Blood: Definition, Components, Types of Groups, and Functions

Functions of Blood in the Human Body – Every human being must have blood in their respective bodies. Blood is a liquid in the human body that is endless. Even though a person bleeds a lot, blood can be recovered in various ways. An example is a blood transfusion.

Then what is blood? Is blood something very important in the human body? This article will discuss about blood. Starting from the definition of blood, types of blood cells, blood type to the function of blood.

Definition of Blood

Blood contains not only hormones, oxygen, nutrients and impurities in the body. Blood becomes the morning seat of plasma, cells and proteins. This is what makes blood have a thicker texture than water.

When viewed more deeply, blood cannot be interpreted only as a liquid that helps the nose run. However, it is also a means of channeling various things in the human body. In addition, blood is actually not completely liquid. Blood consists of solids and fluids.

The solid part of the blood contains various blood cells. The liquid part of blood is known as plasma. Plasma is made up of salt, protein and water. Blood plasma makes up at least 55% of the total blood composition. There are three types of blood cells in the blood. There are red blood cells whose job is to carry oxygen. Platelets are responsible for the blood clotting process. White blood cells are responsible for protecting the body from various diseases that might attack the body.

These blood cells are produced from the bone marrow. Red blood cells can live for about 120 days. Platelets can last up to six days. White blood cells live for less than one day.

These blood cells are produced by the bone marrow. Red blood cells can live for about 120 days, platelets can last up to six days, and white blood cells can live for less than one day.

Blood Components

1. Red blood cells

Red blood cells have the job of transporting oxygen and distributing it throughout the body. Through red blood cells, the oxygen needed by the body will be fulfilled properly.

However, the opposite can also happen. When there is a shortage of red blood cells in the human body, humans will experience anemia.

2. White blood cells

White blood cells have a function as an antibiotic. This means that white blood cells will fight diseases that the human body can succumb to. White blood cells are usually used to maintain the human body’s immunity. If a person lacks white blood cells, it will result in that person easily feeling sluggish, tired or tired.

This happens because the person’s immune system is not balanced. There are about 7,000 to 25,000 white blood cells in the human body. White blood cells work by looking for foreign objects. If on the way the white blood cells find a foreign object in the blood, then a will work to attack the foreign object.

In addition, the content in the white blood cells will also eat the incoming bacteria. Bacteria that enter the circulatory system will be eaten by these white blood cells.

3. Blood plasma

Another blood cell is blood plasma. Blood plasma is slightly yellowish in color. However, the yellow color present in blood plasma is clear and translucent. Blood plasma also has several substances that are beneficial to the human body. Substances carried by blood plasma are minerals, hormones, antibodies, carbon dioxide or waste substances, and the rest of protein breakdown. From this blood plasma that will transport the remaining substances that are not functioning. Then these substances will be absorbed in the small intestine.

4. Platelets

Blood Type Type

Knowledge of blood type is important. This is necessary when there are matters regarding blood such as blood transfusions. The blood used for transfusion must match the blood you have. Rhesus needs to be known during pregnancy. This is necessary, because blood type can also be seen whether it has the potential to become a threat to the life of the fetus or vice versa.

This blood type which is divided into 4 types has several characteristics or characteristics. The following are characteristics of each type of blood group

A blood type

This type of blood type A has characteristics, such as the antigen in this blood group is only A. While the antibodies in the blood plasma are B.

AB blood group

Type AB blood has characteristics, such as red blood cells consisting of antigen A and antigen B. Meanwhile, in the blood plasma there are antibodies A and antibodies B.

B blood group

Type B blood has characteristics, such as red blood cells where the antigen is B and antibodies in the blood plasma are A.

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Blood type O

Type O blood has characteristics, such as antigens on red blood cells, namely antigen A and antigen B. Meanwhile, in blood plasma, antibodies are A and B.

Blood Functions

1. Transport oxygen

One of the first and main functions of blood is to transport oxygen. The air that enters the body and contains oxygen will go to the lungs. After that the air will undergo several processes. Then the oxygen will enter the capillaries in the human body.

The next process is oxygen will enter the blood plasma. The oxygen will diffuse into the red blood cells or called erythrocytes. This happens because of the function of red blood cells which contain hemoglobin or Hb to bind oxygen in the blood.

This process is referred to as deoxygenation. Oxygen in the body will turn into HbO2. Changes can occur around 97%. The rest will be in the blood plasma. After that it will be transported and circulated throughout the human body tissue.

2. Circulate food essence

The next function of blood is to transport and distribute food essences. Blood flows to all parts of the body by spreading food essences brought from oxygen uptake. These food extracts are also obtained from protein, some vitamins or carbohydrates which are obtained from the food that has been consumed.

The process of transporting and spreading this food essence occurs after the process of digestion of food occurs. Before the food extracts are distributed, the food essence will first pass through the liver. This happens to filter out all the toxins and other harmful substances present in the blood.

After the filtering process, then the nutrients or food extracts are circulated throughout the human body. This will make the body get enough food essence and evenly.

3. Circulate hormones

Blood also functions to circulate hormones that enter the body. The hormone is obtained because of a stimulus or stimulus. These stimuli can come from outside the human body, or from within the human body itself.

Blood will transport these hormones. Then the exocrine glands will take hormones that have no benefit. After that, it will be disposed of in special channels in the human body.

While the blood will carry the hormones that have been filtered earlier to the normal channels. This means that there is no special flow as required by the exocrine glands.

4. Attacking bacteria and germs

Blood also functions to attack bacteria and germs that enter the human body. Functions like this can occur because of the function of white blood cells or leukocytes. In the human body, there are five white blood cells. Among them are neutrophils, lymphocytes, basophils, monocytes and eosinophils.

The largest white blood or leukocytes are neutrophils. The amount can reach 60%. Neutrophils have a function to attack germs and bacteria that enter the human body.

Even so, other white blood cells also have other roles. Such as attacking germs, producing antibodies, and removing the remnants of damaged cells.

5. Heal wounds

Blood can also heal wounds. This is one function of the presence of blood in the human body. Part of the blood that plays a role in wound healing is called platelets. Platelets have a role to heal wounds on the human epidermis.

In the process, platelets will release the substances in them. This substance will combine with vitamin K. thus forming blood so that the blood becomes frozen. After the platelets freeze, slowly the platelets will try to cover the wound on the human epidermis.

If the number of platelets in the blood decreases, this will have an impact if there is an injury. Wounds become difficult to treat. Because there is no substance that is able to cover the wound and clot the blood in that part.

6. Carrying the remaining oxidation of body cells

The next function of the blood is to carry the rest of the cell oxidation. The oxidation of these cells is carried out because they are not useful for the body, so they will be removed from the body. This can be seen when the process of doing breathing.

There, there is a process of transporting oxygen. Oxygen is lifted through the blood to the heart organs. Then from the heart will experience a process and circulate to all parts of the body.

After being processed from the heart organ, the oxygen that produces carbon dioxide will eventually be removed through the blood. The disposal process occurs when exhaled simultaneously at the time of exhalation.

7. As a regulator of body temperature

Blood also functions to regulate the temperature of the human body. Body temperature will be kept stable from 36 degrees to 37 degrees Celsius. Body temperature is also affected by blood circulation. The human body temperature is not affected by environmental conditions. However, it is influenced by the human circulatory system.

The results of blood oxidation will produce heat in the body. If the oxidation is good, then the temperature in the body will tend to be good too. If the oxidation is not good, then the temperature in the body will also tend to be bad.

Blood will absorb and distribute heat throughout the body. This fluid will help to maintain homeostasis. Through the release or conservation of warmth. Homeostasis is the regulation of conditions that exist within the human body. Such as moisture content, temperature and carbon dioxide levels.

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Blood vessels can also expand and contract when reacting to outside organisms. Like bacteria or internal hormones. In addition, when a chemical change occurs.

This action will cause more heat to be carried by blood on human skin. The heat can be lost into the air. Blood vessels can shrink again, this will have an impact on reducing heat loss through the skin after body temperature returns to normal again.

8. Removing waste products from cell metabolism

The next function of the blood is to remove waste products from cell metabolism or excretion processes. This happens because not all substances transported by blood are substances that are useful for the human body.

Some substances that do not have the function of the results of this metabolism will be transported by the blood and go to the secretory organs. These substances will flow into the excretion or disposal system. Such as the liver, kidneys and skin.

9. Keeping seeds of disease

Blood has another function, namely harboring germs of disease. In addition, blood can also keep the body fit and healthy. Prevention of diseases carried out by the blood is done through the pieces of blood or platelets in the blood.

This blood platelet functions to harbor germs so that they do not spread throughout the human body. Blood will control it. Germs of disease will also be killed by blood platelets. This is what makes the human body feel healthier.

10. Against disease

White blood cells, also known as leukocytes, are blood components that have a duty to fight disease. The number of blood cells is only a few. About one percent of circulating blood. However, these white blood cells or leukocytes can multiply. These white blood cells will multiply when there is inflammation or an infection. So it becomes more.

11. Transporting water

The volume of the human body is mostly made up of water. This water is in the blood plasma. Water in the human body will flow in the blood vessels and capillaries. This will allow water to reach all organs or parts of the human body.

The need for water in the human body will help prevent various kinds of health problems that can occur. In addition, it can also facilitate the digestive process. Another function of water in the body is that it can help the metabolic system that occurs in the human body.

12. Maintaining acid-base levels of fluids in the body

Blood also functions to maintain acid and alkaline levels of fluids or pH in the human body. This function is carried out to prevent damage to body tissues. This damage can occur because it can be caused by buffer compounds.

13. Carries body waste

Another function of the blood is to carry body waste to the human kidneys and liver organs. Blood has the function of transporting waste to the organs whose job it is to remove and process it for disposal. These organs are the kidneys and liver.

In the kidneys, substances such as uric acid, urea and creatinine are filtered from the blood plasma. The substance will then enter the ureter. Then it will be excreted from the body in the form of urine.

The liver will also remove toxins from the blood. Blood that is rich in vitamins is the result of the absorption of the digestive organs, then it will be cleaned by the liver. After that the vitamins will be circulated to the cells in the body.

Kinds of Blood Diseases

Blood Clotting

Blood clotting itself serves to heal injuries and wounds. The next disease caused by blood is blood clots. In this disease, blood clots will cause blood clots, which can endanger the sufferer.


Hemophilia is a blood disease that can occur if a person already has a high enough blood clotting level. Therefore, people with hemophilia bleed easily and often experience bruising.


Anemia is a disease caused by reduced levels of red blood cells (hemoglobin) in the body. Reduced red blood cells, the oxygen that is transported by red blood cells becomes less than optimal. Symptoms of this disease, such as pale face and skin, body feeling tired, and so on.

Blood cancer

Blood cancer is a disease caused by blood and is practically the same as leukemia. This blood cancer originates from blood cells where the division is not optimal.

Blood Enhancing Foods

Blood booster foods are very diverse. In addition, usually the content of substances in blood-boosting foods, such as iron, vitamin A, vitamin B12, folic acid, and copper.


Foods that contain iron, such as spinach, beef, broccoli, beans, chicken or beef liver, cabbage, and kale.

Vitamin A

Blood-boosting foods that contain vitamin A are usually in the form of fruits, such as melons, watermelons, sweet potatoes, pumpkin, spinach, carrots and peppers.

Vitamin B12

Foods that contain vitamin B12 can also increase a person’s blood. Here are some foods that contain vitamin B12, such as eggs, milk, cheese and red meat.

Folic acid

Some foods that contain folic acid in it, such as soybeans, spinach, rice, beef, and avocado.


Chicken, cherries, nuts, and liver are blood-boosting foods that contain copper.

That’s information about blood. Find other interesting information at . sinaumedia as #FriendsWithoutLimits will always provide interesting book recommendations for Sinaumed’s.

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Author: Wida Kurniasih

Source: from various sources