Response and regulation

• What must organisms be able to detect?

  Changes in their surroundings
• What is a stimulus?

  A change in the surroundings
• Why does a rabbit need to detect a fox?

  To know when it is in danger
• What are sense organs?

  Groups of receptor cells
• How do sense organs function?

  They detect stimuli through receptors
• What is the role of receptors in sense organs?

  To respond to specific stimuli
• What do receptors in the eyes detect?

  Light
• Why is it important for organisms to detect stimuli?

  To respond appropriately to their environment
• What does the human nervous system allow us to do?

  Detect and react to environmental changes
• How do sense organs contribute to the nervous system?

  They detect changes in the environment
• What are the two main parts of the human nervous system?

  Central nervous system and peripheral nervous system
• What is the role of the central nervous system (CNS)?

  It includes the brain and spinal cord
• What does the peripheral nervous system consist of?

  Nerve cells that carry information to/from CNS
• What are nerves made of?

  Bundles of neurones
• What is the function of neurones?

  They carry electrical signals along their length
• What is a synapse?

  A tiny gap between two nerve cells
• How does a signal pass across a synapse?

  It passes chemically to the next neurone
• What happens after the signal crosses the synapse?

  The electrical impulse continues in the next neurone
• What is the flow of information in the nervous system?

  • Information is detected by receptors
  • Signals are sent to the CNS
  • CNS processes information
  • Responses are sent to effectors
• What is an effector in the nervous system?

  An organ, tissue, or cell that produces a response
• What is the role of receptors in the nervous system?

  They detect changes in the environment
• What is the relationship between receptors and effectors?

  Receptors detect changes; effectors respond
• What is the function of the nervous system?

  To detect and react to environmental changes
• How do sense organs contribute to the nervous system?

  They detect changes known as stimuli
• What are stimuli?

  Changes that set off a reaction in the nervous system
• What is the plural of stimulus?

  Stimuli
• What do receptor cells do?

  They detect stimuli and produce electrical impulses
• What stimuli do different sense organs detect?

  • Skin: Temperature, pressure, and pain
  • Tongue: Chemical tastes in food and drink
  • Nose: Chemical smells in the air
  • Eye: Light
  • Ear: Sound
• What are effectors in the nervous system?

  Parts of the body that produce a response
• What is a hormone?

  A chemical messenger produced in glands
• How do hormones travel in the body?

  They are carried by the blood to specific organs
• How does information flow in the nervous system?

  1. Receptors detect stimuli
  2. Receptor cells produce electrical impulses
  3. Impulses are sent to effectors
  4. Effectors produce a response
• What does the nervous system allow us to do?

  Detect and react to environmental changes
• How do sense organs contribute to the nervous system?

  They detect changes in the environment
• What coordinates a response in the nervous system?

  The central nervous system
• What is a reflex action?

  • Protective, automatic response to a stimulus
  • Follows a sequence similar to normal reactions
  • Often does not involve the brain
• What is the nerve pathway followed by a reflex action called?

  Reflex arc
• What is the process of a reflex action?

  1. Stimulus
  2. Receptor
  3. Sensory neurone
  4. Relay neurone
  5. Motor neurone
  6. Effector
  7. Response
• What does a sensory neurone do?

  Transmits impulses from receptors to CNS
• What does a relay neurone do?

  Transmits impulses from sensory to motor neurones