nerves

• What is the resting potential of a neuron?

  -70 millivolts
• What happens during depolarization in a neuron?

  The voltage becomes more positive due to sodium influx
• What causes the axon membrane to become more permeable to sodium ions?

  Opening of voltage-gated sodium ion channels
• How does the action potential propagate along the axon?

  Like a Mexican wave from node to node
• What maintains the resting potential in a neuron?

  Sodium-potassium pump and potassium ion channels
• What triggers the opening of voltage-gated sodium channels?

  A sufficient stimulus that changes the environment
• What is the threshold potential for generating an action potential?

  -55 millivolts
• What occurs when the action potential peaks at +40 millivolts?

  Voltage-gated sodium channels close
• What happens during repolarization of the neuron?

  Potassium ions diffuse out, decreasing voltage
• What is hyperpolarization in the context of action potentials?

  Voltage drops below resting potential, around -80 millivolts
• What are the key stages of an action potential?

  1. Resting potential: -70 millivolts
  2. Depolarization: sodium influx, reaching -55 millivolts
  3. Peak: +40 millivolts
  4. Repolarization: potassium efflux
  5. Hyperpolarization: drops to -80 millivolts
  6. Refractory period: neuron cannot fire again
• What is the all-or-nothing principle in action potentials?

  If threshold is reached, action potential occurs
• How does stimulus intensity affect action potentials?

  Higher intensity increases frequency, not amplitude
• Why is the refractory period important?

  It prevents overlapping action potentials
• What does the refractory period ensure about action potential direction?

  It ensures action potentials travel in one direction
• How does the refractory period limit impulse transmission?

  It restricts the number of action potentials per time
• Why is it important for animals to respond only to significant stimuli?

  • Prevents overwhelming the senses
  • Enhances survival by focusing on critical changes
  • Avoids unnecessary reactions to minor stimuli
• Who is the instructor in the video about neurons?

  Miss Esther
• What is the main focus of the video?

  Neurons and resting potential
• What are the main parts of a myelinated motor neuron?

  • Cell body
  • Dendrites
  • Axon
  • Myelin sheath (Schwann cells)
• What is the function of the cell body in a neuron?

  Contains organelles for protein and neurotransmitter production
• What do dendrites do in a neuron?

  Carry action potentials to surrounding cells
• What is the role of the axon in a neuron?

  Conducts nerve impulses along its length
• What is the myelin sheath made of?

  Layers of lipid from Schwann cells
• What is the function of the myelin sheath?

  Acts as an insulator for the axon
• What are the gaps in the myelin sheath called?

  Nodes of Ranvier
• What happens at the nodes of Ranvier?

  Action potentials can be generated
• What is resting potential in a neuron?

  The difference in electrical charge when inactive
• What is the resting potential value in millivolts?

  -70 millivolts
• Why is the resting potential negative?

  More positive ions outside than inside
• What maintains the resting potential of -70 millivolts?

  The sodium-potassium pump
• How does the sodium-potassium pump work?

  Transports 3 sodium out and 2 potassium in
• What is created by the sodium-potassium pump?

  An electrochemical gradient
• What occurs due to the electrochemical gradient?

  Facilitated diffusion of ions
• Why do potassium ions diffuse out of the axon?

  Higher concentration inside than outside
• Why do sodium ions diffuse into the axon?

  Higher concentration outside than inside
• Why is the cell membrane more permeable to potassium ions?

  More potassium channels than sodium channels
• What happens to sodium channels at high voltage?

  They open to allow sodium influx
• What is the process of maintaining resting potential in a neuron?

  • Sodium-potassium pump actively transports ions
  • 3 sodium ions out, 2 potassium ions in
  • Creates an electrochemical gradient
  • Facilitated diffusion of potassium and sodium ions
  • More potassium channels open than sodium channels
• What should you do if you want to practice questions after the video?

  Visit miss Esther's website