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108 Cards in this Set
- Front
- Back
origin of melanocytes?
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neural crest
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Apocrine sweat glands:
associated with? when are they fxnl? innervation? how do they release product? |
assoc w hair follicles
fxnl after puberty innervated by adrenergic fibers release by merocrine secretion |
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in what layer of the skin are apocrine sweat glands located?
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reticular dermis
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where will you NOT find thin skin?
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palms of hands, soles of feet.
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where are mitotically active keratinocytes located?
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s. basale and deep portion of s. spinosum
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what do langerhans' cells do?
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play role in immune response as Ag presenting cells
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Describe granules of Merkel cells
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80nm, dense cored, neurosecretory, resemble those of adrenal medulla and carotid body
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What do Pacinian corpuscles look like, where are they located, and what do they do?
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large, ovoid, found in deeper dermis, respond to pressure and vibration
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What do lamellar bodies do?
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contribute to formation of intercellular epidermal water barrier
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What kind of receptors are Meisner's corpuscles? Where are they located.
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touch receptors, responsive to low freq stimuli in papillary dermis of hairless skin
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T/F: There are desmosomal connections between keratinocytes and melanocytes
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F. But they do interact by cytocrine secretion (melanocytes --> keratinocytes)
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T/F: melanocytes contain more melanin granules than keratinocytes
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F
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T/F: melanocytes are found in approximately equivalent numbers in all races
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T
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What is the fxn of Merkel cells?
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fxn in cutaneous sensation
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What type of skin is represented by PROMINENT s. corneum, robust s. granulosum and distinct s. lucidum?
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THICK SKIN (thin skin has less prominent s. corneum, poorly developed granulosum and no obv s. lucidum)
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What type of skin covers most of the body surface?
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THIN SKIN
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What type of skin is found on palms of hands/soles of feet?
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THICK SKIN
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Name three things that thin skin contains that thick skin does not.
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hair follicles, sebaceous glands, and arrector pili muscles (all assoc with hair, and thick skin is assoc w palms and soles which have no hair)
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Epidermis is developmentally derived from....?
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ectoderm
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what type of cell makes up >90% of epidermis?
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keratinocytes
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regenerative capacity of skin? High/low?
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highly regenerative (replaced every ~30days)
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What is responsible for our fingerprints?
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the epidermal ridges formed by dermal papillae on which the epidermis rests.
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Name and describe deepest layer of dermis.
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s. basale, simple cuboidal cells resting on basal lamina and attached to it by anchoring fibrils and hemidesmosomes
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what is the most mitotically active layer of the epidermis?
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s. basale (contains stem cells from which new keratinocytes are derived and rise to upper strata)
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Where are melanocytes and Merkel's cells located?
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s. basale
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What is the most prominent layer of the epidermis and what does it look like?
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s. spinosum, several cell layers thick, called spinous or prickle cell layer (shrinking and desmosome cnxns give this look) areas of memb thickening due to desmosomes called nodes of bizzozero
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What happens to the cells of the epidermis as they rise and mature?
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cytoplasm increases, become more flattened
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what important proteins do the cells of s. granulosum contain?
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keratohyalin (granules) and keratin (filaments). responsible for waterproofing of the skin
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what is filaggrin?
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protein that aggregates keratin filaments in the s. corneum. its presence is a marker of keratinocyte apoptosis
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what is the most superficial layer of epidermis in which cells are nucleated?
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s. granulosum
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what layer of epidermis is found only in thick skin?
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s. lucidum (just superficial to s. granulosum)
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cells of s. lucidum are rich in what important substance?
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eleidin (a metabolite of keratohyalin)
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what is the most superficial layer of epidermis? what type of skin is it found in?
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s. corneum, only in THICK skin
(aka SQUAMES, shed by desquamation) |
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Characteristics of s.basale keratinocytes
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basophilic (lots of free ribosomes), long axis perpendicular to s.basale, lots of tonofilaments (int/keratin), high metabolic activity
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Characteristics of s.spinosum keratinocytes
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more eosinophilic, inc. tonofilaments, cuboidal, central nuc, in upper layer, start to synth keratohyalin and lamellar bodies
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What are lamellar bodies?
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membrane coating granules, fuse with PM and spill glycolipid sheets from within onto surface of cell (for waterproofing)
mostly in s.granulosum |
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Characteristics of s. granulosum keratinocytes
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lg amts of keratohyalin granules (no membrane), flattened, lots of lamellar bodies
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Characteristics of s.lucidum keratinocytes
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weakly eosinophilic, extremely flat, no nuc, densely packed filaments in electron dense matrix
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Characteristics of s.corneum keratinocytes
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eosinophilic, lg amts of keratin, very flat, no nuc,
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What layer of epidermis are melanocytes found?
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s.basale
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Melanosomes contain melanin within melanocytes. What other protein is in melanosomes?
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tyrosinase - UV sensitive enzyme involved in melanin synthesis
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What type of melanin is responsible for brown/black pigments? reddish-yellow pigments?
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eumelanin, pheomelanin (this is most apparent in the hair)
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Brief description of melanogenesis
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1. vesicle surrounded by membrane: premelanosome. orderly arrangement of tyrosinase at periphery
2. ovoid melanosome vesicle, parallel filaments w cross-striations on which melanin is deposited 3. increased melanin formation 4. melanin fills vesicle, cytocrine secretion into keratinocyte |
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Explain cytocrine secretion and name the cell that uses it
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exocytosis with concomitant endocytosis. transfer of melanosomes to keratinocytes with v. little cytoplasm transfer
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What is lacking in Addison's disease?
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cortisol from adrenal cortex, too much ACTH --> increase in pigmentation
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What causes albinism?
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inability of mellanocytes to synthesize melanin due to absence of tyrosinase or inability of cells to take up tyrosine
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What disease is marked by degeneration & disappearance of entire melanocytes?
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vitiligo
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What are Langerhans' cells?
What layer are they located in? |
immune response, delayed hypersensitivity rxns, s. spinosum (originate in bone marrow)
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Describe and name granules of langerhans' cells.
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paddle shaped, Birbeck granules, involved in activation of Tcells
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What cells are characterized by a lack of desmosomal connections, lack of tonofilaments and an indented nuc?
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Langerhans' cells
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What do Merkel's cells do? Where are they located?
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role in perception and local endocrine cntrl, located in s.basale and concentrated where sensory perception in acute (fingertips)
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How do Merkel's cells differ ultrastructurally with Langerhans' cells?
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Merkel's contain tonofilaments and desmosomes and have a lobed nucleus (vs. indented) Both types of cells, however, stain clear on H&E
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origin of dermis?
what are the layers? |
mesoderm
papillary and reticular layers |
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What types of CT are present in dermis?
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dense, irregular CT containing type I collagen and thick elastic fibers
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what layer of dermis contains capillary loops? what do they do?
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papillary dermis, caps nourish but do not enter epidermis
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What are Meissner's corpuscles? In what layer of the skin are they located?
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fine touch sensory receptors of the papillary dermis
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What are langer's lines? Where are they located?
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dense bundles of type I collagen and thick elastic fibers oriented into regular lines of tension (if you cut along these lines, it heals better)
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Which layer of dermis is:
thicker? most cellular? has most leukocytes? |
Reticular layer is thicker
Papillary layer is most cellular Reticular layer has more leukocytes |
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What are pacinian corpuscles?
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pressure receptors in Reticular dermis
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What are Krause's end-bulbs?
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Cold and pressure receptors in reticular dermis
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in what area of the dermis are hair follicles and glands found?
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reticular layer of dermis of thin skin
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what type of nerves are sensory receptors of the skin?
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peripheral terminals of afferent nerves
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What types of things do EFFERENT nerve endings supply in the skin?
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blood vessels, arrector pili muscles and sweat glands
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What type of nerve ending lack a connective tissue of Schwann cell investment?
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free nerve endings
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Where do free nerve endings terminate and what kind of info do they relay?
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terminate in s.granulosum and relay info abt fine touch, heat and cold, esp found around hair follicles that serve as mechanoreceptors (cats whiskers)
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What type of nerve endings are enclosed in a CT capsule? What are the 3 types of this category?
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encapsulated nerve endings, Pacinian corpuscles, Meissner's corpuscles, Ruffini's corpuscles
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What are Pacinian corpuscles?
where are they found? |
encapsulated nerve endings, myelinated, in deeper area of reticular dermis (esp fingertips, joints, periosteum, internal organs)
(organized multilayer capsule) |
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What are Meissner's corpuscles? Where are they found?
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encapsulated nerve endings, unmyelinated, located in papillary dermis in hairless skin
(irreg lamellae) |
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What do Meissner's corpuscles convey?
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touch reception, low freq vibrations
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What are Ruffini's corpuscles? Where are they found?
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encapsulated nerve endings, unmyelinated endings of myelinated fibers, spiral path, in reticular dermis, hypodermis and CT of mesenteries, joints, digits and breasts
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What do Ruffini's corpuscles convey?
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pressure and touch reception
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How are epidermal skin appendages derived? Name 3 things that fall under this category.
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derived from downgrowths of epidermal epithelium during development.
include hair follicles (and hair), sebaceous glands and apocrine sweat glands |
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What is the pilosebaceous apparatus?
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consists of hair follicle and its assoc. sebaceous and apocrine sweat glands
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Name the 3 parts of the hair follicle.
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Infundibulum, Isthmus, Inferior segment
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Where does the infundibulum extend?
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from the surface opening of the follicle to the opening of its sebaceous gland (part of the pilosebaceous canal thru which sebum is discharged)
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Where does the isthmus extend?
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from infundibulum to level of insertion of the arrector pili muscle in reticular layer of dermis.
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What is the arrector pili muscle?
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attaches to dermal sheath around hair follicle, extendes superfic. to underlie sebaceous gland, inserts into papillary layer, is SMOOTH MUSCLE. elevates the hair
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Where does the inferior segment extend?
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extends from arrector pili muscle to the dermal papilla at bottom of the bulb
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What is the dermal papilla of the hair follicle?
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tuft of highly vascularized loose connective tissue at the base of the bulb
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What are the matrix cells of the bulb of the hair follicle?
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represent the germinative layer of the follicle, divide and account for hair growth, and differentiate into keratin producing cells and internal root sheath
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What are the 3 layers of the internal root sheath? and describe
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CUTICLE(innermost) - squam cells, touches hair shaft
HUXLEY's layer (middle) HENLE's layer (outermost) - designated external root sheath |
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Where in the hair follicle are melanocytes located?
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in the base of the bulb
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What are the 3 layers of hair? What type of skin is it found in?
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Medulla (innermost) (only in thick hairs)
Cortex Cuticle (outermost) found in THIN SKIN |
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Describe the cortex of a hair
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contains cuboidal cells
undergo differentiation into keratin-filled cells |
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Describe the cuticle of the hair. What layer of the hair follicle is it continuous with?
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contains squamous cells, outermost layer of hair, contiguous with the cuticle of the internal root sheath.
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What part of the hair follicle are sebaceous glands an outgrowth of?
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the external root sheath
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T/F: There is one sebaceous gland associated with each hair follicle.
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F. There are usually several glands assoc. with each hair follicle
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What part of body are sebaceous glands most abundant?
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face, forehead, scalp (greasy areas)
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What type of secretion do sebaceous glands use and what do they secrete?
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holocrine (release entire cytoplasm upon secretion) secretion of SEBUM
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What is the function of sebum?
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coats hair follicle and surface of skin to provide bacteriostatic, emollient, barrier, and phermonal fxn
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Describe steps of sebum production
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1. mitotically active cells @ periphery of acini divide
2. daughter cells synthesize lipid-rich secretory product in cytoplasm 3. nuc shrink, cells disintegrate, secretory product released into pilosebaceous canal |
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Name purpose and types of sweat glands
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purpose: body temp regulation, rid body of waste
types: eccrine and apocrine |
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T/F: Eccrine sweat glands are NOT associated with hair follicles
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T and they are formed from downgrowths of epithelium
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What composes the secretory unit of eccrine sweat glands?
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dark cells, clear cells and myoepithelial cells
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Describe dark cells?
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line lumen of eccrine sweat glands, contain secretory granules, and a mucous-rich material
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Describe clear cells
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underlie dark cells, rich in mito adn glycogen, contain intercellular canaliculi which extend into lumen, secrete watery, electrolyte-rich material
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Describe myoepithelial cells
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form incomplete layer btwn clear cells and basal lamina of eccrine sweat glands, contract and aid in gland's secretions into the duct
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Which type of sweat gland has a more narrow duct and which has a larger duct?
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eccrine have a narrow duct, apocrine have larger ducts
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what type of cells are found in the duct of an eccrine sweat gland and what does it do?
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lined by stratified cuboidal, serve to modify secretory product by absorbing electrolytes and excreting ions, urea, lactic acid, drugs, etc
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What are apocrine sweat glands always assoc with?
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hair follicles
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Where are apocrine sweat glands typically found on the body?
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axilla, areola and perianal region and ceruminous (wax) glands of ear
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Which type of glands are not active until puberty?
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apocrine sweat glands. they are responsive to hormonal influences
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In what layer of skin are apocrine sweat glands located?
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reticular dermis or hypodermis, enveloped by myoepithelial cells
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How are apocrine sweat glands innervated?
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adrenergic fibers
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Which type of gland is associated with emotional sweating?
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apocrine sweat glands
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What layers of skin form the nail bed?
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s. basale and s.spinosum are continuous with the nail bed
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What is another name for the fold of skin covering the proximal end of the nail and aka the cuticle? What layer of skin is it continuous with?
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eponychium, continuous with the s.corneum
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Where do nails grow from?
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mitoses of cells in the matrix of the nail root
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