 10 - 25% made of melanocytes
Startum Spinosum (Prickly Layer)
several cell layers thick, Cells contain a weblike system of intermediate prekeratin filaments attached to desmosomes, Abundant melanin granules and dendritic cells, the keratinocytes appear to have spines
Stratum Granuosum (Granular Layer)
thin layer that consists of 3 to 5 layers in which kerainocyte appearance changes drastically and the process of keratinization (in which the cells fill with the protein keratin) begins. Keratohyaline (help to form keratin in upper layers) and lamellated
Stratum Lucidum (Clean Layer)
appears as a clear translucent band just above the stratum granuosum. 2 to 3 rows of flat, dead keratinocytes
Stratum Corneum (Horny Layer)
20 to 40 cell layers of dead, flat keratinized, membranous sacs, accounts for up to 3 quarters of epidermal thickness.
Functions: Protects from abrasion and penetration, Waterproofs, Barrier against biological, chemical, and physical assaults
Layers of the Epidermis (b)
Dermis (b)
the second major skin region, is strong flexible connective tissue. Its cells are fibroblast, macrophages and occasional mast cells. Richly supplied with nerve fibers, blood vessels, and lymphatic vessels. Has two layers, papillary and reticular layers
Papillary Layer
thin superficial layer is aerolar connective tissue, with fine interlaced mat of loosely woven collegen and elastic fibers. Has superior surface callled dermal papillae.
Dermal Papillae
contain Capillary loops, Meissner's corpuscles (touch receptors), Free nerve endings (pain receptors). Indent overlying epidermis.
Reticular Layer
accounts for 80% of the thickness of the dermis, it is coarse, irregularly arranged, and dense fibrous connective tissue. Collagen fibers provide strength and resiliency, Elastic fibers provide stretch-recoil properties
Cleavage/ Tension Lines
seperations, or less dense regions. Invisible lines that run longitudinally in the skin of the head and limbs. Collagen fibers arranged in bundles form cleavage (tension) lines, Incisions made parallel to cleavage lines heal more readily
Flexure Lines
dermak folds that occur at or near joints, where the dermis is tightly secured to deeper structures (deep creases in palm)
Friction Ridges
Epidermal ridges lie atop deeper dermal papillary ridges to form friction ridges of fingerprints
Skin Color
three pigments contribute to skin color: melanin, carotene, and hemoglobin
Melanin
made in the skin. A polymer made of tryosine amino acids. Range in colors from yellow to tan to reddish-brown to black. Its synthesis depends on an enzyme in melanocytes called tyrosinase and it passes from malanocytes to the basal keratinocytes.
Carotene
yellow to orange pigment, that tends to accumulate in the stratum corneum and in fatty tissue of the hypodermis. Its color is most obvious in palms and soles of feet, where stratum corneum is the thickest.
Hemoglobin
the pinkish hue of fair skin, its is oxygenated in the blood cells circulating through dermal capillaries.
Skin Appendages
include nails, sweat glands, sebacous (oil) glands, and hair follicles and hair.
Sweat Glands
aka sudoriferous glands, are distributed all over the body, except nipples and parts of external genetelia. up to 3 million per person. Two types of glands, eccrine and apocrine.
Eccrine Sweat Glands
secreting glands, are far more numerous and are abundant on palms, soles of feet and forehead. Each is a simple, coiled, tubular gland. Ducts connect to pores. Sweat: 99% water, NaCl, vitamin C, antibodies, dermcidin, metabolic wastes.
Apocrine Sweat Glands
approx. 2000 of them are confined in axillary and anogenital areas. Release product by exocytosis. They are larger and lie deeper in the dermis, and ducts empty into hair follicles. Sebum: sweat + fatty substances and proteins. Functional from puberty onw
Ceruminous Glands
modified specialized apocrine glands found in the lining of the external ear canal. Secretion mixes with sebum and produces cerumen or earwax.
Mammary Glands
secrete milk
Sebaceous (Oil) Glands
simple branched alveolar glands that are found all over the body except in the thick skin of palms and soles. Small on body trunk and limbs but large on face neck and upper chest. Secrete oily substance called sebum. Most develop from hair follicles, Beco
Sebum
Oily holocrine secretion, Bactericidal , Softens hair and skin
Hair
Produced by hair follicles, consists of dead keratinized cells. 3 Layers of keratinized cells (medulla, cortex, cuticle)
Functions: Alerting the body to presence of insects on the skin
Guarding the scalp against physical trauma, heat loss, and sunlight
Di
Medulla
central core of hair, consists of large cells and spaces. Soft keratin absent in fine hairs.
Cortex
a bulky layer surrounding the medulla, consists of several layers of flattened cells
Outermost Cuticle
is formed from a single layer of cells that overlap one another from below the shingles on a roof. Provides strength and helps keep inner layers tightly compacted
Hair (image)
Hair Follicles
fold down from the epidermal surface into dermis. Two-layered wall: outer connective tissue root sheath, inner epithelial root sheath, Hair bulb: expanded deep end
Hair follicle receptor (root hair plexus)
Sensory nerve endings around each hair bulb, Stimulated by bending a hair
Arrector pili
Smooth muscle attached to follicle, Responsible for "goose bumps
Vellus (Hair Type)
pale, fine body hair of children and adult females
Terminal (Hair Type)
coarse, long hair of eyebrows, scalp, axillary, and pubic regions (and face and neck of males)
Hair Growth
Growth phase (weeks to years) followed by regressive stage and resting phase (1-3 months), Growth phase varies (6-10 years in scalp, 3-4 months in eyebrows)
Nail
Scalelike modification of the epidermis on the distal, dorsal surface of fingers and toes
Functions of Integumentary System
1. Protection
2. Body Temperature Regulation
3. Cutaneous Sensation
4. Metabolic Functions
5. Blood Reservoir
6. Excretion
Protection
three types of barriers: chemical (Low pH secretions (acid mantle) and defensins retard bacterial activity), physical/mechanical (Keratin and glycolipids block most water and water- soluble substances
Limited penetration of skin by lipid-soluble substance
Body temperature regulation
~500 ml/day of routine insensible perspiration (at normal body temperature), At elevated temperature, dilation of dermal vessels and increased sweat gland activity (sensible perspirations) cool the body
Cutaneous Sensations
Temperature, touch, and pain
Metabolic Functions
Synthesis of vitamin D precursor and collagenase
Chemical conversion of carcinogens and some hormones
Blood Reservoir
up to 5% of body's blood volume
Excretion
nitrogenous wastes and salt in sweat
Developmental Aspects: Old Age
Epidermal replacement slows, skin becomes thin, dry, and itchy, Subcutaneous fat and elasticity decrease, leading to cold intolerance and wrinkles, Increased risk of cancer due to decreased numbers of melanocytes and dendritic cells
Skin Cancer
Most skin tumors are benign (do not metastasize), Risk factors: Overexposure to UV radiation, Frequent irritation of the skin. Some skin lotions contain enzymes in liposomes that can fix damaged DNA
3 types: Basal Cell Carcinoma, Squamous Cell Carcinoma,
Basal Cell Carcinoma
least malignant, most common, Stratum basale cells proliferate and slowly invade dermis and hypodermis, Cured by surgical excision in 99% of cases
Squamous Cell Carcinoma
second most common, Involves keratinocytes of stratum spinosum, Most common on scalp, ears, lower lip, and hands, Good prognosis if treated by radiation therapy or removed surgically
Melanoma
most dangerous, Involves melanocytes , Highly metastatic and resistant to chemotherapy, Treated by wide surgical excision accompanied by immunotherapy
Characteristics (ABCD rule)
A: Asymmetry; the two sides of the pigmented area do not match
B: Border exh
Rules of Nines
Used to estimate the volume of fluid loss from burns
First Degree Burns
Epidermal damage only, Localized redness, edema (swelling), and pain
Second Degree Burns
Epidermal and upper dermal damage, Blisters appear
Third Degree Burns
Entire thickness of skin damaged
Gray-white, cherry red, or black, No initial edema or pain (nerve endings destroyed), Skin grafting usually necessary
Developmental Aspects: Fetal
Ectoderm - epidermis , Mesoderm - dermis and hypodermis , Lanugo coat: covering of delicate hairs in 5th and 6th month, Vernix caseosa: sebaceous gland secretion; protects skin of fetus
Developmental Aspects: Adolescent to Adult
Sebaceous gland activity increases, Effects of cumulative environmental assaults show after age 30, Scaling and dermatitis become more common
Integumentary System
the skin, complex set of organs that protects body
The Skin
1.5-4.0 millimeters (mm), composed of two distinct regions, the epidermis and dermis
Epidermis
composed of epithelial cells, is the outermost protective shield of the body. A keratinized stratified squamous epithelium consisting of 4 distinct cell types and 4 or 5 distinct layers
Dermis
makes up the bulk of the skin, is a tough leathery layer composed mostly of fibrous connective tissue. Only the dermis is vascularized
Hypodermis (Superficial Fascia)
the subcutaneous tissue deep to the skin. It is not part of the skin, but it shares some of the skins protective functions. It is superficial to the tough connective tissue wrapping (fascia) of the skeletal muscles, consists mostly of adipose tissue. Func
Cells of the Epidermis
keratinocytes, melanocytes, epidermal dendritic cells, and tactile cells
Keratinocytes
main role is to produce keratin, the fibrous protein that helps give the epidermis its protective properties
Melanocytes
the spider-shaped epithelial cells that synthesize the pigment melanin, are found in the deepest layer of the epidermis. As melanin is made it is accumulated in membrane bound granules called melanosomes, that are moved along actin filaments by motor prot
Epidermal Dendritic Cells
arise from bone marrow and migrate to the epidermis. Also called Langerhans cells.
Functions: they imgest foreign substances and are key activators of pur immune system
Tactile Cells
are present at the epidermal-dermal junction. Shaped like a spiky hemisphere. Each cell is associated with a disclike sensory nerve ending. (touch receptors)
Layers of the Epidermis (a)
thick skin which covers the palms, fingertips, and soles of feet; Epidermis consists of 5 layers , or strata (bed sheets); deep to superficial: Stratum Basale, Stratum Spinosum, Stratum Granulosum, Stratum Lucidum, and Stratum Corneum.
Stratum Basale (Basale Layer)
Deepest epidermal layer firmly attached to the dermis, Single row of stem cells, Also called stratum germinativum: cells undergo rapid division, Journey from basal layer to surface
Takes 25-45 days, 10 - 25% made of melanocytes
Startum Spinosum (Prickly Layer)
several cell layers thick, Cells contain a weblike system of intermediate prekeratin filaments attached to desmosomes, Abundant melanin granules and dendritic cells, the keratinocytes appear to have spines
Stratum Granuosum (Granular Layer)
thin layer that consists of 3 to 5 layers in which kerainocyte appearance changes drastically and the process of keratinization (in which the cells fill with the protein keratin) begins. Keratohyaline (help to form keratin in upper layers) and lamellated
Stratum Lucidum (Clean Layer)
appears as a clear translucent band just above the stratum granuosum. 2 to 3 rows of flat, dead keratinocytes
Stratum Corneum (Horny Layer)
20 to 40 cell layers of dead, flat keratinized, membranous sacs, accounts for up to 3 quarters of epidermal thickness.
Functions: Protects from abrasion and penetration, Waterproofs, Barrier against biological, chemical, and physical assaults
Layers of the Epidermis (b)
Dermis (b)
the second major skin region, is strong flexible connective tissue. Its cells are fibroblast, macrophages and occasional mast cells. Richly supplied with nerve fibers, blood vessels, and lymphatic vessels. Has two layers, papillary and reticular layers
Papillary Layer
thin superficial layer is aerolar connective tissue, with fine interlaced mat of loosely woven collegen and elastic fibers. Has superior surface callled dermal papillae.
Dermal Papillae
contain Capillary loops, Meissner's corpuscles (touch receptors), Free nerve endings (pain receptors). Indent overlying epidermis.
Reticular Layer
accounts for 80% of the thickness of the dermis, it is coarse, irregularly arranged, and dense fibrous connective tissue. Collagen fibers provide strength and resiliency, Elastic fibers provide stretch-recoil properties
Cleavage/ Tension Lines
seperations, or less dense regions. Invisible lines that run longitudinally in the skin of the head and limbs. Collagen fibers arranged in bundles form cleavage (tension) lines, Incisions made parallel to cleavage lines heal more readily
Flexure Lines
dermak folds that occur at or near joints, where the dermis is tightly secured to deeper structures (deep creases in palm)
Friction Ridges
Epidermal ridges lie atop deeper dermal papillary ridges to form friction ridges of fingerprints
Skin Color
three pigments contribute to skin color: melanin, carotene, and hemoglobin
Melanin
made in the skin. A polymer made of tryosine amino acids. Range in colors from yellow to tan to reddish-brown to black. Its synthesis depends on an enzyme in melanocytes called tyrosinase and it passes from malanocytes to the basal keratinocytes.
Carotene
yellow to orange pigment, that tends to accumulate in the stratum corneum and in fatty tissue of the hypodermis. Its color is most obvious in palms and soles of feet, where stratum corneum is the thickest.
Hemoglobin
the pinkish hue of fair skin, its is oxygenated in the blood cells circulating through dermal capillaries.
Skin Appendages
include nails, sweat glands, sebacous (oil) glands, and hair follicles and hair.
Sweat Glands
aka sudoriferous glands, are distributed all over the body, except nipples and parts of external genetelia. up to 3 million per person. Two types of glands, eccrine and apocrine.
Eccrine Sweat Glands
secreting glands, are far more numerous and are abundant on palms, soles of feet and forehead. Each is a simple, coiled, tubular gland. Ducts connect to pores. Sweat: 99% water, NaCl, vitamin C, antibodies, dermcidin, metabolic wastes.
Apocrine Sweat Glands
approx. 2000 of them are confined in axillary and anogenital areas. Release product by exocytosis. They are larger and lie deeper in the dermis, and ducts empty into hair follicles. Sebum: sweat + fatty substances and proteins. Functional from puberty onw
Ceruminous Glands
modified specialized apocrine glands found in the lining of the external ear canal. Secretion mixes with sebum and produces cerumen or earwax.
Mammary Glands
secrete milk
Sebaceous (Oil) Glands
simple branched alveolar glands that are found all over the body except in the thick skin of palms and soles. Small on body trunk and limbs but large on face neck and upper chest. Secrete oily substance called sebum. Most develop from hair follicles, Beco
Sebum
Oily holocrine secretion, Bactericidal , Softens hair and skin
Hair
Produced by hair follicles, consists of dead keratinized cells. 3 Layers of keratinized cells (medulla, cortex, cuticle)
Functions: Alerting the body to presence of insects on the skin
Guarding the scalp against physical trauma, heat loss, and sunlight
Di
Medulla
central core of hair, consists of large cells and spaces. Soft keratin absent in fine hairs.
Cortex
a bulky layer surrounding the medulla, consists of several layers of flattened cells
Outermost Cuticle
is formed from a single layer of cells that overlap one another from below the shingles on a roof. Provides strength and helps keep inner layers tightly compacted
Hair (image)
Hair Follicles
fold down from the epidermal surface into dermis. Two-layered wall: outer connective tissue root sheath, inner epithelial root sheath, Hair bulb: expanded deep end
Hair follicle receptor (root hair plexus)
Sensory nerve endings around each hair bulb, Stimulated by bending a hair
Arrector pili
Smooth muscle attached to follicle, Responsible for "goose bumps
Vellus (Hair Type)
pale, fine body hair of children and adult females
Terminal (Hair Type)
coarse, long hair of eyebrows, scalp, axillary, and pubic regions (and face and neck of males)
Hair Growth
Growth phase (weeks to years) followed by regressive stage and resting phase (1-3 months), Growth phase varies (6-10 years in scalp, 3-4 months in eyebrows)
Nail
Scalelike modification of the epidermis on the distal, dorsal surface of fingers and toes
Functions of Integumentary System
1. Protection
2. Body Temperature Regulation
3. Cutaneous Sensation
4. Metabolic Functions
5. Blood Reservoir
6. Excretion
Protection
three types of barriers: chemical (Low pH secretions (acid mantle) and defensins retard bacterial activity), physical/mechanical (Keratin and glycolipids block most water and water- soluble substances
Limited penetration of skin by lipid-soluble substance
Body temperature regulation
~500 ml/day of routine insensible perspiration (at normal body temperature), At elevated temperature, dilation of dermal vessels and increased sweat gland activity (sensible perspirations) cool the body
Cutaneous Sensations
Temperature, touch, and pain
Metabolic Functions
Synthesis of vitamin D precursor and collagenase
Chemical conversion of carcinogens and some hormones
Blood Reservoir
up to 5% of body's blood volume
Excretion
nitrogenous wastes and salt in sweat
Skin Cancer
Most skin tumors are benign (do not metastasize), Risk factors: Overexposure to UV radiation, Frequent irritation of the skin. Some skin lotions contain enzymes in liposomes that can fix damaged DNA
3 types: Basal Cell Carcinoma, Squamous Cell Carcinoma,
Basal Cell Carcinoma
least malignant, most common, Stratum basale cells proliferate and slowly invade dermis and hypodermis, Cured by surgical excision in 99% of cases
Squamous Cell Carcinoma
second most common, Involves keratinocytes of stratum spinosum, Most common on scalp, ears, lower lip, and hands, Good prognosis if treated by radiation therapy or removed surgically
Melanoma
most dangerous, Involves melanocytes , Highly metastatic and resistant to chemotherapy, Treated by wide surgical excision accompanied by immunotherapy
Characteristics (ABCD rule)
A: Asymmetry; the two sides of the pigmented area do not match
B: Border exh
Rules of Nines
Used to estimate the volume of fluid loss from burns
First Degree Burns
Epidermal damage only, Localized redness, edema (swelling), and pain
Second Degree Burns
Epidermal and upper dermal damage, Blisters appear
Third Degree Burns
Entire thickness of skin damaged
Gray-white, cherry red, or black, No initial edema or pain (nerve endings destroyed), Skin grafting usually necessary
Developmental Aspects: Fetal
Ectoderm - epidermis , Mesoderm - dermis and hypodermis , Lanugo coat: covering of delicate hairs in 5th and 6th month, Vernix caseosa: sebaceous gland secretion; protects skin of fetus
Developmental Aspects: Adolescent to Adult
Sebaceous gland activity increases, Effects of cumulative environmental assaults show after age 30, Scaling and dermatitis become more common
Developmental Aspects: Old Age
Epidermal replacement slows, skin becomes thin, dry, and itchy, Subcutaneous fat and elasticity decrease, leading to cold intolerance and wrinkles, Increased risk of cancer due to decreased numbers of melanocytes and dendritic cells