the integumentary system chapter 6. general information about the integumentary system covers...
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General Information About General Information About the Integumentary Systemthe Integumentary System
Covers approx. 2 square Covers approx. 2 square meters (20 sq. ft.)meters (20 sq. ft.)
Accounts for 15% of total Accounts for 15% of total body weightbody weight
Major organ is the skin, but Major organ is the skin, but also includes hair, glands, also includes hair, glands, receptors, and blood vesselsreceptors, and blood vessels
FunctionsFunctionsProtection – physical barrier Protection – physical barrier
against loss of body fluids, physical against loss of body fluids, physical injury, UV light, and pathogensinjury, UV light, and pathogens
Regulates body temperature – Regulates body temperature – sweat, blood circulationsweat, blood circulation
Communication – sensory Communication – sensory receptors relay info. regarding receptors relay info. regarding heat, cold, touch and pain to brainheat, cold, touch and pain to brain
Functions cont’dFunctions cont’d
Excretion of waste – sweat Excretion of waste – sweat glands release small glands release small amounts of ureaamounts of urea
Vitamin D production – Vitamin D production – when exposed to UV light, when exposed to UV light, aids in absorption of calciumaids in absorption of calcium
The SkinThe Skin
Largest organ of integumentary Largest organ of integumentary systemsystem
Thin, superficial layer of Thin, superficial layer of stratified squamous epithelial stratified squamous epithelial tissue called the epidermistissue called the epidermis
Thick, deeper layer of connective Thick, deeper layer of connective tissue called the dermistissue called the dermis
The Skin cont’dThe Skin cont’d
Between skin and muscle Between skin and muscle is the hypodermis, also is the hypodermis, also called the superficial called the superficial fascia or subcutaneous fascia or subcutaneous layerlayer
The EpidermisThe EpidermisDynamic sheet of cells that Dynamic sheet of cells that
forms a waterproof, forms a waterproof, protective wrap over the protective wrap over the body’s surfacebody’s surface
Millions of cells in the Millions of cells in the epidermis are worn away by epidermis are worn away by the activities of everyday lifethe activities of everyday life
Made of stratified squamous Made of stratified squamous epitheliumepithelium
The Epidermis cont’dThe Epidermis cont’d
Deepest layer contains living, Deepest layer contains living, rapidly dividing columnar cells rapidly dividing columnar cells that push older cells toward the that push older cells toward the surfacesurface
Older cells flatten and die as Older cells flatten and die as they near the surface; cell they near the surface; cell contents are replaced by a contents are replaced by a protein called keratinprotein called keratin
Layers of EpidermisLayers of Epidermis
Stratum Stratum corneumcorneum
Stratum lucidumStratum lucidum Stratum Stratum
granulosumgranulosum Stratum Stratum
spinosumspinosum Stratum basaleStratum basale
Stratum BasaleStratum Basale
Deepest layer of epidermisDeepest layer of epidermis Columnar / cuboidal cells form Columnar / cuboidal cells form
bottom layer, closest to vascular bottom layer, closest to vascular dermisdermis
Require nutrients for rapid cell Require nutrients for rapid cell divisiondivision
Push previously formed cells Push previously formed cells toward the surfacetoward the surface
Stratum spinosumStratum spinosum
Multiple-layered Multiple-layered arrangement of cuboidal arrangement of cuboidal cellscells
Contain molecular bridges Contain molecular bridges that connect them to that connect them to adjacent cells, gives them a adjacent cells, gives them a “prickly” appearance“prickly” appearance
Stratum spinosum cont’dStratum spinosum cont’d
Nuclei are often darkened, a Nuclei are often darkened, a condition called pyknosis, condition called pyknosis, which is an early sign of cell which is an early sign of cell deathdeath
Cells begin to die because Cells begin to die because they’re cut off from supply they’re cut off from supply of nutrients and oxygenof nutrients and oxygen
Stratum granulosumStratum granulosum
3 to 5 rows of partially 3 to 5 rows of partially flattened cellsflattened cells
Cells contain granules of Cells contain granules of proteins that stain dark and proteins that stain dark and are intermediate to the are intermediate to the formation of keratinformation of keratin
Stratum lucidumStratum lucidum
Present only in the thick Present only in the thick skin of the palms and solesskin of the palms and soles
3 to 4 rows of flattened, 3 to 4 rows of flattened, dead cells that are mostly dead cells that are mostly transparenttransparent
Stratum corneumStratum corneum
Most superficial layerMost superficial layer20 – 50 rows of flattened, 20 – 50 rows of flattened,
dead cellsdead cellsAre “sloughed off” as a Are “sloughed off” as a
result of normal wear and result of normal wear and teartear
Stratum Corneum cont’dStratum Corneum cont’d
Entire journey from stratum Entire journey from stratum basale to surface takes basale to surface takes between 3 and 4 weeksbetween 3 and 4 weeks
By this time, cells are By this time, cells are nothing but “ghosts” having nothing but “ghosts” having their contents completely their contents completely replaced by keratinreplaced by keratin
Layers of EpidermisLayers of Epidermis
Stratum Stratum corneumcorneum
Stratum lucidumStratum lucidum Stratum Stratum
granulosumgranulosum Stratum Stratum
spinosumspinosum Stratum basaleStratum basale
Skin ColorSkin Color
Melanocytes produce the Melanocytes produce the primary skin pigment, primary skin pigment, melaninmelanin
Located between cells in Located between cells in the stratum basalethe stratum basale
Skin Color cont’dSkin Color cont’d
Melanin is a dark brown Melanin is a dark brown pigment, more melanin result in pigment, more melanin result in darker skin colorsdarker skin colors
Skin color is not determined by Skin color is not determined by number of melanocytes, but by number of melanocytes, but by how much melanin they produce how much melanin they produce (genetic and environmental (genetic and environmental factors)factors)
Skin Color cont’dSkin Color cont’d
Exposing melanocytes to UV Exposing melanocytes to UV radiation results stimulates radiation results stimulates them to produce more melanin, them to produce more melanin, a process called tanninga process called tanning
Melanin has the ability to Melanin has the ability to absorb UV light, protecting absorb UV light, protecting cells’ DNAcells’ DNA
Skin Color cont’dSkin Color cont’d
Skin color can also Skin color can also receive contributions receive contributions from carotene, a from carotene, a yellowish pigment yellowish pigment (most prominent in (most prominent in Asians, but also Asians, but also present in present in caucasians)caucasians)
The DermisThe Dermis
Dense mat of Dense mat of various various connective connective tissuestissues
Rich with Rich with blood vesselsblood vessels
Consistencey Consistencey of a firm wet of a firm wet spongesponge
The DermisThe Dermis
Papillary region Papillary region – contains – contains several papillae several papillae – form friction – form friction ridgesridges
Reticular Reticular region contains region contains accessory accessory organsorgans
Accessory OrgansAccessory Organs
Hair follicles, finger and toe nails, Hair follicles, finger and toe nails, sebaceous glands, and sweat glands sebaceous glands, and sweat glands are all referred to as are all referred to as epidermal epidermal derivatives derivatives because they all grow because they all grow from cells migrating to the dermis from cells migrating to the dermis from the epidermis during from the epidermis during developmentdevelopment
Blood vessels and nerve receptors Blood vessels and nerve receptors grow in from other areasgrow in from other areas
HairHair Protects skin from Protects skin from
injury that may be injury that may be caused by sunlight or caused by sunlight or foreign particlesforeign particles
Grown from a Grown from a downward growth of downward growth of the epidermis into the the epidermis into the dermis called a follicledermis called a follicle
Portion surrounded by Portion surrounded by follicle called the root, follicle called the root, portion above surface portion above surface is the shaftis the shaft
HairHair
Hair follicle and root consist of Hair follicle and root consist of mostly living cells, nourished from a mostly living cells, nourished from a cluster of blood vessels in the base cluster of blood vessels in the base or bulbor bulb
Growth of hair is similar to Growth of hair is similar to replacement of epidermis; cells are replacement of epidermis; cells are pushed to surfacepushed to surface
Hair is made mostly of keratinized Hair is made mostly of keratinized cellscells
HairHair
Hair grows at a rate of 1mm every 3 Hair grows at a rate of 1mm every 3 daysdays
Cutting or shaving it have no effect on Cutting or shaving it have no effect on rate of growthrate of growth
Body regions differ in hair growth rateBody regions differ in hair growth rate Approx. 100 scalp hairs are lost dailyApprox. 100 scalp hairs are lost daily Hair color determined by amt. of Hair color determined by amt. of
melanin present (blonde, brown, or melanin present (blonde, brown, or black); white by decrease in black); white by decrease in production of melanin and air in shaftproduction of melanin and air in shaft
Sebaceous GlandsSebaceous Glands
Also known as oil glands; associated with Also known as oil glands; associated with hair follicles, connected to follicle by a hair follicles, connected to follicle by a ductduct
Produce an oily secretion called sebum Produce an oily secretion called sebum (consists of water, fats, cholesterol, (consists of water, fats, cholesterol, protein, and salt)protein, and salt)
Sebum keeps hair and skin soft and Sebum keeps hair and skin soft and pliable, also increases water-resistancepliable, also increases water-resistance
Production of sebum is accelerated by sex Production of sebum is accelerated by sex hormoneshormones
Sebaceous GlandsSebaceous Glands
May become clogged by excess May become clogged by excess sebum, dead cells, or environmental sebum, dead cells, or environmental debris; forms blackheadsdebris; forms blackheads
If bacteria become established, If bacteria become established, forms a pimple or boilforms a pimple or boil
Sebaceous glands are distributed Sebaceous glands are distributed evenly over entire body except on evenly over entire body except on palms and solespalms and soles
Sweat GlandsSweat Glands
Also known as sudoriferous glandsAlso known as sudoriferous glands Come in two varieties, eccrine and Come in two varieties, eccrine and
apocrineapocrine Eccrine – present entire life, Eccrine – present entire life,
secrete a watery sweat, function secrete a watery sweat, function primarily in coolingprimarily in cooling
Eccrine glands are distributed Eccrine glands are distributed throughout the bodythroughout the body
Apocrine GlandsApocrine Glands
Apocrine – become active during Apocrine – become active during puberty, secrete a thick sweat, highest puberty, secrete a thick sweat, highest concentration located in armpits and concentration located in armpits and groingroin
Proteins in apocrine sweat promote Proteins in apocrine sweat promote growth of bacteria normally found on growth of bacteria normally found on skin; bacteria produce odoriferous skin; bacteria produce odoriferous materialsmaterials
Active primarily in times of emotional Active primarily in times of emotional stressstress
NailsNails Formed from compressed outer Formed from compressed outer
layer of epidermis; mostly layer of epidermis; mostly keratinkeratin
Protect ends of fingers and Protect ends of fingers and toes, function in very fine toes, function in very fine grippinggripping
Visible surface of nail is the Visible surface of nail is the nail bodynail body, covered by flap of , covered by flap of stratum corneumstratum corneum, the , the cuticlecuticle
Deep to cuticle is nail root, Deep to cuticle is nail root, active stratum basale known active stratum basale known as as nail matrixnail matrix
Small, crescent-shaped Small, crescent-shaped portion of matrix is visible, portion of matrix is visible, called the called the lunulalunula
ReceptorsReceptors
Usually consist of the distal ends of Usually consist of the distal ends of nerve cells that are wrapped in nerve cells that are wrapped in connective tissueconnective tissue
Carry impulses toward the brain, Carry impulses toward the brain, millions found in the skinmillions found in the skin
Interpreted by the brain as heat, Interpreted by the brain as heat, pressure, fine touch, and painpressure, fine touch, and pain
Give important information necessary Give important information necessary for maintaining homeostasisfor maintaining homeostasis
HypodermisHypodermis
Connects skin to muscles beneathConnects skin to muscles beneath Contains loose connective tissue, Contains loose connective tissue,
adipose tissue, and dense connective adipose tissue, and dense connective tissuetissue
Insulates deep tissues from extremes Insulates deep tissues from extremes of heat and cold, also provides shock of heat and cold, also provides shock absorbing cushion and energy absorbing cushion and energy storagestorage
Temperature RegulationTemperature Regulation
Blood vessels in the dermis dilate Blood vessels in the dermis dilate (enlarge) or constrict (shrink) to (enlarge) or constrict (shrink) to release more or less heat to the release more or less heat to the environmentenvironment
Evaporation of sweat is an important Evaporation of sweat is an important factor in coolingfactor in cooling
Goosebumps and shivering warm up Goosebumps and shivering warm up the bodythe body