Biology of the Skin Flashcards
What the three layers of the skin?
Epidermis, Dermis, Subcutis
Epidermis is primarily composed of what type of cell>
Keratinocytes
Also some melanocytes, Langerhans cells, Merkel cells
The Dermis is primarily composed of what types of cells
Fibroblasts, collagen, Elastin
Also contains blood vessels and nerve endings
The subcutis is primarily composed of
Fat
Also some blood vessels and fibrous septae
Primary function of the epidermis
Primarily for wound healing and barrier function
Dermis and subcitis
Structural support and innervation
Epidermis sheds itself every 28 days
truth
Epidermis consists of how many sublayers?
4 They are: Stratum Corneum (top layer) Stratum granulosum Stratum spinosum Stratum basale
Stratum basale contains
stem cells, Basal cells adhere to the dermis via hemidesmosomes
What occurs in the corpus spinosum
Cells stop dividing and commence terminal differentiation.
Develop lipids important in barrier function.
What makes the corpus spinosum spiny?
Desmosomes linking Keratin cells.
What is fillaggrin
Present in the stratum corneum, helps keep water inside cells.
Keratins combine with filaggrin into macrofibrils that help create a protective barrier
Brick and mortar analogy
Stratum corneum is a brick wall. The keratinocytes filled with keratin and filaggrin make the bricks and the mortar is a lipid mixture surrounding the keratinocytes providing a water barrier.
The lipids in the brick and mortar analogy come from where?
lamellar granules
Keratin contains what that makes it smell bad when burnt?
Sulfur containing cysteine
What are melanocytes
pigment producing cells. There is about one melanocyte for every 10 keratinocytes
What are Langerhans cells
Dendritic cells in the mid-epidermis. They recognize abnormal antigens in the skin, take them in, process them, present them
Primary cell in the dermis
Fibroblast
Fibroblasts are responsible for
Synthesis and degradation of connective tissue proteins like collagen, elastin, glycosaminoglycans, other glycoproteins.
Injury to skin triggers mitosis of fibroblasts.
They are responsible for would healing and scar formation
Mast cells
specialized cells rich in heparin and histamine
Mast cells release heparin and histamine when?
When they are triggered by injury or binding to IgE antibodies during allergic reaction
What is a pilosebaceous unit
The “hair/oil” unit. Contains a hair follicle, oil gland, apocrine sweat gland( only if in the axilla and anogenital region) and arrector pili muscle
Eccrine sweat glands
True sweat glands, open thoughout the body, not associated with a hair follicle
What is the subcutis
a fat layer that separates the dermis from underlying structures like the fascia, muscles, organs.
What is the role of apoptosis in the epidermis
Normal response to sundamaged cells. Sundamaged keratinocytes are called sunburn cells. Failure to delete these damaged cells can be skin cancer.
Epidermolysis Bullosa Simplex is a disease caused by a genetic mutation in what
Keratin 5/14
What is a Nevus?
A mole…it is just a benign collection of melanocytes
What is melanoma
A malignant collection of melanocytes
