Skin Flashcards
In which epidermal layer are cells undergoing mitosis?
Stratum basale/Stratum germinativum
The malphigian layer is another name for which epidermal layer?
Stratum basale/Stratum germinativum
What are the nodes of Bizzozero?
Slight thickenings at the site of desmosomes between keratinocytes in the stratum spinosum as seen with a light microscope
What are tonofilaments?
bundles of groups of keratin intermediate filaments
In which epidermal layer do cells begin to die by losing their nuclei and cytoplasmic organelles?
Stratum granulosum
What is the functional importance of the contents of keratohyalin granules and lamellar granules?
Keratohyalin granules contain keratin and other related proteins while lamellar granules contain lipids. Both types of granules release their contents out of the keratinocytes in the stratum granulosum to form a sheet that acts as a barrier to penetration and prevents water loss
The amino acid from which melanin is synthesized is…?
Tyrosine
What causes Psoriasis?
When T-cells attack skin cells, causes skin to respond by producing more skin cells than are shed, resulting in a shiny scale-like appearance
In which epidermal layers are melanocytes located?
between stratum basale and stratum spinosum
Name 2 functions of melanin.
- Gives skin dark color
2. Protects cell nuclei from UV radiation
What is the mechanism behind Addison’s disease causing hyperpigmentation?
Adrenal gland fails to produce enough cortisol and aldosterone.
Pituitary gland compensates by producing ACTH which is derived from a precursor of MSH.
More MSH is produced so that there is more production of melanin pigment.
What is the precursor of Melanocyte Stimulating Hormone?
POMC - Propiomelanocortin
Differentiate Albinism from Vitiligo.
In albinism, the melanocytes are present but there is a defect in tyrosinase or in the metabolic pathway of melanin synthesis so no melanin produced.
In vitiligo, the melanocytes disappear completely.
Differentiate Malignant Melanoma from Merkel Cell Carcinomas.
Malignant Melanomas are cancers of melanocytes, while Merkel Cell Carcinomas are cancers of Merkel cells which are very rare.
Explain how melanin is synthesized.
- Tyrosinase converts tyrosine into DOPA (3,4-dihydroxyphenylalanine)
- DOPA undergoes polymerization into the different kinds of melanin
In which layer of the epidermis are Langerhans cells found?
All layers but most prominent in stratum spinosum
Epidermal pegs interdigitate with ______________ of the dermis.
Epidermal pegs interdigitate with dermal papillae of dermis
Differentiate Bullous Pemphigoid from Pemphigous.
In bullous pemphigoid, immune system attacks fibers connecting dermis and epidermis.
In pemphigous, immune system attacks desmosomes of keratinocytes.
State the difference in the connective tissue found in the dermal papillary versus the reticular layer?
Papillary layer; loose areolar CT
Reticular layer; dense irregular CT
What type of collagen is found in the papillary layer of the dermis?
Type 1, 3, and 7.
What plexus supplies the epithelium of the epidermis?
The subpapillary plexus that extends into the dermal papillae just below the epidermis.
What is the function of the arteriovenous anastomoses/shunts?
Thermoregulatory function; constriction during cold weather and dilation during hot weather
What is the difference between unencapsulated nerve endings and encapsulated nerve endings?
Unencapsulated nerve endings - have no collagenous covering or Schwann cells
Encapsulated nerve endings - have collagenous covering and/or Schwann cells
Name 3 types of unencapsulated nerve endings and their functions.
- Merkel cells - pressure and texture of objects
- Root hair plexuses - sense movement of hairs
- Free nerve endings - for pain, itching, and high/low temperature
