The nervous system

• Negative feedback is the body's reaction to external stimuli.
• Homeostasis is the maintenance of a constant internal environment
• The hypothalamus controls homeostasis
• hormones travel around the body via the blood stream
• Sensory Neuron - Receptors to Coordination centre

  Relay Neuron - between sensory and motor (only in reactions)

  Motor Neuron - Coordination centre to Effectors
• electrical impulses are converted into chemical messengers. They then diffuse across the synapse then attach to receptors on the receiving cell
• 2 TYPES OF EFFECTORS:

  Muscles - contract

  Glands - release hormones