The conduction of nerve impulses relies upon the movement of positively-charged ions across the nerve cell membrane. The entry of sodium into the cell produces a wave of positive charge that travels down the length of an axon. Then chemicals called neurotransmitters are secreted out of the end of the axon onto the next nerve in the series (the postsynpatic nerve). This narrow space in between neurons is called the synapse. These neurotransmiiters released by the presynaptic nerve bind to receptors on the postsynaptic nerve. The binding of these receptors opens up channels in this second nerve's membrane that allow sodium ions to enter the nerve cell and initiate another wave of positive charge, and so on... The nerve signal can only move as fast as these ions and neurotransmitters can diffuse to generate this process.
<span>As a professional athlete repeats a given activity many times over, the nerve cells "upregulate" their receptors, meaning that they produce additional receptors to put in the membrane. This is just a natural reaction to the nerve being repeatedly stimulated in the same way over and over. When neurotransmitter is secreted from the presynaptic neuron, there are more receptors on the postsynaptic neuron for it to bind, more channels open up, more ions enter in a shorter time and build up positive charge to create the impulse faster, and so the overall effect is faster. </span>
<span>Additionally, there are sheaths of fatty tissue (called myelin) that insulate the charge in the neuron and allow it to be conducted faster. As people age, these sheaths can start to degrade, making the nerve cell more "leaky" and causing the impulse to be conducted more slowly. </span>
No because it does not use energy, reproduce, have a metabolism, breathe, or maintain homeostasis and its not made up of cells.
Answer:
lytic, because of the quick onset of symptoms after infection
Explanation:
As seen in the question above, the SARS virus tends to develop symptoms very quickly when it is infecting a person. This speed in the development of symptoms is a characteristic of the lytic cycle, in relation to the reproductive cycle of viruses. This is because in the lytic cycle, a virus can infect many cells at once, which accelerates the development of the disease. This cycle allows the virus to use all of the cell's biological machinery to reproduce more copies of the virus. When these copies are ready, the virus causes the destruction of the host cell and the release of new viruses to other cells, where the whole process will be repeated. This is all done very quickly.
The lysogenic cycle does not cause the rapid infection of thousands of cells, since it is necessary that there is an adaptation between the DNA of the cell and the DNA of the virus. This slows down the infection process and, therefore, symptoms appear more slowly.
Are you talking about a fruit fly?
