They can constrict or dilate because their walls are muscular.
Answer:
<u><em>The membrane potential is the basis for the conduction of nerve impulses along the cell membranes of neurons. Ions that are important in the formation of a nerve impulse include sodium (Na+) and potassium (K+). Ion channels and ion pumps are very specific; they allow only certain ions through the cell membrane.</em></u>
Explanation:
<span>obtain approval from medical control</span>
Pain in joints of the arms and legs
