The skin is considered the largest organ of the body. The approximate total area of the skin is about 20 square feet. The major function of the skin is to protect us from microorganisms. Skin also helps them to adjust the temperature of the body and it also allows the sensation of heat, cold and touch. Skin Layers are described below:
There are three Skin Layers. Description of Skin Layers are described below:
- The Epidermis is the outermost layer of skin which provides a waterproof barrier to the skin.
- The Dermis, is present underneath the epidermis, contains tough connective tissue, hair follicles, and sweat glands.
- The Hypodermis is deeper is subcutaneous tissue which is made of fat and connective tissue.
Epidermis Definition Biology:
Epidermis s the upper as well as outer most layer of the two main layers of cells of the skin. The skin is considered the largest organ of the body. The approximate total area of the skin is about 20 square feet. The major function of the skin is to protect us from microorganisms. Skin also helps them to adjust the temperature of the body and it also allows the sensation of heat, cold and touch.
Epidermis Tissue Type
It is an outermost cells layer which is usually composed of flattened, scale-like cells which are called Squamous cells. Beneath the Squamous cells, there are round shaped cells present which are called Basal cells. In the cordial part, there are specialized cells are present which are known as Melanocytes. Melanocytes produced Melanin, it is the special pigment that regulates the color of the skin.
It is basically outermost, thin skin layer that is perceptible by to the eye and its major function to provide protection to the body. It does not comprise of any blood vessels. The dermis is the skin inner layer which consists of Blood and Lymph Vessels, Hair Follicles, and Glands. Glands yield sweat, which helps to normalize body temperature.
Epidermal Skin Layers are composed of many cells. Inside it Keratinocytes, cells are present which are accountable for the production of the specialized protein called Keratin. Keratinocytes cells present in reformist stages of differentiation from the deepest to the superficial layers of cells. They initiate from the basal layer of skin, which is the deeper-most layer, and it progressively moves up to the external layer.
Inside it, there are also specialized cells called Melanocytes are present which spread all over the epidermis basal layer. Melanocytes These are responsible for the Melanin production which is responsible for the determination of skin color of the person. These cells are responsible to provide protection to the skin against ultraviolet radiation which is present in sunlight which has a high tendency to create mutilation in the DNA of skin cells.
Langerhans cells formed in the bone marrow are also existed inside the epidermis and work to sense extraneous constituents and contaminations. These cells involved in boosting the Immune system body.
Merkel cells formed by neural crest cells. These cells are specialized for the acuity of moderate touch.
Layers of Epidermis
The epidermal Skin Layers comprised of Stratified, Squamous Epithelial cells. There are generally four layers of the epidermis:
These Skin layers are very dense. The stratum germinativum is the deepest layer, which connects the epidermis skin to the dermal layer. Inside this layer keratinocyte cells formed. The stratum corneum is the outermost layer, that is water-resistant and averts the bacterial, viral and other foreign agents into the body.
Epidermal functions are given below:
- It is accountable for the safety of the whole body. It guards the interior organs, muscles, nerves, and blood vessels.
- It plays a vital role in the formation of cells of new skin.
- It helps in the formation of melanin which is responsible to provide color to the skin.
- Its major function is to provide corporeal protection to the body.
- It is best for providing Immune protection to the body.
The dermis is the second layer of skin which present underneath the Epidermis and overhead the Subcutaneous layer. It is the most impenetrable layer of the skin, and generally, it is composed of elastic and fibrous tissue. In short, it delivers strength and elasticity to the skin.
The dermal layer is generally composed of two layers of cells:
- Papillary Dermis
- Reticular Dermis.
The Papillary Dermis is a supplementary superficial layer which presents beneath the Epidermal intersection. It is comparatively thin. It is composed of Loose Connective Tissues.
Papillae Dermal layer comprised of the following components:
The reticular dermal layer is the subterranean and impenetrable Dermal layer, that is present overhead the Subcutaneous skin. Reticular Dermis comprised of the following components:
Elastic fibers (interlaced)
Collagen fibers (in parallel layers)
Inside the Skin layers of Dermis comprised of many cells. Fibroblasts are the chief cells and are accountable for the Procollagen and elastic fibers production. After the enzymatic catalyzation, Procollagen is then converted into collagen. Approximately 70% of the weight of the dermal layer is comprised of Collagen.
Supplementary cells which are present in it consist of:
- Mast cells: that comprised of granules of Histamine.
- Vascular smooth muscle cells: present and accountable for relaxation or contraction of the blood vessels to preserve homeostasis of the temperature of the body.
- The principal role is to provide strength to the Epidermis and allow the skin to flourish.
- It also plays a number of vitals roles due to the existence of hair follicles, sweat glands, sebaceous glands, nerve endings, and blood vessels.
- Inside Dermal layers, Nerve endings are present which allows perceiving temperature, touch, pressure, and pain stimuli.
- Sweat glands that are present inside the dermal layer that is accountable for the formation of sweat in answer to various conditions, like stress and heat.
- When sweat evaporates over the skin, it can aid in cooling the body down to sustain homeostasis of the body.
- When bacteria are present on the skin Apocrine sweat glands that are a special type of sweat glands located inside the armpits and near the genital organs are and they yield a dense, greasy sweat that generates the special distinctive body odor.
- Sebaceous glands also present inside the dermal layer which is responsible for sebum exudation of sebum. Sebum is the oily material that aids to keep the skin soggy and helps to avert the entry of foreign substances like microbes.
- Hair follicles are present in the dermal layer of skin which is responsible for hair production around the body.
- Inside this layer of skin blood vessels are present which carry nutrients to the skin and remove waste products formed by metabolism inside the epidermis and dermal layer.
Functions Of Skin
Functions of Skin are described below :
- Skin plays a vital role in the fortification of the human body.
- The skin acts as an automatic barrier which is formed by the cells of the Stratum Corneum layer.
- It provides mechanical strength to the tissues from which body formed.
- Keratin is a special protein type which is present in the skin.
- Melanin is dark-colored pigment present in the skin which is very light-sensitive pigment. It protects skin in contradiction of excessive amounts of ultraviolet (UV) radiation which usually comes from the sun.
- It protects the body from bacterial invasion.
- It defends the skin from physical injuries.
- Skin acts as a sensory organ of the body that efficiently transmit information regarding surrounding to the Brain.
- Inside the Skin somatic sensory receptors for Pressure/touch, heat/cold, pain is present.
- Skin plays the foremost role to maintain the temperature of the body.
- Skin release the heat from the body on the dependence of outside body temperature.
- If the surrounding is hot skin release sweat by the sweat glands that are present in the skin. This evaporation of sweat produces the cooling effect.
- The skin helps in the blood transportation to areas of skin, particularly in the limbs or Appendicular skeleton of the body.
- Skin plays a vital role in the devastation of microorganisms due to this Immune system of the body boost up.
- Langerhans cells, Phagocytic Cells and Epidermal Dendritic cells of the epidermis helps to kill the Microorganisms.
- Skin aid in movement and growth of the body without Grievance.
- With the help of skin, various toxic materials excrete from the body.
- Waste materials expelled out from the body with the help of the skin surface. Amount of waste products is regulated by the volume and composition of sweat
- Skin aids in the removal of water, urea, ammonia and uric acid from the body.
- Skin plays an important role in the synthesis of Vitamin D.
- Vitamin D has different types which Vitamin D3 is formed a 7-dehydrocholesterol molecule of skin reacts with ultraviolet light.
- Vitamin D3is formed in the skin innermost two layers which are called Stratum Basale and Stratum Spinosum.
- But if the exposure of skin to Ultraviolet light is high, this condition causes serious Sun Burn that may lead to Skin cancer if the exposure will be prolonged.