Shiatsu, Reiki, Chakra Balancing, Acupressure and associated modalities recognize a subtle energy system by which chi (life force energy) is circulated through the body. This transportation system is referred to as the meridians. There are twelve main meridians in the body, six yin and six yang.
To better visualize the concept of how chi flows through the chakras and meridians, think of the chakras as the lakes and oceans (main reservoirs of chi) and the meridians as a river-bed, over which water (chi) flows and irrigates the land (the body); feeding, nourishing and sustaining the substance through which it flows. If a dam (blockage) were placed at any point along the river (meridians), the nourishing effect that the water (chi) had on the whole river would stop at the point the dam (blockage) was placed.
When the chi becomes blocked, the rest of the body that was being nourished by the continuous flow, now suffers. Illness and disease can result if the flow is not restored.