Epidermis: Superficial Layer of the Skin

Lesson Plan - Get It!

Audio:

If you haven't yet completed the first Related Lesson in our Skin series, pop on over to the right-hand sidebar now so you'll be ready for this lesson!

The epidermis is the top layer of your skin. This is the part of the skin you see. The epidermis is the outer layer that helps defend your body from invaders.

• Have you ever been around someone who has a cold but you didn't catch it?
• Did you know your skin has a lot to do with that?
• Have you ever noticed the pores in your skin?
• Did you ever get a pimple or a cold sore?

This is your body performing as it should, protecting you from parasites and bacteria!

• Can you think of a time where you had a cold or a skin issue?
• How did your skin feel of look?

Look at the diagram above, then stop and look at the back of your hand.

• Isn't it amazing that what is in the diagram above is right there on the back of your hand?

The epidermis that you see has several layers:

1. Stratum corneum Composed of 10 to 30 layers of corneocytes, surrounded by a protein filled with water-retaining keratin proteins attached together, most of the barrier functions of the epidermis are localized to this layer.
2. Stratum lucidum is the clear or translucent layer found only in the palms and soles. This skin is known as "thick skin" because it has 5 epidermal layers instead of 4.
3. Stratum granulosum is the granular layer, a thin layer of cells in the epidermis. The main function of keratohyalin granules is to bind intermediate keratin filaments together.
4. Stratum spinosum is composed of polyhedral keratinocytes that have large pale-staining nuclei. They are active in synthesizing fibrilar proteins, known as cytokeratin, that build up within the cells.
5. Stratum basale is composed of many keratinocytes, and is associated with cutaneous nerves, and seem to be involved in light touch sensation.
6. Basement membrane separates epidermis from the dermis.

Take another look at the back of your hand. Think about what you just learned about your skin.

• Are you thinking about it differently now?

Before moving on to the Got It? section, explain what type of skin is found only in the palms and soles.