What Are the Functions and Layers of Epidermis and Dermis?
Tissue Type of Epidermis and Dermis
Epidermis and dermis are the layers of the human skin. It is the body's largest organ and plays a crucial role in the overall health and well-being of the body. Skin acts as a barricade between the internal environment and the external environment of the body. The outermost care of the skin is essential. It is necessary to understand the different structures and functions of each layer of skin for taking good care of the skin. The skin surface is made up of different tiers and divided into three main layers: epidermis, dermis, and hypodermis. Let us learn in-depth what epidermis and dermis, the two most important layers of the skin is.
What is Epidermis?
The epidermis is the topmost layer of the skin. It is around 0.05 to 1.5 mm thick. The epidermis is made up of several cells. Keratinocytes cells are found abundantly in the epidermis layer of the skin. Another type of cell is melanocytes that are produced by the corns of the colour. The substance melanin provides the tone to the skin. The third type of cell found in this layer is Langerhans; these cells interact with the white blood cells and act as the immune defense.
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Layer of Epidermis
Let us also discuss the deepest to the most superficial layer of the epidermis.
Stratum Basale
It is the deepest layer of the skin where mitosis occurs. It is the process where cells divide, making new epidermal skin cells. After the division of mitotic the cell undergoes keratinization, a process of progressive cell maturation and migrating to the surface of the skin.
Stratum Spinosum
The cells generating from stratum basale accumulates quickly in this layer through desmosomes (structure joining adjacent cells together)
Stratum Granulosum
As the cells mature and undergo keratinization, it accumulates in this layer and gathers dense granules of basophilic keratohyalin.
Stratum lucidum
Depending on the frictional forces, this layer varies throughout the body. Stratum lucidum, in its thickest form, is found on the palms of the hands and soles of the feet.
Stratum corneum
The layer contains dead and dying cells that are full of mature keratin as it is the outermost layer of the epidermis. The cells change the substance and break the complex chemicals within the cells that causes their death.
What is Dermis?
After the topmost layer, the next middle layer of the skin is the dermis. It is around 0.3 to 3.0 mm thick. This layer consists of connective tissues. The layer consists of some essential components like firmer protein collagen and the fibres of elastic protein. Moreover, this layer contains various immune cells and factors that protect the skin.
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Layer of Dermis
There are only two layers of the dermis, and those are as follows:
Papillary Dermis
The layer consists of areolar connective tissues, dermal papillae that enhances the surface area of the layer, and ridges that extend into the epidermis and dermal papillae. The ridges are responsible for the fingerprints on objects when touched.
Reticular Dermis
The layer consists of dense connective tissues that contain interlacing bundles of elastic fibres and collagen. In between these fibres, there are small quantities of hair follicles, adipose tissue oil glands, nerves, and sweat gland ducts.
Difference Between Epidermis and Dermis
Let us learn the difference between epidermis and dermis based on specific characteristics.
Blood Vessels
Epidermis – The epidermis layer does not contain blood vessels. The oxygen and nourishment they get are from the deeper layers.
Dermis – Dermis layer has a thin network of blood vessels known as capillaries; they are densely located under the epidermis.
Nerves
Epidermis – This layer does not contain nerves.
Dermis – It contains nerves that conduct nerve impulses through the central nervous system towards the brain. The open nerve endings of this layer originate the sense of pain.
Functions
Here are some of the functions of the epidermis layer
It is a barrier between the internal structure and the external environment of the body.
It does not allow the entrance of microorganisms, water, and other substances.
It protects the internal atmosphere of skin from UV rays of the sun and other pollutants.
Functions of The Dermis Layer
It gives skin strength, extensibility, elasticity, and firmness.
Helps provide nutrients and oxygen to the outer layer of the skin
Has antibodies that fight hazardous substances and microbes
The layer initiates the process of inflammation during skin injury to increase the blood in the bloodstream. It makes the immune cells navigate conveniently to fight microorganisms.
FAQs on Difference Between Epidermis and Dermis Explained
1. What is the primary difference between the epidermis and the dermis?
The primary difference lies in their position, structure, and function. The epidermis is the outermost, thin, avascular (lacking blood vessels) layer of the skin that serves as a protective barrier. In contrast, the dermis is the thicker layer directly beneath it, which is rich in blood vessels, nerves, glands, and hair follicles, providing structural support and nourishment to the skin.
2. Why is the dermis often called the "true skin"?
The dermis is called the "true skin" because it performs most of the skin's vital physiological functions. While the epidermis is mainly for protection, the dermis contains:
Blood vessels that nourish the epidermis.
Nerve endings for sensations of touch, pressure, and pain.
Glands such as sweat and sebaceous (oil) glands.
Hair follicles from which hair grows.
Collagen and elastin fibres that provide strength and elasticity.
3. How does keratin make the epidermis tough and protective?
Keratin is a fibrous structural protein that makes the epidermis tough and waterproof. The cells of the outermost layer of the epidermis, the stratum corneum, are dead and densely packed with keratin. This creates a durable, resilient barrier that protects underlying tissues from physical damage, microbial invasion, and dehydration.
4. Do tattoos go into the epidermis or the dermis? Why is this important?
Tattoos are injected into the dermis, not the epidermis. This is crucial for their permanence. The cells of the epidermis are constantly being shed and replaced, so any ink placed there would disappear within a few weeks. Because the dermis is a much more stable layer, its cells trap the ink particles, making the tattoo long-lasting.
5. What are the main layers of the skin, including the epidermis and dermis?
The skin is primarily composed of three main layers:
Epidermis: The outermost, protective layer that acts as a barrier.
Dermis: The middle layer, containing glands, nerves, and blood vessels.
Hypodermis (Subcutaneous Layer): The deepest layer, made mostly of fat and connective tissue, which insulates the body and attaches the skin to underlying muscles.
6. What is the difference between the terms 'epidermis' and 'epidermal'?
The terms refer to the same part of the skin but are different parts of speech. 'Epidermis' is a noun, referring to the outermost layer of the skin itself (e.g., "The epidermis protects the body."). In contrast, 'epidermal' is an adjective used to describe something related to or originating from the epidermis (e.g., "Epidermal cells are constantly shedding.").
7. What structure connects the epidermis to the dermis?
The epidermis is connected to the dermis by a specialised structure called the basement membrane, also known as the dermal-epidermal junction. This thin, fibrous layer anchors the two layers together, preventing them from sliding past each other and, crucially, allowing for the transfer of nutrients from the dermis to the avascular epidermis.
8. What are the main types of cells found in the dermis?
The dermis is a complex layer containing several important cell types. The most prominent are fibroblasts, which produce the collagen and elastin fibres that give the skin its strength and flexibility. Other key cells include macrophages and mast cells, which are part of the immune system and protect against pathogens that get past the epidermis.
9. Can the epidermis function without the dermis? Why or why not?
No, the epidermis cannot function independently. The epidermis is avascular, meaning it has no blood vessels of its own. It relies entirely on the rich blood supply of the dermis for nourishment, oxygen, and waste removal, which diffuse across the basement membrane. Without the supportive dermis, the epidermal cells would quickly die.
10. What are the main functions of the epidermis?
The epidermis serves several critical functions, primarily related to protection. Its key roles include:
Physical Barrier: Shielding the body from pathogens, UV radiation, and physical trauma.
Waterproofing: Preventing water loss from the body due to the presence of keratin.
Skin Tone: Containing melanocytes, the cells that produce melanin pigment, which determines skin colour and provides UV protection.
Sensation: Housing special sensory cells like Merkel cells, which are associated with the sense of touch.
