Please enable JavaScript.
Coggle requires JavaScript to display documents.
The Integumentary System (Chapter 5) (Effects of Aging Include Dermal…
The Integumentary System (Chapter 5)
The Epidermis is composed of strata (layers) with various functions
(5-1)
Thick skin
found on the palms of hands and the soles of feet, contains 5 layers.
only four layers make up
thin skin
, which covers the rest of the body.
Stratum Germinativum
The deepest layer
Intermediate Strata
Each time a stem cell divides, one of the resulting daughter cells enters the next layer, the
stratum spinosum
where it may continue to divide and add to the thickness of the epithelium. The
stratum granulosom
consists of cells displaced from the stratum spinosom. In the thick lskin of the palms and soles, a glassy
stratum lucidum
covers the stratum granulosom.
Stratum Corneum
the most superficial layer of the epidermis. consists of 15-30 layers of flattened and dead epithelial cells that have accumulated large amounts of keratin.
Factors influencing skin color are epidermal pigmentation and dermal circulation
(5-2)
The Role of Pigmentation
Carotene
is an orange yellow pigment that normally accumulates in epidermal cells.
Melanin
is a brown, yellow-brown, or black pigment produced by melanocytes.
Melanocytes
manufacture and store melanin within intracellular vesicles.
Ultraviolet Radiation
comes from the sun, a small amount is beneficial because it stimulates the synthesis of vitamin D in the epidermis, too much produces immediate effects of mild or even serious burns. Melanin helps prevent skin damage by absorbing the radiation before it reaches the deep layers if the epidermis and dermis.
The Role of Dermal Circulation
Cyanosis
a bluish coloration
blood with abundant oxygen is bright red, so blood vessels in the dermis normally give the skin a reddish tint that is most apparent in lightly pigmented individuals. If those vessels are dilated the red tones become much more pronounced.
Sunlight Has Detrimental and Beneficial effects on the skin
(5-3)
The Epidermis and Vitamin D3
When exposed to UV rays, epidermal cells in the stratum spinosum and stratum germinativum convert a cholesterol-related steroid into vitamin D3.
Skin Cancers
the most common skin cancer is basal cell carcinoma, which originates in the stratum germinativum layer. Less common are squamous cell carcinoma. Compared with these common and seldem life threatening cancers, malignant melanomas are extremely dangerous.
The dermis is the tissue layer that supports the epidermis
(5-4)
the
papillary layer
, named after the dermal papillae, consists of loose connective tissue that supports and nourishes the epidermis. This region contains the capillaries and nerves supplying the surface of the skin, The deeper
reticular layer
consists if an interwoven meshwork of dense, irregular connective tissue. Both elastic fibers and collagen fibers are present. The elastic fibers provide flexibility, and the collagen fibers also extend into the subcutaneous layer below.
Blood Vessels
provide nutrients and oxygen and remove carbon dioxide and waste products. Both the blood vessels and the lymphatic vessels help local tissues defend and repair themselves after injury or infection. The nerve fibers control blood flow, adjust gland secretion rates, and monitor sensory receptors in the dermis and the deeper layers of the the epidermis.
The hypodermis is tissue that connects the derims to underling tissues
(5-5)
An extensive network of connective tissue fibers attaches the dermis to the subcutaneous layer, or hypodermis. the boundary between the two is indistinct, and although the hypodermis is not actually a part of the integument, it is important in stabilizing the position of the skin relative to underlying tissues such as skeletal muscles or other organs wile permitting independent movement.
Hair is composed of keratinized dead cells that have been pushed to the surface.
(5-6)
Hairs project above the surface of the skin almost everywhere except the ides and soles of the feet, the palms of the hands, the sides of the fingers and toes, the lips, and portions of the external genital organs. Hairs are nonliving structures produced in organs called hair follicles
The Structure of Hair and air Follicles
The epitheliu at the base of a follicle forms a cap over the
hair papilla
, a peg of connective tissue containing capillaries and nerves.
Sebaceous Glands and Sweat glands are Exocrine Glands found in the Skin
(5-7)
Sebaceous glands
(oil glands) are holocrine glands that discharge an oily lipid secretion into hair follicles or, in some cases, onto the skin. This secretion is called sebum.
Merocrine Sweat Glands*
are coiled tubular glands that discharge their secretions directly onto the surface of the skin.
Sweat glands
provide protection from environmental hazard and cools down the body.
*
Apocrine Sweat Glands
secrete their products into hair follicles in the armpits, around the nipples, and i the groin.
Nails are Keratinized Epidermal Cells That Protect The Tips of Fingers and Toes
(5-8)
Nails
form on the dorsal surfaces of the fingers and toes, where they protect exposed tips and help limit their distortion when they are subjected to mechanical stress.
The
Nail body
consists of a dense mass of dead, keratinized cells.
Nail bed
the bod of the nail covers an area of epidermis
Nail root
an epithelial fold not visible from the surface.
Cuticle
extends over the exposed nail nearest the root
Lunula
a pale crescent
Several Steps are Involved in Repairing the Integument Following an Injury
(5-9)
the integumentary system can respond directly and independently to many local influences or stimuli.
Repair of Skin Injuries
the skin can regenerate effectively even after considerable damage because stem cells are present in both its epithelial and connective tissue components.
The blood cot, or
scab
, that forms at the surface temporarily stores the integrity of the epidermis and restricts the entry of additional microoranisms. Cells of the stratum germinativum rapidly divide and begin to migrate along the sides of the wound to replace the missing epidermal cells. Meanwhile, macrophage and newly arriving phagocytes patrol the damaged area if the dermis and clear away debris and pathogens.
If a wound covers an extensive area or involves a region covered by thin skin, dermal repairs must be under way before epithelial cells can cover the surface.
Effects of Burns
Burns are relatively common injuries that result from exposure of the skin to heat, radiation, electrical shock, or strong chemical agents. The severity of the burn depends on the depth of penetration and the total area affected. The most common classification of burns is based on the depth of penetration. 'the larger the area affected, the greater the impact on the integumentary function.
Effects of Aging Include Dermal Thining, Wrinkling, and Reduced Melanocyte Activity
(5-10)
Skin Injuries and Infections More Common
Such problems are more likely because the epidermis thins as stem cell activity declines.
The Sensitivity of the Immune system is reduced
The number of macrophages and other immune stem cells residing in the skin decreases to around 50 percent of levels seen at maturity. This loss further encourages skin damage and infection
Muscles Become Weaker, and Bone Strength Decreases
Such changes are related to reduced calcium and phosphate absorption due to a decline in vitamin D3 production of around 75 percent
Sensitivity to Sun Exposure Increases
Lesser amounts of melanin are produced because melanocyte activity declines. The skin of light skinned individuals becomes very pale
The Skin Becomes Dry and Often Scaly
Glandular activity declines, reducing sebum production and perspiration.
Hair Thins and Changes Color
Follicles stop functioning or produce thinner, finer hairs. With decreased melanocyte activity, these airs are gray or white.
Sagging and Wrinkling of The skin Occur
The dermis becomes thinner, and the elastic fiber network decreases in size. The integument, therefore, becomes weaker and less resilient. These effects are most pronounced in areas exposed to the sun
The Ability to lose heat Decreases
The blood supply to the dermis is reduced at the same time that sweat glands become less active. This combination makes the elderly less able than younger people to lose body heat. As a result, overexertion or overexposure to high temperatures can cause dangerously high body temperatures
Skin Repairs Proceed Relatively Slowly
it takes 3-4 weeks to complete repairs to an uninfected blister site in a young adult, The same repairs could take 6-8 weeks at ages 65-75. Because repairs are sow, recurrent infections may occur