How does skin work to keep us warm in particular the arrector pilli muscle nerve endings and fat lobules?

Skin is the largest organ of the human body, covering a surface area of approximately 2 square meters (22 square feet). It is composed of three layers: the epidermis, the dermis, and the hypodermis.

The epidermis is the outermost layer of the skin and is made up of keratinized cells that protect the body from the elements. The dermis is the middle layer of the skin and is made up of connective tissue, blood vessels, and nerve endings. The hypodermis is the innermost layer of the skin and is made up of fat lobules.

Arrector pili muscles are small muscles that connect the hair follicles to the dermis. When these muscles contract, they cause the hair to stand on end, which helps to trap warm air near the body and insulate it.

Nerve endings in the skin detect changes in temperature and send signals to the brain, which then triggers the appropriate response to maintain body temperature.

Fat lobules in the hypodermis act as insulation, helping to keep the body warm by preventing heat loss.

In addition to these mechanisms, the skin also helps to regulate body temperature through sweating and shivering. When the body is too warm, the skin produces sweat, which evaporates and cools the skin. When the body is too cold, the skin shivers, which generates heat and warms the body.

By working together, these mechanisms help to keep the body warm and maintain a constant internal temperature, even in changing environmental conditions.