SKIN

INTRODUCTION

A skin is a covering that completely covers the body from the outside. It is also called integumentary system. It is the largest organ or part of our body.

The total surface area of ​​the skin is about 2 meters square and its thickness is approximately 1 to 2 mm.

The structure of the skin consists of layers of skin, glands, nails and hair.

Layers of the Skin (Layers of the Skin).

There are mainly three layers of skin.

1. Epidermis
2. Dermish
3. Hypodermis

1 Epidermis.

It is the most superficial and outermost layer of the skin. Its structure consists of stratified columnar epithelium tissue. This layer does not contain blood vessels.

The epidermis is not evenly distributed throughout the body. Somewhere it is thicker like the soles of the feet and the palms of the hands. Somewhere its thickness is also less, like the part of the cornea of ​​the eye.

In the epidermis layer, cells grow from the basement layer and up to the superficial layer.It takes about 35 to 40 days for the entire epidermis to be replaced.

The epidermal layer consists of the following layers.

A. Stratum Corneum (Stratum Corneum).

This is the outermost layer among all the layers. Dead cells are arranged in a line. These cells are flat and very thin.

This layer contains keratin. It is a protein. It works to protect the cells inside and prevents them from drying out.

It maintains the elasticity of the skin and helps to keep it soft.

This layer is constantly worn away due to external wear and tear.

B. Stratum Lucidum.

This layer is also made up of dead and flattened cells. It is also called block layer because the cells in this layer do not contain water and nucleus.

This layer contains a protein called LEDN. It works to protect the skin from the ultraviolet rays coming from the sun.

Ç. Stratum Granulosum (Stratum Granulosum).

Because these cells contain granules, it is called the granulosum layer.

This layer is 2 to 4 cell rows thick.

D. Stratum Germinative.

This layer is the innermost layer of the epidermis.

This layer produces new cells from time to time and they rise towards the cell surface. Two types of cells are found here, precal cells and basal cells.

2. Dermis Layer (Dermis Layer).

This layer of skin is below the epidermis. It contains connective tissue. This layer contains collagen fibers, elastic fibers and reticular fibers. Due to which the elasticity of the skin is maintained. These fibers are important in providing strength and support to the skin.

Cells in the dermis include fat cells, fibroblasts and macrophages cells.

The dermis layer is composed of a papillary layer and a reticular layer. Both of which are connected to each other, cannot be separated.

The dermis layer consists of blood vessels, lymph vessels, hair follicles, sensory nerve endings,

Sweat gland, sebaceous gland etc. structures are present

3. Hypodermis Layer

This layer is below the dermis layer. It is also called the subcutaneous layer.

This layer is made up of loose fibrous connective tissue. It is thicker than the dermis. It contains blood vessels, lymph vessels and nerves.

• Functions of the Skin (Functions of the Skin).

The skin forms a continuous covering around the outside of the body, thereby acting as the first line of protection.

Prevents micro-organisms from entering the body directly.

Prevents any external injury or any harmful elements from entering the body.

It plays a very important role in maintaining normal body temperature.

The skin provides an outer frame work to the body. It is the largest organ in the body.By covering all the organs on the outside, it works to give shape to the body.

It synthesizes vitamin D in the body. In which there is a chemical called Seven D Hydrocholesterol in the skin. which converts ultra violet rays from the sun into vitamin d3 and cholecalciferol. Thus it acts to synthesize vitamin D.

The skin also functions to excrete waste products and harmful substances from the body. It also excretes some waste products from the body through the secretion of perspiration.

Some substances are also absorbed through the skin. This is also a no route to medication.In which the skin absorbs certain ointments and medicines applied to it and sends them into the systemic circulation.

Sensory nerve endings are located in the skin. Which helps in transmitting the impulses of touch, temperature and pain etc. to the brain. This gives us an interpretation of every stimulation.

The skin also serves to store certain nutrient materials such as fat.

Skin plays an important role in wood healing.

• Skin color.

The color of the skin is based on the amount of melanin in the skin. This melanin is secreted by melanocytes cells in the stratum basalis, a deep layer of the skin. Which determines skin color and skin pigmentation.

Melanin is present everywhere in the skin, but it is more abundant in the genital area, nipples, underarms, etc., and due to this, these areas appear dark in color.

Dark skinned individuals have more melanin than light or fair skinned individuals.

• Sweat glands.

A cluster-shaped gland is located in the dermis layer of the skin. Which is called sweat gland. The Bodima sweat gland secretes a transparent, colored lash fluid called sweat. That action is called spiration.

Two types of sweat glands are mainly found.

1. Eccrine sweat glands.

This type of sweat gland is distributed almost all over the body. This sweat gland is located in the duct. This duct opens on the upper part of the skin and pours the secretion of the sweat gland (sweat) on the skin. This type of sweat gland is not located in places like nail bed, vulva, penis tip, lips, ear drum.

When the outside environment is hot and the temperature rises, these glands become active and secrete sweat. This is called the action of transpiration and thus it also works to maintain body temperature.

Composition of sweat.

Urea
Lactic acid
Albumin
Fat
Sodium chloride
Sugar
Ascorbic acid

The above components are found in the composition of sweat.

2. Apocrine glands.

These glands are arranged deep in the body. It is inactive before puberty. During puberty it increases in size and becomes active. This type of gland is located in the axilla, groin etc. and it also secretes sweat.

• Sebaceous glands.

In the dermis layer of the skin, there is a sebaceous gland, a simple structure connected to the hair follicle.

The cells in this gland secrete a viscous oil. It is called sebum.

This sebum is thicker than liquid. It contains lipid substances.

This sebum acts as a barrier in the opening of the hair follicle. So that micro organism can be prevented from entering the body. Thus it performs a protective function.
It acts as a lubricant to keep hair follicles and skin soft.

• Structure and Functions of Hair.

Hair is a structure of keratinized epithelium tissue. They originate from the dermis layer of the skin and are scattered over most of the skin. It lies like a layer on the skin.

Hair is not found on sole of foot, tip of penis, vulva and nipple. Apart from that, hair is found on almost the entire body.

Hair is divided into two parts. In which the part visible above the skin is called the smooth of hair and the pressed part under the skin is called the root of hair.

There are three layers around the hair. The basalmost structural layer is called papilla of hair or bulb of hair. In which the blood vessels are located and it provides nutrition to the hair structure to grow.

Above it is the cortex layer. Which contains melanin. Which gives color to hair. In this layer, the matrix germinal is located on the side of the bulb.

The topmost layer of the hair is called the medulla. It is a layer made of keratin and is loosely distributed around the outside.

Functions of hair.

The main function of hair is protection in the body. As the hair in the scalp insulates the body from heat and cold.

Eyebrow hair prevents bright light and glare from entering the eye directly, and helps prevent sweat from entering the eye.

Apart from this, foreign body or dust particles are prevented from going directly into the eyes. Eye laces also prevent foreign bodies or dust particles from entering the eye.

The hairs in the nostrils moisten and warm the inhaled air and prevent dust particles or foreign material from entering the respiratory track.

With the help of the secretion of the sebaceous gland opening in the hair, the skin remains lubricated, and the skin stops drying.

Hair is present around body openings like anus, vagina, etc. which are connected with the function of protection.

• Structure and function of nail.

It is a structure made of dry keratinized epithelium tissue in the epidermis layer. They are located at the end of the dorsal surface of the hands and feet. They are made of keratin.

It appears pink in color because it is scattered on the skin, but it does not appear pink in color due to the blood supply at the bottom of the nail.

The structure of the nail can be described as follows.

The innermost part of the nail is called the nail root. It is the part pressed under the skin. The overlying layer is called Eponychium, which covers the nail root.

The visible part of the nail is called the body of the nail. Which is made up of keratinized dead cells.

The part of the body of the nail that is spread over the epithelium layer of the skin is called the nail bed. From there the part extending in front of the skin is called free edge. which is the extended part of the finger or thumb beyond the skin. It is a complete dead cell. Which can be cut and removed.

Functions of Nails.

Useful for grasping or grasping any objects.

Helpful for scratching or removing anything.

Nails protect our fingers, toe and thumb.

It is an indicator to assess the patient’s clinical condition.

• Heat Regulation.

Heat is produced in the body through different processes and excess heat is lost from the body through different mechanisms. Normal heat in the body means its temperature is maintained.

Heat production takes place in the body through the following actions.

Metabolism of food
Exercise
Hormones
Emotions
Age

Heat loss occurs in the body through the following actions.

Excess hits in the body are lost from the body through the skin through the following mechanisms. Mechanism of heat loss can be described as follows.

Radiation.

This hit is transferred from the warm object to the total object. In which there is no physical contact between the two objects. Most body hits are lost through this mechanism.

As in summer, the heat is transferred to the body through radiation due to excessive sun exposure.

Conduction.

In this mechanism the body hit is transferred from the hot side to the cold side by coming into direct contact. Like exposure to cold surfaces or cold clothes causes body heat loss. The least amount of hit loss is observed through this mechanism.

Convection.

This heat is lost through the circulating air. As cold air is passed over any body part that is exposed, hit loss occurs through this mechanism.

Heat loss is observed through this mechanism due to windows, doors or fans being on.

Evaporation.

Due to conversion of this liquid to vapor, hit loss is observed from the surface. In which transpiration occurs on the body surface and body heat is lost through evaporation.

Thus through the above method heat loss from the body causes additional heat loss and the normal temperature of the body is maintained.

Nervous system control, hypothalamus, blood circulation etc. also depend on body temperature regulation.