Anatomy and Physiology of the Skin and Soft Tissues Flashcards
Layers of Skin
1. Epidermis
Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinosum
Stratum basale
2. Basement membrane - dermal epidermal junction
3. DermisWhere do you find stratum lucidum?
Only in the sole of the feet, the palm of the hands and on the fingertips
How thick is stratum granulosum?
Only 2-5 cell layer thick (usually 3)
What cells are found in stratum granulosum?
Keratinocytes and Langerhans cells. These cells are also found in the stratum spinosum.
What are desmosomes?
Desmosomes are proteins that connect the cells on the sides (both the lateral sides and above and below sides)
What are the cells in the epidermis?
Keratinocytes, Merkel cells, Langerhans cells, melanocytes
What is special about the stratum basale?
It is the only metabolically active layer of the epidermis. Also called stratum germinosum. This layer contains the keratinocytes, melanocytes and Merkel cells. It is a single layer of epidermal cells.
What are keratinocytes?
Made up 80% to 90% of cells in the epidermis. The terminally differentiated keratinocytes are called corneocytes: flattened cells, no nucleus or cytoplasm. The keratinocytes differentiate into corneocytes in the stratum granulosum.
What are Merkel cells?
One of the 4 cell types found in the epidermis of the skin, associated with touch receptors. These cells are attached to keratinocytes by desmosomes.
What are Langerhans cells?
One of the 4 cell types found in the epidermis. These cells are in the stratum spinosum and are bone marrow-derived and important in the immune function of the skin.
What are the functions of the epidermis?
- Protect from water loss
- Provides a mechanical barrier to the invasion of bacteria and other pathogens (acid mantle, shedding of skins to keep bioburden at a tolerable level)
- Protects from shear, friction and toxic irritants
- Synthesis of vitamin D
- Provides pigmentation
what is the basement membrane zone?
The basement membrane zone is the dermal-epidermal junction.
What does the basement membrane contain?
- Fibronectin (an adhesive glycoprotein)
- Type IV collagen (a non-fiber forming collagen)
- Heparin Sulfate proteoglycan
- Glycosaminoglycan
What is the function of the basement membrane zone?
It anchors the epidermis to the dermis with the Retes ridges or Rete pegs which are protrusions of epidermis into the dermis. The height of these ridges tends to decline with age: 55% from 3rd to 9th decades of life.
What is the dermis?
The dermis is the 2nd layer of the skin, below the epidermis. It is 2 mm - 4 mm thick. It is the bulkiness layer of the skin. It is vascularized and innervated.
What are the major proteins in the dermis?
The major proteins in the dermis are collagen and elastin.
What are the two different areas of the dermis?
Papillary dermis and Reticular dermis
What is the papillary dermis?
The papillary dermis in the top portion of the dermis where the dermis interweaves with the rete ridges from the epidermis. The papillary dermis and the rete ridges combine to form the dermal papillae. In the dermal papillae, there is a small capillary loop which supplies oxygen and nutrients to the epidermis.
There are also pain touch receptors in the papillary dermis.
What composed the papillary dermis?
The papillary dermis is composed of collagen and reticular fibers.
What is the reticular dermis?
The reticular dermis is the lower portion of the dermis. It is composed of collagen and cutaneous blood vessels.
What are the main dermal cells?
Fibroblast, Macrophages, Lymphocytes, Mast cells
What are fibroblasts?
Fibroblasts are the main connective tissue cells. They synthesize collagen, elastin and other extracellular matrix proteins.
What are macrophages?
The macrophages are monocytes that have differentiated and migrated into the tissues. They phagocytize bacteria and cellular debris and waste.
What are lymphocytes?
Lymphocytes are white blood cells which help to mediate the immune response in the skin.
