Peripheral nervous system
Some of your peripheral nervous system (PNS) is under your voluntary control - the nerves that carry instructions from your brain to your limbs, for example. As well as controlling your muscles and joints, it sends all the information from your senses back to your brain. Other parts of your PNS are controlled by the brain automatically. This is the autonomic nervous system. It manages some things your body does 'without thinking' like digestion and temperature control.