Action potentials (i.e. nerve impulses) occur in several types of animal cells<span>, called </span>excitable cells<span>, which include </span>neurons<span>, </span>muscle cells<span>, </span>endocrine<span> cells, and in some </span>plant cells<span>. </span><span>It takes around 40 action potentials for a smell sensation to be reported.</span>
<span>Guarana i think but i'm not very sure</span>
<span>The exosphere is the fifth and final layer of the atmosphere. This layer is a little thicker than the theremosphere at 500-1000 km thick.</span>
<span>d. The majority of bacteria on earth can cause disease, if given the opportunity.
Most bacteria don't cause disease and some are even beneficial to the body (good bacteria). </span>
