Unit III Flashcards
What are the functions of skin?
decoration/beauty barrier vitamin D synthesis water homeostasis thermoregulation insulation/calorie reservoir touch/sensation
What type of melanin produces black to brown pigment?
Eumelanin
*Eutopia!
What type of melanin produces yellow to red-brown pigment?
phenomelanin
Where do light skin melanocytes cluster?
top of nucleus
Where can you find dark skin melanocytes in the cell?
**larger and evenly distributed throughout the cytoplasm
Where do hair follicles originate?
In the subcutaneous fat
Name the four layers of the skin starting from the most superficila layer
stratum corneum
stratum granulosum
stratum spinosum
stratum basalis
What is the stratum granulosum comprised of?
Has Keratohyalin granules and inside granules you have profilaggrin which is a precursor to filaggrin
Where can you find profilaggrin?
In keratohyalin granules
What is the function of filaggrin?
Filaggrin cross-links keratin tonofilaments and is important in the barrier function of the skin. Filaggrin is mutated in dry skin conditions including ichthyosis and atopic dermatitis.
What is the function of the stratum spinosum?
Has a “prickly” or spiny appearance due to desmosome attachments between cells
What are tonofilaments?
protein structures (keratin filaments) that insert into the dense plaques of desmosomes on the cytoplasmic side of the plasma membrane
What is the function of a desmosome?
attaches keratinocytes to each other
What is the function of a hemidesmosome?
attach basal cells firmly to the basal lamina of the dermal
epidermal junction
Difference between desmosome vs hemidesmosome?
desmosome is attachment between cells
hemidesmosomes are attachments to the basal lamina of the dermal epidermal junction (deeper in the cell)
What type of cells are found in the stratum basalis?
keratinocytes - either a single layer cuboidal or columnar
stem cells of the epidermis found here
What is the stratum lucidum?
- a thin, light staining band seen only in thick skin
- cells of this layer no longer have nuclei or organelles
- between the stratum corneum and granulosum
Where in the dermis is the capillary network that is blood supply for epidermis?
the papillary layer
What part of the dermis is the pathway for defense cells?
the papillary layer
What are Meissner’s corpuscles and where are they found?
sensory cells found in the papillary layer of the dermis
Senses **fine touch and tactile discrimination
What part of the dermis contains extensive collagen and elastic fibers that provide strength and flexibility?
The reticular layer
Where in the dermis do epidermal derivatives such as glands and hairs and plays a major role in their development and functioning?
The reticular layer
What part of the dermis has a pathway for major blood vessels arranged specifically to facilitate thermoregulation?
the reticular layer
What part of the dermis has a site of nerve tracts and major sensory receptors?
the reticular layer