Anatomy Organs Understanding the 11 Body Organ Systems By Rod Brouhard, EMT-P Updated on January 04, 2024 Medically reviewed by Michael Menna, DO Fact checked by Nick Blackmer Print Table of Contents View All Table of Contents Circulatory Lymphatic Respiratory Integumentary Endocrine Gastrointestinal Urinary Musculoskeletal Nervous Reproductive Immune FAQ An organ system is a group of organs that work together in the body to perform a complex function, such as pumping blood or processing and utilizing nutrients. There are 11 major organ systems in the human body: The circulatory (cardiovascular) systemThe lymphatic systemThe respiratory systemThe integumentary systemThe endocrine systemThe gastrointestinal (digestive) systemThe urinary (excretory) systemThe musculoskeletal systemThe nervous systemThe reproductive systemThe immune system Organ systems work together with other organ systems to keep the body in good health. For example, the circulatory and digestive systems work together to deliver nutrients throughout the body. With the exception of the reproductive system, each is necessary for survival. This article discusses the 11 organ systems, including how they work, what organs they contain, and why they’re important. Peter Dazeley / Getty Images Circulatory System The circulatory system transports oxygen and nutrients to all corners of the body. It also carries away carbon dioxide and other waste products. When people talk about this organ system, they’re usually talking about the cardiovascular system at large, which includes the: HeartBlood vessels (arteries and veins)The blood itself 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 extra 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. How Your Circulatory System Works Lymphatic System The lymphatic system is the drainage system of the body. It plays an important role in your immunity, blood pressure regulation, digestion, and other functions. This organ system carries excess fluid, proteins, fats, bacteria, and other substances away from the cells and spaces between cells. It does this using: Lymph vessels Lymph nodes Lymph ducts Various glands The lymphatic vessels 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, which is why it is also a part of the immune system. This includes lymphocytes and monocytes (white blood cells) and antibodies (proteins that recognize bacteria and viruses). Benefits of Lymphatic Drainage Respiratory System The respiratory system is 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). This organ system contains the following: LungsTrachea (windpipe)Airways of the respiratory tree 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. An Overview of Respiratory Failure Integumentary System The integumentary system is unique because it is the largest and only single-organ system in the body. It protects the body from the external environment and helps regulate body temperature. The integumentary system is the skin and all the structures in it, including the: Sweat glandsHair folliclesNailsNerves The Skin and How It Works Endocrine System The endocrine system mostly regulates metabolism and uses the products of digestion. Along with the nervous system and immune system, it’s generally considered one of the most complicated systems in the body. This organ system includes all the glands that secrete hormones into the bloodstream, including: AdrenalGonads (ovaries and testicles)HypothalamusPancreasParathyroidPinealPituitaryThymusThyroid The Endocrine System and How It Works Digestive System The gastrointestinal (GI) system is sometimes referred to as the gut or the digestive system. It is responsible for breaking down foods into nutrients, which the body needs for energy, growth, and cell repair. This system includes all the organs that carry food from where it enters the body to where it exits, including the following: MouthEsophagusStomachSmall intestineLarge intestineRectumAnus The pancreas, gallbladder, and liver are also part of this organ system. The GI tract and the endocrine system have a lot of interaction. The endocrine system produces the hormones that regulate digestion and the absorption of nutrients. The GI system also owes a lot to the vagus nerve, the main contributor to the parasympathetic nervous system, which regulates bodily functions. The vagus nerve is involved in slowing metabolism, lowering heart rate and blood pressure, and stimulating the mechanics of digestion. How Your Digestive System Works One Organ, Two Organ Systems Some organs belong to more than one organ system. The pancreas, for example, can be considered a part of the digestive system because it secretes enzymes that help the body break down fat, protein, and starch. It is also part of the endocrine system because it produces hormones that help regulate blood sugar. Urinary (Excretory) System The urinary system includes: KidneysUretersBladderUrethra These organs work together to filter blood and remove toxins and waste from body tissues. The removal of excess fluid through this organ system also helps regulate blood pressure. Tips for Keeping Your Urinary System Healthy Musculoskeletal System The musculoskeletal system provides the framework and the engine for our movement, posture, and physical abilities. This organ system includes: The skeletonAll the muscles, tendons, and ligaments attached to the skeleton Muscles in the Body There are three types of muscles in the body: 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. Skeletal System Your body's skeletal system contains 206 bones: The 80 bones of the axial skeleton (your spine and the core of your body)The 126 bones in the appendicular skeleton (your arms, legs, and bones away from the core) In addition to providing your body's structure and facilitating its mobility, the skeletal system contains bone marrow to produce blood and lymph cells. It stores fat in the body, as well as key minerals like calcium. Anatomy and Diseases of the Musculoskeletal System Nervous System The nervous system is a network that makes it possible for different parts of the body to communicate with one another. Think of it as your body’s command station. All body processes, reactions, thoughts, and movements stem from this organ system. The nervous system is incredibly detailed and includes the following: BrainSpinal cordAll the nerves connected to both of these organs It contains the only tissue that isn’t fed directly through contact with blood. What You Need to Know About the Nervous System Reproductive System 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, which is to produce offspring. There are two parts of male reproductive system: PenisTesticles Three parts comprise the female reproductive system: VaginaUterusOvaries Aside from their direct roles in reproduction, the ovaries and testicles also play important roles in the endocrine system, producing estrogen, testosterone, and progesterone. The External and Internal Female Reproductive Organs Immune System The immune system helps the body fight against infection and other diseases. It 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 ship: Each one has a primary duty and is cross-trained for other jobs. These are the primary organs of the immune system: 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 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 organ systems work together? There are many examples. For instance, the nervous system sends signals to the musculoskeletal system to control movement. The circulatory system and respiratory system work together to make sure your cells receive oxygen. Is skin an organ? Yes. Skin is both an organ and an entire organ system. How Much Do Your Organs Weigh? 17 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. How does the blood circulatory system work? National Cancer Institute. Introduction to the human body: components of the lymphatic system. National Library of Medicine: MedlinePlus. Alkalosis. MedlinePlus. Skin. Endocrine Society. Your health and hormones. National Institute of Diabetes and Digestive and Kidney Diseases. Your digestive system & how it works. Breit S, Kupferberg A, Rogler G, Hasler G. Vagus nerve as modulator of the brain-gut axis in psychiatric and inflammatory disorders. Front Psychiatry. 2018;9:44. doi:10.3389/fpsyt.2018.00044 Endocrine Society. Pancreas—islets of Langerhans. National Cancer Institute. Introduction to the human body: introduction to the urinary system. National Cancer Institute. Introduction to the human body: introduction to the skeletal system. National Cancer Institute. Introduction to the human body: muscle types. National Cancer Institute SEER Training Modules. Introduction to the skeletal system. National Cancer Institute. Introduction to the human body: introduction to the nervous system. Sweeney MD, Zhao Z, Montagne A, Nelson AR, Zlokovic BV. Blood-brain barrier: from physiology to disease and back. Physiol Rev. 2019;99(1):21-78. doi:10.1152/physrev.00050.2017 MedlinePlus. Male reproductive system. MedlinePlus. Female reproductive system. Institute for Quality and Efficiency in Health Care. What are the organs of the immune system? By Rod Brouhard, EMT-P Rod Brouhard is an emergency medical technician paramedic (EMT-P), journalist, educator, and advocate for emergency medical service providers and patients. See Our Editorial Process Meet Our Medical Expert Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit