nervous system

• Central Nervous System (CNS)

  Made up of the brain and the spinal cord
• Peripheral Nervous System (PNS)


  Transmits messages throughout the whole body from the brain and also relays messages back to the brain
• The CNS and PNS are clearly connected and work together so the whole system functions effectively
• Brain


  • Central to maintaining life and has many functions including: basic functions such as regulating body temperature, heart rate and breathing; language (production and understanding); co-ordinating movement; coding sensory data from the sensory organs; problem-solving and planning
• Spinal Cord


  Ensures that signals from the brain are transmitted to the rest of the body via the PNS
• Divisions of the Peripheral Nervous System

  • Somatic Nervous System
  • Autonomic Nervous System
• Somatic Nervous System


  Transmits and receives messages from the senses, then directs the muscles to move appropriately
• Divisions of the Autonomic Nervous System

  • Sympathetic Nervous System
  • Parasympathetic Nervous System
• Sympathetic Nervous System


  Associated with the 'fight or flight' response, prepares the body for physical activity
• Parasympathetic Nervous System


  Popularly known as the 'rest and digest' system, helps to conserve the body's activity levels and energy
• Sympathetic Nervous System


  Like the accelerator in a car
• Parasympathetic Nervous System


  Like the brake in a car
• How Ross is likely to respond to avoid burning himself

  1. Receives a signal from the skin in his hand that he can sense heat

  2. Signal is sent from the senses via the PNS and then to the CNS

  3. PNS sends a signal to the muscles in his hand to remove his hand from the hot plate

  4. Muscles in his hand go into action and Ross takes his hand off the hot plate
• Neuron


  Cells within the nervous system, the building blocks of communication within the body
• Types of neurons


  • Sensory
  • Motor
  • Relay
• Sensory Neurons


  • Send information to the brain regarding the senses, carry information from the PNS towards the CNS, can only transmit messages
• Motor Neurons


  • Carry signals from the CNS toward the organs, muscles and glands in the body, can both transmit and receive messages
• Relay Neurons


  • Also known as Interneurons, connect the sensory neurons to the motor neurons, based in the CNS, can both transmit and receive messages
• Synapse


  The junction where two neurons meet
• Cholinergic synapse


  Synapses that use acetylcholine (ACh) as a neurotransmitter
• Transmission at a synapse

  1. Electrical impulses cannot 'jump' across synapses

  2. When an electrical impulse arrives at the end of the axon on the presynaptic neurone, neurotransmitters are released from vesicles at the presynaptic membrane

  3. The neurotransmitters diffuse across the synaptic cleft and temporarily bind with receptor molecules on the postsynaptic membrane

  4. This stimulates the postsynaptic neurone to generate an electrical impulse that then travels down the axon of the postsynaptic neurone

  5. The neurotransmitters are then destroyed or recycled to prevent continued stimulation of the second neurone