Skin-Csoka Flashcards
List the constituents of the following:
Papillary Dermis
Reticular Dermis
Hypodermis
Papillary Dermis: loose connective tissue
Reticular Dermis : DICT, type I collagen, elastic fibers
Hypodermis: adipose tissue, loose connective tissue
What type of tissue is present in the epidermis and dermis?
Epidermis: epithelial
Dermis: connective tissue
Vitamin D is produced by the penetrance of UV light.
UV light is involved in several other regulatory function
Epidermis is keratinized stratified squamous epithelium with what 5 layers?
basement membrane
stratum basale: keratinocyte cells are generated here
stratum spinosum
stratum granulosum
stratum lucidum: thin layer of clear cells
stratum corneum: the keratinized thick layer
Melanin is less abundant in thick skin. True or false?
True
Thick skin (palms, soles of feet) lack hair and sebaceous glands.
As you move up from the _______________, the cells are essentially differentiating as you’re moving upwards. The keratin is synthesized as you’re moving upwards coinciding with differentiation.
stratum basale
Keratinocytes in skin undergo distinct stages of differentiation that are found in distinct layers of the skin
What is the epithelium of epidermis?
keratinized stratified squamous epithelium
What is another term for skin?
integument= cutaneous layer
The skin is the largest organ in the body. True or false?
True!!
What is the difference between thick and thin skin?
The layers of the epidermis of thin skin are not defined as in the thick skin. Thick skin has a thicker S. corneum and pronounced S. granulosum. Thick skin also has sweat glands.
Thick skin has no hair follicles or sebaceous (oil) glands and is less pigmented. Ridges that hold epidermis to dermis are higher to resist shear.
What are the type of cells in thick skin for the following?
- S. Basale
- S. spinosum
- S. Granulosum
- S. lucidum
- S. Corneum
- S. Basale: stem cells; attached to the basement membrane
- S. spinosum: spiny (due to desmosomes)- keratinization begins
- S. Granulosum: hydrophobic lipid envelope
- S. lucidum: translucent appearance
- S. Corneum: dead cells
What attached keratinocytes to each other and to the basement membrane?
desmosomes
hemidesmosomes
What warps around the type IV collagen and hooks it to the dermis?
anchoring fibrils
What type of collagen is present in the dermis?
Type I and III
What is responsible for the spiny characteristic of stratum spinosum?
desmosomes
its appearance enhanced by dehydration and fixing as compared to in vivo; visible with both light and electron microscopes
The cells of S. granulosum stain darker due to the presence of granules which contain what? What is its function?
filaggrin which links tonofibrils together to form dense bundles of keratin that fill the cell
What is the function of keratohyaline granules?
dehydration of the cell and promotion of crosslinking of keratin fibers
How is fillaggrin made?
profilaggrin is first highly phosphorylated by kinases; when it is cleaved into filaggrin, phosphate groups are removed by phosphates
the filaggrin will then crosslink the keratin to get the layer of the S. corneum
S. Granulosum also contain this which allows for a semi-permeable barrier?
lamellar bodies with the lipid rich secretion
S. Granulosum also contain this which contains a lipid-rich secretion that is expelled into extracellular space and waterproofs the skin. Barrier is semi-permeable which is very important in pharmacology.
lamellar bodies
Stratum corneum contains this which helps to stabilize the cell membrane of the dead keratinocyte.
involucrin helps to stabilize the cell membrane in the absence of the nucleus
Stratum corneum contains this which helps to stabilize the cell membrane of the dead keratinocyte.
involucrin which helps to stabilize the cell membrane in the absence of the nucleus
This abnormality of epidermal keratinocytes generates abnormal keratinocytes and differentiation.
psoriasis
- keratinocytes reach the surface in 3-5 days instead of 30 (normal)
- thickening of the S. corneum –> microabscess in the epidermis
- influx of lymphocytes into the dermis
- angiogenesis like phenomenon occurring as well
This class of abnormality of epidermal keratinocytes is an autoimmune disease or keratin mutations. Give examples.
blistering diseases:
- bullous pemphigoid: autoimmune attack to hemidesmosomes
- pemphigus vulagaris: autoimmune attack to desmosomes; prominent in the oral cavity
- epidermolysis diseases: mutation of keratin or hemidesmosome structures; defect in anchoring between epidermis and dermis
This abnormality of epidermal keratinocytes is due to the lack of sun, high latitudes, winter, and poor diet. Give examples.
vitamin D deficiencies:
- osteomalacia: lack of bone mineralization in ADULTHOOD; softened bones
- Rickets: lack of bone mineralization in CHILDHOOD
What systems does vitamin D deficiency affect?
brain: depression, schizophrenia
Respiratory: asthma, wheezing
Circulatory: high BP, coronary heart disease
Muscle: aches, weakness, Crohn’s dz, multiple sclerosis, rheumatoid arthritis
Bone: rickets, osteomalacia, cancer, influenza, tuberculosis
Pancreas: Type I diabetes
What are the 3 main types of non-keratinocytes found in the epidermis and are of importance?
- melanocytes: pigment producing cells from neural crest
- langerhans cells: antigen presenting dendritic cells from bone marrow
- merkel cells: mechanoreceptors, from neural crest
Melanocytes and merkel cells indistinguishable in an H& E slide (Both are found in the S. basale)
Langerhans cells are found in the S. spinosum or higher
What are the two types of pigment produced in melanocytes?
eumelanin= brown/black pheomelanin= red
Melanosomes are primarily taken up by what?
keratinocytes as opposed to melanocytes
-melanocyte synthesize the melanosomes which are transported on dendrites and phagocytosed by keratinocytes
What is significant about melanin?
-protection against UV light
What amino acid is converted to melanin?
tyrosine
Where are melanosomes degraded?
in the upper layers of the skin within lysosomes
UV light_________ the production of melanin by the secretion of melanocyte stimulating hormone (MSH) in the pituitary gland.
increases