The metabolic activity of any tissue is limited by its blood supply; the more active any organ, the more blood it needs and the more extensive its vascularization. The changes in metabolic activity ...

There are three types of blood vessel: arteries, veins and capillaries. The heart is a muscular organ that pumps blood around your circulatory system. The circulatory system is the heart and all the ...

Water and nutrients are important to keep living things alive and healthy. Animals, including humans, get these from what they eat and drink, but how do the water and nutrients get transported around ...