Skin Flashcards
layers of epidermis
stratum corneum, stratum granulosum, stratum spinosum, stratum basale
layers of dermis
papillary dermis, reticular dermis
stratum corneum (3 functions)
barrier, resist abrasion (squamous cells), waterproofing (lamellar bodies = caulking b/t cells)
stratum granulosum
deep to stratum corneum; contains cytoplasmic keratohyaline granules (incl. filaggrin)
filaggrin
a type of keratohyaline granule found in stratum granulosum; facilitates organization of keratin intermediate filaments - important for transition to anucleate cells of overlying stratum corneum
stratum spinosum
cell types = keratinocyes and langerhans cells; keratinocytes attached to eachother w/ desmosomes;
acantholysis
diseases where spinous cells lose desmosomal attachments, separate from eachother
acanthosis
thickening of spinous layer
stratum basale
cell types = keratinocytes and merkel cells; keratinocytes have a uniform size and shape with less cytoplasm than overlying cells; cap of melanin over this layer to protect DNA from UV light
How long does maturation take from bottom to top of epidermis?
30 days
3 important components of dermis
(1) fibroblasts: synth collagen and elastic fibers, (2) collagen, (3) elastic fibers
papillary dermis
top layer of dermis; thin layer underneath epidermis, consists of delicate collagen fibers
reticular dermis
deep to papillary dermis; contains thick collagen bundles in net-like pattern; superficial vascular plexus and deep vascular plexus
vascular plexus in reticular dermin
(1) superficial: @ junction b/t papillary dermis and reticular dermis, (2) deep: b/t dermis and underlying subcutis
subcutis
contains adipose; richly vascular; divided into lobules by fibrous “septa” (collagenous extensions from overlying dermis)
where are the dermal papillae protrusions longest?
places with a lot of shear force (palms and soles of foot)
rete ridges
on border of dermis and epidermis - for withstanding shear force (architectural feature of stratum basale)
psoriasis
stratum corneum doesn’t come off fast enough -> thickened stratum corneum
basal cell carcinoma
most common malignancy, occurring in stratum basale
stratum basale basal cells
basal cell has desmosomes and hemidesmosomes to maintain the integrity of epidermis; gives rise to keritinocytes above it (replacing sloughed cells)
melanocytes location and structure
in epidermis; have hemidesmosomes but not desmosomes to keratinocytes
origin of melanocytes
neural crest cells
function of melanocytes
make melanin, transfer it to basal keratinocytes
melanosomes
brown bodies in melanocytes; skin color based on number of melanosomes, not melanocytes
langerhans cell structure
in epidermis (stratum spinosum); cytoplasm has birbeck granules; no desmosomal attachments to keratinocytes
origin of langerhans cells
bone marrow
function of langerhans cells
intraepidermal antigen-presenting cell
neural structures in skin
meissners corpuscle, merkel ending, pacinian corpuscle
meissners corpuscle
messy nerve ending; senses light touch; located in acral skin
merkel ending
in basal layer of epidermis; nerves come through basement membrane to touch the merkel cells, which provide a neural function
pacinian corpuscle
circular lamella; present in skin that senses pressure and vibration
skin appendages (3)
Hair, glands, nails
Hair cycle
anagen (growing) –> catagen (involuting) –> telogen (resting)
hair follicle
epithelial portion that supports growth of hair shaft
where does hair color come from?
melanocytes donate melanin to hair shaft
types of glands related to skin appendages
(1) sebaceous (2) eccrine (sweat) (3) apocrine (scent)
function of subcutaneous tissue (hypodermis)
insulation, energy reserve, mechanical cushion
sebaceous gland
for lubrication; found on hair-bearing skin, increased density on face, empties into hair follicle, lipid-producing sebocytes
what type of secretion is involved for sebaceous glands?
holocrine
eccrine glands
sweat glands for temp regulation; coiled gland; Na/K ATPase pumps in duct lining to resorb Na+
acrosynringium
extension of eccrine gland to skin surface
apocrine glands
for scent (i.e. pheromones); axillary and perineal; larger gland and acini than eccrine sweat gland; odorless secretion - converted to odor by bacteria on skin
where are nails formed
at base of nail bed (matrix)