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The epidermis and dermis are the parts of the human body's layer of skin that serves as the body's first line of defence against foreign particles. It is the human body's largest organ and serves as a barrier between the outside and inside environments. Dermis consists of the connective tissues, blood vessels, glands, hair follicles, etc and is situated at the inner part of the two main skin layers. Epidermis refers to the outermost layer of the human body that is visible to the eyes.
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Key takeaways: Epidermis, Dermis, skin, Blood vessels, Cells, Connective Tissue, Organs
Epidermis
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The epidermis forms the skin's outermost layer and is made up of keratinocytes, which are cells formed of a protein called keratin. The epidermis, which is made up of four layers, protects and safeguards the inside cells and tissues. The five layers of the epidermis include stratum basale, stratum spinosum, stratum granulosum, stratum lucidum and stratum corneum.
Function of Epidermis
- It serves as a barrier between the body's internal structure and its external environment.
- It prevents germs, water, and other substances from entering.
- It shields the skin's interior environment from the sun's UV radiation and other contaminants.
Layers of Skin
Dermis
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The dermis is the layer of the skin that lies beneath the epidermis. Dermis is made of up fat, fibres, collagen, and blood vessels which keeps the skin flexible and strong. When exposed to sunshine, the dermis is also involved in the manufacture of Vitamin D. They also play a role in body temperature regulation. The layers of dermis are papillary dermis and reticular dermis.
Function of Dermis
- It provides skin with strength, elasticity, and firmness.
- It assists in the transport of nutrients and oxygen to the skin's outer layer.
- It has antibodies that protect against harmful chemicals and microorganisms
- During a skin injury, the layer causes inflammation to increase the amount of blood in the bloodstream. It allows immune cells to traverse more easily in order to combat germs.
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Difference between Epidermis and Dermis
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| Epidermis | Dermis |
|---|---|
| An organism's outermost layer of cells that covers its body. | It is the layer of living cells below the epidermis consisting of nerve endings, blood vessels, sweat glands as well as hair follicle. |
| It does not contain any blood vessels | It comprises of a thin network of vessels called capillaries |
| Nerves are absent. | It's made up of nerves that carry nerve signals from the brain to the central nervous system. This layer's open nerve endings are the source of pain sensations. |
| It is found in both plants and animals. | It is found only in animals. |
| It receives necessary nutrients and oxygen from the dermis by diffusion. | It receives necessary nutrients and oxygen from the dermis by diffusion. |
Things to Remember
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- The layers of the human skin are epidermis and dermis. It is the body's largest organ, and it is vital to the body's overall health and well-being.
- The skin serves as a barrier between the interior and external environments of the body.
- The epidermis is the skin's outermost layer. It ranges in thickness from 0.05 to 1.5 mm. The epidermis is made up of several different types of cells.
- The dermis is the next middle layer of the skin after the epidermis. It ranges in thickness from 0.3 to 3.0 mm. Connective tissues make up this layer.
- The epidermis and dermis combine to produce the skin's fundamental bodily covering, both of which protect interior organs from dehydration, infections, and other harm.
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Sample Questions
strong>Ques. What is epidermis? (2 marks)
Ans. The epidermis is the skin's outermost layer, made up of cells called keratinocytes, which are formed of a protein called keratin. The epidermis, which consists of four layers, provides protection and safeguards the cells and tissues present inside.
Ques. What is dermis. (2 marks)
Ans. The dermis is the layer of the skin that lies beneath the epidermis. Fat, fibres, collagen, and blood vessels make up this layer, which keeps the skin flexible and strong. When exposed to sunshine, the dermis is also involved in the manufacture of Vitamin D. Dermis also helps in regulating the temperature of the body.
Ques. What is the thickness of dermis and epidermis? (2 marks)
Ans. The thickness of epidermis ranges from 0.05 to 1.5 mm and the thickness of dermis ranges from 0.3 to 3.0 mm.
Ques. Write the function of epidermis. (3 marks)
Ans. The functions of epidermis are:
- It serves as a barrier between the body's internal structure and its external environment.
- It prevents germs, water, and other substances from entering.
- It shields the skin's interior environment from the sun's UV radiation and other contaminants.
Ques. Write the functions of dermis. (4 marks)
Ans. The functions of dermis are:
- It provides skin with strength, elasticity, and firmness.
- It assists in the transport of nutrients and oxygen to the skin's outer layer.
- It has antibodies that protect against harmful chemicals and microorganisms
- During a skin injury, the layer causes inflammation to increase the amount of blood in the bloodstream. It allows immune cells to traverse more easily in order to combat germs.
Ques. Write the difference between epidermis and dermis. (5 marks)
| Epidermis | Dermis |
|---|---|
| An organism's outermost layer of cells that covers its body. | It is the layer of living cells below epidermis consisting of nerve endings, blood vessel, sweat glands as well as hair follicle. |
| It does not contain any blood vessels | It comprises of a thin network of vessels called capillaries |
| Nerves are absent. | It's made up of nerves that carry nerve signals from the brain to the central nervous system. This layer's open nerve endings are the source of pain sensations. |
| It is found in both plants and animals. | It is found only in animals. |
| It receives necessary nutrients and oxygen from the dermis by diffusion. | It receives necessary nutrients and oxygen from the dermis by diffusion. |
Ques. What are the different layers of epidermis. (5 marks)
Ans. Here are the layers of epidermis:
Stratum Basale: It is the place where mitosis takes place in the deepest layer of the skin. It is the division of cells that results in the formation of new epidermal skin cells. After mitotic division, the cell proceeds through keratinization, which is a process of gradual cell maturation and migration to the skin's surface.
Stratum Spinosum: Desmosomes allow cells from the stratum basale to swiftly concentrate in this layer (structure joining adjacent cells together).
Stratum Granulosum: This layer acquires thick granules of basophilic keratohyalin as the cells mature and undergo keratinization.
Stratum lucidum: This layer fluctuates throughout the body depending on frictional forces. Stratum lucidum can be seen on the palms of the hands and the soles of the feet in its thickest state.
Stratum corneum: As the epidermis's outermost layer, it comprises dead and dying cells that are full of mature keratin. The cells alter the substance and break down the complex molecules within the cells, causing the cells to die.
Ques. What are the different layers of dermis? (3 marks)
Ans. Here are the layers of dermis:
Papillary dermis: Areolar connective tissues, dermal papillae that increase the layer's surface area, and ridges that extend into the epidermis and dermal papillae make up the layer. When things are touched, the ridges are responsible for leaving fingerprints.
Reticular dermis: Dense connective tissues with interlacing bundles of elastic fibres and collagen make up this layer. There are modest amounts of hair follicles, adipose tissue oil glands, nerves, and sweat gland ducts in between these fibres.
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