Stimulus response path ways

• Receptors


  Cells that allow us to detect different types of stimuli
• Primary types of receptors

  • Chemoreceptors
  • Mechanoreceptors
  • Pain receptors
  • Thermoreceptors
  • Photoreceptors
• Chemoreceptors


  • Sensitive to chemicals, such as odour molecules in the air, located in the nose and tongue
• Mechanoreceptors


  • Sensitive to touch, pressure, sound, and motion, located in the skin, inner ear, and muscles
• Pain receptors

  • Sensitive to chemical changes in damaged cells, located throughout the body, but most in the skin
• Thermoreceptors


  • Sensitive to temperature changes, located in the skin
• Photoreceptors


  • Sensitive to light, located in the eyes
• Stimulus-response pathway


  1. Receptor detects the stimulus

  2. Sensory neuron transmits the signal to a co-ordinator

  3. Motor neuron transmits a signal to an effector which produces a response
• Action potential


  • An electrical message that travels along neurons to transmit information from one part of the body to another
• All-or-None Law

  • Action potential either happens fully or not at all, like flipping a switch on or off
• Speed


  • Myelin sheaths speed up the transmission of action potentials by allowing the electrical pulse to jump from gap to gap along the neuron
• Transmission Between Neurons

  Action potential causes the release of neurotransmitters which cross over a synapse to the next neuron, carrying the message forward