The integumentary system consists of the skin, hair, nails, and glands. The skin is the largest organ and has three layers - the epidermis, dermis, and hypodermis. The epidermis is made of stratified squamous epithelium with keratinocytes, melanocytes, Merkel cells, and Langerhans cells. It has five layers and provides protection, temperature regulation, sensation, vitamin D synthesis, and more. The dermis contains collagen, fibers, blood vessels and glands. It regulates temperature and provides strength and elasticity. Hair, nails, and glands are also part of this system and provide protection, sensation and other functions. Common disorders include freck

1. Integumentary SystemIntegumentary System
Chapter 5Chapter 5

2.  Objectives:Objectives:
1- Describe the functions of the1- Describe the functions of the
integumentary system.integumentary system.
2- Identify the major structures found in the2- Identify the major structures found in the
three layers of the skin.three layers of the skin.
3. Describe the anatomy and physiology of3. Describe the anatomy and physiology of
hair and nailshair and nails
4. Define some common4. Define some common
dermatopathological disorders.dermatopathological disorders.

3.  This system is divided into:This system is divided into:
1- skin1- skin
2- hair2- hair
3- glands3- glands
4- nails4- nails
5- nerve endings5- nerve endings
I)I) SkinSkin
Skin is an organ because it consists ofSkin is an organ because it consists of
different tissues that are joined to perform adifferent tissues that are joined to perform a
specific function.specific function.
Largest organ of the body in surface area andLargest organ of the body in surface area and
weight.weight.
DermatologyDermatology is the medical specialtyis the medical specialty
concerning the diagnosing and treatment ofconcerning the diagnosing and treatment of skinskin
disorders.disorders.

5. Anatomy (structure)Anatomy (structure)
EpidermisEpidermis (thinner outer layer of skin)(thinner outer layer of skin)
DermisDermis (thicker connective tissue layer)(thicker connective tissue layer)
HypodermisHypodermis (subcutaneous layer or Sub-Q)(subcutaneous layer or Sub-Q)
Muscle and boneMuscle and bone
Physiology (function)Physiology (function)
1- Protection1- Protection
- physical barrier that protects underlying- physical barrier that protects underlying
tissues from injury, UV light and bacterialtissues from injury, UV light and bacterial
invasion.invasion.
- mechanical barrier is part- mechanical barrier is part non specificnon specific
immunityimmunity (skin, tears and saliva).(skin, tears and saliva).

6. 2- Regulation of body temperature2- Regulation of body temperature
- high temperature or strenuous- high temperature or strenuous
exercise; sweat is evaporated from theexercise; sweat is evaporated from the
skin surface to cool it down.skin surface to cool it down.
-- vasodilationvasodilation (increases blood flow)(increases blood flow)
andand vasoconstrictionvasoconstriction (decrease in(decrease in
blood flow) regulates body temp.blood flow) regulates body temp.
3-Sensation3-Sensation
- nerve endings and receptor cells that- nerve endings and receptor cells that
detect stimuli to temp., pain, pressure anddetect stimuli to temp., pain, pressure and
touch.touch.

7. 4- Excretion4- Excretion
- sweat removes water and small amounts of- sweat removes water and small amounts of
salt, uric acid and ammonia from the bodysalt, uric acid and ammonia from the body
surfacesurface
5- Blood reservoir5- Blood reservoir
- dermis houses an extensive network of- dermis houses an extensive network of
blood vessels carrying 8-10% of total blood flowblood vessels carrying 8-10% of total blood flow
in a resting adult.in a resting adult.
6- Synthesis of Vitamin D (cholecalciferol)6- Synthesis of Vitamin D (cholecalciferol)
-UV rays in sunlight stimulate the production-UV rays in sunlight stimulate the production
of Vit. D. Enzymes in the kidney and liver modifyof Vit. D. Enzymes in the kidney and liver modify
and convert to final form;and convert to final form; calcitriolcalcitriol (most(most
active form of Vit. D.) Calcitriol aids in absorptionactive form of Vit. D.) Calcitriol aids in absorption
of calcium from foods and is considered aof calcium from foods and is considered a
hormone.hormone.

8.  Epidermis: keratinized stratified squamousEpidermis: keratinized stratified squamous
epithelium with four distinct cell types and fiveepithelium with four distinct cell types and five
distinct layers.distinct layers.

10. Cells in the epidermis:Cells in the epidermis:
- keratinoytes- keratinoytes
- melanocytes- melanocytes
- Merkel cells- Merkel cells
- Langerhans’ cells- Langerhans’ cells
1- Keratinocytes: most abundant1- Keratinocytes: most abundant
- produce keratin (fibrous protein)- produce keratin (fibrous protein)
- protective; waterproofing the skin- protective; waterproofing the skin
- continuous mitosis- continuous mitosis
- form in the deepest layer called the- form in the deepest layer called the stratumstratum
basalebasale
- cells push their way up to the surface- cells push their way up to the surface wherewhere
they are dead cells filled withthey are dead cells filled with keratin; willkeratin; will
slough off. Regenerates everyslough off. Regenerates every 25-45 days.25-45 days.

12. 2- Melanocytes:2- Melanocytes:
- cells produce brownish/black pigment- cells produce brownish/black pigment
called melanin. (8% of epidermal cells)called melanin. (8% of epidermal cells)
- stratum basale- stratum basale
- branching processes (dendrites)- branching processes (dendrites)
- melanin accumulates in melanosomes- melanin accumulates in melanosomes
and transported along dendrites ofand transported along dendrites of thethe
melanocytes to keratinocytes.melanocytes to keratinocytes.
- melanin accumulates on the superficial- melanin accumulates on the superficial aspectaspect
of the keratinocyte shielding itsof the keratinocyte shielding its nucleus fromnucleus from
harmful UV light.harmful UV light.
- lack of melanin: albino- lack of melanin: albino

14. 3- Merkel cells:3- Merkel cells:
- stratum basale- stratum basale
- epidermis of hairless skin- epidermis of hairless skin
- attach to keratinocytes by desmosomes- attach to keratinocytes by desmosomes
- make contact with a sensory neuron ending- make contact with a sensory neuron ending
called a Merkel disc (touch).called a Merkel disc (touch).
4- Langerhans’ cells:4- Langerhans’ cells:
- star-shaped cells arising from bone marrow- star-shaped cells arising from bone marrow
that migrate to epidermis.that migrate to epidermis.
- epidermal dendritic cells (macrophages)- epidermal dendritic cells (macrophages)
- interact with a WBC called a T- helper cell- interact with a WBC called a T- helper cell
- easily damaged by UV light.- easily damaged by UV light.

17. Stratum corneum
Stratum lucidum
Stratum
spinosum
Stratum
granulosum
Stratum
basale

18. 5 layers of the epidermis:5 layers of the epidermis:
1-1- Stratum corneum (horny layer)Stratum corneum (horny layer)
-- layer has many rows of dead cells filled withlayer has many rows of dead cells filled with
keratinkeratin
-- continuously shed and replacedcontinuously shed and replaced
(desquamation)(desquamation)
-- effective barrier against light, heat andeffective barrier against light, heat and
bacteriabacteria
- 20-30 cell layers thick- 20-30 cell layers thick
- dandruff and flakes- dandruff and flakes
- 40 lbs. of skin flakes in a lifetime (dust mites!)- 40 lbs. of skin flakes in a lifetime (dust mites!)

19. 2-2- Stratum lucidumStratum lucidum
-- seen in thick skin of the palms and soles ofseen in thick skin of the palms and soles of
feet.feet.
- 3-5 rows of- 3-5 rows of clearclear flat dead cellsflat dead cells
- keratohyalin (precursor) to keratin- keratohyalin (precursor) to keratin
3-3- Stratum granulosumStratum granulosum
- 3-5 rows of flattened cells- 3-5 rows of flattened cells
- nuclei of cells flatten out- nuclei of cells flatten out
- organelles disintegrate cells eventually die- organelles disintegrate cells eventually die
- keratohyalin granules (darkly stained)- keratohyalin granules (darkly stained)
accumulateaccumulate
- lamellated granules secrete glycolipids into- lamellated granules secrete glycolipids into
extracellular spaces to slow water loss in theextracellular spaces to slow water loss in the
epidermisepidermis

20. 4-4- Stratum spinosumStratum spinosum: “spiny layer”: “spiny layer”
- 8-10 rows of polyhedral (many sided)- 8-10 rows of polyhedral (many sided)
cellscells
- appearance of prickly spines- appearance of prickly spines
- shrink when prepared for slide- shrink when prepared for slide
- melanin granules and Langerhans’ cell- melanin granules and Langerhans’ cell
predominatepredominate

22. 5-5- Stratum basale:Stratum basale: deepest epidermal layerdeepest epidermal layer
- attached to dermis- attached to dermis
- single row of cells- single row of cells
- mostly columnar keratinocytes- mostly columnar keratinocytes
- with rapid mitotic division- with rapid mitotic division
- stratum germinativum- stratum germinativum
- contain merkel cells and melanocytes- contain merkel cells and melanocytes
- 10-25%- 10-25%

25.  Dermis:Dermis:
- flexible and strong connective tissue- flexible and strong connective tissue
- elastic, reticular and collagen fibers- elastic, reticular and collagen fibers
- cells: fibroblasts, macrophages (WBC),- cells: fibroblasts, macrophages (WBC),
mast cells (histamine).mast cells (histamine).
- nerves, blood and lymphatic vessels- nerves, blood and lymphatic vessels
- oil and sweat glands originate- oil and sweat glands originate
- two layers: papillary and reticular- two layers: papillary and reticular

26. 1- Papillary layer:1- Papillary layer:
- loose connective tissue with nipple like- loose connective tissue with nipple like
surface projection called dermalsurface projection called dermal papilla.papilla.
- capillaries- capillaries
- contain pain receptors- contain pain receptors
- contain touch receptors (Meissner’s- contain touch receptors (Meissner’s
corpusclescorpuscles
- dermal ridges- epidermal ridges-- dermal ridges- epidermal ridges- patternpattern
called fingerprintscalled fingerprints

27. 2- Reticular layer:2- Reticular layer:
- dense irregular c.t.- dense irregular c.t.
- collagen fibers offer strength- collagen fibers offer strength
- holds water- holds water
- dermal tearing causes stretch marks.- dermal tearing causes stretch marks.
- striae- striae
Skin color: attributed to melanin,Skin color: attributed to melanin, hemoglobinhemoglobin
and carotene.and carotene.
Race is determined by amount of melanin not #Race is determined by amount of melanin not #
of melanocytes.of melanocytes.

28. Local accumulation of melanin will result inLocal accumulation of melanin will result in
freckles and pigmented moles.freckles and pigmented moles.
Melanin is made through interaction withMelanin is made through interaction with
tyrosinase present in melanocytestyrosinase present in melanocytes
UV light stimulates melanin production. ExcessiveUV light stimulates melanin production. Excessive
UV light can damage DNA and cause solarUV light can damage DNA and cause solar
elastosis (elastin fibers clump)elastosis (elastin fibers clump)
Carotene is formed from Vit. A and deposits inCarotene is formed from Vit. A and deposits in
stratum corneum and imparts an orange tone tostratum corneum and imparts an orange tone to
skinskin

29. FrecklesFreckles

30. Hemoglobin (blood) will impart pinkish tones toHemoglobin (blood) will impart pinkish tones to
skin. Blushingskin. Blushing
1- Redness (erythema) - reddened skin,1- Redness (erythema) - reddened skin,
embarrassment, fever, hypertension,embarrassment, fever, hypertension,
inflammation, or allergyinflammation, or allergy
2- Pallor/blanching - pale skin, emotional2- Pallor/blanching - pale skin, emotional
distress or anemia, low blood pressuredistress or anemia, low blood pressure
3- Jaundice - liver disease, bile deposited in3- Jaundice - liver disease, bile deposited in
tissuetissue
4- Bronzing - bronze coloration (Addison's4- Bronzing - bronze coloration (Addison's
disease) hypofunction of adrenal cortexdisease) hypofunction of adrenal cortex
5- Black & blue - bruises, escaped blood clots in5- Black & blue - bruises, escaped blood clots in
tissue spaces (clotted blood masses =tissue spaces (clotted blood masses =
hematomas)hematomas)

31. Hair color:Hair color:
Dark hair: mostly melaninDark hair: mostly melanin
Blond and red hair: melanin with Fe and S.Blond and red hair: melanin with Fe and S.
Gray hair: loss of pigment (decr. tyrosinase)Gray hair: loss of pigment (decr. tyrosinase)
White hair: air bubbles in the medullary hairWhite hair: air bubbles in the medullary hair
shaft.shaft.

32.  Hair (pili)Hair (pili)
- main function is- main function is
protectionprotection
- hair root nerve- hair root nerve
plexus for touchplexus for touch
- normal hair loss in- normal hair loss in
adult 70-100adult 70-100
hairs/dayhairs/day

35. Hair anatomy:Hair anatomy:
- composed of dead columns of keratinized- composed of dead columns of keratinized
cells.cells.
- shaft: is the superficial portion of hair- shaft: is the superficial portion of hair
- root: below the surface in the dermis- root: below the surface in the dermis
Shaft and root are composed of three layers:Shaft and root are composed of three layers:
inner medulla, middle cortex and outer cuticle.inner medulla, middle cortex and outer cuticle.
Inner medulla has 2-3 rows of polyhedral cellsInner medulla has 2-3 rows of polyhedral cells
where pigment is locatedwhere pigment is located
Cortex is major portion of shaftCortex is major portion of shaft
Cuticle is scaly and heavily keratinized (shingles)Cuticle is scaly and heavily keratinized (shingles)

36. Vellus hair: fine hairVellus hair: fine hair
Terminal hair : coarser hair; axillary and pubicTerminal hair : coarser hair; axillary and pubic
region. Grow in response to sex hormonesregion. Grow in response to sex hormones
Hirsutism: excessive hairiness: incr. androgensHirsutism: excessive hairiness: incr. androgens

37. Hair follicle surrounds the root.Hair follicle surrounds the root.
Bulb is the enlargement at the end of the follicle.Bulb is the enlargement at the end of the follicle.
- Also houses the germinal layer- Also houses the germinal layer
Papilla (nipple like) is located in the bulb and isPapilla (nipple like) is located in the bulb and is
where the blood supply nourishes the hair.where the blood supply nourishes the hair.

38. Arrector pili (pl. pilorum) is smooth muscle locatedArrector pili (pl. pilorum) is smooth muscle located
in the dermis and is attached to the side of thein the dermis and is attached to the side of the
hair shaft.hair shaft.
- fright, cold and emotions will contract muscle- fright, cold and emotions will contract muscle
and pull hair in vertical position. “Goose bumps”.and pull hair in vertical position. “Goose bumps”.

40. Glands:Glands:
Two types of glands exist in the integument.Two types of glands exist in the integument.
- Sebaceous glands (oil glands)- Sebaceous glands (oil glands)
- Sudoriferous glands (sweat glands)- Sudoriferous glands (sweat glands)
Sebaceous glands: (holocrine glands)Sebaceous glands: (holocrine glands)
- connected to hair follicle- connected to hair follicle
- not found on palms and soles of feet- not found on palms and soles of feet
- secretes sebum (fats, cholesterol and- secretes sebum (fats, cholesterol and
proteinsproteins
- keep hair from drying out, keeps skin moist- keep hair from drying out, keeps skin moist
- whiteheads, blackheads and acne- whiteheads, blackheads and acne

43. Whitehead:Whitehead: When the trapped sebum andWhen the trapped sebum and
bacteria stay below the skin surface, abacteria stay below the skin surface, a
whiteheadwhitehead is formed.is formed.

44. Blackhead:Blackhead: AA blackheadblackhead occurs when theoccurs when the
trapped sebum and bacteria partially open to thetrapped sebum and bacteria partially open to the
surface and turn black due to melanin, the skin'ssurface and turn black due to melanin, the skin's
pigment. Blackheads can last for a long timepigment. Blackheads can last for a long time
because the contents very slowly drain to thebecause the contents very slowly drain to the
surface.surface.

45. Sudoriferous glands: exocrine glandsSudoriferous glands: exocrine glands
- millions located throughout the skin- millions located throughout the skin
- two types:- two types:
- eccrine: more common (merocrine)- eccrine: more common (merocrine)
- originate in subQ layer- originate in subQ layer
- duct empties on skin surface- duct empties on skin surface
- palms and soles of feet- palms and soles of feet
- sweat is watery (99% H- sweat is watery (99% H220)0)
- sweating regulated by- sweating regulated by
sympathetic nervous systemsympathetic nervous system

47. - apocrine: axillary and pubic region- apocrine: axillary and pubic region
- duct empties onto hair follicle- duct empties onto hair follicle
- viscous fluid- viscous fluid
- causes body odor (“b-o “) when- causes body odor (“b-o “) when
bacteria break it downbacteria break it down

48. Ceruminous glands: located in ear onlyCeruminous glands: located in ear only
- modified apocrine glands- modified apocrine glands
- originate in Sub Q layer- originate in Sub Q layer
- ducts open onto EAM.- ducts open onto EAM.
- produces cerumen (ear wax) : brown- produces cerumen (ear wax) : brown
sticky substance that prevents foreignsticky substance that prevents foreign
material from entering.material from entering.

50. Nails:Nails:
- Produced by cells in the epidermis- Produced by cells in the epidermis
- Nail plate (body): visible portion- Nail plate (body): visible portion
- Nail root: located under cuticle- Nail root: located under cuticle
- Lunula: half moon crescent shaped- Lunula: half moon crescent shaped
white portion under cuticlewhite portion under cuticle
- Nail bed: located under nail plate- Nail bed: located under nail plate
- Hypoxia: decr. oxygen in blood,- Hypoxia: decr. oxygen in blood, nailnail
bed will turn blue-bed will turn blue- cyanosiscyanosis

52. Nerve endings:Nerve endings:
- Exteroceptors (stimulus outside of body)- Exteroceptors (stimulus outside of body)
- Pacinian (lamellated) corpuscles: deep- Pacinian (lamellated) corpuscles: deep
pressure and stretchpressure and stretch
- Meissner’s (tactile) corpuscles: light- Meissner’s (tactile) corpuscles: light touch,touch,
vibration and discriminativevibration and discriminative touch.touch.
- hair root plexus- hair root plexus
- free (naked) nerve endings: nociceptors- free (naked) nerve endings: nociceptors
(pain) and thermoreceptors ( hot –(pain) and thermoreceptors ( hot – deepdeep
and cold- surface)and cold- surface)
- Ruffini’s corpuscles: deep pressure- Ruffini’s corpuscles: deep pressure

53. Pacinian corpusclePacinian corpuscle

54.  HypodermisHypodermis
- called subcutaneous, Sub-Q or- called subcutaneous, Sub-Q or
superficialsuperficial fasciafascia
- anchors skin to underlying structures- anchors skin to underlying structures
- contains adipose tissue and blood- contains adipose tissue and blood
vesselsvessels
- common site for injection- common site for injection

55. Dermatopathological termsDermatopathological terms
 Macule – flat spot on skin with color (freckle)Macule – flat spot on skin with color (freckle)
 Wheal – round and temp. elevation of skinWheal – round and temp. elevation of skin
(hives)(hives)
 Papule - solid elevated area, epidermal andPapule - solid elevated area, epidermal and
papillary (insect bite)papillary (insect bite)
 Nodule - large papules extending intoNodule - large papules extending into
subcutaneous layer (cyst)subcutaneous layer (cyst)
 Vesicle - papule with fluid core (varicella zosterVesicle - papule with fluid core (varicella zoster
virus)virus)
 Pustule - papule with pus core (acne)Pustule - papule with pus core (acne)
 Erosion - ruptured vesicle (ulcer)Erosion - ruptured vesicle (ulcer)
 Xeroderma - "dry skin"Xeroderma - "dry skin"
 Hemangiomas - benign tumor in the dermisHemangiomas - benign tumor in the dermis
(capillary and cavernous)(capillary and cavernous)

56.  Sebaceous hyperplasia - enlargement of theSebaceous hyperplasia - enlargement of the
sebaceous glandsebaceous gland
 Pruritis - irritating itching sensation of the skinPruritis - irritating itching sensation of the skin
 Seborrheic dermatitis - inflammation aroundSeborrheic dermatitis - inflammation around
abnormally active sebaceous glandsabnormally active sebaceous glands
 Basal cell carcinoma - malignant cancerBasal cell carcinoma - malignant cancer
originating in the germinative layeroriginating in the germinative layer
 Squamous cell carcinoma - malignant cancerSquamous cell carcinoma - malignant cancer
originating in the top layer of the skinoriginating in the top layer of the skin
 Malignant melanomas - metastasizingMalignant melanomas - metastasizing
melanocytesmelanocytes