25 Amazing Blood Facts For Kids, Types And Components

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Why Is Blood Important?

Blood plays an important role in carrying nutrients and oxygen to the important organs in our body. While kids may fret at the slightest sight of blood, they may be intrigued to know more about blood. Read this post as we tell more about blood for kids.

Human blood performs many essential functions, such as fighting infections, transporting hormones and nutrients around the body. It also transports waste materials to the lungs, kidneys, and digestive system to b expelled from the body. Keep reading as we unravel some interesting facts about blood regarding its importance, components, and functions in the human body.

What Is Blood?

Blood is a connective tissue made up of different cells, each performing a specific job (1). Blood is made up of four major components — plasma, red blood cells, white blood cells, and platelets. The yellowish liquid part of blood is called plasma, which makes up more than half of your blood. Plasma contains water, proteins, and salts. The solid part of the blood contains different cells, including red blood cells, white blood cells, and platelets (2).

Types of Blood Groups

There are eight types of blood — A+, A-, B+, B-, AB+, AB-, O+, and O-. The classification of blood types is based on the presence, absence, or combination of specific antigens in our red blood cells. If you have A antigen, your blood type is A. If you have a B antigen, your blood type is B. If you have both antigens, your blood type is AB. If you have neither A nor B antigen, your blood type is O. Blood groups are genetically inherited from parents.

Knowing your blood type can help save your life in extreme situations. The blood can be Rh-positive or Rh-negative, depending on the presence and absence of the Rh protein, respectively. Some people may have a B-positive blood type, while others may have B-negative(2).

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What Does Blood Do?

Now that we have discussed the types of blood, we will now look into the various functions of blood. The three major functions of blood in our body are transportation, protection, and regulation. Let us discuss the three functions in detail (3).

  • Transportation: The primary function of blood is to carry oxygen from the lungs to the cells and deliver carbon dioxide to the lungs. Blood carries nutrients, electrolytes, hormones, and waste products around the body.
  • Defense: White blood cells protect us against pathogens and foreign bodies. They help the blood to clot after an injury, preventing blood loss and healing damaged tissues.
  • Regulation/Maintenance of homeostasis: Blood plays a vital role in maintaining our body temperature. The increased blood flow near our skin helps in the loss of heat from the body. Blood also helps maintain the acid-alkali (base) balance in the body.

Types Of Blood Cells

Blood is made up of red blood cells, white blood cells, platelets, and a yellowish fluid called plasma. Red blood cells carry oxygen from the lungs to all parts of the body. White blood cells help your body fight germs. Platelets are tiny cells that help the blood clot to stop cuts and wounds from bleeding. Plasma carries nutrients, proteins, and hormones to different parts of the body. Let us understand RBCs, WBCs, and platelets in detail ((1),(2),(3),(4)).

  1. Red blood cells (RBCs): Red blood cells play an important role in carrying oxygen around the body. Each of the red blood cells contains an iron-rich protein called hemoglobin. Why is blood red? You may ask. Well, hemoglobin binds to oxygen and carries oxygen from the lungs to all parts of the body. This reaction with oxygen and makes the blood red. Also known as erythrocytes, these cells account for 40 to 45% of blood volume. Each hour, approximately four to five billion RBCs are produced in the bone marrow. RBCs develop in the bone marrow and circulate in the body for around 120 days.
  1. White blood cells (WBCs): Also known as leukocytes, WBCs are an important part of our immune system. WBCs help us in maintaining our health and protect us from diseases and infections. They produce antibodies to fight bacteria, viruses, and other foreign bodies. When the human body fights an infection, it generates WBCs in greater numbers! There are five types of WBCs, namely neutrophils, lymphocytes, eosinophils, monocytes, and basophils, which are a part of the immune system. Some WBCs may have a life cycle of a day, while others may last longer.
  1. Platelets:Platelets or thrombocytes are small oval-shaped sticky cells. They help form blood clots to limit bleeding when your skin is cut or when you get injured. Platelets gather and seal the injured area. They are produced in the bone marrow and last for around six to 12 days.

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Components Of Blood

Blood is made of about 20% solid and 80% liquid (water) (1). Apart from the RBCs, WBCs, and platelets, the other components of blood include (5):

  • Plasma in which red and white blood cells are suspended
  • Fat globules
  • Carbohydrates, proteins, and hormones
  • Different gases, such as oxygen, nitrogen, and carbon dioxide

How Does Blood Travel Through The Body?

The heart is a muscle, roughly the size of a fist. The human heart is the most hard-working organ. It is always beating, all day and all night, even when you are asleep. As the heart beats, it pumps blood through a system of blood vessels called the circulatory system (6). With each beat, your heart  pumps oxygen-rich blood throughout the body using a complex system of arteries, veins, and capillaries.

Arteries: Arteries carry oxygen-rich blood (oxygenated in the lungs) from the heart to the body.

Veins: The deoxygenated blood travels back to the lungs and heart through the veins to get oxygenated and sent back to the body.

This cycle keeps on repeating. In fact, you can feel the blood traveling around the body at different pulse points, such as the neck and the wrist. These pulse points have large, blood-filled arteries that run close to the skin surface.

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25 Facts About Blood For Kids

It’s time for some amazing facts about blood ((1),(3),(4),(7),(8)).

  1. The temperature of blood (38 °C or 100.4 °F) is slightly higher than the average body temperature (37 °C or 98.6 °F).
  1. The average pH of blood is about 7.4. However, it can range from 7.35 to 7.45 in healthy individuals.
  1. Dr. Karl Landsteiner first identified the human blood groups A, B, AB, and O in 1901.
  1. Blood is viscous and sticky. Its viscosity is around five times greater than water.
  1. Complete blood count (CBC) is a common blood test that helps evaluate hemoglobin, WBC, RBC, platelet, and differential blood counts as well as hematocrit red blood cell volume (HCT). CBC test helps diagnose infections, blood disorders, blood loss, and certain types of cancers.
  1. Blood constitutes approximately 8% of the body weight.
  1. The digestive tract absorbs the nutrients from the food you eat. All the nutrients then travel in the bloodstream to reach the liver for processing.
  1. Males have an average of five to six liters of blood, while females have around four to five liters of blood.
  1. A newborn baby has about one cup of blood in their body.
  1. Blood plasma is almost 92% water! A variety of substances, mostly proteins, are suspended in the plasma.
  1. Albumin, globulins, and fibrinogen are the three types of plasma protein present in the blood.
  1. Plasma is yellow in color. Mostly made up of water, plasma contains proteins, sugars, hormones, and salts.
  1. People with type O blood are called universal donors. They can donate blood to anyone, but they can only receive a blood transfusion from another individual with the same blood type.
  1.  The professionals who are trained to draw blood are called phlebotomists.
  1. Some types of blood disorders include anemia (different types), idiopathic thrombocytopenia, leukemia, myeloma, sickle cell disease, sickle cell anemia, sickle cell trait, thalassemia, and thrombophilia.
  1. Individuals who suffer from anemia, thalassemia, and sickle cell disease have abnormally low hemoglobin.
  1. Healthy adults have 700 times higher red blood cells than white blood cells.
  1. A healthy individual has about 35 trillion red blood cells.
  1.  The body generates erythrocytes (RBCs) at a rate of about 2.4 million per second.
  1.  Blood cannot be made or manufactured. In fact, it cannot be substituted with any other fluid.
  1.  Blood donors are the only source of blood for patients who need a blood transfusion.
  1.  Bone marrow is like a spongy material inside the bone. It produces blood cells.
  1.  In adults, the bone marrows are usually present in the pelvic bones, breast bones, and the bones of the spine.
  1. Hemoglobin is a pigment that changes color depending on the saturation level of the oxygen. Blood with more oxygen appears red, while less oxygenated blood appears dusky red or “blue”.
  1. Every time you donate blood, you can potentially save up to three lives as the donated blood can be transfused as such or separated into packed red cells, platelets and plasma – to be transfused to three different patients.

Frequently Asked Questions

1. What blood type has the most allergies?

According to a study, people with B blood group are at a higher risk of developing allergies. Another study showed that allergic rhinitis and asthma predominantly occur in people with the O blood group, whereas atopic dermatitis is common in non-O blood group (9) (10).

2. What blood type lives the longest?

It is considered that people with the O blood group have higher chances of living longer. However, there’s no clinical study or research that could validate the consideration.

Blood plays an essential role in transporting nutrients, hormones, and waste products in the body. It also helps regulate body temperature and defend the body against foreign bodies. Blood is of eight types and comprises different types of cells, namely red blood cells, white blood cells, platelets, and plasma. Blood also comprises other components such as proteins, gases, and fat globules. Introducing children to these interesting facts about blood can intrigue them and motivate them to research more about this essential connective tissue.

Key Pointers

  • Blood is a major constituent of the human body that keeps nutrients and oxygen flowing.
  • Regulation of body temperature and protection against diseases are two of the most important functions of blood.
  • More interesting facts about the temperature, function, and blood constituents in this post as you scroll through.


MomJunction's articles are written after analyzing the research works of expert authors and institutions. Our references consist of resources established by authorities in their respective fields. You can learn more about the authenticity of the information we present in our editorial policy.
1. Blood: Texas Heart Institute
2. Blood: U.S. National Library of Medicine
3. Payne, J. What is blood?: Patient
4. What is blood?: OneBlood
5. Overview of blood and blood components: Children’s Wisconsin
6. Blood flow through the body: LibreText libraries, UC Davis
7. An overview of blood: BCcampus Open Textbooks
8. Facts about blood: John Hopkins Medicine
9. Dr. Kauser Abid; Prevalence of ABO Blood Groups and their Association with Dust, Pollen and Skin Allergy in Young Adults; APIMS
10. Nur Hidayah Dahalan et al.; Association of ABO blood groups with allergic diseases: a scoping review; BMJ
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Swati Patwal

Swati Patwal is a clinical nutritionist, a Certified Diabetes Educator (CDE) and a toddler mom with over eight years of experience in diverse fields of nutrition. She started her career as a CSR project coordinator for a healthy eating and active lifestyle project catering to school children. Then she worked as a nutrition faculty and clinical nutrition coach in different... more

Dr. Anuradha Bansal

Dr. Anuradha Bansal is a pediatrician and neonatologist working as assistant professor in the Department of Paediatrics at PIMS Jalandhar. She has done her MBBS and MD Pediatrics at GMCH, Chandigarh. Thereafter, she polished her skills as senior resident at MAMC, Delhi. She has also done IAP Fellowship in Neonatology at GMCH, Chandigarh and obtained the membership of the prestigious... more