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185 Cards in this Set

  • Front
  • Back
# of layers of skin
two
layers of skin named
epidermis & dermis
layer NOT considered part of skin
hypodermis
epidermis: cellular composition
stratified squamous keratinized epithelium
epidermis: # of layers, thick skin
5 layers
dermis: composition/tissue type
connective tissue
dermis: # of layers
two
hypodermis: composition
adipose tissue
epidermis: origin
ectoderm
layers of epidermis most evident in
thick skin
layers/strata from deep to shallow
(1) stratum germinativum
(2) stratum spinosum
(3) stratum granulosum
(4) stratum lucidum
(5) stratum corneum
thick skin located
on palms of hand & soles of feet
stratum germinativum aka
stratum basale
stratum germinativum: cell types
single layer of cuboidal or columnar cells
stratum germinativum cells lie on
basal lamina
stratum germinativum cells attached to basal lamina by
hemidesmosomes
stratum germinativum cells attached to each other by
desmosomes
stratum germinativum is layer of cells in which phase of division?
mitosis
stratum spinosum: cell type(s)
polygonal with spiny projections
stratum spinosum cells form
"intercellular bridges"
intercellular bridges aka
locations of desmosomes
intercellular bridges: function
contribute to cohesiveness of epidermis
is cell division occurring in the stratus spinosum?
yes; mitosis
malphigian layer
stratum germinativum + stratum spinosum together
malphigian layer: characteristic
region of keratinocyte proliferation
stratum granulosum: cell type(s)
keratinocytes
stratum granulosum: characteristics
basophilic granules
stratum granulosum: # of types of granules
two
keratohyaline granules
basophilic granules, NOT membrane bound
membrane-coating granules
membrane-bound granules
stratum granulosum: function(s) of granules
form a barrier to microorganisms, foreign substances, and water
granules contain
glycosaminoglycans & phospholipids
granules located
in ECM (after being extruded)
medication patches: mechanism
lipid-soluble (to get meds through layers of skin)
lamellar bodies aka
membrane-bound granules
stratum lucidum: cell type characteristics
acidophilic, translucent, anucleate, and without organelles
stratum lucidum: most prominent in
thick skin
stratum lucidum: not evident in
thin skin
stratum corneum: cell type characteristics
flattened, keratin-filled, without organelles or nucleus; aka horny cells/squams
horny cell aka
squam
first degree burns classified by
damage to superficial epidermis
first degree burn: effect
cells of stratum germinativum remain viable and regenerate epidermis
second degree burns classified as
complete destruction of epidermis
second degree burn: effect
epidermis regenerated by remnants of sweat glands and hair follicles
third degree burns classified by
destruction of epidermis & dermis; "full-thickness burn"
third degree burn: effect
necessitates skin graft; loss of fluids causes hypovolemia and shock (if >15% BSA in adults; >10% BSA children)
cell types (#) found in epidermis
four
keratinocytes: origin
ectoderm
melanocytes: origin
neural crest
langerhans cells: origin & function
dendritic, antigen presenting cells
merkel cells: function
specialized keratinocytes involved in touch
predominant cell type in epidermis
keratinocytes
stratum corneum comprised of
dead keratinocytes
keratinocytes undergo
specialized differentiation
basal cell carcinoma: % of skin cancers
70%
basal cell carcinoma arises in which region of skin?
regions of skin containing sebaceous glands
basal cell carcinoma: frequent sites
eyelids & bridge of nose
basal cell carcinoma: age of onset
after 40 (usually fair-skinned people)
basal cell carcinoma: histology
cells form discrete nests or islands of cells that resemble normal basal cells
basal cell carcinoma: risk of metastasis
rare/seldom
squamous cell carcinoma: % of skin cancers
20%
squamous cell carcinoma: histology
complete replacement of normal epithelium with pleomorphic cells
squamous cell carcinoma: prognosis
depends upon location, size, & depth of penetration into dermis (as opposed to degree of anaplasia)
squamous cell carcinoma: risk of metastasis
2-5% metastasize to regional lymph nodes
langerhan's cells: location
stratum spinosum
langerhan's cells: relation to adjacent cells
NOT attached to adjacent keratinocytes by desmosomes
langerhan's cells: correlation
similar to dendritic cells in lympoid tissues
langerhan's cells: function
engulf invading microorganisms in epidermis & present antigens to lymphoid cells
granules inside langerhan's cells called
Birbeck granules
langerhan's cells: migration out of epidermis & into
lymphatics in dermis, then to local lymph nodes
langerhan's cells: HIV
cytoplasm of langerhan's cells contains HIV-1 & may serve as a resevoir for the virus in infected persons
langerhan's cells: staining
gold impregnation (NOT H&E)
melanocytes: origin
neural crest
melanocytes: location
stratum germinativum
melanocytes: replication
slowly, throughout life
melanocytes maintain
epidermal-melanin units
epidermal-melanin units
consist of one melanocyte associated with a fixed # of keratinocytes
epidermal-melanin units: preponderance
vary regionally, but not by race or gender
ratio of melanocytes to keratinocytes
changes in different areas across same person
melanocytes: connection(s)
to basal lamina but NOT surrounding keratinocytes
melanocytes attach to basal lamina
via hemidesmosomes
melanocytes contain enzyme
tyrosinase (in large amounts)
tyrosinase: fucntion
convert tyrosine to melanin (multi-step pathway)
cytocrine secretion
process by which melanin granules are injected into keratinocytes
melanocytes: view/staining
require special stains to see
melanocytes comprise
cells with the FEWEST number of melanin granules within them
melanin on slides mostly located
in keratinocytes
melanin granules: location
above nuclei of keratinocytes in strata germinativum and stratum spinosum
melanin granules: role
to protect dividing cells from UV radiation (i.e. nuclear umbrellas!)
melanin granules: degredation
fuse with lysosomes in keratinocytes
melanin granules: timing of degredation
fully degraded by the time the keratinocytes reach the stratum granulosum
melanin granules: degredation speed
slower in dark-skinned individuals, where melanin granules may be evident in supper strata of epidermis
malignant melanoma: % of skin cancers
2%
malignant melanoma: prognosis
poor
malignant melanoma: risk of metastasis
high risk because cells are neural crest in origin and therefore are highly migratory
malignant melanoma: histology
nests of pigmented cells that penetrate the epidermis; also invade the dermis where they access blood vessels and lymphatics
merkel cells: location
thick skin where touch is acute
merkel cells: function
mechanoreceptive cells because of proximity/association with nerve endings
merkel cells are
specialized keratinocytes
merkel cells contain
80nm neurosecretory granules
merkel cells: histology
cannot be distinguished from keratinocytes in H&E preparations
dermis: # of layers
two distinct layers
dermis: 1st layer
papillary
dermis: 2nd layer
reticular
papillary dermis: composition
loose CT
papillary dermis: contains which type(s) of cell(s)?
fibroblasts, mast cells, macrophages, leukocytes
papillary cells comprise
major part of dermal papillae or pegs
reticular dermis comprised of
dense irregular CT
tissue of reticular dermis formed by
type I collagen fibers
reticular fibers: cells inside are __ in number compared to papillary layer?
fewer
reticular layer of dermis aka
subcutaneous connective tissue
distinctive feature: thin versus thick skin
thickness of epidermis only
thick skin aka
glabrous skin
thick skin: location
areas exposed to greater wear and abrasion
thick skin: examples
soles of feet and palms of hands
# of epidermal layers in thick skin
5
prominent layers in thick skin
stratum lucidum & stratum corneum
thick skin: characteristic(s)
hairless; no sebaceous glands
thin skin aka
hairy skin
thin skin: location
everywhere thick skin is not
thin skin: characteristics of layers
no distinct stratum lucidum & very thin stratum corneum
hypodermis: classification
NOT considered part of skin!
hypodermis: location
deep to dermis
hypodermis aka
superficial fascia or subcutaneous CT
hypodermisL composition
loose CT with fat cells
fat cells vary depending upon
degree of obesity of individual
appendages of skin
hair follicles, sweat glands, sebaceous glands, mammary glands, nails
hair follicles are
invaginations of epidermis with bulbous terminal dilations
bulbous terminal dilations aka
hair bulbs
hair bulbs undergo
periods of growth/regeneration
bulb location
on dermal papilla
dermal papilla under bulb contains
capillaries that nourish the hair follicle
cells of hair bulb similar to
stratum germinativum
sweat glands are
invaginations of epidermis into underlying connective tissue
two types of sweat glands
eccrine and apocrine
eccrine sweat glands: form
simple, coiled, tubular glands
eccrine sweat glands: secretions
non-viscous fluid
secretions of eccrine sweat glands: function
evaporation of fluid cools skin
excretory function of eccrine sweat glands
secrete catabolites in sweat
eccrine sweat glands: histology
lightly staining, simple cuboidal acini and darkers staining, stratified cuboidal ducts
eccrine sweat glands: myoepithelial cells
specialized cells tha squeeze secretions from sweat acini
myoepithelial cells: classification
epithelial (not smooth muscle cells)
myoepithelial cells: histology
acidophilic because they contain actin filaments
apocrine glands are
specialized glands located in the axillary, areolar, and anal regions
ducts of apocrine glands
open into hair follicles
apocrine glands: secretions
viscous, odorless fluid
reason secretions cause odor
because of action of bacteria residing on skin
possible function of apocrine glands
attract mates
apocrine sweat glands become active
at puberty
example of a highly modified apocrine sweat gland
mammary gland
sebaceous glands: development
in association with hair follicles
sebaceous glands only found in
hairy/thin skin
exceptions to where sebaceous glands are found
skin of lips, glans penis, and clitoris
sebaceous glands secrete
sebum
sebaceous glands: method of secretion
holocrine
sebaceous glands become active
at puberty
sebaceous glands: pathology
respond to hormones --> clog --> become site for bacterial growth
sebaceous glands: cells at base
germinal cells
sebaceous glands: histology
as cells fill with sebum, nuclei become pyknotic and eventually are lost
nails are
plates of keratinized epithelial cells
nails: clinical significance
nail plates are transparent and therefore allow for quick assessment of blood oxygenation level
cyanosis
poor oxygenation
nail root is
germinal region
nail bed: location
beneath nail plate
nail bed: composed of
stratum germinativum and stratum spinosum (malphigian layer) only
epithelium of nail bed arises from
nail matrix
nail matrix extends
deep to the root
nail grows
from proximal end & slides over nail bed
nail bed does not contribute to
nail plate
skin: major function
sensory receptive organ
skin contains
# of specialized sensory receptors
free nerve endings
unmyelinated axons that penetrate basal lamina of epidermis to enter stratum germinativum and stratum spinosum
free nerve endings ramify
along epithelial cells
free nerve endings involved in
temperature & pain perception
free nerve endings function in
crude touch (e.g. cornea)
free nerve endings: example of clinical pathology
free nerve endings lost in diabetics
meissner's corp[uscles: location
thick (glaborous) skin & skin of lips & nipples
meissner's corpuscles are
specialized encapsulated receptors
meissner's corpuscles found
within dermal papillae of thick skin
meissner's corpuscles: function
descriminative touch
descriminative touch
ability to descriminate two points
pacinian corpuscles detect
pressure and vibratory senses
pacinian corpuscles: location
dermis & hypodermis of thin & thick skin
location with most pacinian corpuscles
fingertips
pacinian corpuscle: struacture
encapsulated receptor