Applied science nervous impulse

• What is the primary function of a motor neurone?

  To transmit nervous impulses away from the cell body
• What is the role of dendrites in neurones?

  Dendrites increase communication with other neurones
• What is the function of the myelin sheath?

  It provides insulating properties to the neurone
• What happens at the Node of Ranvier?

  Action potentials jump at these points due to the absence of myelin sheath
• What does the axon do?

  It carries nerve impulses in one direction only
• In what form do nerve impulses travel along neurones?

  As electrical signals
• What type of neurone carries impulses towards the cell body?

  Sensory neurone
• What is the role of the sodium-potassium pump during resting potential?

  It transports 3 Na+ out of the axon and 2 K+ into the axon
• What occurs during the depolarization phase of an action potential?

  Na+ channels open, allowing Na+ ions to move into the axon
• What happens during the repolarization phase of an action potential?

  K+ channels open, allowing K+ to move out of the axon
• Why does a myelinated neurone transmit nerve impulses more quickly?

  Myelin acts as an insulator, allowing action potentials to jump between Nodes of Ranvier
• What is the significance of the phospholipid bilayer in action potential formation?

  It is impermeable to ions, requiring channel proteins for ion movement
• What is the sequence of events when an action potential arrives at the presynaptic membrane?

  1. Calcium ion channels open, Ca²⁺ floods in
  2. Synaptic vesicles move and fuse with the presynaptic membrane
  3. Neurotransmitter is released into the synaptic cleft (exocytosis)
  4. Neurotransmitter diffuses across and binds to receptors
  5. Sodium ion channels open, allowing Na+ to diffuse in
  6. Postsynaptic neurone becomes depolarised, leading to an action potential if above threshold
• How is the neurotransmitter removed from the synaptic cleft?

  Enzymes break it down, and products are taken back to the presynaptic neurone
• What must happen to calcium ions before the next action potential can occur?

  They need to be actively transported out of the presynaptic knob
• What are common symptoms of Parkinson's disease?

  Tremors and difficulty walking
• What causes Parkinson's disease?

  A lack of dopamine release
• How do drugs used to treat Parkinson's affect synaptic transmission?

  They increase dopamine levels by mimicking dopamine or preventing its breakdown
• What are common symptoms of Alzheimer's disease?

  Memory loss and confusion
• What causes Alzheimer's disease?

  A lack of acetylcholine release
• How do drugs used to treat Alzheimer's affect synaptic transmission?

  They inhibit acetylcholinesterase, preventing acetylcholine breakdown
• What are common symptoms of depression?

  Fatigue and feelings of helplessness
• What causes depression?

  A lack of serotonin release
• How do drugs used to treat depression affect synaptic transmission?

  They increase serotonin levels by preventing its breakdown or inhibiting its uptake
• What is the function of the smooth endoplasmic reticulum (SER) in the presynaptic membrane?

  It synthesizes and transports lipids and reforms neurotransmitters into vesicles
• What is the function of mitochondria in the presynaptic membrane?

  They form ATP needed for pumping Ca²⁺ out and reforming neurotransmitters