Membrane Potential

Card Set Information

Membrane Potential
2013-03-24 19:27:25
BIO 220

Show Answers:

  1. Membrane potential is due to:
    due to differential distributions of ions and charge
  2. Resting potential
    of nontransmitting neuron= -65 to -70 mv
  3. Outside cell:

    • Na+ = 150 mM
    • K + = 5 mM
  4. Outside cell:
    • Cl- : 130 mM
    • A- : 0.2 mM
    • Ca: 2 mm
  5. Principle cation outside
  6. A-
    proteins and negative amino acids
  7. principle anion outside
  8. Inside Cell: 
    • Na+ : 15 mM
    • K+ : 100 mM
  9. Inside Cell: 
    • Cl-: 13 mM
    • A-: 65-100 mM
    • Ca : 0.0002 mM
  10. Principle cation inside
  11. Principle anion inside
  12. Even though all cells of body have membrane potential, what?
    Effect depends on what?
    • only neurons and muscle cells/ fibers can change theirs iin response to stimuli
    • upon the type of gated ion channel that opens
  13. What is the ballance between diffusion graident and electrical attraction?
    • Na+ wants to diffisue into cell, down its concentration gradient
    • K+ diffuses out of cell, down its concentration gradient
    • Negative charges inside cell attract K+ back in
  14. Explain membrane potential at rest?
    • membranes more permeable to K than for Na+
    • Therefore, resting MP is most influenced by K+
  15. What does sodium-potassium pump do?
    counteracts leaks
  16. What is the net Result of MP?
    • inside relatively negative compared to outside
    • negative interior also results from the presence of non-diffusible anions
  17. Explain graded potentials.
    • occur at synapses on dendrites and neuronal cell bodies
    • Excitatory post-synaptic potentials (EPSPs) and Inhibitory post-synapatic potentials (IPSPs)
  18. Effect of graded potentials?
    depends upn type of gated ion channel that opens
  19. hyperpolarization
    occurs if K+ or Cl- channels open
  20. depolarization
    occurs if Na+ channels open (NA+ goes in)
  21. Graded potentials
    magnitude of change depends on the strength of the stimulus
  22. Threshold
    (-50 to -55 mV) if via graded potentials, a neuron reaches threshold an anciton potential is triggered
  23. action potential
    rapid change in membrane potential caused by selective opening of voltage-gated ion chanels
  24. Action potentials are __. Explain
    • all-or-none; amplitude not affected by strength of stimulus. Once it reaches threshold, it goes to completion (to 40 mV and in same pattern)
    • The magnitude/ strength of the stimulus is reflected by the frequency of the AP, not the height of it
    • # of APs represents strength of stimulus