Blood: its components and vital tasks


Transporting nutrients, fending off diseases, healing wounds: blood performs a number of vital tasks and is made up of different components. We present an overview.

Components of blood

About half of what constitutes blood is water. This is followed by red blood cells, which make up about 43%. The other components are proteins, platelets, fat, sugar, common salt and white blood cells. The proportion of white blood cells amounts to just 0.07%. The blood cells – red and white corpuscles as well as platelets – are formed by blood stem cells in the bone marrow. Only when they have matured do the blood cells enter the blood, where they perform vital tasks for the body.

Which tasks the blood performs

Blood is also referred to as the «liquid organ». An adult human being has 5 to 6 litres. This corresponds to around 8% of a person’s body weight. Blood is always on the move – transported to almost every last part of the body by a network of blood vessels no less than 96,000 kilometres long – in its mission to perform vital tasks:

  • blood carries nutrients from the intestinal tract to the body's cells, supplying them with energy.
  • blood transports waste products to the excretory organs such as the kidneys and liver.
  • and blood ensures that heat reaches all the organs and that excess heat is dissipated through the skin. This enables the human body to run at an ideal «operating temperature» of 37 degrees Celsius.
It fends off pathogens

The white blood cells play a key role in this. By immediately sounding the alarm when they detect harmful intruders, they activate the body's defence system.

it heals wounds

If you cut your finger or scrape your skin, a protective crust quickly forms made of clotted blood. Platelets and proteins from the blood plasma are responsible for the clotting. Blood serum is blood plasma without fibrinogen, which plays a central role in this blood clotting process. The liquid blood serum is formed when the blood clotting process is complete.

Blood is always on the move – transported to almost every last part of the body by a network of blood vessels no less than 96,000 kilometres long.

What blood plasma is

To transport the solid blood cells through the body, blood plasma – the yellowish, slightly turbid and liquid part of the blood – is required. In addition to water, blood plasma contains fats, salts, hormones and proteins. The most important plasma protein is albumin. Because it binds water, it regulates the fluid content inside and outside the blood vessels, keeping it constant.

Why blood is red

Red blood cells – which look like dented discs – consist to a good 90% of haemoglobin. This is also known as blood pigment. It makes sense: the high iron levels in haemoglobin are what give blood its characteristic red colour. But this is not all. Since haemoglobin is able to transport oxygen through the body, it also ensures the proper functioning of individual cells. For the body to produce haemoglobin, it must be sufficiently supplied with iron, vitamin B12 and folic acid.


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