Epidermis

Definition

The epidermis is the outermost layer of the skin, serving as a protective barrier against environmental threats and pathogens. It is composed primarily of keratinocytes and lacks blood vessels.

5 Must Know Facts For Your Next Test

1. The epidermis contains multiple layers, including the stratum corneum which provides a tough barrier against pathogens.
2. Keratinocytes in the epidermis produce keratin, a protein that strengthens the skin's protective barrier.
3. Langerhans cells within the epidermis play a crucial role in detecting and presenting antigens to immune cells.
4. The epidermal layer undergoes constant renewal, with old cells shedding off as new ones form from the basal layer.
5. Normal microbiota on the epidermis help prevent colonization by pathogenic microbes through competitive inhibition.

Review Questions

• What role do keratinocytes play in the function of the epidermis?
• How does the stratum corneum contribute to innate nonspecific host defenses?
• What is the significance of Langerhans cells in the immune response?

Related terms

Dermis:

The thicker inner layer of skin beneath the epidermis, containing blood vessels, nerves, and connective tissue.

Keratinocyte: A type of cell found in the epidermis responsible for producing keratin.

Langerhans Cell: A type of dendritic cell in the epidermis involved in antigen presentation to T-cells.