Answer:
If a stimulus to a neuron is great enough, ___<u>t</u><u>h</u><u>r</u><u>e</u><u>s</u><u>h</u><u>o</u><u>l</u><u>d</u>_____ is reached and an action potential is generated.
First answer is , as the work of ventricle is to push blood to he whole body , so it has to be strong or it can not pump blood to head to the toe !
as in frog (an amphibian ) it has only three chambers as two artia and one ventricle, so the oxygenated blood from left artia and deoxygenated blood from right , combines and thus partial oxygenated blood is circulated !