What are the functions of the substances in the blood?

The blood is an amazing way to deliver all kinds of important and interesting materials around our body to the organs and tissues that need it the most and is efficient in removing harmful substances from the body. In blood, there are two major constituents; plasma and red blood cells. Red blood cells are vital because they pick up oxygen from the lungs to take to tissues through a specialised structure known as haemoglobin that is extremely important in aerobic respiration as it depends on the presence of oxygen. In the plasma there are all sorts of substances that help our body maintain homeostasis but also carry away waste products in the body. They transfer substances such as carbon dioxide, urea, hormones, antibodies (white blood cells), soluble nutrients, glucose and proteins. In this way, the blood is the ultimate delivery system that picks up and drops off the necessary requirements for each part of the body.