The Body Systems Map

A body systems map gives you a practical overview of what the body's major systems do and how they connect. Textbooks do not always group them in exactly the same way, but it is helpful to recognise the main systems and understand that their functions overlap.

An organ system is a group of organs and other structures that work together to perform major functions or meet the body's needs. There is no single compulsory way to divide the body into systems. Many anatomy textbooks describe eleven major organ systems, but some separate structures that others combine. For this introductory map, we discuss the muscular and skeletal systems together as the musculoskeletal system , and the closely linked immune and lymphatic systems together. These are useful teaching groupings rather than rigid biological boundaries. Moving gases and materials The circulatory system moves blood through the body. For this map, it includes the heart, blood vessels and blood. Blood transports oxygen, carbon dioxide, nutrients, hormones, immune cells, heat and waste products between different parts of the body. The respiratory system includes the airways and lungs. It moves air in and out and allows gas exchange, with oxygen moving into the blood and carbon dioxide moving from the blood into the lungs to be breathed out. Communication and coordination The nervous system includes the brain, spinal cord and nerves. It detects information, processes it and sends rapid signals that contribute to sensation, movement, thinking and the automatic regulation of many body functions. The endocrine system includes glands, organs and specialised cells that release hormones into the blood. These chemical signals help regulate processes including growth, metabolism, stress responses, blood glucose, puberty and reproduction. Food, fluids and waste The digestive system includes the mouth, oesophagus, stomach, intestines, liver, gallbladder and pancreas. It breaks food down, absorbs nutrients and water, processes absorbed materials and passes undigested material out of the body. The urinary system includes the kidneys, ureters, bladder and urethra. The kidneys filter blood, remove wastes and extra water, and help regulate salts, acidity and blood pressure. The rest of the urinary tract carries, stores and passes urine. Movement, support and protection The musculoskeletal system includes bones, joints, skeletal muscles, tendons and ligaments. Together they provide support and stability, protect important structures and allow movement. The integumentary system includes the skin and associated structures such as hair, nails and glands. It forms a protective barrier, contributes to temperature regulation and contains receptors involved in sensation. Defence, fluid return and reproduction The immune system protects against infections and other biological threats. It involves specialised cells, tissues and organs throughout the body. The lymphatic system overlaps closely with immune function but also has other roles. Its vessels return excess tissue fluid towards the bloodstream, lymph nodes help organise immune responses, and lymphatic vessels in the gut carry some absorbed fats. The reproductive system includes organs involved in producing sperm or eggs, producing sex hormones and supporting reproduction. In typical female reproductive anatomy, the uterus can support pregnancy. The exact organs and functions differ between typical male and female reproductive anatomy. How the systems work together These system names are useful maps, not walls. The same organ may contribute to more than one system, and most everyday body functions rely on several systems at once. During a brisk walk, for example, skeletal muscles use more energy. Breathing and circulation adjust to support gas exchange and oxygen delivery. Nervous and hormonal signals help coordinate those changes, while the skin contributes to heat loss as body temperature rises. The point of the map is therefore not to force every function or symptom into one box. It gives you a starting structure for understanding how different parts of the body contribute to the same task.

Body systems are useful maps, not separate compartments. Each has broad roles, but organs can contribute to more than one system and most body functions depend on several systems working together.