Integument Flashcards
What germ layer does epidermis come from?
Ectoderm
What germ layer does dermis come from?
mesoderm
irregular projections at epidermal-dermal junction
dermal papillae
What does the epidermis have that strengthens its adhesion to the dermis?
epidermal ridges
What does thick skin have that thin skin does not have?
a fifth layer- stratum lucidum
What are the 4 layers of epidermis in thin skin?
Stratum corneum, stratum granulosum, stratum spinosum, stratum basale
What is the predominant cell type of the epidermis?
Keratinocyte
How is the stratum basale bound apically?
by desmosomes
How is the stratum basale bound basally?
Hemidesmosomes
What is typically the thickest layer in epidermis?
Stratum spinosum
What type of cells are in the stratum spinosum?
polyhedral cells with central nuclei and spiny processes
Where do keratin filaments assemble into microscopically visible bundles called tonofibrils?
stratum spinosum
What are granules made up of?
tonofibrils and filaggrin
What are fully keratinized cornified cells called?
squames
What are melanocytes derived from?
Neural crest cells
Where are melanocytes found?
Scattered along the stratum basale
What are antigen presenting cells that provide defense against pathogens that are found in the epidermis?
Langerhans cells
What do langerhans cells develop from?
monocyte precursor
Where are langerhans cells identifiable?
Stratum spinosum
Epidermal cell replacement is initiated by what?
the division of stem cells in the stratum basale
What are the layers of the dermis?
papillary layer and reticular layer
What type of connective tissue makes up the papillary layer?
loose connective tissue
What type of connective tissue makes up the reticular layer?
dense irregular connective tissue with coarse elastic fibers
Where are langer’s lines formed?
reticular layer of the dermis
What is the subpapillary plexus?
a rich, nutritive capillary network located between papillary and reticular layers
What type of connective tissue makes up the hypodermis?
loose connective tissue
What does the extensive vasculature in the hypodermis promote?
rapid uptake of insulin or drugs injected into the tissue
Epithelial tactile cells that function as low-threshold mechanoreceptors which are essential for sensing gentle touch
merkel cells
Where are merkel cells abundant?
in highly sensitive skin such as the finger tips and hair follicles
What do merkel cells lack that keratinocytes have?
melanosomes
Where are free nerve endings located?
in the papillary dermis and they extend into the lower epidermal layers
What is the function of free nerve endings?
respond primarily to high and low temperatures, pain, and itching. May also function as tactile receptors
What are encapsulated receptors that are responsive to light touch or low frequency stimuli?
Meissner’s corpuscle
Where are lamellated (pacinian) corpuscles found?
deep in the reticular dermis and hypodermis; also found in CT of visceral organs, wall of the rectum, and urinary bladder
What are lamellated corpuscles specialized for?
sensing coarse touch, pressure (sustained touch) and vibration
How is sebum secreted?
holocrine secretion
simple, coiled glands found extensively throughout skin
eccrine sweat glands
What cells facilitate expulsion of secretion of eccrine seat glands?
myoepithelial cells
large-lumen, tubular glands
apocrine sweat glands
how do apocrine sweat glands secret sweat?
merocrine secretion
