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BIOL 2085 Chapter 5
Terms in this set (69)
Outer most protective shield of the body. Consists of keratinized stratified squamous epithelium.
Produce fibrous protein keratin. These cells make up the most of the epidermis. They are tightly connected by desmosomes. Arise form the deepest part of the epidermis (stratum basale)
Epidermal growth factor
Prompts mitosis which results in new cells pushing older cells towards the surface. These old cells are dead by the time they reach the skin surface.
Spider shaped cells that make up 10-25% of the cells in the deepest epidermis. They produce pigment melanin. They are found in the deepest layer of the epidermis.
Dendritic cells (lagerhans)
Arise from bone marrow, Ingest foreign substances, and are the activators of the immune system.
Tactile (merkel) cells
Present at epidermal-dermal interface. Sensory touch receptors (each cell associated with sensory nerve endings)
Most superficial layer; 20-30 layers of dead cells, essentially flat membranous sacs filled with keratin. Glycolipids in extracellular matrix.
Typically five layers of flattened cells, organelles deteriorating; cytoplasm full of lamellar granules (release lipids) and keratohyaline granules.
Stratum Spinosum (prickly layer)
Several layers of keratinocytes unified by desmosomes. Cells contain thick bundles of intermediate filaments made of pre-keratin.
Deepest epidermal layer; one row of actively mitotic stem cells; some newly formed cells become part of the more superficial layers. See occasional melanocytes and dendritic cells.
Stratum Lucidum (clear layer)
Only in thick skin; thin, translucent band superficial to the stratum granulosum; a few rows of flat, dead keratinocytes.
Controlled cellular suicide; nucleus and organelles break down; plasma membrane thickens, allows cells to slough off as dandruff and dander.
Dermis (Papillary Layer)
Areolar connective tissue with collagen and elastic fibers and blood vessels; Consists of loose tissue ( phagocytes can patrol for microorganisms); Dermal papillae (superficial peglike projections.
Most contain capillary loops, some contain Meissner's corpuscles, some contain free nerve endings, In thick skin lie atop dermal ridges that cause epidermal ridges.
Enhance gripping ability, contribute to sense touch, pattern is fingerprint.
80% of dermal thickness, Dense fibrous connective tissue, Elastic fibers provide stretch-recoil properties, collagen fibers (provide strength and resiliency)
Dermal folds at or near joints, Dermis tightly secured to deeper structures, Skin cannot slide easily for joint movement, Visible on hands, wrists, fingers, soles, toes.
Silvery- white scars referred to as "stretch marks", Extreme stretching causes dermal tears.
From acute, short-term trauma, fluid-filled pocket that separates epidermal and dermal layers
Two forms (reddish-yellow to brownish-black). Color differences due to amount and form, produced in melanocytes, Migrates to keratinocytes to form "pigment shields" for nuclei.
Yellow to orange pigment (most obvious in palms and soles), Accumulates in stratum corneum and hypodermis, can be converted to to vitamin A for vision and epidermal health.
Blue skin color- low oxygenation of hemoglobin.
Fever, hypertension, inflammation, allergy, embarrassment
Anemia, low blood pressure, fear, anger
Inadequate steroid hormones in Addison's disease
Clotted blood beneath skin (hematomas)
Are called pili and consist of largely dead keratinized cells.
Large cells, air space, contains soft keratin, and is missing in fine hairs.
Several layers of flattened cells
Single layer of cells like shingles on a roof, prevent hair from "matting" and are the most keratinized portion of hair.
Extend from epidermal surface to dermis; two-layered wall- part dermis, part epidermis.
Expanded deep end; hair follicle receptors (root hair plexus), wraps around hair bulb, sensory nerve endings- touch receptors.
smooth muscle attached to follicle; responsible for goose bumps.
Dermal tissue- blood supply
Pale fine body hair of children and adult females.
Coarse long hair of eyebrows, scalp (at puberty appears in axillary and pubic regions of both sexes) appears on the face and neck of males as a result of androgens.
Scalelike modifications of epidermis; act as protective cover for distal, dorsal surface of finger and toes, contain hard keratin, nail matrix is where growth occurs.
Eccrine sweat glands
Most numerous; abundant on palms, soles, and forehead; ducts connect to pores; function in thermoregulation (regulated by the sympathetic nervous system); their secretion is sweat (99% water, salts vitamin c, antibodies, dermcidin (micro-killing peptide), metabolic waste.
Apocrine Sweat Glands
Confined to axillary and anogenital areas; secretions consist of sweat+fatty substances+proteins; Larger than eccrine sweat glands; ducts empty into hair follicles; begin functioning at puberty.
Lining of external ear canal; secretes cerumen (earwax)
Sebaceous (oil) glands
Widely distributed; most developed from hair follicles and secrete into hair follicles; relatively inactive until puberty; secrete sebum (oily holocrine secretion, bactericidal, softens hair and skin)
Function of the Integumentary System
Protection, body temperature regulation, cutaneous sensation, metabolic functions, blood reservoir, and excretion.
Chemical Barrier (integumentary system) Skin Secretion
Low pH (acid mantle) retards bacterial multiplication; dermicidin in sweat and bactericidal substances in sebum killing bacteria; Skin cells secrete defensins that also kill bacteria.
Chemical Barrier (integumentary system) Melanin
Defense against UV radiation damage
Physical Barriers (integumentary system)
Flat, dead cells of stratum corneum (bricks) surrounded by lipid (mortar); Keratin and glycolipids block most water and water-soluble substances (in and out)
Biological Barriers (integumentary system)
Dendritic cells of the epidermis (present foreign antigens to white blood cells) ; macrophages of dermis (Second line of defense, present foreign antigens to white blood cells); DNA (absorbs UV radiation, converts the radiation to hear)
If body temperature rises, dilation of dermal vessels and increased sweat gland activity cools the body.
Perspiration that occurs if the environmental temperature remains below 86 degrees Fahrenheit
Cutaneous sensory receptors- part of nervous system- detect temperatures, touch, and pain.
Allow us to feel clothing against skin
Alert us to bumps or contacts with pressure
Hair follicle receptors
wind blowing through hair
Free nerve endings
help us sense pain
Metabolic functions (integumentary system)
Synthesis of vitamin D precursor (transported by blood) and collagenase (aids in turnover of collagen); chemical conversions of carcinogens and activate some hormones.
Blood reservoirs (integumentary system)
Contains up to 5% of body's blood volume ( dermal blood vessels constrict to cause blood to by-pass skin allowing more blood for other organs)
Excretion (integumentary system)
Nitrogenous wastes and salt in sweat
Risk factors for skin cancer
Overexposure to UV radiation-damages DNA and disables p53; frequent irritation of skin
Basal Cell Carcinoma
Least malignant; most common cancer in skin. Stratum basale cells proliferate and slowly invade dermis and hypodermis. Cured by surgical excision in 99% of cases.
Squamous Cell Carcinoma
Second most common type of skin cancer. Involves keratinocytes of stratum spinosum. Usually scaly reddened papule on scapl, ears, lower lip, and hands. Does metastasize. Good prognosis if treated by radiation therapy or removed surgically.
Cancer of melanocytes; most dangerous; treated by wide surgical excision accompanied by immunotherapy
A: asymmetry; the two sides of the pigmented area do not match.
B: border irregularity; exhibits indentation.
C: color; contains several (black, brown, tan, sometimes red or blue)
D: diameter; larger than 6mm (size of a pencil eraser.
Tissue damage caused by heat, electricity, radiation, certain chemicals (denatures proteins and kills cells)
Burns (Immediate threat)
Catastrophic loss of fluids; dehydration and electrolyte imbalance (leads to renal shutdown and circulatory shock)
Burns (long term threat)
Infection becomes main threat following dehydration; sepsis is the leading cause of death in burn victims.
First degree burn
Epidermal damage only; localized redness, edema (swelling), and pain. Healing in 2 to 3 days.
Second degree burns
Epidermal and upper dermal damage, blisters appear. Heals in three to four weeks.
Third degree burns
Entire thickness of skin involved; skin gray-white, cherry red, or blackened. Not painful (nerve ending destroyed) or swollen. skin grafting usually necessary.
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