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Chapter 5 Integumentary System (5-10 Effects of aging include dermal…
Chapter 5 Integumentary System
Intro Integumentary
Cutaneous membrane
(skin) organ composed of the superficial epithelium or epidermis
5-1 Epidermis
Stratum Corneum
15-30 layers of flattened and dead epithelial cells that has large amounts of keratin
Keratinized/cornified. Usually shed in large groups
Intermediate Stratum
Stratum Spinosum
Each time cell divides it goes to this, may continue to add/ continue thickness of epithelium
Stratum Granulosum
Consits of cells displayed from stratum spinosum
Keratin
Stratum Lucidum
In the thick skin they are flattened, densely packed and filled with keratin
Stratum Germinativum
Accessory Structures
Includes hair, nails and a variety of exocrine glands
Five Major functions
1, Protection
Skins protects everything underneath and prevents loss of fluids
Temp. Maintenance
Skin maintains normal temp by regulating heat exchange with envirenment
Synthesis and storage of nutrients
Epidermis synthesizes vitamin D, for building block for a hormone that aids calcium
Sensory Reception
Receptors detect touch, pressure, pain and temp. stimuli and relay info to nervous system
Excretion and secretion
excrete salts, water, and organic wastes like breast milk
5-2 Skin Color
Role of pigmentation
Carotene- orange/yellow pigment in epidermis
Melanin- Brown, yellow or black from melanocytes
Melanocytes-Manufacture and store melanin within intracellular vesicles (freckles is an example)
Ultraviolet radiation simulates vitamin D
Role of dermal circulation
Blood with abdundant oxygen is bright red so blood vessels give off red tint usually in light pigmented people.
Cyanosis- Skin takes bluish coloration
Usually shows in thin parts of skin like lips, ears and beneath nails
Response to cold or circulatory/respiratory disorders like heart failure or severe asthma.
5-3 Sunlight has detrimental and beneficial effects on the skin
The epidermis and vitamin D
absorbed modified and released by the liver and converted by the kidneys into calcitriol a hormone for absorbtion of calcium and phosphorus by the small intesine
If inadequate supply, then it can lead to abnormally weak and flexible bones.
Skin Cancers
Most common form of cancer.
Basal Cell Carcinoma
Most common form of skin cancer, which originates in stratum germinativum layer
Squamous cell carcinomas
Less common, Involves more superficial layers of epidermal cells.
Malignant Melanomas
Extremly Dangerous, From a mole
5-4 The dermis is the tissue layer that supports the epidermis
Papillary Layer
Consists of loose connective tissue that supports and nourishes epidermis
Contains capillaries and nerves supplying the surface of the skin
Reticular Layer
Consists of the an interwoven meshwork of dense irregular connective tissue
Elastic fibers provide flexibility and the collagen fibers limit tht flexibility to prevent damage to the tissue
Blood vessels provide nutrients and oxygen and remove carbon dioxide and waste products.
Both blood vessels and lymphatic vessels help local tissues defend and repair themselves after injury or infection
Nerve fibers control blood flow, adjust gland secretion rates and moniter sensory receptors in the dermis and the deeper leyers of the epidermis- will provide sensations of touch, pain, pressure and temp.
5-5 The Hypodermis is tissue that connects the dermis to underlying tissues
Hypodermis
Connective tissue fibers attaches the dermis to subcutaneous or..
Consists of loose connective tissue with many fat cells
These adipose cells provide "baby fat" which reduces heat loss
Subcutaneous fat also serves as an energy reserve and a shock absorber for the rough-and-tumble activites
Quite elastic, below superficial region, contains no vital organs and few capillaries- lacks vital organs
5-6 Hair is composed of keratinized dead cells that have been pushed to the surface.
The structure of hair and hair follicles
The epithelium at the base of a follicle forms a cap over the hair papilla, a peg of connective tissue containing capillaries and nerves.
Hair are nonliving structures produced in organs called hair follicles
Hair root (portion that anchors the hair into the skin) the point at which this occurs is about halfway to the skin surface and hair root and shaft
Each hair shaft consists of 3 layers of dead keratinized cells
cuticle is made up of overlapping shingle like layer of cells
Cortex which is the underlying leyer
Medulla makes up the core of the hair, contains flexible soft keratin: the cortex and the cuticle contains thick layers of hard keratin which gives the hair stiffness
A hair in the scalp grows from 2-5 years at a rate of 0.3 mm per day
Functions of Hair
500,000 hairs o the head protect the scalp from UV light, help cushion a light blow to the head and provide insulation
Hairs in nostrils and external ear canals help prevent entry of foreign particles, eyelashes preform similar for eye
Sensory neve is associated with base of each hair follicle, you can move shalf of even a single hair
Arrector Pili, bundle of smooth muscle cells form this muscle which extends from the papillary dermis to the connective tissue sheath that surrounds each hair follicle.
Hair Color
Hair color produced by melanocytes at the hair papilla, different forms of melanin produce hair colors that range from black to red.
5-7 Sebaceous glands and sweat glands are exocrine glands are exocrine glands found in the skin.
Sebaceous (oil) glands
Sebaceous glands are holocrine glands that discharge oily lipid secretion into hair follicles or into the skin
Contraction of the arrector pili muscle that elevates the hair squeezes the sebaceous fland forcing the oily secretions into hair follicle and onto surrounding skin
These secretions are called Sebum that lubricates the hair and skin and inhibits the growth of bacteria
Sebaceous follicles are large sebaceous glands that discharge sebum directly onto the skin. Located on face, back, chest, nipples ad external genitalia
Sebaceous glands are sensitive to changes in the concentrations of sex hormones.
Acne develops to individuals with large sebaceous glands during adolescence, Sebaceous ducts become blocked and secretions acumalate cause inflammation and a pimple
Sweat Glands
Apocrine Sweat Glands
Sweat glands that secrete their products into hair follicles in the armpits, around the nipples and the grion
At puberty these glands begin discharging a sticky,cloudy and potentially odorous when bacteria break it down as a food source
Merocrine Sweat Glands
Coiled tubular glands that discharge their secretions directly onto the surface of the skin are
More numerous and widely distributed than apocrine glands palms and soles have the highest numbers
To cool the surface of the skin and lower body temp.
5-8 Nails are Keratinized epidermal cells that protect the tips of fingers and toes
Nails form on dorsal surfaces of fingers and toes where they protect the exposed tips and help limit their distortion when subjected to stress like running or grasping objects
Nail body consists of dense mass of dead Keratinized cells nail body is underneath surrounding epithelium
Body of the nail covers an area of epidermis called nail bed, nail production occurs at nail root and epithelial fold not visible from the surface
A portion of stratum corneum of the fold extends over the exposed nail nearest the root forming the cuticle
Underlying blood vessels gives the nail the pik color but near root leaving a pale cresent moon is the luna
5-9 Several steps are involved in repairing the integument following an injury
Repair of skin injuries
When damage extends throught the epidermis and into the dermis, bleeding occurs.
The blood clot or scab that forms at the surface temporarily restores the integrity of the epidermis and restricts the entry of additional microorganisma
If wound covers extensive area or involves a region covered by thin skin dermal repairs must be under way before eithelial cells can cover the surface.
The combination of blood clot, fibroblasts and an extensive capillary network is called ganulaion tissue
The formation of this rather inflexible fibrous noncellular scar tissue can be considered a practical limit to the healing process
The thickened area of scar tissue is called a keloid, is covered by shiny smooth epidermal surface. most commonly develop on upper back shoulders anterior chest and earlobes
Effects of Burns
The larger the area affected the greater the impact on integumentary function
5-10 Effects of aging include dermal thinning, wrinkling and reduced melanocyte activity
Skin injuries and infections become more common
The sensitivity of the immune system is reduced
Muscles become weaker and bone strength decreases
Sensitivity to sun exposure increases
Skin becomes more dry and often scaly
Hair thins and changes color
Sagging and wrinkling of the skin occur
The ability to lose heat decreases
Skin repairs proceed relatively slowly
5-11 The integumentary system provides protection for all other body systems
Provides protection from dehydration environmental chemicals and impacts
Seperated and insulated from rest of body by subcutaneous layer but is interconnected with rest of body by extensive circulatory network of blood and lymphatic vessels