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1. I was interested in our

1. I was interested in our discussion of paralysis and Christopher Reeve’s ability to move his foot in response to pain. The movement of the foot away from pain is an involuntary process that does not require any signals to reach the upper part of the nervous system. If this movement can be accomplished without the help of the brain, is it possible, that other, more complex movements, could be completed or learned? Take walking for instance; walking requires many parts of the brain including the cerebellum and the medulla. These brain structures are located under the large cerebral cortex and are considered the move primitive parts of the brain. Walking for most people does not require any conscious thought and is accomplished through muscle memory. I know that right now it’s not possible for a person who is paralyzed to walk, but in the future, after millions of years of evolution, humans will not need our brains to walk. We can see from the brains of less intelligent creatures that brain structure has changed considerably over millions of years, so it is not unreasonable to hypothesize that the human brain may also evolve. If we were able to move the boxes required for walking lower in the nervous system, our brains may be able to accomplish more complex tasks because there is more room and energy for these tasks. The ability to complete more intricate processes may be favorable adaptations and be selected upon during natural selection.

 

2. Action Potential and resting potential are alike in many ways. Both involve the change in charge across a semi-permeable membrane. In a typical cell, there are more potassium ions inside the cell and more sodium ions located outside the cell. In the cell membrane, there are potassium-sodium pumps that help the two ions move from inside to outside the cell without passing through the hydrophobic bilayer. When the cell is at rest, the potassium pump is typically open, while the sodium pump is closed. This allows potassium ions to move from inside the cell to the outside. This movement towards the outside of the cell is known as diffusional force, which is balanced by electrical force, which is pulling the potassium ions back into the cell. So, the potassium ions move out of the cell because statistically, they have more of chance of moving in this direction, but once there has been a net movement of potassium ions, a electrical gradient is created, where the inside of the cell becomes more negative. The potassium ions will then start to move towards the positive charge (electrical force). This movement creates a voltage across the cell (-60 mV)-also known as the resting potential. So, the ability of potassium ions to diffuse across the membrane creates the resting potential of a cell.

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