Subtitles section Play video Print subtitles How to Understand the Human Body Systems. You don't have to be a doctor to know the skin you're in. Find out what each body system does to get a better understanding of what's really going on inside of you. You will need and human body. Step 1. Journey into the digestive system, which is made up of your stomach, liver, teeth, tongue, pancreas, intestines, and esophagus. The digestive system breaks down food and absorbs nutrients for use as energy. Step 2. Take a look inside the respiratory system, consisting of your lungs, nasal passages, bronchi, bronchial tubes, pharynx, trachea, and diaphragm. This system takes in oxygen, gets it into the bloodstream, and removes carbon dioxide from the body. Step 3. Travel along the nervous system, made up of your spinal cord, brain, nerves, eyes, ears, tongue, and nose. The nervous system is what makes you see what you see, feel what you feel, taste what you taste, smell what you smell, and think what you think. Step 4. Understand the excretory system. Your kidneys, bladder, ureters, and skin all function to control water and salt balance. Step 5. Know your endocrine system, which consists of your pituitary gland, adrenal gland, thyroid gland, and gonads or ovaries. These organs produce hormones and regulate the body. Step 6. Take a spin around the circulatory system, made up of blood, blood vessels, your heart, and lymph, which transport nutrients, metabolic waste, water, salts, and disease-fighting cells. The circulatory system is responsible for getting oxygen to your organs. Step 7. Stroll through the musculoskeletal system, consisting of bones and muscles that provide movement and protection. Your skull is actually a series of fused bones that act as a hard protective helmet for your brain. Step 8. Get into the integumentary system, made up of your skin. Skin provides body heat regulation, holds receptors for stimuli response, maintains tissue moisture, and protects the body from injury and bacteria. Did you know The skin is the human body's largest organ.