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Scientific Beauty News Letter
6. Epidermis: Your Outer Cover!
The intact surface of the skin is pitted by the orifices of Sweat glands and hair follicles. They are called pores. Epidermis is actually your outer cover. This layer is upon the dermis, hence the name: Epidermis.
Epidermis basically is a stratified squamous epithelium. Under the squamous cells are the rounded basal cells, and the deepest part of epidermis also contains Melanocytes. These melanocytes give colour to the skin by producing Melanin.
It is made up of the Keratinocytes which proliferate. It provides basic protection from the pathogens. It actually prevents the pathogens from entering the body. It makes the skin as the natural barrier to infections.
Epidermis is also responsible for the amount of water released from the body into the atmosphere. This is called as transdermal water loss.
In humans, the epidermis is thinnest on the eyelids that is about 0.05 mm and thickest on the palms and soles, that is about 1.5 mm. The epidermis is thickest on the friction surfaces and thinnest over the eyelids, on lower parts of abdomen and around the external genitalia.
All the cells of epidermis are attached to each other by ‘Desmosomes”. These are also called attachment plaques. The cells are not fused into each other, but the cell membranes are attached like the zipper. Externally the gaps between the cells is filled with the extracellular fluid. Due to this type of structure, the cells cannot slough off easily, at the same time it allows nutrient fluids to reach here from the dermis.
The Epidermal cells multiply in the stratum basale which is in direct contact with the dermis. The cells divide here and gradually ascend towards the surface, manufacturing Keratin. Finally they die in the upper part, forming a horny layer.
Epidermis is mainly made up of four types of cells.
1. About 90% of epidermal cells are the Keratinocytes. They are also callse Corneocytes. These cells produce the protein Keratin, which is a waterproofing protein of epidermis and it also reduces the friction.
2. About 5 percent cells are the Melanocytes. They are the dendritic cells only found in the deepest layers of the epidermis. They produce melanin, and are associated with the Keratinocytes by means of cytoplamsmic processes. Each melanocyte on an average supplies melanin to 35 to 40 keratinocyes.
3. About 2 to 3 percent cells of the epidermis are the Langerhans cells. They are derived from the bone marrow and make essential part of the epidermal defence system.
The function of these cells is to detect foreign bodies(Antigens) which have penetrated the epidermis.
4. Markel cells are the next type of the cells of epidermis. These are situated between the keratinocytes in the basale layer and remain in contact with the nerve endings. They are many a times in a form of clusters called Markel Corpuscels. They work as mechanoreceptors and are involved in the function of touch.
Credit : Rahul Phate’s
Scientific Beauty News Letter
6. Epidermis: Your Outer Cover!
The intact surface of the skin is pitted by the orifices of Sweat glands and hair follicles. They are called pores. Epidermis is actually your outer cover. This layer is upon the dermis, hence the name: Epidermis.
Epidermis basically is a stratified squamous epithelium. Under the squamous cells are the rounded basal cells, and the deepest part of epidermis also contains Melanocytes. These melanocytes give colour to the skin by producing Melanin.
It is made up of the Keratinocytes which proliferate. It provides basic protection from the pathogens. It actually prevents the pathogens from entering the body. It makes the skin as the natural barrier to infections.
Epidermis is also responsible for the amount of water released from the body into the atmosphere. This is called as transdermal water loss.
In humans, the epidermis is thinnest on the eyelids that is about 0.05 mm and thickest on the palms and soles, that is about 1.5 mm. The epidermis is thickest on the friction surfaces and thinnest over the eyelids, on lower parts of abdomen and around the external genitalia.
All the cells of epidermis are attached to each other by ‘Desmosomes”. These are also called attachment plaques. The cells are not fused into each other, but the cell membranes are attached like the zipper. Externally the gaps between the cells is filled with the extracellular fluid. Due to this type of structure, the cells cannot slough off easily, at the same time it allows nutrient fluids to reach here from the dermis.
The Epidermal cells multiply in the stratum basale which is in direct contact with the dermis. The cells divide here and gradually ascend towards the surface, manufacturing Keratin. Finally they die in the upper part, forming a horny layer.
Epidermis is mainly made up of four types of cells.
1. About 90% of epidermal cells are the Keratinocytes. They are also callse Corneocytes. These cells produce the protein Keratin, which is a waterproofing protein of epidermis and it also reduces the friction.
2. About 5 percent cells are the Melanocytes. They are the dendritic cells only found in the deepest layers of the epidermis. They produce melanin, and are associated with the Keratinocytes by means of cytoplamsmic processes. Each melanocyte on an average supplies melanin to 35 to 40 keratinocyes.
3. About 2 to 3 percent cells of the epidermis are the Langerhans cells. They are derived from the bone marrow and make essential part of the epidermal defence system.
The function of these cells is to detect foreign bodies(Antigens) which have penetrated the epidermis.
4. Markel cells are the next type of the cells of epidermis. These are situated between the keratinocytes in the basale layer and remain in contact with the nerve endings. They are many a times in a form of clusters called Markel Corpuscels. They work as mechanoreceptors and are involved in the function of touch.
Credit : Rahul Phate’s
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