Lesson 7- The Integument- Cutaneous Membraneo Outer epidermis: superficial epitheliumo Inner dermis: connective tissues- Accessory Structures: dermiso Hairo Nailso Multicellular exocrine glands- Hypodermis: not part of the integument o Loose connective tissue separates integument from deep fascia around other organs- 5 main functions of the skino Protection of underlying tissues and organso Excretion of salts, water and organic wasteso Maintenance of body temperatureo Production of melanin, keratin, vitamin D3, and storage of lipidso Detection of touch, pressure, pain and temperature- Epidermiso Composed of stratified squamous epithelium o Keratinocytes-types of epithelial cells that contain large amounts of keratin protein- Layers of Epidermiso Stratum corneum The horn layer, exposed surface of skin. Exposed skin surfaces have cornification (formations of protective superficial layers of cells filled with keratin) Cells are dead; stratum corneum is water resistant but not waterproof Takes 7-10 days for cell to move from basale to corneumo Stratum lucidum Clear layer, only in thick skin Cells are flattened, densely packed with keratin, devoid of organelles o Stratum granulosum The grainy layer Stops dividing, starts producing keratin and keratohyalin o Stratum spinosum Spiny layer Produced by division of stratum basale Cells shrink until cytoskeletons stick out, continue to divide increasing thickness of epithelium o Stratum basale Attached to basement membrane by hemidesmosomes Forms epidermal ridges Basal cells/germinative cells Ridge patterns on skin increases surface area and friction, ensuring a secure grip- Caroteneo Skin pigment found in orange vegetableso Too much can turn skin orange- carotenosiso Can be converted to Vitamin A, lack of this causes blindness- nyctalopia- Melanino Yellow-brown pigmento Produced by melanocytes in stratum basale (amino acid tyrosine)o Stored in transport vesicles—melanosomes- Melanocyteso Melanin protects skin from sun damageo UV radiation Causes DNA mutations Melanosomes of keratinocytes concentrate around nucleus to protect DNA- Illness that Affect Skin Coloro Jaundice Yellow color Buildup of bile produced by livero Pituitary tumor Excess MSH (melanocyte-stimulating hormone) Extremely bronze tan o Addison’s disease Disease of the pituitary gland- releases ACTH (adrenocorticotropic hormone), similar on skin color as MSH Skin darkening o Vitiligo Loss of melanocytes- autoimmune reaction by antibodies Loss of color- Vitamin D3 Productiono Epidermal cells produce D3 in presence of UV radiationo Liver and kidneys convert D3 to calcitrolo Insufficient D3 can cause rickets- The Papillary Layer of the Dermis (superficial)o Areolar tissueo Contains smaller capillaries, lymphatics, and sensory neurons - The Reticular Layer of the Dermiso Dense irregular connective tissueo Larger blood vessels, lymphatic vessels and nerve fiberso Collagen and elastic fibers- Dermatitiso Inflammation of papillary layero Characterized by itch or pain, can spread across entire integument - Fibers Found in the Dermiso Collagen fibers Strong, resist stretching but bend easilyo Elastic fibers Permit stretching then recoil to original length, provide flexibilityo Skin turgor: water content in the skin Provides flexibility and resilience Dehydrated skin loss of turgor - Cleavage Lineso Tension lineso Collagen and elastic fibers in the dermis Parallel Resist force in specific direction Surgeons chose incisions parallel to cleavage lines- reduce swelling - Parallel cut heals well, perpendicular cut pulls open and scars- Skin Damage at the Dermiso Sagging/Wrinkles caused by Age Dehydration Hormonal changes UV exposure Wrinkles can be treated with Retin A to stimulate skin repair o Stretch marks Thickened skin resulting from excessive stretching of skin (damages dermis)- Hypodermis o Stabilizes the skino Allows separate movemento Made of elastic areolar and adipose tissues, distribution determined by hormones, removed by liposuction o Few capillaries and no vital organs (superficial region contains large arteries/veins-blood reservoir)o Distribution determined by sex hormoneso Subcutaneous injections using hypodermic needles - The Hair Follicleo Located in the dermis, produce nonliving hairo Base is surrounded by sensory nerves-root hair plexuso Accessory structures Arrector pili- involuntary smooth muscle causes hair to stand up- Goose bumps Sebaceous glands- lubricate hair, control bacteria growth- Regions of Hairo Hair root: lower part of the hair Attached to integumento Hair shaft: upper part of the hairo As hair is pushed towards the surface, the epithelial cells are keratinized and die when they become part of the hair shaft - Types of Hairo Vellus hair- “peach fuzz” Soft, fine Cover most of body surfaceo Terminal hairs Heavy, pigmented Head, eyebrows and eyelashes Vellus hairs replaced by terminal hairs on limbs, armpits, pubic area - Sebaceous glands and Sweat glandso Sebaceous Holocrine glands Secrete sebumo Two types of sweat glands Apocrine glands Merocrine (eccrine) glands- Sebaceous (Oil) Glandso Simple branched alveolar glands Hair follicleso Sebaceous follicles Discharge directly onto skin surface Found on face, back, chest, nipples, external genitalia Sebum- Lubricates and protects the epidermis- Inhibits bacteria - Apocrine Sweat Glandso Armpits, around nipples, groino At puberty, secrete products into hair follicles o Not for thermoregulation- produce sticky, cloudy secretionso Break down and cause odors (caused by bacteria)o Apocrine sweat glands actually release their contents by merocrine secretion - Merocrine (Eccrine) Sweat Glandso Widely distributed, especially on palms and sideso Water, salts, and organic compounds o Functions Cools skin Excretes water and electrolytes Flushes microorganisms and harmful chemicals from skin- Control of Glandso Autonomic Nervous System (ANS)—subconscious control Controls sebaceous and apocrine sweat glands Works simultaneously over entire body (not possible for regional control)o Merocrine sweat glands Controlled independently Occurs locally o Thermoregulation Main function of sensible perspiration Works with cardiovascular system Regulates body temperature - Nailso Metabolic disorders (ex. Respiratory disorders,
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