Textbook Question
Identify the different portions (a–d) of the cutaneous membrane and the underlying layer of loose connective tissue (e) in the diagram to the right.
a. ____
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5. Integumentary System
The Epidermis: Cells
2:50 minutesProblem 15
Textbook Question
In which layer(s) of the epidermis does cell division occur?
Verified step by step guidance1
Understand the structure of the epidermis: The epidermis is the outermost layer of the skin and is composed of several sublayers. These layers include (from deepest to most superficial): stratum basale, stratum spinosum, stratum granulosum, stratum lucidum (only in thick skin), and stratum corneum.
Identify the layers involved in cell division: Cell division primarily occurs in the deepest layers of the epidermis, specifically the stratum basale and, to a lesser extent, the stratum spinosum. These layers contain keratinocytes that are actively dividing to replace cells lost from the surface.
Focus on the stratum basale: The stratum basale (also called the basal layer) is a single layer of cuboidal or columnar cells. It contains mitotically active basal cells that divide to produce new keratinocytes. These keratinocytes migrate upward through the layers of the epidermis.
Consider the stratum spinosum: The stratum spinosum (also called the prickle cell layer) is located just above the stratum basale. While cell division is less frequent here, some keratinocytes in this layer may still divide, contributing to the replenishment of the epidermis.
Summarize the key layers: Cell division occurs primarily in the stratum basale and occasionally in the stratum spinosum. These layers are essential for maintaining the integrity and function of the epidermis by continuously producing new cells.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Epidermis Structure
The epidermis is the outermost layer of the skin, composed of multiple layers of cells. It is primarily made up of keratinocytes, which are responsible for the production of keratin, a protein that provides protection. Understanding the structure of the epidermis is essential to identify where specific functions, such as cell division, occur.
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Stratum Basale
The stratum basale, or basal layer, is the deepest layer of the epidermis where active cell division takes place. This layer contains stem cells that continuously divide to produce new keratinocytes, which then migrate upwards to replenish the skin surface. Recognizing the role of the stratum basale is crucial for understanding the regeneration of the epidermis.
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Stratum Spinosum
The stratum spinosum, or spiny layer, is located above the stratum basale and also plays a role in cell division, albeit to a lesser extent. Cells in this layer begin to flatten and start the process of keratinization. Understanding the function of the stratum spinosum helps clarify the overall process of skin renewal and the transition of cells as they move towards the skin's surface.
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