nervous system paper2🩷

• The human nervous system enables humans to react to their surroundings and to coordinate their behaviour
• Peripheral Nervous System


  The part of the nervous system that includes all the nerves outside the brain and spinal cord
• Central Nervous System


  The part of the nervous system that includes the brain and spinal cord
• Stimulus


  Any change in the surroundings
• Receptor


  Cells that detect a change
• Information passes along cells


  As electrical impulses to the central nervous system (CNS)
• Coordinator


  The CNS
• Effector


  Muscles contracting or glands secreting hormones
• Stimulus


  Detected by receptors
• Receptors


  Information passes along cells as electrical impulses to the CNS
• CNS


  Coordinates the response of effectors
• Effector


  Response
• Types of neurones


  • Sensory neurones
  • Relay neurones
  • Motor neurones
• Sensory neurones


  Carry impulses from the receptors to the central nervous system (CNS)
• Relay neurones


  Connect the sensory neurones to the motor neurones in the CNS
• Motor neurones


  Carry impulses from the CNS to an effector
• Neurones are not joined together; they have small gaps between them
• Synapse


  The gap between neurones
• What happens at a synapse


  1. When an impulse reaches the end of a neurone, a chemical (neurotransmitter) is released across the gap

  2. The chemical then diffuses across the synapse

  3. When the chemical reaches the next neurone this starts another impulse
• Stimulus


  Something that detects change in the environment
• Receptor


  Something that detects change
• Parts of the central nervous system

  • Brain
  • Spinal cord
• Effector


  A muscle that brings about a response or a gland that secretes a hormone to restore prime conditions
• The CNS coordinates the body's responses to stimuli
• Components of a reflex arc

  • Receptor cells
  • Sensory neurone
  • Coordinator (spinal cord)
  • Motor neurone
  • Effector (muscles)
• Reflex actions are automatic and rapid; they do not involve the conscious part of the brain
• Reflex actions are important as they protect the body from injury
• Pathway of the reflex arc

  1. Receptor cells detect stimulus

  2. Sensory neurone carries impulse to spinal cord

  3. Coordinator (spinal cord) processes impulse

  4. Motor neurone carries impulse to effector (muscles)

  5. Effector (muscles) respond