Blood & Our Circulatory Systems
Published on 12 Jan 2022

Our lives are dependent on a healthy heart that never stops. The heart’s strong and rhythmic beating helps blood circulate through our body, bringing oxygen and nutrients to our organs and carrying metabolic waste and carbon dioxide away. But do you know why blood would have to travel through our heart twice before going into the circulation again?

Our blood is made up of four key components, namely red blood cells, white blood cells, platelet and plasma. Red blood cells help transports oxygen from the lung to our organs and remove carbon dioxide from organs to lungs. White blood cells can be considered as the fighter our of immune system and help protection us from viral infection. Platelets are bandages that our body has that helps block blood vessels around wounds to stop bleeding. And the plasma is the medium that carries red blood cells, white bloods cells, platelets and nutrients in the circulatory systems.

In the circulatory system, our heart is the centre of two circulatory circuits, with each circuit connecting to our lungs and the rest of our body. Deoxygenated blood from our organs would be led by veins to enter the heart. It will be pumped to the lungs, become oxygenated and return to the heart. As the concentration of oxygen in the lung is higher than that in the deoxygenated blood, this concentration gradient flavours the binding of oxygen to the red blood cells. The now oxygenated blood will enter the systemic circuit through arteries and travel to the rest of the body. As blood travels through our organs, the oxygen and nutrients in blood would diffuse to the organ’s cells, while waste and carbon dioxide from the cells would also diffuse to blood because of the concentration gradient, becoming deoxygenated and return to the heart via veins.

People who failed to have a normal level of either one of these components could have severe disease that are life-threatening. For example, people with a deficiency in red blood cells have anaemia. The deficiency might be caused by insufficient iron intake or genetic disorder. A change of diet could improve the former cause but the latter would require a bone marrow transplant. We should also have a healthy diet with balanced nutrients so that our blood suffice the nutritional need of our body.