You will need to know the five major human body systems for the ASVAB. Your body consists of major systems that work together to keep you alive. (And staying alive is a good thing, so be sure to thank your circulatory system and all the rest!) These systems include the ones listed here.
| System | Components | What the System Does |
|---|---|---|
| Central nervous system | Brain, spinal cord, and nerves | Receives, processes, and responds to all physical stimuli; for example, if you burn your hand on the stove, this system prompts you to remove your hand from the stove |
| Circulatory system | Heart, blood, and blood vessels | Delivers oxygenated blood from the heart to the rest of the body and returns the blood to the heart to be oxygenated again |
| Digestive system | Mouth, esophagus, stomach, small and large intestines, rectum, and anus | Breaks down food into smaller substances that the body can absorb and process into energy and eliminates the resulting waste |
| Musculoskeletal system | Bones, joints, voluntary and involuntary muscles | Bones support the body’s muscles and organs; joints allow bones to move; voluntary muscles work in pairs to move joints; involuntary muscles, which you can’t control, are found in organs such as the heart |
| Respiratory system | Nose, nasal cavity, trachea, lungs, and blood | Inhales air, uses the oxygen in the air to release energy, and exhales the carbon dioxide that results from this process |
