The skin, your body's largest organ, serves a myriad of functions. Your skin is the first defense against outside pathogens; it is the mechanism that regulates your body temperature; it keeps your other organs in place comfortably inside your body. You could not survive without skin and when it becomes damaged, it can affect many body systems.
The integumentary system is comprised of all three layers of your skin; the epidermis, dermis and subcutaneous layers. If the skin becomes damaged by fire, disease or injury, the integumentary system is directly affected. Depending on the degree of damage, one or all three layers can be affected. The integumentary system is the first body system affected by damaged skin.
The skin contains nerve cells that allow us to feel and interact with our environments. Nerve cells in our skin allow us to feel pain, which creates a useful response to avoid hot, sharp or otherwise dangerous objects. If the nerves in the skin are damaged, they can become unresponsive, which affects the nervous system's ability to detect threats and can lead to further injury.
The endocrine system includes all of the glands in the body. Damaged skin can affect the endocrine system in a variety of ways. The exocrine glands, or sweat glands, are found in the skin and can be directly damaged when the skin is damaged. Other glands are founds inside of the body and are not likely to be directly damaged, but they can be affected by bacteria and viruses that enter through the skin.
The skin is also associated with the excretory system. The lungs, kidneys and urethra also belong to this system. Waste products are excreted through the skin in the sweat in very small amounts. The skin also holds in the body's fluids. If the skin is damaged, the body can become dehydrated and the excretory system will not function properly.
Muscular and Circulatory Systems
The skin directly covers the muscles and blood vessels, so any severe damage to the skin can also affect these tissues. Usually, if the skin suffers a third degree burn, the subcutaneous layer is damaged and the muscles and blood vessels can also be damaged. In addition, an infection contracted through a break in the skin can harm muscle tissue and infect the blood.
The skin does not interact with the skeletal system directly, but it can still affect it if damaged. Injury to the skin can introduce pathogens that can affect the blood which can eventually affect nutrient and oxygen transport to the body systems, including the skeletal system. Also, since the skeletal and muscular systems directly interact, damaged muscles (caused by skin damage) can impair the skeletal system.
Digestive and Respiratory Systems
These two systems are probably the least likely to be affected by damage to the skin, but if an infection spreads through the body after entering the skin, it can eventually affect and damage either one or both of these systems.