Anatomy Organs Understanding the 11 Body Organ Systems By Rod Brouhard, EMT-P Rod Brouhard, EMT-P Facebook LinkedIn Twitter Rod Brouhard is an emergency medical technician paramedic (EMT-P), journalist, educator, and advocate for emergency medical service providers and patients. Learn about our editorial process Updated on February 16, 2022 Medically reviewed Verywell Health articles are reviewed by board-certified physicians and healthcare professionals. These medical reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. by Jenny Sweigard, MD Medically reviewed by Jenny Sweigard, MD LinkedIn Jenny Sweigard, MD, is board-certified in internal medicine. She is an in-patient physician at Novant Health Huntersville Medical Center in North Carolina. Learn about our Medical Expert Board Print Table of Contents View All Table of Contents Circulatory Lymphatic Respiratory Integumentary Endocrine Gastrointestinal Urinary Musculoskeletal Nervous Reproductive Immune Frequently Asked Questions An organ system is a group of organs that work together to perform a complex function. There are 11 organ systems in the human body. All of these are required for survival, either of the person or of the species. This article discusses the 11 organ systems, including how they work, what organs they contain, and why they're important. Maskot / Getty Images Circulatory System When we think of—and talk about—the circulatory system, we're usually talking about the cardiovascular system, which includes the: HeartBlood vessels (arteries and veins)The blood itself The circulatory system transports oxygen and nutrients to all corners of the body. It also carries away carbon dioxide and other waste products. In order for blood to make it everywhere it needs to go, the circulatory system maintains the blood flow within a certain pressure range. Blood pressure that's too high puts undue stress on other organs and tissues. Low blood pressure means the blood—and its nutrients—won't make it to where it needs to go. High blood pressure damages the body slowly and quietly, while low blood pressure brings on symptoms immediately. How Your Circulatory System Works Lymphatic System The heart and blood vessels are not the only organs circulating fluid around the body, and blood is not the only circulated fluid. The lymphatic system transports lymph (a fluid) using: Lymph vessels Lymph nodes Lymph ducts Various glands The lymphatic system plays an important role in your immunity, blood pressure regulation, digestion, and other functions. The lymphatic system is the drainage system of the body. It carries excess fluid, proteins, fats, bacteria, and other substances away from the cells and spaces between cells. The lymphatic vessels filter the lymph fluid. They then move the fluid into collecting ducts, which return the fluid to your bloodstream. The lymphatic system also helps create and circulate vital cells that fight disease (part of the immune system, which is covered below). This includes lymphocytes and monocytes (white blood cells) and antibodies (proteins that recognize bacteria and viruses). Recap The lymphatic system helps carry away excess fluid and other substances from your cells. It removes waste products from this lymph fluid and returns the fluid to the bloodstream. Benefits of Lymphatic Drainage Respiratory System The respiratory system contains the: LungsTrachea (windpipe)Airways of the respiratory tree It's responsible for breathing, which is the controlled movement of air in and out of the body (ventilation). It also moves oxygen and carbon dioxide into and out of the bloodstream (respiration). One of the least understood responsibilities of the respiratory system is to help regulate the body's pH balance, or the body's balance of acids and bases. Carbon dioxide is made into carbonic acid, which affects the pH balance. The respiratory system regulates this pH level when it releases carbon dioxide from the body. Breathing issues may indicate a condition that affects the body's acidity. Recap The respiratory system is responsible for moving oxygen into the body and carbon dioxide out of the body. Removing carbon dioxide, an acid, helps to regulate the body's pH levels (the balance of acids and bases in the body). What Respiratory Failure Means Integumentary System The integumentary system is skin and all the structures in it, including the: Sweat glandsHair folliclesNailsNerves The integumentary system is unique because it is the only single-organ system. Skin is both an organ and the entire organ system. The Skin and How It Works Endocrine System The endocrine system includes all the glands that secrete hormones into the bloodstream. The endocrine system and the nervous system are generally considered two of the most complicated systems in the body. The endocrine system mostly regulates metabolism and uses the products of digestion. The Endocrine System and How It Works Gastrointestinal (Digestive) System The gastrointestinal (GI) system is sometimes referred to as the gut. It includes all the organs that carry food from where it enters to where it exits, including the: EsophagusStomachIntestines The GI tract and the endocrine system have a lot of interaction. The GI system also plays host to a very important nerve called the vagus nerve. This is the main contributor to the parasympathetic nervous system, which regulates bodily functions. The vagus nerve has a lot to do with slowing metabolism, lowering heart rate and blood pressure, and stimulating the mechanics of digestion. How Your Digestive System Works Urinary (Excretory) System The urinary system is made up of the: KidneysUretersBladderUrethra These organs work together to filter blood and remove toxins and waste from body tissues. The removal of excess fluid through the urinary system also helps to regulate blood pressure. Tips to Avoid Problems With Your Urinary System Musculoskeletal System This includes the: SkeletonAll the muscles, tendons, and ligaments attached to it The musculoskeletal system provides the framework and the engine for our movement, posture, and physical abilities. The three types of muscles in the body are: Skeletal (voluntary)Smooth (visceral or involuntary), which are inside walls of organs like the intestinesCardiac (heart muscle) Only skeletal muscle is considered part of the musculoskeletal system. Anatomy and Diseases of the Musculoskeletal System Nervous System The nervous system includes the: BrainSpinal cordAll the nerves connected to both of these organs The nervous system is incredibly detailed and includes the only tissue that isn't fed directly through contact with blood. What You Need to Know About the Nervous System Reproductive System The reproductive system is the only system that is split into two parts. Half of us have: PenisTesticles The other half has: VaginaUterusOvaries This is the only organ system that is not complete in any one body and requires another person (or medical intervention) to complete its mission. The Female Reproductive System Immune System The immune system is listed last because, while it's important for survival, all of its organs are borrowed from other organ systems. The immune system organs work like sailors on a navy ship: Every sailor has a primary duty and is cross-trained for other jobs. The primary organs of the immune system are: Lymph nodes Bone marrow Thymus Spleen Adenoids Tonsils Skin Because of the interplay between organs from various other systems, the immune system is one of the most complicated systems of all. How Your Immune System Works Summary Your body has 11 different organ systems. Each group of organs has a different complex function, such as movement, breathing, or digestion. In some cases, one organ system works closely with another on a particular task. For example, the endocrine system interacts with the gastrointestinal system to control digestion and metabolism. When your organ systems are working properly, they help your body stay in balance and maintain your health. Frequently Asked Questions What does an organ system do? An organ system is defined as a group of organs that work together to perform bodily functions. For example, the organs in the gastrointestinal (GI) system each play a unique, important role in food digestion. What organs are in the nervous system? Organs located in the nervous system include the brain, spinal cord, and the nerves. The nervous system can be thought of as the "command center" of the body, since it is in charge of overseeing the body's systems. Which organs are in the respiratory system? Organs in the respiratory system include the lungs, trachea (windpipe), and the airways of the respiratory tree that allow for breathing. These airways include the mouth and nose, sinuses, pharynx (throat), and bronchial tubes. Was this page helpful? Thanks for your feedback! Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit 13 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Institute for Quality and Efficiency in Health Care (IQWiG). How does the blood circulatory system work? Merck Manual. Overview of the lymphatic system. Cleveland Clinic. Lymphatic system. Merck Manual. Overview of the respiratory system. MedlinePlus. Alkalosis. Merck Manual. Endocrine glands. Merck Manual. Overview of the digestive system. Merck Manual. Overview of the urinary tract. Merck Manuals. Overview of the musculoskeletal system. Merck Manual. Overview of the nervous system. Merck Manual. Overview of the immune system. Cleveland Clinic. Nervous system. Cleveland Clinic. Respiratory system.