Biology Grade 12: Resting Potential and Polarization

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9 Questions

What is the term used to describe the difference in electrical potential between the inside and outside of the cell membrane during resting state?

resting potential

Which ion has a high concentration in the interstitial fluid outside the neuron?

Na+

Which ion has a high concentration in the axoplasm inside the neuron?

K+

Which ion diffuses inside the neuron due to the concentration gradient?

Na+

During resting state, sodium channels are opened.

False

What is the term used to describe the difference in electrical potential between the inside and outside of the neuron in its resting state?

Resting potential

Which ion has a high concentration in the interstitial fluid outside the neuron?

Na+

Which ion has a high concentration in the axoplasm inside the neuron?

K+

During resting potential, potassium ions tend to diffuse outside the neuron while sodium ions diffuse inside.

True

Study Notes

Resting Potential

  • The inside of the neuron membrane has a negative electrical potential compared to the outside, known as resting potential, ranging from -40mV to -90mV.
  • The interstitial fluid has a high concentration of sodium ions (Na+), approximately 16 times higher outside the neuron than inside.
  • The axoplasm has a high concentration of potassium ions (K+), approximately 25 times higher inside the neuron than in the outer interstitial fluids.

Ion Movement and Concentration

  • Due to the concentration gradient, sodium ions (Na+) tend to diffuse into the neuron, while potassium ions (K+) tend to diffuse out of the neuron.
  • The neuron membrane is more permeable to potassium ions (K+) than sodium ions (Na+), resulting in potassium ions leaving the neuron faster than sodium ions entering.

Na-K Pump and Ion Transport

  • Sodium and potassium ions are transported across the membrane against their concentration gradient by a carrier protein called the Na-K pump.
  • Energy is used through ATP to facilitate this process.
  • The difference in permeability results in a high concentration of cations (+ve charged ions) outside the neuron compared to inside.

Ion Channels

  • Sodium channels are opened, but potassium channels are closed at resting potential.

Resting Potential

  • The inside of the neuron membrane has a negative electrical potential compared to the outside, known as resting potential, ranging from -40mV to -90mV.
  • The interstitial fluid has a high concentration of sodium ions (Na+), approximately 16 times higher outside the neuron than inside.
  • The axoplasm has a high concentration of potassium ions (K+), approximately 25 times higher inside the neuron than in the outer interstitial fluids.

Ion Movement and Concentration

  • Due to the concentration gradient, sodium ions (Na+) tend to diffuse into the neuron, while potassium ions (K+) tend to diffuse out of the neuron.
  • The neuron membrane is more permeable to potassium ions (K+) than sodium ions (Na+), resulting in potassium ions leaving the neuron faster than sodium ions entering.

Na-K Pump and Ion Transport

  • Sodium and potassium ions are transported across the membrane against their concentration gradient by a carrier protein called the Na-K pump.
  • Energy is used through ATP to facilitate this process.
  • The difference in permeability results in a high concentration of cations (+ve charged ions) outside the neuron compared to inside.

Ion Channels

  • Sodium channels are opened, but potassium channels are closed at resting potential.

Learn about the resting potential and polarization of neurons, including the concentration of sodium and potassium ions inside and outside the neuron.

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