Mammalian Skin-Features, Structure, and Functions

Skin is the largest organ of our body. It protects our internal organs from external elements such as cold air, wind, rain, etc. It also helps regulate our body temperature. Human skin is composed of three layers: epidermis, dermis, and hypodermis.

Epidermis is the outermost layer and contains dead cells called keratinocytes. These cells form the protective barrier against environmental damage. Dermis is located below the epidermis and consists of connective tissue. Hypodermis is the deepest layer of the skin and contains fat tissues.

Features Of Mammalian Skin

The features of mammalian skin are:

1. Hairs are present in the skin of mammals.

2. Different types of epidermal glands are present in the skin.

3. They have highly stratified (multilayered) and cornified (tough) epidermis.

4. Their dermis is many times thicker than the epidermis.

Composition Of Mammalian Skin

The skin of mammals is composed of the following layers:

Epidermis

The epidermis is composed of stratified squamous epithelium. It consists of several layers. These layers have different types of cells. There are the following layers in the epidermis:

(a) Stratum Corneum: The outer dead layer of cells is called stratum corneum. Rapid cell divisions take place in the deepest layer of the epidermis. It pushes the cells toward the surface of the skin. These cells die and become keratinized. Keratinized cells form the outer skin layer. This layer is called the stratum corneum.

Keratin is insoluble in water. Therefore, the stratum corneum prevents dehydration. It defends the body from toxic substances and microorganisms. Prevention from dehydration is an important adaptation in mammals. It helped mammals to adapt to the terrestrial environment.

(b) Stratum Malpighian: It is present below the stratum corneum. It is composed of living cells. These cells continuously divide and form a stratum corneum.

Dermis

It is the thickest portion of mammalian skin. It contains blood vessels, lymphatic vessels, nerve endings, hair follicles, small muscles, and glands. Leather is made from the dermis by a special tanning process (leather process).

Hypodermis

The hypodermis is present below the dermis. Its composition is different from the other vertebrate classes. Blood vessels pass from the hypodermis and enter the dermis. Blood vessels are absent in the epidermis. Hypodermis consists of loose connective tissue, adipose tissue, and skeletal muscles.

Connective tissues: They form ground tissues in the dermis.

Adipose tissues: They store energy in the form of fat. They also provide insulation in cold environments.

Skeletal muscles: They allow the skin to move independently.

Hairs

Hair is composed of keratin-filled cells. It is developed from the epidermis. Hair has the following parts:

1. Hair shaft: The portion of hair that comes out from the skin is called the hair shaft.

2. Root: The portion of hair embedded in the skin is called the root.

3. Arrector pilli: It is smooth muscle. It is attached to the sheath of a hair follicle. This sheath is composed of connective tissues. This sheath surrounds the bulb of the hair root. The muscle contracts. It pulls the follicle. Thus hair becomes erect. This is called a goose bump in humans.

Advantages of Erection of Hairs:

There are two Advantages of Erection of Hairs:

This action warms the body in other mammals. Air is filled between hairs. This air acts as an insulating layer between the erect hair and skin.

Some animals are frightened and erect their hair. It makes them larger. Thus their predators do not attack them.

Functions Of Mammalian Skin

1. Skin regulates body temperature in humans and a few other animals. The skin of Horses has many sweat glands. The pores of sweat glands open and close. It is used for perspiring or sweating.

2. The skin screens out harmful ultraviolet rays from the sun.

3. Skin also absorbs rays. These rays convert a chemical in the skin into vitamin

4. The skin is also an important sense organ. It contains many sensory receptors for hearing, cold, touch, pressure, and pain. It has many nerve endings. These nerve endings detect harmful factors in the environment.

5. Skin has many glands. They produce different secretions.