Skin layer overview Flashcards
What are the 3 layers of the skin?
epidermis, dermis, subcutis
What are the primary skin cells of the epidermis?
keratinocytes (primary), melanocytes, langerhans, Merkel cells
What is an important feature the epidermis lacks?
no blood vessels or nerve endings
What layer is primarily made of fibroblasts, collagen, and elastic cells?
dermis
If you were to bleed from a pencil stick, what layer are you in at minimum?
dermis
What layer of skin contains the fat?
subcutis
What is also found in the subcutis layer?
blood vessels and fibrous septae
What is the primary job of the epidermis?
primary barrier fxn, protection, and wound healing
What are the jobs of teh dermis and subcutis?
structural support, vascular support, innervation
How long does it take for a new epidermal layer to grow?
28+ days
What part of the epidermis do stem cells grow?
basal layer (shed from surface)
Describe the differentiation of the stem cells from the basal layer
cells terminally differentiate as they move upward
What is the order of the layers in the epidermis? (outside-in)
corneum, granulosum, spinosum, basale
What is important about hemidesmosomes?
basal cells adhere to the dermis (basement membrane zone) via hemidesmosomes
As the cells that are migrating from the basale layer to the spinous layer, what is important about their growth?
they stop dividing and start terminal differentiation
As the cells of the spinous layer develop, what improves the barrier function of the skin?
develops lipid from lamellar granules
Where are desmosomes located?
spinous layer of the skin
What is the function of the desmosomes?
spiny cells that adhere the KC to one another
The granular cell layer synthesizes what to be used in the outer cell layers?
profilaggrin
What type of granules are synthesized in the granular cell layer?
intracellular keratohyaline granules
What would be histologically prevalent of the stratum corneum?
nuclei and organelles degenerate, cells flatten
Another water barrier is in the stratum corneum. Describe it
profilaggrin processed into filaggrin that combines with keratins to form macrofibrils creating a protective layer
T/F stratum corneum is different at different locations throughout the body
true
What are the bricks of the stratum corneum?
flattened keratinocytes filled with keratin and filaggrin
What is the mortar of the stratum corneum?
lipid mix surrounding keratinocytes providing a water barrier
What forms the intermediate filaments?
keratins combining
What is significant about keratin and its function?
pairs differently to stabilize the cell against stress (different in different locations)
Melanocytes produce pigment. Where are they derived from? What is their function?
neural crest cells=> transfer melanin to surrounding keratinocytes
Where are melancocytes found?
living with the basal cells and stretching into the spinosum layer
Which skin cell is important in allergic reaction AND tumor/antigen surveillance? where does it live?
Langerhans cells and mid-epidermis
What is an epidermal cell that that is associated with light touch sensation?
Merkel cells
What is the primary function of the dermis?
support layer that varies in thickness
What structures can be found in the dermis?
vasculature, nerves, sweat and oil glands, hair follicles
What is the primary cell in the dermis? What is its origin?
fibroblasts and mesenchymal origin
What is the responsibility of the fibroblasts in the dermis?
synthesis and degration of connective tissue proteins (collagen, elastin, GAGs)
An injury to the skin triggers the mitotic activation of which cells?
fibroblasts (wound healing and scar formation)
Which cells located in the skin are associated with wound healing and allergic reactions?
mast cells (wheal and flare rxn)
Hair follicles extend through dermis into what? what does each follicle have associated with it?
hair follicles extend through dermis into subcutis and oil gland is associated
What does the pilosebaceous unit consist of?
hair follicle, sebaceous gland, apocrine sweat glands, arrector pili muscle
What are the “true” sweat glands and where are they?
Eccrine sweat glands are located throughout the body
Where do the eccrine sweat glands open and what is their fxn?
open directly onto the skin and regulate temp by evaporative cooling of sweat
What is the fat layer that separates the dermis from the underlying structures?
subcutis
What is the role of the subcutis?
insulation, energy source, injury protection
What is the normal response to sundamaged cells?
apoptosis of keratinocytes
What occurs if the hemidesmosomes are damaged or altered?
Bullous pemphigoid
If the desmosomes of the spinous layer are damaged, what is the result?
pemphigus vulgaris
Genetic defects in filaggrin is assocated with what disease and what layer of the epidermis?
atopic dermatitis and stratum corneum
What is a genetic mutation in keratin 5/14 associated?
epidermolysis bullosa simplex
What will be the clinical Sx of epidermolysis bullosa simplex?
blisters due to K5/14 filament mutation not allowing the hemidesmosome and basal KC attachment
What is a nevus?
Mole=> benign collection of melanocytes
What is a melanoma?
growth of malignant melanocytes
What are diseases that are associated with the subcutis?
panniculitis
