homeostasis is maintaining a stable internal environment
the nervous system detects and reacts to stimuli
the endocrine system releases hormones into the bloodstream which travel around the body
the central nervous system is made up of the brain, spinal cord and nerves
sensory neurones carry electrical impulses to the central nervous system
motor neurone carries electrical impulses from the CNS to the effector
the main effectors are muscles and glands
receptors detect stimuli
the reflex arc: stimuli -> receptor -> sensory neurone -> spinal cord -> motor neurone -> effector
a synapse is the gap between two neurones
in a synapse, electrical impulses are converted to chemicals to diffuse across the gap then converted back to electrical signals when it reaches the neurone
