Hormonal Communication

• Homeostasis: maintaining a constant internal environment despite changes in internal and external factors.
• • Negative feedback: the mechanism that reverses a change, bringing the system back to the optimum set point.

  
• • Positive feedback: the mechanism that increases a change, taking the system further away from the optimum.

  
• • Sensory receptors: cells/sensory nerve endings that respond to a stimulus in the internal or external environment of an organism and can create action potentials.
  • Effector: a cell, tissue or organ that brings about a response.