Membrane potential

• What does ICF stand for in the context of body fluids?

  Intracellular fluid
• What does ECF stand for?

  Extracellular fluid
• What is the resting membrane potential of a typical neuron?

  • -70 mV

  
• Which ion has a higher concentration inside the cell?

  K+
• Which ion has a higher concentration outside the cell?

  Na+
• What is the function of the Na+/K+ pump?

  It maintains Na+ and K+ gradients across the plasma membrane
• What percentage of total body fluid is intracellular fluid?

  40%
• What percentage of total body fluid is extracellular fluid?

  20%
• What is the primary role of the cell membrane?

  It provides cellular structure and acts as a physical barrier
• What are the functions of the plasma membrane?

  • Provides cellular structure
  • Maintains fluidity of the cell
  • Acts as a physical barrier
  • Selectively permeable to substances
• What is the concentration of K+ in extracellular fluid?

  5 mM
• What is the concentration of Na+ in intracellular fluid?

  15 mM
• What is passive transport?

  It seeks to establish equilibrium between intracellular and extracellular compartments
• How do positively charged particles move in relation to negatively charged compartments?

  They flow into negatively charged compartments
• What is the difference between simple diffusion and facilitated diffusion?

  Simple diffusion occurs without assistance, while facilitated diffusion requires channels
• What are leak channels?

  Ion channels that are always open
• Why does the plasma membrane have higher permeability for K+ than for Na+ or Cl-?

  There are more K+ leak channels in the membrane

  
• What are ligand-gated ion channels?

  Channels that open or close in response to ligand binding
• What are voltage-gated ion channels?

  Channels that open or close in response to changes in membrane potential
• What does the Na+-K+ ATPase transport?

  3 Na+ out for 2 K+ in

  
• What is endocytosis?

  Bringing substances into the cell

  
• What is exocytosis?

  Bringing substances out of the cell
• What are the major ions in intracellular and extracellular fluid?

  • Intracellular (ICF): K+ (150 mM), Na+ (15 mM), Cl- (10 mM)
  • Extracellular (ECF): K+ (5 mM), Na+ (145 mM), Cl- (115 mM)

  
• What is the resting membrane potential (RMP)?

  The difference in electrical charge across the plasma membrane at rest
• What is the approximate RMP in a typical neuron?

  • 70 mV
• How is the resting membrane potential maintained?

  By the Na+/K+ ATPase
• What happens when K+ channels open in the membrane?

  K+ ions efflux occurs, moving the membrane potential towards -90 mV
• What happens when Na+ channels open in the membrane?

  Na+ ions influx occurs, moving the membrane potential towards +60 mV
• What are the implications of resting membrane potential for ion flux?

  • RMP = -70 mV
  • If K+ channels open, K+ efflux occurs
  • If Na+ channels open, Na+ influx occurs
  • Membrane potential changes towards equilibrium potentials
• What is the electrochemical gradient?

  The combined effect of charge and concentration gradients across the membrane
• What is the Nernst equation used for?

  To calculate the equilibrium potential of ions
• What is the equilibrium potential for K+?

  • -90 mV
• What does the Nernst equation take into account?

  Concentrations of ions inside and outside the cell
• What is the significance of stable ion gradients?

  They are essential for normal physiological functions
• What occurs during repolarization?

  The membrane potential returns towards the resting potential

  
• What is hyperpolarization?

  A change in membrane potential that makes it more negative

  
• What is the role of the resting membrane potential in ion movement?

  It influences the direction of ion flow when channels open
• What happens to membrane potential when ion channels open?

  It changes as ions move towards their equilibrium potential
• What is the relationship between RMP and ion channels?

  RMP determines how ions will flow when channels are opened
• What is the effect of opening K+ channels on membrane potential?

  It causes the membrane potential to move towards -90 mV