The Grand Canyon of Arizona is one of world’s largest and
steepest canyons. It ranges up to 277 miles long and 18 miles wide. Its
formation is carved due to the erosive power of the water’s current. As heavy rains continue to occur, more rocks
and stones erode and fall which adds length and width to the Grand Canyon.
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>
Answer:
1. metal
2. nonmetal
3. lower
4. higher
5. in the middle
Explanation:
100% Correct of answers your welcome :)
Answer:
This happens because viruses mutate and vary according to the environment they face. That is why different strains occur and appear every day, which must be updated in the vaccines, in order to have immunity up to date and keep up with the viral mutation without making us sick.
Explanation:
Viruses are acellular structures that do not have their own metabolism or replication method, it is because they must dominate and invade the human body so that its DNA or RNA is coupled to the human and this uses the human machinery to be able to replicate.
On the other hand, as infections occur and viruses appear, they can associate with bacteria forming bacteriophages, they can mutate within an organism that is infected by more than one viral infection and they can even adopt retrovirus mechanisms, which day by day. These new viruses are called as new strains, which evolve and will have to be coupled with vaccines.
Vaccines are a method of natural ACTIVE immunity, that is, part of the virus is inoculated, so that it generates the formation of a specific antibody in the body.
Hey there!!
Your answer is epithelial tissue. This tissue is the one that does it part to protect all of the other cells around too or form the external barrier.
Hope this helps!!
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Ans
