Introduction to Dermatology and Epidermis Flashcards
What is the largest organ?
Skin
What are the seven functions of the skin?
- Beauty
- Barrier
- Vitamin D Synthesis
- Water Homeostasis
- Thermoregulation
- Insulation/ Calorie Reservoir
- Touch/ Sensation
What type of skin always burns, but never tans?
Type I Fitzpatrick
What type of skin easily burns and tans minimally?
Type II Fitzpatrick
What type of skin initially burns and gradually tans?
Type III Fitzpatrick
What type of skin minimally burns and tans well?
Type IV Fitzpatrick
What type of skin rarely burns and tans dark?
Type V Fitzpatrick
What type of skin never burns and is always tan?
Type VI Fitzpatrick
What type of cells make up the epidermis?
Stratified squamous cells.
What two layers make up the dermis?
Papillary layer and the reticular layer
Name five adnexal structures?
- Apocrine glands
- Eccrine glands
- Hair
- Nails
- Sebaceous glands
What cells make up subcutaneous fat?
Adipocytes
What are two locations in which you can find thick skin?
Palms and the soles of feet
What converts 7-dehydrocholesterol to cholecalciferol (Vitamin D3)?
UVB in the skin
Cholecalciferol (Vitamin D3) and Ergocalciferol (Vitamin D2) are absorbed by what organ?
Intestine
Vitamin D2 and Vitamin D3 are converted to calcidiol (25-hydroxy Vitamin D) by what organ?
Liver
What is the active form of calcidiol? And what organ makes it active?
1,25-dihydroxy-Vitamin D is the active form and it is activated by the kidney
What are three cell types found in the epidermis?
- Keratinocytes (barrier layer)
- Melanocytes
- Langerhans Cells
Keratinocytes produce keratin. What is keratin?
Keratin is the intracellular fibrous protein of the skin.
Melanocytes are pigment producing cells. What is their embryologic derivative?
Neural crest cells
Where are melanocytes located?
Basal layer
Tyrosine gives rise to what color pigment?
Melanin
What are melanosomes?
Granules of melanin
What is the function of melanin?
Protection of DNA from UV light
What are Langerhans cells?
A type of dendritic cell in the epidermis derived from bone marrow stem cells
True or False: Skin color variation is due to the number of melanocytes in the skin.
False.
What two factors determine skin color variation?
- Due to the type of melanin produced
2. Due to the distribution of melanosomes
There are two types of melanin. What are they and what color?
- Eumelanin: black to brown pigment
2. Pheomelanin: Yellow to red brown pigment
Distribution of melanosomes lead to either light or dark skin. Describe the distributions that contribute to light and dark skin.
Light skin: melanosomes distributed in clusters above the nucleus
Dark skin: melanosomes distributed individually throughout the cytoplasm
What cells compose the stratum basalis?
Keratinocytes (stem cells)
Name three types of cellular attachments found in the stratum basalis.
- Hemidesmosomes
- Desmosomes
- Tonofilaments
What type of cellular attachment protein in the stratum basalis attaches the keratinocytes to each other?
Desmosomes
What type of cellular attachment protein in the stratum basalis attaches the basal cells firmly to the basal lamina of the dermal epidermal junction?
Hemidesmosomes
What type of cellular attachment protein in the stratum basalis inserts into the dense plaques of desmosomes on the cytoplasmic side of the plasma membrane?
Tonofilamets
What is the microscopic appearance of the stratum spinosum?
Prickly due to the desmosome attachment between cells.
In what layer does the synthesis of involucrin and membrane coating granules begin to develope?
Stratum spinosum
Keratohyalin granules are found in what layer?
Stratum granulosum
Keratohyalin gransules contain profilaggrin (filaggrin precursor). What is the function of filaggrin?
Filaggrin cross-links keratin tonofilaments and is important in the barrier funtion of the skin.
Ichthyosis and atopic dermatitis are cause by what mutated protein?
Filaggrin
Stratum lucidum is found in what type of skin?
Thick
True or False: Cells in the stratum lucidum do not have nuclei and organelles.
True
What is the outermost layer of the epidermis?
Stratum corneum
Meissner’s corpuscles are found in what layer of the dermis?
Papillary Layer
What is the function of Meissner’s corpuscles?
Senses fine touch
The reticular layer contains extensive collagen and elastic fibers. What corpuscles can be found in this layer?
Pacinian corpuscles
What is the function of Pacinian corpuscles?
Sense vibration, pressure, and touch
Meissner’s corpuscles consist of what types of cells?
Schwann cells and sensory nerve terminals wrapped by fibroblast and collagen
Meissner’s corpuscles are found in what type of skin?
Thick
Pacinian corpuscles are found in what type of skin?
Both thick and thin
What type of sweat glands are located in the axillary, pubic and perianal regions?
Apocrine sweat glands
When do apocrine sweat glands begin functioning?
Puberty
What leads fluids, produced by apocrine glands, to create odor?
Bacterial interaction with the secretions
Eccrine sweat glands are distributed over most of the body except:
Lips, under nails, glans penis, glans clitoris, and labia minora
What is the role of eccrine sweat glands?
Thermoregulation
What type of gland produces watery, enzyme-rich, isotonic secretions?
Eccrine sweat glands
Hair consists of what two structures?
Central medulla of soft keratin and a cortex and cuticle of hard keratin
How long is the growth period of hair?
2-3 Years
What muscle, when contracting, allows the hair to stand on end?
Arrector pili (smooth muscle)
Sebaceous glands produce what type of oil substance?
Sebum (mixture of lipids)
Development of sebaceous glands is accelerated by what event?
Puberty
