What are types of blood cells?

There are three types of blood cells – red blood cells, white blood cells and platelets. 

Red blood cells (Erythrocytes)

Red blood cells or erythrocytes are the most abundant type of blood cells in the body, making up almost half the total amount. 

Red blood cells are biconcave, disc shaped, bright red in color, and rich in hemoglobin. Mature red blood cells in humans are anucleate, leaving more space to store hemoglobin. 

The main function of red blood cells is carrying oxygen from the lungs to the tissues throughout the body and carrying carbon dioxide from the tissues back to the lungs to be expelled during exhalation. Hemoglobin, an iron-rich respiratory pigment, plays a pivotal role in helping red blood cells transport oxygen throughout the body.  

White blood cells (leukocytes)

White blood cells or leukocytes are an integral part of the immune system and play a vital role in fighting infections. They make up a very small part of the total blood cells in the body, accounting for less than 1%. 

White blood cells are colorless, irregularly shaped, and devoid of hemoglobin. They have one large, centrally located nucleus. 

There are 5 types of white blood cells. They play different roles in the immune system although they all work together to fight off infections. The 5 types of white blood cells are grouped into two main categories based on presence or absence of small protein granules in the cytoplasm. 

Granulocytes (have granules) – Neutrophils, eosinophils and basophils.

Agranulocytes (lack granules) – Lymphocytes and monocytes.

• Neutrophils are involved in fighting bacterial and fungal infections. They work by engulfing pathogens and destroying them.
• Eosinophils are primarily involved in destroying parasitic and cancer cells. 
• Basophils play a role in triggering inflammatory responses. 
• Lymphocytes produce antibodies to fight against foreign antigens.
• Monocytes act as scavengers removing dead cells and damaged components of the blood.

Platelets (thrombocytes)

Platelets are irregular in shape and make up a very small part of the total blood cells, accounting for less than 1%. They play a key role in controlling bleeding by releasing substances necessary for blood coagulation. 

Thrombocytopenia, a condition associated with low platelet count, can cause excessive bleeding and loss of blood.