Neurons + neuronal communication

• What is the basic structure and function of a neuron?


  A neuron consists of a cell body, dendrites, and an axon, functioning to transmit electrical signals.
• How do neurons establish their resting membrane potential?


  Neurons establish their resting membrane potential through the distribution of ions across the membrane.
• What is the action potential in neuronal communication?


  The action potential is a rapid change in membrane potential that allows neurons to communicate with each other.
• What are the methods used to measure electrical potentials in neurons?


  Electrical potentials can be measured using patch clamping, intracellular recording, and extracellular recording.
• What happens to the membrane potential when a neuron is at rest?


  At rest, the inside of the membrane is more negatively charged than the outside, making it hyperpolarized.
• What occurs when a neuron becomes activated?


  When activated, the inside of the membrane becomes more positively charged, resulting in depolarization.
• Who conducted significant research on neuronal potentials in 1939?


  Hodgkin and Huxley conducted significant research on neuronal potentials in 1939.
• What establishes the electrochemical gradient across a neuronal membrane?


  The electrochemical gradient is established by specialized pumps moving ions against their concentration gradients.
• What role does the neuronal membrane play in ionic movement?


  The neuronal membrane is relatively impermeable, restricting ion movement to specialized channels.
• What is the composition of the neuronal membrane?


  The neuronal membrane is composed of lipids and proteins, including ion channels and pumps.
• How does the Na⁺/K⁺-ATPase pump function?


  The Na⁺/K⁺-ATPase pump uses ATP to pump three sodium ions out and two potassium ions into the cell.
• What is the typical resting membrane potential (V_m) of a neuron?


  The typical resting membrane potential (V_m) is around -70 mV.
• What determines the resting membrane potential?


  The resting membrane potential is principally determined by the concentrations of Na⁺ and K⁺ ions.
• What is the equilibrium potential of an ion?


  The equilibrium potential is the membrane voltage required to prevent the movement of an ion down its concentration gradient.
• How does the Nernst equation relate to membrane voltage?


  The Nernst equation calculates the membrane voltage due to a specific ion based on its concentration gradient.
• What is the Nernst equation for calculating equilibrium potential?


  The Nernst equation is given by $E =$$58 \, \text{mV} \times \log \left(\frac{[C]_{out}}{[C]_{in}}\right)$.
• What are the equilibrium potentials for K⁺ and Na⁺ ions?


  The equilibrium potential for K⁺ is -90 mV and for Na⁺ is +50 mV.
• Why is the resting membrane potential closer to E_K than E_Na?


  The resting membrane potential is closer to E_K because there are many more K⁺ channels than Na⁺ channels, making the membrane more permeable to K⁺.
• What happens to ion flow at constant V_m?


  At constant V_m, the net flow of ions is zero because the passive flow of K⁺ out is matched by the leak of Na⁺ in.
• What do sodium channels do during an action potential?


  Sodium channels permit the rapid influx of sodium into the cell upon opening, causing depolarization.
• What do potassium channels do during an action potential?


  Potassium channels permit the rapid efflux of potassium out of the cell upon opening, resulting in hyperpolarization.
• What two forces act on ions across the membrane?

  Ions are influenced by the electrostatic force and the force of diffusion.
• What does the Goldman Hodgkin Katz equation calculate?


  The Goldman Hodgkin Katz equation calculates the resting membrane potential (V_m) based on the permeability of different ions.
• What is the formula for the Goldman Hodgkin Katz equation?


  The formula is $V_m =$ 58 \, \text{mV} \times \log \left(\frac{P_K [K^+]_{out} + P_{Na} [Na^+]_{out}}{P_K [K^+]_{in} + P_{Na} [Na^+]_{in}}\right).
• How do you calculate V_m ignoring permeability?


  Ignoring permeability, $V_m =$$58 \times \log \left(\frac{4 + 140}{140 + 10}\right) =$$-1.0 \, \text{mV}$.
• How do you calculate V_m considering permeability?


  Considering permeability, $V_m =$$58 \times \log \left(\frac{50 \times 4 + 140}{50 \times 140 + 10}\right) =$$-76 \, \text{mV}$.
• What is the role of optogenetics in neuronal communication?


  Optogenetics uses light to control neurons, with blue light depolarizing and yellow light hyperpolarizing them.
• What triggers an action potential?


  An action potential is triggered by a depolarizing stimulus that reaches a specific threshold.
• What is meant by an all-or-nothing event in the context of action potentials?


  An all-or-nothing event means that once the threshold is reached, the action potential occurs fully or not at all.
• How does an action potential propagate?


  An action potential propagates without decrement along the axon.
• What happens at the peak of an action potential?


  At the peak of an action potential, the membrane potential approaches E_Na.
• What occurs during the refractory periods after an action potential?


  After an action potential, the membrane is inexcitable during its refractory periods.
• What are the two types of refractory periods?


  The two types of refractory periods are absolute and relative refractory periods.
• What causes the absolute refractory period?


  The absolute refractory period results from the inactivation of Na⁺ channels and lasts until the resting membrane potential is restored.
• What causes the relative refractory period?


  The relative refractory period results from the hyperpolarization phase, requiring a greater stimulus to reach threshold.
• What is the significance of the action potential graph?


  The action potential graph illustrates the changes in membrane potential during depolarization and repolarization phases.
• How does action potential conduction differ in myelinated and non-myelinated axons?


  Action potential conduction is faster in myelinated axons due to saltatory conduction compared to non-myelinated axons.