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Membrane Potentials and Neuronal Function in Anatomy & Physiology

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Terms in this set (22)

  • What is membrane potential?
    The membrane potential is the voltage difference across a cell's plasma membrane caused by unequal ion distribution and selective membrane permeability.
  • What is resting membrane potential?
    The resting membrane potential is the steady voltage of a cell at rest, typically about -70 mV in neurons, with the inside more negative than the outside.
  • What are the three main types of ion channels?
    Leak channels are always open; ligand-gated channels open when a chemical binds; voltage-gated channels open or close in response to membrane potential changes.
  • How do leak channels function?
    Leak channels are always open, allowing ions to move passively down their concentration gradients.
  • What triggers ligand-gated ion channels to open?
    Ligand-gated channels open when a specific chemical messenger (ligand) binds to them.
  • How do voltage-gated ion channels operate?
    Voltage-gated channels open or close in response to changes in the membrane potential.
  • Describe the chemical gradient for Na+ and K+ at rest.
    Na+ concentration is higher outside the cell, K+ concentration is higher inside, creating chemical gradients driving Na+ in and K+ out.
  • What is the electrical gradient across the membrane at rest?
    The inside of the cell is negative relative to the outside, attracting positive ions inward.
  • What is the electrochemical gradient?
    The electrochemical gradient combines chemical and electrical gradients to determine ion movement direction and force.
  • How does the electrochemical gradient affect Na+ at rest?
    It strongly favors Na+ entry into the cell due to both chemical and electrical gradients.
  • How does the electrochemical gradient affect K+ at rest?
    It is more balanced; chemical gradient pushes K+ out, electrical gradient pulls K+ in, with a slight tendency to leave the cell.
  • How does K+ movement contribute to the negative resting membrane potential?
    K+ leaks out through channels, leaving behind negative charge inside, making the inside more negative.
  • What role does the Na+/K+ ATPase pump play in resting potential?
    It maintains ion gradients by pumping 3 Na+ out and 2 K+ in, preserving the negative resting membrane potential.
  • What are the main parts of a neuron?
    A neuron has a cell body (soma), dendrites, axon, axon terminals, and a myelin sheath.
  • Function of the neuron cell body (soma)?
    Contains the nucleus and organelles; integrates incoming signals.
  • Function of dendrites?
    Receive signals from other neurons.
  • Function of the axon?
    Conducts action potentials away from the cell body.
  • Function of axon terminals?
    Release neurotransmitters to communicate with other cells.
  • Role of the myelin sheath?
    Insulates the axon and increases the speed of electrical signal conduction.
  • What is depolarization?
    Membrane potential becomes less negative (more positive) than resting potential.
  • What is repolarization?
    Membrane potential returns to resting value after depolarization.
  • What is hyperpolarization?
    Membrane potential becomes more negative than the resting potential.