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 body's muscles, bones and joints together as the musculoskeletal system . We also discuss the body's immune defences alongside the fluid return network called the lymphatic system . These are more of useful teaching groupings than rigid biological boundaries. Moving gases and materials The heart, blood vessels and blood work together as the circulatory system . This system moves blood through the body. Blood transports oxygen, carbon dioxide, nutrients, hormones, immune cells, heat and waste products between different parts of the body. The airways and lungs form the respiratory system . They move air in and out and allow 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 brain, spinal cord and nerves form the nervous system . They detect information, process it and send rapid signals that contribute to sensation, movement, thinking and the automatic regulation of many body functions. Chemical messages carried in the blood help coordinate many slower or longer lasting body processes. The glands, organs and specialised cells that produce these hormones make up the endocrine system . These signals help regulate growth, metabolism, stress responses, blood glucose, puberty and reproduction. Metabolism means the chemical reactions that keep cells and the body functioning, including reactions that use and release energy. Food, fluids and waste The mouth, oesophagus, stomach, intestines, liver, gallbladder and pancreas work together as the digestive system . They break food down, absorb nutrients and water, process absorbed materials and pass undigested material out of the body. The kidneys, ureters, bladder and urethra make up the urinary system . The kidneys filter blood, remove wastes and extra water, and help regulate salts, acidity and blood pressure. The ureters carry urine from the kidneys to the bladder, the bladder stores it, and the urethra carries it out of the body. Movement, support and protection Bones, joints, skeletal muscles, tendons and ligaments work together as the musculoskeletal system . They provide support and stability, protect important structures and allow movement. The skin and its associated structures, including hair, nails and glands, form the integumentary system . They create a protective barrier, contribute to temperature regulation and contain receptors involved in sensation. Defence, fluid return and reproduction Specialised cells, tissues and organs throughout the body work together as the immune system to protect against infections and other biological threats. A network that returns excess tissue fluid towards the bloodstream and helps organise immune responses is called the lymphatic system . Lymphatic vessels in the gut also carry some absorbed fats. Organs involved in producing sperm or eggs, producing sex hormones and supporting reproduction make up the reproductive system . 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 different system names are only useful maps. 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 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.