Anatomy & Physiology Integumentary #8


Which layer of the epidermis is the location where the process of surface keratin formation begins?


  1. Stratum basale
    • Rationale:

      The stratum basale is a single layer of columnar cells. Keratin formation does not begin in this layer of the epidermis.

  2. Stratum corneum
    • Rationale:

      While keratin is contained in the stratum corneum, this is not the layer of the epidermis where keratin formation begins.

  3. Stratum spinosum
    • Rationale:

      Cells in stratum spinosum are rich in ribonucleic acid (RNA); therefore, they are well equipped to initiate the protein synthesis that is required for the production of keratin. However, surface keratin formation does not begin here.

  4. Stratum granulosum
    • Rationale:

      The process of surface keratin formation begins in the stratum granulosum. Keratohyalin is located within the cells of this layer of the epidermis and are required for the formation of surface keratin.


Keratin protects the skin from dehydration and its formation begins in the epidermis.


Learning Outcomes

The cells of the epidermis are found in five distinct layers, or strata. Each layer is named for its functional or structural characteristics. The strata of the epidermis are listed below in order from most superficial to the deepest. The layers are as follows:
Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinosum
Stratum basale.
Surface keratin formation begins in the stratum granulosum.

Test Taking Tip

Try to eliminate choices as incorrect based on your knowledge. By doing this, you will not be guessing randomly but will be exercising “informed guessing.”

Video Rationale