Epidermal layers (order, location, function)
List the five layers of the epidermis in order from deep to superficial.
Stratum basale → Stratum spinosum → Stratum granulosum → Stratum lucidum (thick skin only) → Stratum corneum
Name two structural differences between thick and thin skin.
Thick skin has a stratum lucidum and thicker stratum corneum, and lacks hair follicles; thin skin lacks lucidum and contains hair follicles?
These cells produce keratin and make up most of the epidermis. Where are they found?
Keratinocytes, found in all layers of the epidermis
This is the deepest epidermal layer. Name the layer AND state what important process occurs here.
stratum basale, and it is where mitosis occurs
Which type of skin contains sebaceous glands, and why?
thin skin, because sebaceous glands are associated with hair follicles
These cells produce melanin. In which layer are they primarily located?
Melanocytes, located in the stratum basale
This layer appears “spiny” under the microscope. Why does it look that way?
What is the stratum spinosum, and it appears spiny due to desmosome connections between keratinocytes?
Which skin layer is avascular, and where does it receive nutrients from?
The epidermis, and it receives nutrients from diffusion from the dermis
These immune cells are found in the epidermis. What is their function
Epidermal dendritic (Langerhans) cells, and they function in immune defense
This layer contains keratohyalin granules. What layer is it, and what process is beginning here?
What is the stratum granulosum, and keratinization is beginning?
Which layer of skin contains blood vessels, glands, and hair follicles?
The Dermis
These cells function in light touch. Where are they located?
Merkel cells, located in the stratum basale
This layer is only found in thick skin. Where is thick skin located, and why does this layer exist there?
What is the stratum lucidum? Thick skin is found on the palms and soles, and this layer provides extra protection against friction.
Explain why thick skin is better adapted for friction.
Because it has a thicker stratum corneum and stratum lucidum for added protection?
How does melanin protect underlying tissues?
Absorbing UV radiation and protecting DNA from damage.