Integument Flashcards
Epidermis
Outermost layer of thick and thin skin
Dermis
Connective tissue layer beneath the epidermis that contains specializations like hair. It is connected through the basement membrane.
Hypodermis
Adipose tissue layer that is not part of the integument
Thin skin
Most of the body is covered with thin skin. It contains all layers of the epidermis except the stratum lucidum. The layer of corneum is very thin compared to thick skin.
Thick skin
Thicker layer of skin present in areas of the body like the palms of the hand and soles of the feet. It has a thicker stratum corneum and contains the stratum lucidum layer.
Keratinocytes
Most abundant type of cell in the epidermis that is present within each layer. They contain keratin (intermediate fibers) filaments and are connected to each other by desmosomes.
Langerhan’s cells
Cells within the epidermis that can act as antigen presenting cells and phagocytes. They are derived from monocytes and act as early immunoresponders to bacteria that breaks through the skin.
Merkel cells
Cells within the epidermis that are associated with free nerves and have a sensory role in the skin.
Melanocytes
Cells located within the stratum basale that give rise to pigmentation by synthesizing melanin contained in granules.
Layers of the epidermis
From the bottom up:
- Basale
- Spinosum
- Granulosum
- Lucidum (thick skin)
- Corneum
Stratum basale
Deepest and most active (mitotically) layer that is attached to the basement membrane and separates the epidermis from the dermis. The cells are connected to each other by desmosomes (contains cadherin) and connected to the basement membrane by hemidesmosomes (contains integrin).
Stratum spinosum
Spiny cell layer of the epidermis. It is an artifact of tissue shrinkage during preparation because the cytoplasm shrinks during dehydration of cell prep. Desmosomes hold onto the adjacent cell which gives rise to the spiny appearance.
Stratum granulosum
Layer that contains granules in the cytoplasm. The two types of granules are keratohyalin and lamellar cells.
Stratum lucidum
First dead cell layer of the epidermis that is clear and contains compressed, dead squames. It is present in thick skin, but not thin skin.
Stratum corneum
Outermost layer of the epidermis that contains dead keratinocytes. It acts as a barrier for desiccation and prevents infection from bacteria.
- It is thicker in thick skin, thinner in thin skin
Keratohyalin
Non-membrane bound granules within the stratum granulosum