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What does blood do?

Blood is a multifunctional wonder fluid. Ever thought about what it actually does?

What is blood made of?

Blood serves a multitude of important functions in the body, so it is naturally composed of many different things. What we think of as blood – the red and white blood cells, along with platelets – makes up only 45% of blood. The rest consists of liquid called plasma, which is primarily made up of water but also contains proteins, glucose, mineral ions, hormones and carbon dioxide.


The primary functions of blood

The system of blood vessels (vascular system) is responsible for transporting messages and nutrients throughout our body; it protects us from harmful items and helps regulate our entire system, so the body stays in balance. 

Distributing energy

The vascular system helps ensure that energy is absorbed and distributed throughout the body. This starts with the lungs. As oxygen enters your lungs it is being rapidly infused into your blood in exchange for the carbon dioxide waste that you exhale out (called “gas exchange”). The now freshly oxygenated blood cells will travel to a compartment in the heart called the left atrium, through to another compartment called the aorta and on to an intricate network of blood vessels that supply oxygen to our organs and muscles. 

Blood also plays a huge role in processing the foods and drinks that we consume. Most of the nutrients we eat are digested and absorbed through the small intestine. From there, our blood helps transport and distribute these nutrients throughout the body.

Filtering waste 

As blood spreads oxygen and nutrients through the body it also helps the body transport waste products. The blood carries carbon dioxide waste back to the lungs, and it also plays a part in ensuring that the liver and kidneys are able to filter the blood for waste products. 

Neutralising and healing

The body reacts quickly to cuts and scrapes by using platelets, fibrin and other substances to create a clot so that the blood vessel wall has time to heal. To learn more about how blood clots work, read this.

White blood cells are also key players in the body’s immune system. Along with antibodies, they travel through blood vessels in order to identify and neutralise harmful agents like bacteria and viruses.

Transporting messages

Your blood is a communications expert. It transports messages throughout the body in the form of hormones, which tell our cells what to do – everything from growing hair for a beard to triggering our instinct to sleep.

Finally blood also keeps us warm by helping to moderate body temperature. Contrary to popular belief, it does not become thicker or thinner in order to keep the body warm. When the body is cold, blood vessels contract (shrink) in order to reduce blood flow to outer areas like the skin, fingers and toes. This ensures that the body’s vital internal organs stay warm. On the other hand when it is too warm, the blood vessels dilate (expand) in order to release heat from the body.

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