Science

• What is the function of the Central Nervous System (CNS)?


  The processing center for the nervous system that sends and receives information from the PNS.
• What are the two main organs of the CNS?

  The brain and the spinal cord.
• How does the Peripheral Nervous System (PNS) function?

  It regulates sensation, movement, and organ function by sending information from the CNS to body systems and relaying information back to the CNS.
• What is the role of the cerebrum in the brain?

  It controls memory, speech, motor functions, and thought.
• What percentage of the brain's volume does the cerebrum make up?

  90%
• What does the cerebellum control?


  Balance and coordinates voluntary reflexes such as muscle actions.
• What is the function of the brainstem?

  It controls involuntary activities such as breathing, heart rate, and digestion.
• What does the nucleus of a neuron contain?

  DNA.
• What is the role of the cell body in a neuron?

  It supplies energy and nutrients for the activity of the neuron.
• What are dendrites in a neuron?

  Fine branches that receive messages from receptors and other neurons.
• What is the function of the axon?

  It is a long structure through which the nerve impulse passes along.
• What does the myelin sheath do?

  It covers the axon and acts as an electrical insulator.
• What happens at the axon ending?

  When an impulse reaches the axon ending, it is released for the message to be passed along at the synapse junction.
• What do sensory neurons do?

  They relay information from tissues and organs to the CNS.
• What is the function of motor neurons?


  They transmit messages from the CNS to the effectors such as muscles and glands.
• What do interneurons do?

  They enable communication between sensory or motor neurons and the CNS.
• What is a reflex response?


  It is responding without thinking.
• What percentage of the human brain is made of fat?

  Sixty percent.
• At what age is the human brain fully formed?

  Age 25.
• What is the storage capacity of the human brain?

  It is considered virtually unlimited.
• How fast can brain information travel?

  Up to 400 km per hour.
• What is a common myth about brain usage?

  That you only use 10 percent of your brain.
• What is the average weight of the human brain?

  1. 5 kg.
• How many neurons are in a piece of brain tissue the size of a grain of sand?

  100,000 neurons.
• How many synapses are in a piece of brain tissue the size of a grain of sand?

  1 billion synapses.
• How much power can the human brain generate?

  About 23 watts.
• What are the functions of the nervous system?

  • Processing sensory information
  • Controlling voluntary and involuntary actions
  • Regulating bodily functions
• What parts make up the CNS and PNS?

  CNS:

  • Brain
  • Spinal cord

  
  

  PNS:

  • Nerves outside the CNS
• How do the CNS and PNS work together?

  • CNS processes information
  • PNS relays information to and from the body
• How does the body react differently to touching a hot object compared to seeing a tiger?

  Touching a hot object:

  • Reflex response
  • Immediate withdrawal

  
  

  Seeing a tiger:

  • Involves conscious thought
  • May trigger fight or flight response
• What is the pupillary reflex response?

  • An involuntary reflex
  • Keeps out excessive light
  • Protects the eyes
• What are other examples of involuntary reflexes?


  • Sneezing
  • Coughing
  • Yawning