BIOL 223 Membrane Potentials - 1

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BIOL 223 Membrane Potentials - 1
2011-10-30 19:39:34
anatomy physiology membrane potentials

Study Cards for Membrane Potentials BIOL 223 CSN
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  1. How is information transmitted across an electrical synapse?
    ions flow passively through gap junctions
  2. List the two advantages of an electrical synapse discussed in class?
    • faster communication
    • all gap junctioned cells are synchronized
  3. When the presynaptic neuron is connected to a postsynaptic cell by means of gap junctions, you have what type of synapse?
    electrical synapse
  4. A presynaptic neuron with a bulbous knob that is seperated from a postsynaptic membrane by a synaptic cleft is known as a _______ synapse.
  5. List the seven steps that occur in the activation of a chemical synapse.
    • electrical signal travels along the presynaptic neuron
    • electrical charge opens Ca2+ channels and calcium ions flow in
    • Ca2+ influx causes the synaptic knob to release ligands
    • ligands diffuse across the synaptic cleft and bind to receptor proteins
    • ion channels on the postsynaptic membrane open
    • ions flow into the postsynaptic cell causing a new electrical signal to be initiated
    • electrical signal causes some activity in the postsynaptic cell
  6. List the three methods for removing neurotransmitters discussed in class.
    • diffusion - ligands diffuse away
    • enzymatic breakdown
    • uptake by cells - through endocytosis
  7. Why is it important to remove ligands from protein receptors in chemical synapses.
    to stop whatever action is occuring in the postsynaptic cell
  8. The potential of an undisturbed cell is known as the:
    resting membrane potential
  9. What is the resting potential of a neuron?
    -70 mV
  10. What is the resting potential of adipose tissue?
    40 mV
  11. What is the resting potential for cardiac muscle tissue?
    90 mV
  12. What is the resting potential for skeletal muscle?
    85 mV
  13. List the three factors that help to maintain resting membrane potential.
    • unequal distribution of ions across the membrane
    • selective permeability of the cell membrane
    • charge difference across the membrane
  14. The fact that the outside of a membrane is slightly negative and the inside is slightly positive is known as:
  15. Ions moving across a membrane create a:
  16. The accumulation of negative charges along the inside of the cell membrane is due to:
    negatively charged proteins
  17. Sodium has a higher concentration _______ the cell.
  18. Potassium has a higher concentration _______ the cell.
  19. Chloride has a _______ concentration outside the cell.
  20. True or False: Ions need a membrane channel to cross the cell membrane.
  21. True or False: A non-lipid soluble molecule can gain cross the membrane even without a channel.
    False - a non-lipid soluble molecule without a channel cannot get into the cell
  22. True or False: Lipid soluble molecules can diffuse across the cell membrane very easily.
  23. The immediate inside of the cell membrane will have a _______ charge.
  24. The immediate outside of the cell membrane will have a _______ charge.
  25. If the cell was made freely permeable what would happen to the relative charges and concentration of ions?
    they would reach equilibrium
  26. A gradient created due to the charge of an ion is an:
    electrical gradient
  27. A gradient related to the concentration of ions is a:
    chemical gradient
  28. The net effect of electrical and chemical gradients is the:
    electrochemical gradient
  29. In what direction would an electrical gradient cause a positive ion to move?
    into the cell
  30. Define equilibrium potential.
    the potential for concentrations of specific ions to be the same inside the cell and outside the cell
  31. In what direction will chemical gradients cause sodium to move?
    into the cell
  32. In what direction will electrical gradients cause sodium to move?
    into the cell
  33. What is the equilibrium potential for sodium ions?
    +66 mV
  34. What direction would electrical gradients cause potassium to move?
    into the cell (towards the negative charge)
  35. In which direction would chemical gradients cause potassium to move?
    out of the cell (towards lower concentration)
  36. What is the equilibrium potential for potassium?
    -90 mV
  37. Which has the weaker electrochemical gradient, sodium or potassium?
    potassium - due to opposing electrical and chemical gradients
  38. Which gradient is stronger, electrical or chemical, particularly in regards to potassium ions?
  39. The cytoplasm and ECF have an overall _______ charge.
  40. True of False: All cells have the same potential for energy, regardless of class.
    False - each cell class has a different potential for energy