Neuron Resting Potential Study Notes

Neuron Resting Potential Study Notes

Lesson Overview

  • Topic: Neuron and Resting Potential

  • Chapter: 11

  • Page Reference: 366

Unmyelinated Nerve Impulse

  • Voltage Difference: Neurons establish a voltage difference between the inside and outside of the cell membrane, which is essential for nerve impulses.

  • Conduction Mechanism:

    • The movement of ions across the axon cell membrane determines the conduction of nerve impulses.

    • Electrode Measurement:

    • The cytoplasm side of the cell membrane is slightly negative.

    • The extracellular side is positive.

  • Potential Energy:

    • The charge separation across the membrane is a form of potential energy, known as:

    • Membrane Potential: Potential energy due to charge separation across the membrane.

Resting Membrane Potential

  • Definition:

    • The potential difference in a resting neuron is measured at approximately -70 mV.

  • Polarization Process:

    • The generation of resting membrane potential is referred to as polarization.

  • Cellular Composition:

    • Large negatively charged proteins are present in the intracellular fluid but not in the extracellular space.

    • The cell membrane is nearly impermeable to chloride ions (Cl-) located inside the cell.

Sodium-Potassium Pump (Na-K Pump)

  • Function:

    • The Na-K pump is crucial for maintaining the charge separation across the membrane.

    • It uses ATP for active transport, moving:

    • 3 Na+ ions out of the cell

    • 2 K+ ions into the cell.

    • Results in an excess positive charge outside the neuron.

  • Ionic Movement:

    • Sodium (Na) and potassium (K) diffuse across membrane channels, with potassium diffusing out faster than sodium diffuses back in.

    • This differential diffusion contributes to the polarized state of the resting membrane.

Sodium-Potassium Pump Mechanism

  1. Carrying Capacity:

    • The carrier protein adopts a shape allowing the uptake of three sodium ions (Na+).

  2. Energy Consumption:

    • ATP is split, and a phosphate group is transferred to the carrier protein.

  3. Ion Release and Reuptake:

    • A change in the carrier protein's shape causes the release of three Na+ ions outside the cell.

    • This altered shape permits uptake of two potassium ions (K+) from outside.

  4. Recycle Carrier Protein:

    • The release of the phosphate group returns the carrier to its original shape, ready to repeat the cycle.

  • This pump inherently creates a gradient in which small amounts of Na+ and K+ leak across the membrane following their concentration gradients.

Additional Class/Homework Notes

  • Reading Assignments:

    • Continue reading from Chapter 11 (pages 373-377).

    • The question work booklet contains review diploma questions but may not be ideal for practice in this chapter. Refer to practice questions within the readings.

  • Study Strategies:

    • Consider drawing flowcharts and mapping processes step-by-step in your notes to enhance understanding.

  • Reminder:

    • Prepare for the neuron quiz scheduled for the next class session.