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139 Cards in this Set
- Front
- Back
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What is the function of skin
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it is the first line of defense against the environment --> its general function is protection
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organization of the integumentary system
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1)Epidermis
2)Dermis |
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thick skin is composed of these layers
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1)Stratum basale
2)Stratum spinosum 3)Stratum granulosum 4)Stratum lucidum 5)Stratum corneum |
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thick skin is found:
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in areas of high physical stress- the palms of hands and soles of feet
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thin skin is composed of these layers
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1)Stratum basale
2)Stratum spinosum 3)Stratum granulosum 4)Stratum corneum |
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deepest epidermal layer
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stratum basale
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what cells make up the stratum basale?
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one row of mitotically-active stem cells and some newly formed skin cells of the more superficial layers. some melanocytes and epidermal dendritic cells
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how is the stratum basale attached to the basement membrane?
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through hemidesmosomes
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desmosomes
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durable interconnections found where tissue is under mechanical stress
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in which layer of skin are epidermal ridges found?
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stratum basale
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what is the purpose of epidermal ridges?
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to increase the surface area and strength of the attachment to the basement membrane via increasing the number of hemidesmosomes present
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what senses pain in the stratum basale?
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free nerve endings
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what senses light touches in the stratum basale?
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merkel cells
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what composes the stratum spinosum?
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-several layers of keratinocytes unified by desmosomes
-thick bundles of intermediate filaments made up of pre-keratin -langerhans cells |
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what are all of the cells of the epidermis called?
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keratinocytes
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langerhans cells
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a type of macrophage present in the epidermis that are important for immune function
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what layer is the stratum spinosum superficial to?
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the stratum basale
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in what layer of skin are there abundant levels of langerhans cells?
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the stratum basale
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composition of the stratum granulosum:
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-3-5 layers of flattened cells
-deteriorating organelles -cytoplasm full of lamellated organelles --> release lipids and keratohyaline granules |
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what layer is the stratum granulosum superficial to?
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the stratum spinosum
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in what layer does the process of keratinization and cell death begin in the epidermis?
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the stratum granulosum
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what granules do cells in the stratum granulosum form?
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-keratohyaline granules
-lamellated granules |
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what is the importance/purpose of keratinohyaline granules?
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-important for the formation of keratin
-causes keratin filaments to aggregate in parallel ways |
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what is the importance/purpose of lamellated granules?
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-excrete a waterproof glycolipid into the extracellular space that prevents water loss --> renders the skin partially impermeable
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where is the stratum lucidum present?
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only in thick skin
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are cells alive or dead in the stratum lucidum?
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dead
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what layer is the stratum lucidum superficial to?
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the stratum granulosum
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what is the composition of the stratum lucidum?
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2-3 rows of flattened, densely packed dead keratinocytes; no organelles; filled with keratin
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what layer is the stratum corneum superficial to in thick skin?
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the stratum lucidum
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what layer is the stratum corneum superficial to in thin skin?
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the stratum granulosum
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what is the most superficial layer of skin?
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the stratum corneum
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composition of the stratum corneum?
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-20-30 layers of dead cells (flat membranous sacs filled with keratin)
-glycolipids in the extracellular space |
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what is insensible perspiration?
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when water moves to the surface of the skin to evaporate when the body needs to cool down
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what is sensible perspiration?
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sweating from sweat glands
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how long does it take for keratinocytes to reach the stratum corneum from the stratum basale?
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7-10 days
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how long does a keratinocyte spend in the corneum?
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2 weeks
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how long does it take to acquire a totally new epidermis?
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24-45 days
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what is the main difference between the epidermis and the dermis?
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the epidermis is not vascularized while the dermis is
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what kind of tissue composes the dermis?
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connective tissue
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what are the two layers of the dermis?
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papillary and reticular
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where in the dermis are friction ridges formed?
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the papillary layer
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what is the most important layer of skin in providing resistance and strength?
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the reticular layer
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what kind of tissue composes the reticular layer?
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dense irregular connective tissue
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what kind of tissue composes the papillary layer?
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aerolar conective tissue
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what are fingerprints?
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a film of sweat coming out from pores along the crests of epidermal ridges
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what is the function of epidermal ridges?
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-increasing the friction and gripping ability of the fingers and feet
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what kind of nerves are present in the epidermal ridges?
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Messiner's tactile
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where are cleavage lines present?
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in the reticular layer of the dermis
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why are cleavage lines important?
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surgeons will cut by following the cleavage line. a cut on a different angle would damage the elastic fibers preventing them from recoiling and therefore slowing down the scar tissue formation.
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what is the cutaneous plexus?
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a network of blood vessels between the reticular layer and the hypodermis
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what do lamellated corpsucles sense?
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deep pressure/vibration in the reticular layer of the dermis
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why is BPA a problem?
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it is lipid soluble, and can move off of paper receipts water bottles and through to the blood stream where it can bind to estrogen receptors and mimic its effects
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what 3 pigments determine human skin pigmentation?
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-melanin
-carotene -hemoglobin |
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what is the role of melanin?
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-skin color
-vitamin d production -uv protection |
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how is melanin produced and get to protecting cell DNA?
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1)produced by melanocytes
2)it is packaged in melanosomes 3)melanin is transferred to keratinocytes 4)melanin concentrated on the sunny side of the nucleus |
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why are some people dark-skinned?
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melanosomes are bigger and can reach the stratum granulosum. in lighter-skinner people, melanosomes fuse with lysocomes and more superficial layers lose color
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what is carotene and how is it obtained?
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it is an orange-yellow pigment obtained from the diet
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where does carotene accumulate?
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in the cells of the stratum corneum and in the fat tissue in the dermis and epidermis
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why is carotene important?
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-it can be converted into vitamin A which is important for the maintenence of skin elasticity
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what is pallor?
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paleness of the skin resulting in the decreased vascularization of the face and anemia due to hemoglobin not being bound to oxygen
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what causes blushing?
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increased vascularization of the skin caused by increased binding of oxygen to hemoglobin
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what are the appendages of the skin?
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-glands
-hairs |
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what is a gland?
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one or more cells that make and secrete a watery-based fluid
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what are the two types of glands?
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endocrine and exocrine
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what does an endocrine gland do?
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it releases it's products in the blood or lymphatic fluid, and the action is far away from the gland on target tissues
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what does an exocrine gland do?
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secretes it's products onto body surfaces (skin) or into body cavities
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what are the two types of exocrine gland?
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merocrine and holocrine
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how do merocrine glands function?
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secrete their products via exosytosis
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where are merocine glands found?
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the pancreas, most sweat glands, salivary glands
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how do holocrine glands function?
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accumulate products and rupture.
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where are holocrine glands found?
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sebaceous glands
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what cells are sweat glands commonly associated with? why?
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myoepithelial cells that contract in response to the autonomous nervous syetem to squeeze sweat out
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where are eccrine/merocrine sweat glands found?
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palms, soles, forehead
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what do eccrine/merocrine sweat glands produce?
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99% h2o and waste metabolites (ammonia, uric acid)
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how does sweat provide protection?
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it decreases the chance of infection from certain microbial colonies
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where are apocrine sweat glands commonly found?
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in the axillary and anogenital regions
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what is the composition of apocrine sweat gland secretions?
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water and metabolic wastes along with proteins and fatty acids --> results in a musky odor
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when do apocrine sweat glands begin to develop?
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puberty
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where are sebaceous oil glands not found?
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in the thick skin of the soles and palms
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what is the composition of sebaceous glands?
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sebum: triglycerides, cholesterol, proteins, electrolytes
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what is the purpose of sebum?
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to maintain the lubrication of the skin and protect keratinized cells so they do not dry out, and to slow water loss
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what is hair composed of?
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keratinized dead cells = hard keratin
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what is the function of hair?
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-sensory organ to detect insects and particles on the skin, nose, and eyes
-protect and insulate the scalp |
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macroscopic organization of hair
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shaft and root
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microscopic organization of hair
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medulla, cortex, and cuticle
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composition of hair medulla
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central core made of large cells (contains soft keratin) and air spaces
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composition of hair cortex
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several layers of flat cells surrounding the medulla
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composition of hair cuticle
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outermost single cell layer, heavily keratinized to protect the inner layers
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from where do hair follicles originate?
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from a folding of the epidermis into the dermis
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what are the organs producing hair?
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follicles
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what is the bulb in relation to hair follicles?
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the deep end of the follicles within the dermis where the hair root begins
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what is the root hair plexus?
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sensory nerve terminals that wrap the bulb
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composition of the follicle
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-connective tissue root sheath
-glassy membrane -epithelial sheath -hair matrix -arrector pili |
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where does hair growth begin?
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in the bulb at the level of the hair matrix (stem cells)
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3 phases of hair growth
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1)anagen- active growth (2-5 years)
2)catagen- transition (2 weeks) 3)telogen- resting (5 weeks) |
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vellus hairs
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present all of the body and in children
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terminal hairs
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are heavy (eyelashes, brows) appear more frequently after puberty (under the control of anagens)
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partial thickness burns
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appear red and painful but do not usually cause scar tissue (1st and 2nd degree burns)
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characteristics of 1st degree burns
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-damage to epidermis
-typical of sunburns |
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characteristics of 2nd degree burns
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-damage to epidermis and superficial layers of the dermis
-accessory structures not affected -development of blister/swelling -pain -infection can develop -~2 weeks recovery |
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full thickness burns
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the entire skin is involved; not as painful as 2nd degree burns because the layer with nerves is damages
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characteristics of 3rd degree burns
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-hypodermis is exposed
-no stratum basale --> no mitotic cells --> theoretically no reproduction of new epidermis |
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the consequences of waiting for a skin graft are
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-infection
-dehydration |
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3 main steps of tissue repair
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1)inflammation
2)organization 3)regeneration and fibrosis |
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2 types of muscles
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striated and smooth
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layers of organization of skeletal muscle (outer to inner)
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epimysium, perimysium, fasicle, endomysium, muscle fibers
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epimysium
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the outermost layer of skeletal muscle; surrounds the muscle organ and separates it from other tissues and organs
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perimysium
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a layer of fibrous connective tissue that wraps around the fasicle; contains blood vessels and nerve terminations
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muscle fasicle
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groups of muscle fibers contained within the perimysium
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endomysium
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layer of aerolar connective tissue that separates an individual muscle fiber; contains capillaries for nutrients
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myosatellite cells
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muscular stem cells
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tendons
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where the 3 layers of connective tissue fuse together at the end of each muscle to connect to bone
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aponeurosis
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flat, sheet-like tendons that attach muscles to other muscles
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sarcolemma
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cell membrane of the muscle
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sarcoplasm
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cytoplasm of the muscle
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sarcomere
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the smallest contractile unit of the muscle; measured from z-line to z-line
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a-band
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the darkest region of the sarcomere where actin and myosin overlap
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h-band
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lighter region of the sarcomere; the middle part of myosin that does not overlap with actin
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i-band
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the lightest region of the sarcomere where there is only actin
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z-line/disk
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structural protein that anchors actins in the sarcomere
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m-line
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holds myosins in place in the sarcomere
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tropomyosin
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a double-stranded protein that covers the active site of each g-actin
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nebulin
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protein that maintains the position of g-actin in thin filaments
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f-actin
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composed of a double strand of 300-400 g-actins
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g-actins
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globular proteins in the thin filaments of the sarcomere
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active site in the thin filaments of the sarcomere
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where actin binds to myosin
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tropinin
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binds to tropomyosin, g-protein, and 2 Ca ions
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where is the site of the cross-bride between actin and myosin?
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the myosin head
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function of titin
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helps the muscle to spring back after contraction --> elasticity
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terminal cisternae
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expansion of the SR in proximity of the i- and a-band's junctions
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Ca2+ free concentration in the terminal cisternae in comparison to the sarcoplasm
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at rest is 1000 times higher
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sarcoplasmic reticulum (sr)
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the equivalent of the smooth endoplasmic reticulum in other cells
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calsequestrin
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a protein that reversibly binds to ca2+ within the terminal cisternar
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consequence of calsequestrin
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there is free and bound ca2+ --> makes the concentration 40000 times highter than within the sarcoplasm --> causes movement into the sarcoplasm
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transverse tubules (t-tubules)
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tubes contiguous with the sarcolemma that invaginate within the sarcoplasm; they are not part of the sr
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function of the t-tubules
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can depolarize and transmit ap's deep within the muscle as an extension of the sr
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triad
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a pair of terminal cisternae and a t-tubule
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neuromuscular junction
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synapses between a somatic motor neuron and a skeletal muscle cell
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process of neural control of muscle contraction
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1)cell body of alpha-motor neuron in spinal cord
2)alpha-motor neuron sends AP through myelinatex axon 3)AP reaches neuromuscular junction 4)ACh is released in synaptic cleft 5)ACh binds to the nicotinic ACh receptors in the motor end plate 6)Depolarization of the motor end plate 7)sequence of events by which transmission of an AP along the sarcolemma leads to the sliding of myofilaments |
