Responding to stimuli

• Stimulus

  Any change in the environment of an organism that is detected by a receptor and causes a response in the organism
• Examples of external Change in Environment

  Sunlight, Temperature, Predators
• Examples of internal changes in environment

  energy, dehydration, virus, bacteria
• Mechanoreceptors

  Stimulated by a mechanical force / pressure

  Located in the muscle, skin and inner ear

  Touch, Sound, Balance, Position and Blood Pressure
• Chemoreceptors

  Respond to chemical substances

  Located in the nose and tounge

  Taste, smell, Blood PH, Pain
• Thermoreceptors

  Respond to changes in temperature

  Located in the skin

  Increases in temperature, Decreases in temperature
• Photoreceptors

  Respond to light

  Located in the eyes

  Dim lights (rod cells), Bright lights and colours (cone cells)
• Examples of physiological response

  Increased heart rate, sweating, fever
• Example of behavioral response

  Running away, sleeping
• Response

  The change / reaction of an organism caused by a stimulus
• Effector

  A muscle, gland or organ that produces a response to a stimulus