What is Hematology?

Hematology is the branch of biology. Hematology is the medical field that deals with the treatment of blood disorders and cancers, such as hemophilia, leukemia, lymphoma, and sickle-cell anemia. Hematologists and hematopathologists are medical professionals who specialize in illnesses of the blood and its components.

Anatomy of blood

One of the most vital components of life is blood. Blood is found in almost every mammal with a circulatory system. Plasma, blood cells, and platelets make up blood, which is a fluid connective tissue. It transports oxygen and nutrients to all of our cells and tissues as it circulates throughout our bodies. It accounts for 8% of our total body weight. The average adult has approximately 5-6 liters of blood. Scarlet red or purple-red is the color of the blood.

Components of blood

In the composition of blood, there are multiple cellular formations. The main components of blood are plasma, red blood cells (RBC), white blood cells (WBC), and platelets.


Plasma is the liquid component of the cells. It is pale yellow and when separated, from plasma consists of salt, enzymes, and nutrients. Blood plasma also contains proteins and other components that are essential for human health. Albumin is the most abundant protein in plasma. Albumin binds to and transports chemicals like hormones and certain medicines, preventing fluid from leaking out of blood vessels and into tissues. Plasma serves as a reservoir, allowing it to either replace depleted water supplies or absorb excess water from tissues. 

Red blood cells (RBC)

Red blood cells, also called erythrocytes, consist of hemoglobin. They are produced by the bone marrow, a protein that gives the red color to the blood and enables it to carry oxygen from the lungs and deliver it to all of the body tissues. Red blood cells carry carbon dioxide away from the tissue and back to the lungs. When the number of red blood cells is low, it can cause anemia.

This image shows the structure of red blood cells (RBC).
CC BY 3.0 | Image Credits: https://commons.wikimedia.org | BruceBlaus

White blood cell (WBC)

White blood cells are also called leukocytes are fewer than red blood cells.  White blood cells are responsible for defending the body against infection. They circulate throughout the body and originate from the bone marrow. White blood cells are mainly classified into five types, they are neutrophils, eosinophils, lymphocytes, monocytes, and basophils.

This image show the components of white blood cells.
CC BY 3.0 | Image credits: https://commons.wikimedia.org | BruceBlaus


Platelets are also called thrombocytes. It has tiny disc-shaped cells that regulate the when if any part of the body is damaged. Platelets are fewer in number than red blood cells. It helps to clot the blood and prevent bleeding.

Functions of blood

Blood is responsible for regulating so many functions in the body, they are:

  • It helps to regulate the body temperature.
  • It helps to transport nutrients and hormones.
  • Blood provides the body’s cells with oxygen and removes carbon dioxide.
  • The blood is filtered into the kidney to eliminate nitrogenous waste from the blood plasma. The liver is also responsible for removing toxins from the blood.

Who is called a Hematologist?

Internal medical doctors or pediatricians who specialize in problems of the blood, bone marrow, and lymphatic system are called hematologists. They are specialists who may work in hospitals or blood banks. Hematologists who have worked in labs are called hematopathologists. Hematologists spend a significant amount of time examining your blood. They do diagnose illnesses. They also provide therapies such as blood transfusions. Hematologists are mostly concerned with lymphatic organs and bone marrow, and they may diagnose blood count or platelet anomalies. The lymph nodes, spleen, thymus, and lymphoid tissue are all organs that are fed by blood cells, and hematologists treat them. Oncology is the study of the diagnosis and treatment of cancer. A person with blood cancer, such as leukemia or myeloma, may see both an oncologist and a hematologist, or a specialist who is trained in both specialties. Many oncologists receive hematology training and see patients with non-cancerous blood disorders.

 Various diseases and disorders are affecting the blood, they are:


Anemia is a condition wherein the red blood cell (RBC) cannot transport enough oxygen to the body parts which are in need. This condition arises because of two conditions; one being the decrease in the number of red blood cells and the other being the deformed/inefficient hemoglobin. Anemia is one of the important underdiagnosed conditions, and if it is untreated, it can cause many severe complications, such as cardiovascular diseases.

Bleeding disorders

Bleeding disorders are a range of illnesses in which the body's blood clotting process is impaired. After an injury, these conditions can cause excessive and prolonged bleeding.


A malaria-carrying mosquito bites a human host. The malaria parasite enters the bloodstream, multiplies in the liver cells, and is then released back into the bloodstream, where it infects and destroys red blood cells.

Blood cancer

This can affect the function of the blood cells. Leukemia, myeloma, and lymphoma are examples of blood cancer, they are originating in the bone and blood marrow.


The formation of a clotted mass of blood within the cardiovascular system is called thrombosis. The clotted mass is called a thrombus.

What are the risk factors for hematological disorders?

The risk factors for hematological disorders are:

  • Aging
  • Poor diet
  • Autoimmune disease
  • Liver or thyroid disease
  • Pregnancy
  • High blood pressure
  • Obesity
  • Smoking

Diagnosis and treatment of hematological disorders

Infection, anemia, inflammation, hemophilia, blood diseases, leukemia, and the body's response to chemotherapy treatments are all illnesses that can be evaluated with hematology testing. Tests might be routine and consistent, or they can be used to diagnose significant illnesses in an emergency. A blood test can often provide an accurate assessment of body conditions and how internal or external influences may affect a patient's health.

Common hematology test

Complete blood cell count

It is one of the most common hematology tests. Anemia, clotting problems, blood cancers, immune system abnormalities, and infections can all be diagnosed with this test, which is usually done as part of a standard exam.

Bone marrow biopsy

This process can aid in the diagnosis and monitoring of anemia, thrombocytopenia, and various cancers.

Platelet count

This test helps to diagnose and monitor bleeding disorders.

Treatments of hematological disorders

Different treatments that may be used in hematological disorders include:

  • Vitamin B12 injections and folic acid pills are used to treat blood diseases such as megaloblastic anemia.
  • Hematologists manage the treatment of various blood cancer chemotherapies.
  • Diet change.
  • To prevent excessive blood coagulation, anticoagulation treatment is used.

Context and Applications

This topic is significant in the exams at school, graduate, and post-graduate levels, especially for

  • Bachelors of Science in biology
  • Bachelors of Science in medicine
  • Bachelors of Science in human anatomy and physiology

Practice Problems

Question 1: Vitamin essential for blood clotting is______.

  1. Vitamin A
  2. Vitamin B
  3. Vitamin K
  4. Vitamin C

Answer: Option 3 is correct.

Explanation: The body uses vitamin K to aid in blood clotting. Warfarin is a drug that is used to prevent blood clots. Vitamin K may reduce the effectiveness of warfarin by facilitating blood clotting.

Question 2:  Which leucocytes in the blood release heparin and histamine?

  1. Neutrophil
  2. Basophil
  3. Eosinophil
  4. Monocyte

Answer: Option 2 is correct.

Explanation: Heparin, an anticoagulant, is found in basophil. It's a white blood cell type.

Question 3:  Life span of red blood cells (RBC) is _____________.

  1. 150 days
  2. 250 days
  3. 360 days
  4. 120 days

Answer: Option 4 is correct.

Explanation: The life span of red blood cells (RBC) is 120 days.

Question 4: ______ disease is caused due by the increase in white blood cells.

  1. Leukemia
  2. Anemia
  3. Lupus
  4. Melanoma

Answer: Option 2 is correct.

Explanation: Anemia is a condition in which the number of red blood cells in the blood is reduced. Anemia is one of the most commonly underdiagnosed diseases.

Question 5: How many types of blood corpuscles are there?

  1. 4
  2. 5
  3. 2
  4. 3

Answer: Option 3 is correct.

Explanation: The blood corpuscles are of 3 types. They are colored corpuscles- erythrocytes, Colorless corpuscles – Leucocytes and blood platelets.

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