Blood Study Guide


Blood is a tissue made up of 80% water and 20% solid.

The tissues are mostly made of plasma that contains crucial components like proteins, glucose, and salts to carry nutrients to the body’s different cells. It strengthens the body’s immune system and fights against infections or diseases in our body.

Blood helps our body to maintain optimal temperature. It carries hormones to the body cells and helps in healing of wounds, by clotting the wound with a unique component called platelet.

Components of Blood

Blood comprises three major components: white blood cells, red blood cells, and platelets, and contains fats, sugar, carbohydrates, proteins, hormones, and salts.

Red blood cell

  • It carries oxygen to different parts of the body and has a lifespan of 120 days, after which it renews itself from the food we take in.
  • Red blood cells are also called erythrocytes. RBCs are the most plentiful among the components of the blood.
  • Red blood cells do not have a nucleus. They are circular, biconcave, disc-shaped, and can form any shape which allows them to pass through narrow capillaries.
  • Red blood cells are also the smallest of all the human cells.

White blood cell

  • White blood cells or leukocytes are produced from the multipotent cells in the bone marrow known as hematopoietic stem cells.
  • It is further divided into granulocytes and agranulocytes, differentiated by the presence and absence of granules in the cytoplasm.
  • The condition of having fewer white blood cells is also known as leukopenia.
  • The white blood cells increase in number when an individual has an infection.
  • The white blood cells act as antibodies and defend against any infection and disease from the body.


  • The platelets or thrombocytes are microscopic in size and have irregular shapes. Platelets have a lifespan of 5 to 9 days, and are also responsible for the growth of an organism.
  • The presence of a high number of platelets can result in stroke, myocardial infarction, and pulmonary embolism. On the other hand, lower platelet counts could also lead to excessive bleeding in the organism.
  • The average count of platelets present in humans is found to be 150,000 to 450,000 per cubic millimeter.

Blood Types

There are four main types of blood. However, they are distinguished into 8 types of blood or blood groups based on the presence and absence of antibodies and inherited antigenic substances from the parents.

Types of bloodSource

  • The main four types of blood are group A, group B, group O, and group AB.
  • Blood groups or types should be checked for their compatible match in blood transfusions.
  • A person with blood type O is considered a universal donor because they can donate blood to people with other blood groups.
  • A person with blood group AB is also known as a universal recipient as their blood group matches with all other blood groups and can receive any type of blood.


  • To maintain good health, we should take care of ourselves and treat our bodies with utmost priority.
  • We should also keep our diet balanced with the demands of our body to stay fit.
  • Food that triggers health issues should be avoided and encourage the food that keeps us healthy.


1. What is blood? Explain?

Blood is the liquid substance that flows in our body through veins and arteries. It is generated from the bone marrow and pumped by the heart to different body parts. Blood is red and transports oxygen and nutrients to the body cells. The color of the blood is red due to a unique substance or pigment called hemoglobin.

2. What are the three types of blood?

The three types of blood are; Platelets, White blood cells (WBC), and Red blood cells (RBC).

3. What are the 8 types of blood?

The 8 types or group of blood are O (positive), O- (negative), A (positive), A- (negative) B (positive), B- (negative), AB (positive) and AB- (negative).

4. What are the functions of WBC?

White blood cell or WBC helps the immune system fight against antibodies and infectious diseases.

5. What are the 6 types of anemia?

The most common six types of anemia are:

  • Aplastic anemia
  • Thalassemia
  • Iron deficiency anemia
  • Sickle cell anemia
  • Pernicious anemia
  • Fanconi anemia

6. What is the fastest way to cure anemia?

Anemia is a disease or a deficiency caused by less hemoglobin in red blood cells in the body. Blood transfusion and bone marrow transplant are the fastest ways to heal to cure anemia. But, the treatment varies with the types of anemia an individual suffers from.

For example, a person with iron-deficiency anemia should take iron supplements and change their diet. A person with aplastic anemia should go for blood transfusion and medication or a bone marrow transplant.

7. What kills red blood cells?

Many agents could kill or minimize the number of red blood cells in our body. An agent or antibodies like snake venom, toxic chemicals, and malaria could kill red blood cells in the body. Chemicals in medicine like penicillin can also kill RBC. Daily exercise is good for the body, yet excessive exercise could also kill red blood cells.

8. How many colors of blood are there?

There are five different colors of blood depending upon the animal’s presence and absence of pigment. They are red, blue, green, yellow and orange.

9. What are the fastest ways to increase red blood cells?

There are many ways to enrich RBCs in our bodies. Maintaining a good diet, such as eating iron-rich food, can quickly increase the production of red blood cells.

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  1. What is blood? Accessed Nov 26, 2021.
  2. Blood. Accessed Nov 26, 2021.
  3. Blood. Accessed Nov 26, 2021.

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