CHAPTER 5 The Integumentary System. The parts of the integument: Skin Sweat and Oil glands hairs...
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Transcript of CHAPTER 5 The Integumentary System. The parts of the integument: Skin Sweat and Oil glands hairs...
CHAPTER 5
The Integumentary System
The Integumentary System
The parts of the integument:SkinSweat and Oil glands hairsNails
The Integumentary System: The Skin
The skin is pliable yet tough, allowing it to take constant punishment from external organs.
Facts:Covers 2.2 meters, weighs 4 to 5 kg, and
accounts for about 7% of total body weight in the average.
Thickness varies from 1.5 to 4.0 mm or more in some areas.
Millions of dead cells rub off dailyA totally new epidermis every 25 to 45 daysThe average person sheds 18kg (40lbs) of skin
flakes in a lifetime
The Skin
The Skin: Epidermis
The epidermis is a keratinized stratified squamous epithelium consisting of four distinct cell types or five distinct layers.
Cells of the epidermis:1. Keratinocyte produce keratin2. melanocyte produce melanin3. Langerhans’ cell are
macrophages4. Merkel cells (epidermal
dendritic cells) function as a sensory receptors for touch
Layers of the EpidermisThick skin: covers the
palms, fingertips, and soles of the feet
Five Layers (strata) from deep to superficial
1. stratum basale2. stratum spinosum3. stratum granulosum4. stratum lucidum5. stratum corneum
Thin skin: covers the rest of the body
**stratum lucidum is absent and the other strata are thinner
The Skin:Dermis
The dermis, composed mainly of dense, irregular connective tissue, is well supplied with blood vessels, lymphatic vessels, and nerves.
Cutaneous receptors, glands, and hair follicles reside within the dermis
Layers of the dermis
From superficial to deep:1. papillary layer exhibits
dermal papillae that protrude into the epidermis above and the epidermal ridges that produce fingerprints.
2. reticular layer is thicker and the connective tissue fibers are much more densely interwoven.
Skin Color
Skin color reflects the amount of pigments (melanin and carotene) in the skin and the oxygenation level of hemoglobin in blood
1. Melanin is the only pigment made in the skin.
ranges in color from yellow, redish brown, to black
Stimulated by exposure to ultraviolet radiation in sunlight and protects the nuceli from damaging effects of UV radiation
Homeostatic Imbalance
1. stiae = stretch marks Tears in the dermis
2. blisters = separation of dermis and epidermis
Homeostatic imbalance
Excessive sun exposure can cause clumping of elastin fibers, leading to
leathery skin, temporarily depresses the immune systemAlter the DNA of skin cells which may cause
cancer
Homeostatic Imbalance
1. Cyanosis = poorly oxygenated blood
Homeostatic imbalance
Redness, or erythema = redding of skin
Pallor or blanching
Homeostatic balance
Jaundice or yellow cast =
Homeostatic imbalance
Bronzing =
http://www.aldfoundation.org/materials.html
Homeostatic imbalance
Black-and-blue marks; bruises; hematomas
Appendages of the Skin
Skin appendages, which derive from the epidermis, include:
HairsHair folliclesNailsGlands
Sweat (Sudoriferous) Glands
Found all over the body except the nipples and the external genitalia
More than 2.2 million per person
Sweat glands: Eccrine glands
Merocirne glandsFound over most
of the bodyThermoregulationSweat is 99%
waterSalts, Vit C.,
antibodies, metabolic wastes and lactic acid
Sweat Gland: apocrine
Largely confinded to the axillary and anogenital areas
Larger than eccrine glands and their ducts empty along hair follicles
Start production around puberty
Function is unknownCerunminous glandsMammary glands
Sebaceous (oil) glands
Located all over body except palms of hands
SebumFunctions to softens
and lubricates the hair and skin
Prevents hair from becoming brittle, and slows water loss from the skin
Bacterialcidal action
Homeostatic imbalance
WhiteheadsBlackheadsAcne Seborrhea “cradle
cap”
Hairs and Hair Follicles
Hair: main function is sensory protection