By Hilde Schjerven, Ph.D.. All of us have a general idea about what blood is. The heart pumps it through our own body, and we want it to live. It’s used to swear eternal friendship. We use it to save lives. If we’re sick, the physician can test our blood to learn what’s wrong. But how do the blood reflect how we’re ill, and why is it so crucial to life?


What are the components of blood? If you lose too much blood, for example in a injury or an accident, it may be life-threatening, and you might require a . We have the ability to donate up to half a liter, which is roughly 10 percent of our total blood volume, however such blood donation requires overall good health, and time to rest and recuperate afterwards.

Roughly half of the blood volume includes different blood cells, while the other half is blood plasma, the liquid that allows your blood to flow through your entire body. Every component in the bloodstream has their own important role, which is introduced in this report. is crucial for life. A human can survive for days and even weeks without , but just a couple of days without water. The reason is that water is a source that constantly recycles.

Good to know

We lose water from our body through urine and as evaporation from our through . Neither of these processes are something we can consciously control, but they’re important processes for temperature control in addition to eliminating waste products. On the other hand, our water consumption is under our control. We get water from what we drink, but also through meals.

Mild dehydration can cause , overheating, or , but isn’t life-threatening under normal conditions. In cases of extreme dehydration, you can get liquid through intravenous transfusions straight to your blood. Along with providing blood its fluidity, so that blood cells can be transported throughout the body, water is also critical as a solvent for transportation of nutrients and waste products.

Keep in mind

, vitamins, glucose, and various forms of proteins, as well as the water, constitute the blood plasma. Although the colour of the blood is red, the colour of the blood plasma is in fact yellow. The red color comes from the massive number of red bloods cells, as will be clarified below. The yellow color of the blood plasma comes from the many water-soluble components, like nutrients and various signaling molecules.

Carrier factor

Furthermore, your blood is the carrier of different waste products, which are filtered out of the blood into the urine via the kidneys. Additionally, the blood comprises various proteins which have both structural as well as regulating or signaling functions. One kind of significant structural components are the coagulation factors that are needed for proper blood clotting. Insulin is a good example of signaling molecule. People suffering from diabetes must carefully monitor and adjust the glucose and insulin levels in their blood, to ensure a correct balance.

The cells in our blood are divided into two major types: The red blood cells, and the white blood cells. Moreover, there are specialized cell fragments, called platelets, which are derived from a particular kind of white blood cells, the megakaryocytes. The red blood cells (RBC, also called erythrocytes) consume about 45 percent of the entire blood volume.


The red color is because of abundant amounts of the protein hemoglobin, which binds and transports oxygen from the lungs through our entire body. The white blood cells are crucial for our , which can broadly be divided into the innate and the adaptive immune system. The innate immune system recognizes patterns which are associated with pathogens, and mounts a speedy reaction towards infections.

The adaptive immune cells recognize specific eptiopes, and may be educated to recognize epitopes associated with . The response of adaptive immune cells are slower, but the instruction contributes to a “memory” so that upon after experiences, we can quickly recognize and remove the threat. Immunization relies on the capability of the adaptive immune system to recognize the pathogen and produce a protective “memory” or immunization. Lastly, the platelets, also called thrombocytes, aren’t cells, but instead cell fragments. They’re critical for blood coagulation, to make sure that upon a cut or damage to a blood vessel, the bleeding will stop.