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Key Words
Key Words
- axon
- myelinated
- nodes of ranvier
- sodium
- potassium
- nervous system
- calcium
- -70mv
- axon
- dendrites
- saltatory conduction
- action potential
- resting potential
- electrochemical
- sodium potassium pump
- depolarization
- repolarization
- voltage gated channels
- synapse
- stimulus
- refreactory
- recovery
- hyperpolarization
Watch first, it explains the entire mechanism of generating an action potential, important for the neurons of the Nervous System through the electrochemical gradient of the interior and exterior of the cell.
Important Videos to explain the process of the nerve impulse mechanism and action potentials
Important Videos to explain the process of the nerve impulse mechanism and action potentials
Outline the events in the image above. (6 marks)
Outline the events in the image above. (6 marks)
Resting Potentials
Resting Potentials
A resting potential is the difference in charge across the membrane when a neuron is not firing
- In a typical resting potential, the inside of the neuron is more negative relative to the outside (approximately –70 mV)
Neurons generate and conduct electrical signals by pumping positively charged ions (Na+ and K+) across their membrane
- The unequal distribution of ions on different sides of the membrane creates a charge difference called a membrane potential
The maintenance of a resting potential is an active process (i.e. ATP dependent) that is controlled by sodium-potassium pumps
- The sodium-potassium pump is a transmembrane protein that actively exchanges sodium and potassium ions (antiport)
- It expels 3 Na+ ions for every 2 K+ ions admitted (additionally, some K+ ions will then leak back out of the cell)
- This creates an electrochemical gradient whereby the cell interior is relatively negative compared to the extracellular environment (as there are more positively charged ions outside of the cell and more negatively charged ions inside the cell)
- The exchange of sodium and potassium ions requires the hydrolysis of ATP (it is an energy-dependent process)
oscilloscope-trace.mp4
Explain the meaning of each of these key words
- Resting Potential
- Depolarize
- Action Potential
- Repolarize
- Hyperpolarize
- Refractory Period
The nerve Impulse
The nerve Impulse
- Depolarisation occurs when ion channels open and cause a change in membrane potential
- The ion channels that occupy the length of the axon are voltage-gated (open in response to changes in membrane potential)
- Hence, depolarisation at one point of the axon triggers the opening of ion channels in the next segment of the axon
- This causes depolarisation to spread along the length of the axon as a unidirectional ‘wave
Test your knowledge! Review the Key Words
Test your knowledge! Review the Key Words
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