Descending tracts are the pathways by which motor
signals are pass through from the brain to lower motor neurones. Thus, all
the neurones within the descending motor system are classed as upper motor
neurones. The lower motor neurones then directly innervate muscles to produce
movement. Their cell bodies are found in the cerebral cortex or the brain stem,
with their axons remaining within the CNS.
Global warming, increase in co2 which melts land ice
Action potential is a mechanism of transfer of ions across the plasma membrane down their elctrochemical gradient. Action potential is regenerated by the influx of ions such as sodium in case of voltage gated sodium channels. The voltage gated channels can be either open or closed depending on the action potential. Depolarization of membrane leads to the opening of these channels that allow the sodium ions to enter the cell down their electrochemical gradient. The threshold of action potential is reached when the entry of sodium ions out reach the exit of potassium ions from the cell. This leads to the generation of action potential.
Nitrogen in gaseous amount is 78% which is present in atmosphere. It has to be combined with other elements, or fixed, in order to be used by plants. Lightning is one way fixation of atmospheric nitrogen because when lightning occurs, the extreme heat melts the nitrogen molecules bond, allowing nitrogen to combine with oxygen and form nitrogen oxides.
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What is atmosphere?</h3>
An atmosphere is referred to a layers of gases which envelope a planet, and is held in place by the gravity of the planetary body.
By a series of microbial transformations nitrogen is made available to plants, which in turn ultimately sustain all animal life.
For more information regarding, atmospheric nitrogen, visit:
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