Blood is a fluid connective tissue connecting blood cells, plasma and platelets. It circulates all through the circulatory system of humans, delivering nutrients and oxygen to different cells and tissues. It also passes metabolic waste products away from the very same cells. On an average, blood constitutes about 8% of the mass of the body, and an adult’s body has around 5-6 litres of blood.
Blood comprises blood cells suspended in the blood plasma. Plasma accounts for 55% of the volume of the blood, it mainly comprises glucose, proteins, hormones, mineral ions, carbon dioxide and even the blood cells. In plasma, albumin is the chief protein, and it operates to control the colloidal osmotic pressure of blood. Mainly, blood cells are RBCs (red blood cells), WBCs (white blood cells) and platelets.
In the vertebrate blood, the most abundantly found blood cell is red blood cells. It contains an iron-containing protein – haemoglobin, promoting oxygen transport by associating reversibly to this respiratory gas, and highly increasing their blood solubility. On the contrary, carbon dioxide is usually transported extracellularly as bicarbonate ions are transported in the plasma.
Important Functions of Blood
The main function of blood is to transport nutrients and oxygen and eliminate wastes from the cells of the body. The various other functions of blood are the distribution of heat, defense, and maintaining homeostasis.
Defense – Role of Blood in Defense
There are different forms of WBCs protecting from exterior threats such as the pathogenic bacteria which enter the bloodstream in a wound. Various other WBCs find and destroy the internal threats like the cells having mutated DNA, which can grow and multiply to become carcinogenic, or even the body cells infected with the viruses.
Blood platelets and some of the proteins that are dissolved in plasma interact to produce clots blocking the ruptured sites of blood vessels when the vessels get damaged, leading to bleeding. Hence, the body is prevented from any further loss of blood.
Transportation – Role of Blood in Transportation
The food we consume has nutrients that are absorbed in the digestive tract. Most of the nutrients directly pass from the bloodstream to the liver, which is processed and released into the bloodstream to deliver to the cells of the body.
Oxygen diffuses into the blood that moves from the lungs to the heart, which then is pumped to the entire body. Additionally, the blood picks the by-products and cellular wastes too, and passes them to different structures to be eliminated.
Homeostasis – Role of Blood in Maintaining Homeostasis
The body temperature is regulated through the negative-feedback loop. When blood passes through the vessels of the skin, heat can be dissipated to the environment and the blood getting back to the body can be cooler. On the contrary, on a colder day, blood gets diverted from the skin to preserve a warmer tone. If conditions are extreme, it can lead to frostbite.
Also, blood aids in maintaining the balance of chemicals in the body. The pH of tissues is regulated by the buffers found in the blood, such as proteins and associated compounds. Further, blood also aids in regulating the water content of the cells.
Some other functions of blood
Apart from the above-mentioned functions, blood is involved in performing the following roles too –
- Blood aids in eliminating urea, lactic acid and carbon dioxide
- Involved in immunological functions, such as circulation of the white blood cells, identifying foreign particles by the antibodies
- It responds to broken blood vessels, coagulation, converting blood from liquid to a semisolid gel that stops bleeding
- Involved in hydraulic functions
- Performs messenger functions, even that of transporting hormones and signalling tissue damage
This was a brief on the functions of blood. Explore related articles, at NEET BYJU’S.
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