Skin

         Skin is an integumentary system that covers the outside of the body. it is highly essential to protect internal organs and prevent the entrance of pathogens.
                                The skin is composed of three major tissues:
1.Epidermis. 2.Dermis. 3. Hypodermis.
   

1. Epidermis

Epidermis is the upper layer of the skin. The order most layer consists of flat, thin and scale -like dead cells

it is separated from the dermis by basement membrane it contains melanocytes. giving colour to the skin. The deepest layers of epidermis have the nerve ending.

2. Dermis

The dermis is the middle layer. it is thick but elastic. the dermis consists of nerves,hair follicles, sweat glands and sebaceous glands [oil glands]. The sweat glands separate sweat from the blood.

The sebaceous gland secretes sebum which keeps the skin smooth and shiny. The arectotpili is the smooth muscle necessary to move the hair.

3.Hypogermis

It is the lower most layer which contains large amount of adipose tissue. 

 Functions of skin

1. Skin protects the internal organs of our body.

2.It prevents the entrance of infectious agents.

3.Skin regulates the body temperature.

4.It reduces water loss.

5.Skin can prepare Vitamin D with the help of sunlight.

6.It allows us to feel touch. pain and temperature.

7.Skin acts as an excretory organ and excretes sweat.