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Integumentary System. Integumentary System consists of the Skin and its accessory organs. The skin may not typically be thought of as an organ, but it is made of tissues that work together as a single structure to perform unique and critical functions.
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Integumentary System Integumentary System consists of the Skin and its accessory organs
The skin may not typically be thought of as an organ, but it is made of tissues that work together as a single structure to perform unique and critical functions
Functions of the Integumentary System • Protection • Temperature regulation • Sensations • Storage of chemical compounds • Excretion of wastes • Synthesis of compounds (Vitamin D3)
The skin is made of multiple layers of cells and tissues, which are held tounderlying structures by connective tissue Epidermis Dermis Hypodermis
Epidermis Composed of: Stratified squamous epithelium Contains: the skin pigment Melanin • Lacks blood vessels (avascular)- gets all nutrients from blood supply in dermis
Dermis Thicker than the epidermis Composed of: Nervous Tissue Connective Tissue Muscle Tissue Epithelial Tissue Contains: Blood Vessels Touch receptors Accessory Organs
Dermis Contains Vasculature Provides blood supply/nutrients to all skin cells Plays role in thermo-regulation (vasodialation/constriction)
The dermis contains many different touch receptors. Different types of touch have different receptors.
Basement Membrane Separates the epidermis and dermis
Significance in health: • The basement membrane must be broken down in order for cancer cells to invade surrounding tissue. Image shows cancer cell (green) crossing the basement membrane (red)
Hypodermis Composed of: loose connective tissue adipose tissues Contains: Major blood vessels • Binds the skin to the underlying organs
Burn classification based upon what layer(s) of tissue have been damaged
Epidermis Contains 5 layers! We are only concerned with 2 in this class ALIVE! Stratum Basale – Inner most layerLocation of actively dividing epithelial cells and melanocytes DEAD! Stratum Corneum – Outer most layerDead cells serve as protective barrier
Colored scanning electron micrograph (SEM) of human skin Stratum Corneum Stratum Basale Dermis
Keratinization Cells divide in Stratum Basale and push older cells up to surface. Cells starve and die as pushed away from dermis. Keratinization is the hardening process these cells undergo as they die. Keratin is a type of fibrous structural proteins.
Keratinization Keratinization- the cementing of keratin fibers(cytoskeleton protein) in the dead cells. Constant shedding and replacement grows new EPIdermis every 25-45 days Calluses- Thickening of the Stratum Corneum due to rubbing and pressure
Melanin A dark pigment produced by melanocytes.
Melanocytes are located in the bottom layer of the epidermis
Melanin Absorbs UVradiation which protects the deeper tissues Tanning and dark skin color comes from melanocytes producing more melanin NOT due to more melanocytes
Hair Found on most skin surfaces Exceptions: Palms Soles of feet, Lips Nipples Parts of the genitalia Functions: Prevent heat loss Decrease sun exposure Touch receptors
Hair is a keratinous filament growing out of the epidermis. It is primarily made of dead, keratinized cells.
Hair follicles • Follicles are the hair producing structures. • Extend from the surface into the dermis • Each hair develops from STRATUM BASALE cells in the base of the hair follicle • Cells undergo keratinization and form into hair rather than a layer like skin
Arrectorpili muscle- bundle of smooth muscle attached to each hair follicle -When the muscle contracts, hair within the follicle tends to stand on end -Emotional upset and cold can stimulate the arrectorpili muscles to contract causing goose bumps
DON’T WORRY ABOUT ALL THIS! Just showing that hair is actually pretty complicated…
Nails Protective coverings Composed of keratinized stratified squamous epithelial cells. Arise from the epidermis. Look familiar?
Nails The nail forms at the nail root, which has a matrix of proliferating cells from the stratum basale that enables the nail to grow continuously
Nails As the nail develops, it slides forward over a layer of epithelium called the nail bed to which the nail remains attached
The nail bed is rich in blood vessels, making it appear pink, except at the base, where a thick layer of epithelium over the nail matrix forms a crescent-shaped region called the lunula (the “little moon”).
Sebum: Amixture of fatty material and cellular debris, secreted into the hair follicles Function: Helps keep the hair and skin soft, pliable and relatively waterproof. Sebacous Glands- produce an oil secretion called sebum
Sudoriferous glands(sweat glands) • Sweat is mostly water with small amounts of salt, urea and uric acid • Location: • Nearly all regions of the skin, most numerous in the palms and soles • Located in deeper dermis or superficial subcutaneous layer. • Structure: • Gland consists of tiny tube (duct) that originates as a ball-shaped coil closed at its deepest end • Coiled duct lined with sweat secreting epithelial cells • Duct opens at the surface as a pore
Two Types of SudoriferousGlands: Apocrine Eccrine Sudoriferous glands
Apocrine • Respond to: • Emotional stress (emotionally upset, frightened or experiencing pain) • Location: • Numerous in the armpits and groin • Development: • Glands development stimulated by sex hormones • Begin to function as an individual becomes sexually mature (puberty) • Eccrine • Respond to: • Elevated body temperatures • Location: • Entire body • Development: • Functional from birth
Eccrine- More numerous, Ubiquitious, Used to regulate body temperature. Empty onto skin. Sweat Glands- Eccrine and Apocrine • Apocrine- • Axillary, and pubic areas only. • Develop during puberty • Do not regulate body temp. • Activated by stress and arousal. Empty onto hair follicle.
Diseases, Disorders, and Injuries of the Integumentary System
Acne What causes acne?
Acne Acne • Body can produce an excess amount of sebum and dead skin cells • These build up in the hair follicles and form a plug • This creates an environment where bacteria (that we all have on our face) can thrive. • The openings of the sweat glands aren't normally involved in acne
Acne is a skin disturbance that typically occurs on areas of the skin that are rich in sebaceous glands (face and back). Hormones, stimulate the release of sebum from sebaceous glands.
Albinism Albinism is a complete or partial absence of pigment in the skin, hair and eyes Albinism results from inheriting a defective gene involved in the production of melanin.
Netherton Syndrome Defect in keritinization causes over shedding of cells