The Integumentary System Chapter 4
The Integumentary System
Chapter 4
Integumentary System
Structure EpidermisDermisSubcutaneous
Functions of the skin
The “Birthday Suit”Combination of 4 main
tissuesEpithelial – outer layerConnective – underlies & connects dermisSmooth Muscle – erect hairNervous – sensory receptors
Structure allows it to carry out many functionsProtection, hydration, sensation, color, temperature regulation, etc.
Very durable
Functions of the Skin
ProtectionTemperature regulation
SensationsStorage of chemical compounds
Excretion of wastes
Synthesis of compounds
Determines characteristics
Structure of the Skin2
principal partsEpidermisDermis
Beneath the DermisSubcutaneous
EpidermisStratified squamous epithelium
Approximately every month we shed entire skin surface
Consists of keratinocytes
Layers of the Epidermis (bottom to top)
Stratum Germinativum Cuboidal cells Mitosis occurs
Stratum Spinosum Germinal cells shrink
Cells look spiny
Stratum Granulosum Produces keratohyaline & keratin
Cells die
Stratum Lucidum Found only in thick skinned or calyces areas (hands, feet, elbows, knees)
“Clear layer” Filled with keratin
Stratum Corneum Multiple dead layers
“Cornified” Waterproof
Layers of the Epidermis
Variations in Skin Color
Pigments Melanin
Produced by melanocytesProtects skin from UV rays
CaroteneRed pigment of “gingers”
Lack of pigment
Albino
Dermal blood supply “Blushing”
Epidermis & Dermis
Epidermis is avascular (contains no vessels)
Dermis is highly vascular (contains blood vessels)
Epidermis receives nourishment from dermis
Cells furthest away from nourishment die
Dermal Layer2 layers
Papillary layer Reticular layer
Connective tissue
Loose Fibrous (collagen firm & elastic)
Adipose
Contains Blood vessels Nerves Glands Hair follicles
Papillary LayerMost superficial layer
Loose connective tissue
Surface area increased by papillae Form fingerprints for grip
Reticular LayerDeeper layerDense, irregular connective tissue (collagen)
Contains Blood vessels Glands Deep pressure receptors
Subcutaneous LayerLoose connective
tissuePacked with adipocytes (fat cells)
Stabilizes position of skin, shock absorber, energy storage/source
Epidermal Appendages
HairGlandsNails
Hair (Pili)Came with mammalsEmbryological development & distribution
Life span of hairWhat does hair do for mammals?
Functions of Hair
ProtectionThermoregulationSensoryMinor? role in humans
beauty
Hair Structure
ShaftSuperficial
RootBelow surface
Hair StructureMedulla
Soft core
CortexHard core
Gives hair stiffness
CuticleOutermost layer
Hair Develops in Follicles
Location Deep in dermis
Structure External root sheath
Internal root sheath
BulbContains matrix
Hair papillaContains blood vessels and nerves
http://www.tgfolk.net/sites/gtg/tfb-elect.html
Arrector PiliSmooth muscle attaches to follicle
Raises hairsEmotional response, cold
Function- traps air
GlandsSebaceous glands
Connected to hair folliclesSecrete a waxy, oily substance (sebum)
Develop in utero at about 5 months
Secretion increases at puberty
GlandsSweat glandsEccrine glandsFound just about everywhere (esp. palms & soles)
Produce “perspiration”Water, salt, met. wastes
http://www.pg.com/science/skincare/Skin_tws_35.htm
GlandsSweat glands (scent glands)Called Apocrine sweat glands
Specific type of sweat gland
Found near hair folliclesAxillary & genital regions
Develop at puberty
http://www.pg.com/science/skincare/Skin_tws_35.htm
The Skin with Sweat Glands
NailsDorsal surfaces of ends of fingers & toes
Primate featureGrasping
Nail Structure
Nail bodyFree edgeNail root
Matrix
Lunula (moon)
Skin Cancer- MelanomaSquamous Cell
Carcinoma
Basal Cell Carcinoma
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