Forward chaining as the name suggests, start from the known facts and move forward by applying inference rules to extract more data, and it continues until it reaches the goal, whereas backward chaining starts from the goal, move backward by using inference rules to determine the facts that satisfy the goal.
with each heartbeat,the heart pumps blood throughout our bodies,carrying oxygen to every cell,after delivering oxygen the blood returns to the heart the heart then sends the blood to the lungs to pick up more oxygen.
<h3><em>The circulatory system consists of three independent systems that work together: the heart (cardiovascular), lungs (pulmonary), and arteries, veins, coronary and portal vessels (systemic). The system is responsible for the flow of blood, nutrients, oxygen and other gases, and as well as hormones to and from cells.</em></h3>
