The brain

• Nerve System


  Controls sight, hearing, taste, smell, and feeling (sensation)
• Nerve System consists of

  • Voluntary system
  • Involuntary system
• Voluntary actions


  Require a conscious decision to be made
• Involuntary actions


  Do not involve conscious decisions, are much faster and produce the same response
• Involuntary actions


  Are due to reflexes
• Involuntary (Autonomic) System consists of


  • Sympathetic system
  • Parasympathetic system
• Sympathetic system


  Prepares you for action for any possible type of emergency
• Parasympathetic system


  Relaxes your body after periods of stress or danger
• Brain


  • Essential organ that controls many body functions
  • Receives and interprets all the sensory information like sights, sounds, smells and tastes
  • Has many complex parts that work together to help you function
• Components of the brain

  • Cerebral cortex
  • Cerebellum
  • Frontal lobes
  • Corpus callosum
  • Hypothalamus
  • Medulla
  • Meninges
• Frontal lobes


  Located in the front part of your brain, right behind your forehead, controls voluntary movement, speech and intellect, carry out higher level mental processes such as thinking, decision making & planning
• Medulla


  Located directly above the spinal cord in the lower part of the brain stem and controls many vital autonomic functions such as heart rate, breathing, swallowing and blood pressure
• Components of a neuron

  • Nodes of Ranvier
  • Myelin Sheath
  • Neurilemma
  • Axon terminal
  • Schwann's cell
  • Axon
  • Nucleus
  • Dendrites
• Nerve cells (neurons)


  Transmit messages or impulses around the body, examples include motor neurones and sensory neurons
• Stimulus


  Sets of an exchange of chemicals from within & outside a nerve cell across the neuron's cell membrane
• Myelin sheath


  A fatty white substance that surrounds the axon, forms a protective, insulating layer & enables electrical impulses to transmit quickly & efficiently along the nerve cells
• Schwann's cells


  Special cells that wrap around most nerve cells, collectively they make up the myelin sheath
• Dendrite


  Receive impulses and carry them towards the cell body
• Axon terminal


  Conduct impulses away from the cell body to other cells
• Structure of a synapse

  • Pre-synaptic membrane
  • Post-synaptic membrane
  • Synaptic cleft
• How the synapse functions

  1. Electrical impulse travels along an axon

  2. Triggers the nerve-ending of a neuron to release chemical messengers called neurotransmitters

  3. Neurotransmitters diffuse across the synapse (the gap) & transmit signal

  4. They bind with receptor molecules on the membrane of the next neuron

  5. Synapse transfers electric activity from one cell to another
• Neurotransmitter


  A chemical released at the synapse that diffuses across the gap and sets off a new nerve impulse or muscle contraction
• Disorders of the brain

  • Multiple sclerosis (MS)
  • Alzheimer's Disease
  • Dementias
  • Brain Cancer
  • Epilepsy and Other Seizure Disorders
  • Mental Disorders (Anxiety, Bipolar disorder, Depression, Post-traumatic stress disorder (PTSD), Schizophrenia)
  • Parkinson's and Other Movement Disorders
  • Stroke and Transient Ischemic Attack (TIA)