Skin, Hair follicles

The entire surface of the body is covered with skin. It is the extensive   organs in the body. The mammalian skin consists of two major layers – the epidermis and linear dermis. Epidermis-This is further divided into three layers knows as cornified or horny layer,granular and malpighian layer. The cornified or horny layer is upper most layer of the  flat dead cells. This layer protects the body against loss of water and entering of foreign bodies. It also protects the under lying layers from excessive harmful radiation of the sun.

Granular layer contains living cells. It lies just below the cornified layers. The cells become gradually tightened and longer until they are up it cornified cells.

Malpighian layer is a layer of living cells where active cells division takes place.

The layer contains dark melanin pigment which gives the skin its colour. Black people have more melanin than white people, this pigment is absent in Albino. Both cornified layer, granular and Malpighian layers have Keratin which is responsible for the toughness and flexibility of the skin.

DERMIS.

The dermis is a thick of layer of connective tissues. This layer consists of blood vessel, sweat glands, sebaceous gland, hair follicle, erector muscles, sensory cell and fatty cell.

Blood vessels supply food and oxygen to the tissues of the skin, and the blood in the capillaries determine the among of heat that is lost from the skin surface by radiation and convention.

Sweat gland – is a coiled tube which arises from the dermis and continues as sweat duct that opens at the surface of the skin as sweat pores.

The sweat gland is well supplied with blood capillaries from which the sweat gland absorbs waste product such as waste, sodium chloride, small amount guinea as sweat and sent them to surface

Why the skin through the sweat pore: When the sweat evaporates from the skin, it has a cooling effect on the body. It also concerned with temperature sebaceous gland.

Each hair follicles is supplied with at least two sebaceous glands which secretes

only substance called SEBUM which imbrication’s the hair and keeps it flexible. The sebum also contain  lysozyme which kills bacteria and viruses.

HAIR FOLLICLES

 Each hair lies a deep pit called hair follicle of the hair itself projects out y the skin is the hair. Erected hair shaft traps a layer g air between them to prevent heat loss by convention which is a function in temperature regulation.

The call of the produces the hair and hair itself is made up of protein called Keratin.

HAIR ERECTOR MUSCLES This a slender muscle which runs each from each side of the hair to the base of the Malpighian layers. The contraction of the muscle makes the hair to stand upright and its relaxation.

FATTY CELL (ADIPOSE TISSUE)These cells are formed below the dermis .They are round in shape and act as insulating Layers against heat loss. They also act as energy reserve and protect the skin from mechanical danger