Functions of the Integumentary System
The integumentary system - the system that makes up our skin, nails, hair and certain glands - is not only the largest body system but has multiple functions to keep our bodies in homeostasis and running smoothly. Without skin you couldn't sense that mosquito crawling up your arm, cool down after a basketball game or keep out millions of menacing bacteria, fungi, and other icky stuff from invading your body. This study guide will help you understand the main functions of the integumentary system and how it helps our other body systems too.
The skin is the body's first defense system against outside invaders. At any given moment you have millions of bacteria, fungi, and other creatures crawling on you. Fortunately, they cannot gain access through your skin and must enter through other portals like your mouth, eyes, and nose. If you get a scratch, cut or burn, however, that protective shield goes away leaving your body unprotected. This is why washing your skin with soap and water after injury is so important. Your skin also helps your immune system fight dangerous bacteria that do get in. Langerhan's cells, which live in the top layer (the epidermis) of your skin gobble up immune invaders and present them to special immune system cells called lymphocytes which learn how to recognize and destroy them. Other cells in the skin secrete a substance called sebum which keeps water from going out or coming in. People get their skin color from special cells in the skin called melanocytes. These cells produce the brown pigment melanin to help filter out the sun's ultraviolet rays. If you stay out in the sun too long your melanocytes can't make enough melanin and you get a sunburn, so remember to slather on the sunscreen, slap on a hat and seek the shade.
Temperature, touch, tickle and itch. These are sensations you feel because nerve fibers extending from the spine supply sensation to specific areas on your skin called dermatomes. These sensations are transmitted from the skin to the central nervous system and interpreted by your brain. Your autonomic nervous system, the system that stimulates muscles to contract without you being aware of it (heart, blood vessels, intestines) has nerve fibers that carry impulses to the hair roots and the sweat glands. These nerve fibers respond to changes in temperature or other stimuli. Normally your body hair lies at an angle flush with your skin . When you are cold, tiny muscles attached to each hair follicle gently pull the hair follicle deep in the dermis causing it to stand upright perpendicular to your skin. This muscle - the arector pili- is responsible for you getting goosebumps. Nerve fibers also extend to your sweat glands which are stimulated when your body needs to cool down.
Regulates Body Temperature
Nerves, blood vessels, and sweat glands in the deep layers of your skin help you to warm up and cool down. If your body temperature were to fall suddenly - for example, if you fell into an icy lake- blood vessels would constrict or tighten in response to the autonomic nervous system resulting in a decrease of blood flow through the skin. This response helps the body to conserve heat, protecting your internal organs. Now your friends pull you out and you are sitting by a warm fire drinking chicken soup and starting to warm up. Your skin starts to become too hot and your internal body temperature rises. Small arteries deep in your skin start to dilate or expand increasing the blood flow to the skin surface. Your sweat glands increase sweat production and the heat is evaporated away cooling the skin.
The skin also excretes sweat which contains water urea, lactic acid and electrolytes.
Vitamin D Production
When your skin is exposed to sunlight, it helps the kidney turn the precursor of vitamin D into its active form. Vitamin D is needed for building strong and healthy bones. Only a small amount of exposure to UV light is needed (around 15 minutes a day) for this process, however, so limit your time in the sun without sunscreen.
How Your Skin Helps Other Body Systems
Helps your muscles by providing calcium ions necessary for muscle contractions(vitamin D is needed for calcium absorption).
Provides input to the brain for interpreting sensations of pain, pressure, tickle and itch
Changes deep in the skin (dermis) causes skin blood vessels to constrict or dilate helping to regulate blood flow to the skin helping out the cardiovascular system.
Helps the kidneys by partially activating vitamin D so the kidney can convert it into calcitriol, vitamin D's active form. Your skin also helps your digestive system because without calcitriol, your digestive tract could not absorb calcium taken in from the foods you eat.
Hair inside our nose helps filter particles from the air we inhale helping out our respiratory system