MCM Final - Skin Flashcards
how are glands classified?
mode of secretion, cell number, and method of product distribution, ductal morphology, glandular morphology
development of gland
invagination of epithelium
merocrine
aka eccrine
product released by exocytosis
-fusion of granules with plasmalemma
holocrine
entire cell dies and release product
apocrine
release membrane bound particles
method of distribution for pancreas?
exocrine and endocrine
exocrine
secrete via duct
endocrine
secrete into blood or lymphatics
paracrine
secrete into extracellular space
simple gland
single tube structure
compound gland
duct has branches
coiled gland duct
simple gland that is twisted/coiled
tubular gland
cells all same size
alveolar gland
cells enlarge toward bottom
aka acinar gland
serous glands
secrete watery suspension of proteins and enzymes that travels down ducts
ex/ parotid salivary gland
mucus gland
secrete viscous colloid with enzymes, proteins, and glycoproteins
ex/ goblet cells, sublingual and palatine salivary glands
mixed gland
secrete both serous and mucus
ex/ submandibular salivary gland
cell types in glands
parenchyma is the functional tissue and stroma are the cytoskeleton elements
organization of stroma in glands
form lobes that surround lobules
acini
secretory component of gland
significance of mitochondria in ducts of glands?
burning energy, so something important is going on
interlacated duct
portion of delivery route in gland that is where product secreted and forms tube
three division of the skin
epidermis, dermis, hypodermis
**hypodermis technically not apart of skin
epidermis
specialized stratified epithelium
protection from fluid loss, UV, and infection
dermis
dense irregular connective tissue
has specialized structures:
-vessels, nerves, glands, hair follicles
hypodermis
subcutaneous connective tissue
functions:
- attaches skin to underlying structures - padding, insulation, energy source - molds external appearance
thick epidermis
on palmar and plantar surfaces
no hair
thin epidermis
on rest of body not palms or plantar region
hairy
keratinocytes
cells of the epidermis
has keratin intermediate filment
three layers of epidermis?
stratum granulosum, stratum spinosum, and stratum basalis
stratum basalis
cuboidal cells on basal lamina of dermal-epidermal junction
attached by hemidesmosomes
high mitotic activity - renewal of epidermis cells (keratinocytes)
chalone
soluble protein produced within tissue that reversibly inhibits mitosis
vitamin A and skin
inhibitory role in skin differentiation
stratum spinosum
plays role in protection and water loss
lots of desmosomes - tight junctions between cells
resist shearing abrasive forces
stratum granulosum
have keratohyaline granules and keratinosomes
forms gooey cement that prevents water loss
keratohyalin granules
in stratum granulosum of skin and are non-membrane bound granules of RNA, polysaccharides and peptides
keratinosomes
in stratum granulosum of skin
membrane coated granules
secrete glyco-phospholipids and GAGs that are intercellular cement
cell envelope
layer close to cytoplasm
lipid envelope
consists of extracellular lipids >ceramides
keratinized layer of skin
outermost layer of epidermis
keratinocytes are flattened discs
consists of stratum lucidum and stratum corneum
desquamation
final process of removing top layer of keratinized cell
does not happen by abrasion***
-active mechanism of dishesion by lipolytic enzymes at outer epidermis
melanocytes
specialized cell of the epidermis
in the basal layer of the epidermis
produce pigment - melanin
secrete pigments in melanosomes
pigmentation of skin?
eumelanin- brown-black
pheomelanin - red-yellow
keratinocytes pick up the pigments from the melanosomes (secreted by melanocytes)
melanocyte activity?
all at the same constant rate
difference in pigmentation due to differing rates of kerationcytes taking in the pigment
melanine production
precursor is tyrosine
produced in melanocytes secreted to kerationcytes via melanosomes
langerhans cells
specialized cells of the epidermis
-produced in marrow and reside in the skin
act as antigen-presenting cells (immune response)
express Fc, MHCII, and C3 receptors
can be damaged by UV
make interleukin-1 which induces T cells to make IL-2 and proliferate
merkel cells
specialized cells of the epidermis
found int he stratum basalum
function in sensation as mechanoreceptors
Dermis
irregular connective tissue underlying the epidermis
two layers: reticular layer and papillary layer
epidermal pegs
portion of epidermis that drops to the papillary layer of the dermis
dermal papillae
portion of dermis that is in contact with the epidermal pegs
forms the papillary layer of the dermis
papillary layer of dermis
formed from the epidermal pegs and dermal papillae
contain connective tissue, blood vessels, nerve and neurosensory organs (meissners corpuscles)
reticular layer
layer of dermis below the papillary layer
has connective tissue, hair follicles, nerves and neurosensory organs, blood and lymph vessels, and blands
meissners corpuscles
in the papillary layer of the dermis
pacinian corpuscles
in the reticular layer of the dermis
is epidermis vascular?
NO - receives nutrients by diffusion
what is the dermal epidermal junction composed of?
1 basal cell plasmalemma (and hemidesmosomes)
2 basal lamina
3 connective tissue fibers below the basal lamina
-anchoring fibrils (type VII collagen)
hair follicles
follicular sheath shares characteristics with the epidermis
-can proliferate as new source of epidermis
has arrector pili muscle and sebaceous gland
sebaceous bland
occur in proximity to hair follicles
secrete product of holocrine secretion
-oily, waxy sebum
inhibits evaporation and aids in thermal homeostasis
also keeps skin soft and hair from drying out
sweat glands
sweat is hypotonic
under cholinergic control - merocrine (eccrine) glands
simple coiled tubular gland:
dark cells (pyramidal - contain secretion glanules)
-clear cells (primary cells in producing sweat)
-myoepithelial cells (contractile)
merocrine sweat glands
simple coiled tubular gland with three cell types (dark, clear, and myoepithelial)
under cholinergic control
apocrine sweat glands
simple coiled tubular gland
empty into hair follicle
produce odorless mix of proteins and pheromones
-odor from bacteria degradation
under adrenergic influence
meissners corpuscles
specialized in the dermis
responsible for two point sensation
-in the dermal papillae
pacinian corpuscles
sense pressure and vibration (deeper)
in the dermis and hypodermis
looks like an onion
