Our bodies are made up of twelve biological systems that perform the everyday functions we need for living. They are listed below.

• CIRCULATORY SYSTEM
  The Circulatory System consists of the heart, blood, arteries, veins and capillaries. It primarily pumps blood to and from the heart to supply oxygen to the body.
  
  
• DIGESTIVE SYSTEM
  The Digestive System, whose organs include the mouth, esophagus, stomach, liver, gallbladder, pancreas, the small and large intestines and the rectum, allows the body to break down and absorb food, and remove waste.
  
  
• ENDOCRINE SYSTEM
  The Endocrine System is a collection of glands that secrete hormones into the blood which regulate growth, development and homeostasis (the regulation of the body’s temperature and the balance between acidity and alkalinity (pH)).
  
  
• IMMUNE SYSTEM
  The Immune System is the body’s defense against agents such as bacteria and viruses. It includes the lymph nodes, spleen, bone marrow and white blood cells, among others.
  
  
• INTEGUMENTARY SYSTEM
  The Integumentary System, which is primarily the skin, also includes hair and nails. It provides protection from the outside world.
  
  
• LYMPHATIC SYSTEM
  The Lymphatic System, which includes the lymph nodes, lymph ducts and lymph vessels, is a secondary circulatory system that helps the body fight infection and maintain its fluid balance.
  
  
• MUSCULAR SYSTEM
  The Muscular System provides motor power for all movements of body parts. Not just the movements that are under our control like walking, but also those like breathing, food digestion and blood circulation.
  
  
• NERVOUS SYSTEM
  The Nervous System is the body’s electrochemical communication system. It controls voluntary actions (like walking) and involuntary actions (like breathing). It includes the central nervous system which is mainly the brain and spinal cord, and the peripheral nervous system which are the nerves that connect all other parts of the body to the central nervous system.
  
  
• REPRODUCTIVE SYSTEM
  The Reproductive System, which includes the penis and testes in males, and the vagina, uterus and ovaries in women, allows humans to reproduce.
  
  
• RESPIRATORY SYSTEM
  The Respiratory System, which is composed of the lungs and respiratory passages, allows us to breathe.
  
  
• SKELETAL SYSTEM
  The Skeletal System, primarily bones and cartilage, is the hard structure that provides a frame for the body and helps us move.
  
  
• URINARY SYSTEM
  The Urinary System, made up of the kidneys, ureters, bladder and urethra, removes wastes from the blood and body in the form of urine.
  
  
• OVERALL GOOD HEALTH
  Overall Good Health is the general condition of the body and mind being vigorous and free from disease.