The Nervous System

• How is a nerve cell adapted for its function?

  • Function: carry electrical impulses
  • Adaptations: Long, thin, lots of branched connections to either end (dendrites) which allows them to pass messages to other nerve cells

  
• What is needed for a nerve cell to communicate with another?

  Synapse
• What is a synapse?

  • Connection between nerve cells
  • When an electrical signal reaches the end of a nerve, it releases chemicals that cross the gap to the next nerve cell.
  • These chemicals trigger a new signal, which continues through the next nerve, repeating the process.

  
• What is the central nervous system and what does it do?

  • brain and spinal cord.
  • It controls and coordinates the body's responses by processing information from the senses and sending instructions to muscles and organs.
  • It acts as the body's control centre, regulating movement, thoughts, and vital functions like breathing and heartbeat
• What is the nervous system?

  • The nervous system controls the body's responses.
  • It includes the central nervous system (CNS) (brain and spinal cord) and the peripheral nervous system (PNS) (nerves).
  • It detects changes, processes information, and sends signals to muscles and organs
• What passes along nerve cells?

  Electrical impulses.
• What is the gap between two neurones called?

  Synapse
• What is released across a synapse?

  Chemicals
• What is the role of a receptor?

  To detect a stimulus.
• What is the role of a sensory neurone?

  To transfer a signal from a receptor to the CNS (central nervous system)
• What is the role of a motor neurone?

  To transfer a signal from the CNS to an effector
• What is the role of a relay neurone?

  To transmit a signal from a sensory neurone to a motor neurone
• What is a reflex?

  An automatic response to a stimulus
• Pathway of a reflex arc:

  stimulus➔ receptor ➔ sensory neurone  ➔ relay neurone  ➔ motor neurone  ➔ effector  ➔ response
• Examples of reflexes:

  • sneezing
  • blinking when you get dust in your eye
  • moving your hand away from a hot object
• Why are reflexes important?

  Protect us from harm
• The diagram below shows part of a reflex arc. Which structure is being indicated?

  Receptor

  
• The diagram above shows part of a reflex arc. Which structure is being indicated?

  Sensory neurone

  
• The diagram above shows part of a reflex arc. Which structure is being indicated?

  Relay neurone

  
• The diagram above shows part of a reflex arc. Which structure is being indicated?

  Effector