integumentary system
TRANSCRIPT
The Integumentary System
Group 4
Integumentary System
• is the organ system that protects the body from damage, comprising the skin and its appendages.
• the largest of the body's organ systems.• this system accounts for about 12 to 15 % of total
body weight.• composed of 3 major layers of tissue:
the epidermis, dermis, and hypodermis.• The study of the skin is Dermatology
Skin
• Layers of the skinConsists of 3 main layers:
EpidermisDermisHypodermis
Epidermis
• Outermost or the epidermal layer• Composed of stratified squamous, keratinized cell
epithelial cells• Held together by highly convoluted, interlocking
cellular links called desmosomes • Is the thickest where it receives the most abrasion and
weight (on the palms of the hand and the soles of the feet)
• There are 5 layers of the epidermis
Epidermis
• The 5 layers of the epidermis (from outermost to deep):Stratum CorneumStratum LucidumStratumGranulosumStratum SpinosumStratum Germinativum/Basale
Epidermis
• Stratum CorneumHorny or leathery layerForms the outermost layer of the epidermis Consist of dead cell converted to proteinMany layers thickThe thickness of this layer is determines by the
amount of stimulation on the surface by abrasion or weight bearing.
Epidermis
• Stratum LucidumClear layerLocated directly beneath the s. corneumOnly one or two cell layers thick Cells are transparent and flat
Epidermis
• Stratum GranulosumGranular layerConsists of two to three layers of flattened cellsGranules tend to accumulate in these cells,This layer is very active in keratinizationIn this layer, the cells lose their nuclei and become
compact and brittle
Epidermis
• Stratum SpinosumSpiny or prickly layerConsists of several spiny-shaped cellsIn this layer, desmosomes are still quite prevalent
Epidermis
• Stratum GerminativumInnermost and most important or the regenerative layerContains the only cells capable of dividing by mitosisThe epidermis will regenerate itself only so long as the s.
germinativum remains intactHas basal layer called Stratum Basale which rests on the
basement membraneContains melanocytes which produces a pigment called
melanin
Dermis
• Also known as the corium • Lies directly beneath the epidermis• Often referred to as the “true skin”• Composed of dense CT with tough white collagen
fibers and yellow elastin fibers• Blood vessels, nerves, lymph vessels, sweat glands,
hair follicles, sebaceous glands are all embedded in this layer
• Can be divided into two portions
Dermis
• Two portions:Papillary portionReticular Portion
Dermis
• Papillary portionArea adjacent to the epidermis
• Reticular PortionFound between the papillary portion and the fatty
subcutaneous tissue beneath
Hypodermis
• Also called the hypoderm, subcutaneous tissue, or superficial fascia
• Lowermost layer of the integumentary system
• It is in this layer where hypodermic injections are given
• Attaches the reticular layer to the underlying organs
Functions
• Thermoregulation• Protection• Attachment site for sensory receptors/Sensation• Excretion• Storage and synthesis
Functions• Thermoregulation
Normal body temp. is regulated by blood vessel dilation and constriction in the dermis of the skinHigh temperature
Dilate surface blood vessels Sweating
Low temperature Surface vessels constrict shivering
Functions• Protection
Physical AbrasionDehydrationUltraviolet radiationsPrevents passage of harmful chemical agentsBody’s first line of defenseKills most bacteria and microorganisms that make contact
with our skin (acid mantle)Lipid content of the skin inhibits excessive loss of water
and electrolytes through the skinMelanin protects us from harmful uv rays of the sun
Functions
• Attachment site for sensory receptors/SensationMechanoreceptors - responds to mechanical
pressure or distortion.There are 4 main types of mechanoreceptors:
Pacinian corpusclesMeissner's corpusclesMerkel's discsRuffini endings
Functions
• Mechanoreceptors:Pacinian Corpuscle
-or Lamellar corpuscle
-they are nerve endings in the skin, responsible for sensitivity to vibration and deep pressure.
-large encapsulated endings located in the subcutaneous tissue.
-sense transient disturbances at high frequencies.
-rapid adapting
-located at the deep subcutaneous tissue
Functions
• Mechanoreceptors:Meissner’s Corpuscle
-or Tactile Corpuscle
-they are a type of nerve ending in the skin that is responsible for sensitivity to light touch and vibration.
-rapid adapting
-located superficially
Functions
• Mechanoreceptors:Merkel’s disc
-or Merkel nerve endings
-play a major role in the static discrimination of shapes, edges, and rough textures.
-slow adapting
-most sensitive of all the 4 mechanoreceptors
-located superficially
Functions
• Mechanoreceptors:Ruffini ending
-or Bulbous Corpuscle or Ruffini Corpuscle
-respond to sustained pressure
-also a thermoreceptor
-slow adapting
-located in the deep layers of the skin
Functions
• ExcretionWhere salts and urea exits during sweatingExcretes also dead cells
Functions
• Storage and synthesisAids in the absorption of CaVitamin D synthesis through exposure to
ultraviolet lightStores lipids and water
Accessory structure of the skin
• Hair
• Nails
• Sebaceous glands
• Sweat glands
• Ceruminous glands or wax
• Mammary glands
Accessory structure of the skin
• Hairsmain characteristic of all mammalsCovers the entire part of the body except the palms
of the hands and the soles of the feetEpidermal growths that function in protectionShaft, root, and follicleEach individual hair is composed of three parts
Accessory structure of the skin
• Three layers of the hair:CuticleCortexMedulla
Accessory structure of the skin
• CuticleOutermost portionConsists of several layers of overlapping scale-like
cells
Accessory structure of the skin
• CortexPrincipal portion of the hairIts cells are elongated and united to form flattened
fibers
Accessory structure of the skin
• MedullaMiddle or central part of the hairComposed of cells with many sides which
frequently contain air spaces
Accessory structure of the skin
• Parts of the hair:Hair shaftRootHair follicle
Accessory structure of the skin
• Hair shaftVisible portion of the hair
• RootFound in an epidermal tube called the hair follicle
• Hair follicleMade of an outer CT sheathWhere production of hair occursBundles of smooth muscle fibers that make up the
arrector pili muscle
Nails
• Plates of highly packed, keratinized cells
• Protection, scratching, & manipulation
• Formed by cells in nail bed called the matrix
• 1 mm / week
• Has 4 parts
• Fingernails grow faster than toenails
• As we age, the rate of the nail growth, slows
Nails
• Parts:Nail matrixNail rootEponychiumLunulaNail bodyFree edgeNail grooveNail bed
Nails
• Nail MatrixThe tissue which the nail protectsPart of the nail bed that rests beneath the nail and
contains nerves, blood vessels and lymph vesselsResponsible for producing the nail itself
• Nail rootPart of the nail attached to the nail bedIt is the bas of the nail underneath the skin
Nails
• EponychiumOr cuticleIs a stratum corneum that extends out over the
proximal end of the nail body
• LunulaWhite crescent at the proximal end each nailThe size varies from person to person and
sometimes from nail to nail due to genetic factors
Nails
• Nail bodyVisible part of the nail
• Free edgeanterior margin of the nail bodycorresponds to the abrasive or cutting edge of the
nail
Nails
• Nail grooveOr nail foldare the cutaneous slits into which the lateral
margins are embedded.
• Nail bedFrom which the nail growsSkin beneath the nail
Nail groove
Sebaceous Glands
• Usually connected to hair follicles
• Holocrine glands
• Fats, cholesterol, proteins, salts, and cell debris
• Moistens hair and waterproofs skin
Sweat (sudoriferous) glands
Eccrine sweat glands
Merocrine glands
Water, salt, wastes
Function is to cool the body (also nervous)
Apocrine sweat glands
Larger, merocrine glands
Associated with hair follicles
More viscous – fatty acids and proteins
Odor occurs when broken down by bacteria
Ceruminous glands
Modified sudoriferous glands
Secrete cerumen (ear wax)
Mammary glands
Secrete milk
Skin color
• Genetic factorsSame number of melanocytesAlbinism
• Environmental factorsUv light or x-rays
• Physiological factors
Amount of blood
Amount of oxygen
CyanosisCarotene accumulationJaundice – liver disorder
Skin Diseases
• Albinism-also called achromia, achromasia, or achromatosis, is a congenital disorder characterized by the complete or partial absence of pigment in the skin, hair and eyes due to absence or defect of tyrosinase, a copper-containing enzyme involved in the production of melanin
Skin Diseases
• Skin Allergies
Skin Diseases
• Skin Cancer-Skin cancer is a condition caused by exposure to certain light rays from the sun and from tanning beds
-this cancer has been on the rise in the general population for many years and has emerged as the leading type of cancer in men.
Wound healing
• InflammationBlood vessels dilate and become permeable
Heat, redness, swelling and pain
• Shallow cutsEpithelial cells migrateContact inhibition
Deeper wounds
• Inflammatory phaseFibrin forms clot
• Migratory phaseFibroblasts make granulation tissue
• Proliferative phase
• Maturation phase
• Scars – hypertrophic scar keloid
Burns
• First degree or partial thickness burnOnly epidermis is damagedErythema, mild edema, surface layer shedHealing – a few days to two weeksNo scarring
• Second degree- deep partial-layer burnDestroys epidermisBlisters form Healing depends on survival of accessory organsNo scars unless infected
• Third degree or full-thickness burnDestroys epidermis, dermis and accessory organs
of the skinHealing occurs from margins inwardSkin grafting may be needed
AutograftHomograft
• Rule of Nines