Component of blood, morphology and functions of each blood cell

        Blood is the primary transport medium that is responsible for supplying nutrients and oxygen to the cells in the body. The three functions of the blood are transportation, regulation and protection. The blood is about 45% formed fragments and 55% blood plasma. The formed elements are the cellular components of the blood while the liquid part is plasma. Blood consists of four major components :

 

1)    Red Blood Cells (Erythrocytes)

2)    White Blood Cell (Leukocytes)

3)    Platelets (Thrombocytes)

4)    Plasma

 

ERYTHROCYTES

        First and foremost the erythrocytes or also known as the red blood cell. It is a biconcave disc shaped cell that contains oxygen carrying protein called haemoglobin. The haemoglobin is what gives the red colour of the blood. The biconcave discs diameter is around 7-8μm and the function of its shape is to increase the surface area for oxygen and carbon dioxide diffusion. Erythrocytes does not have a nucleus and it cant reproduce. The red blood cell is produced in the bone marrow. The structure is highly elastic and are able to squeeze through capillary walls without rupturing. Red blood cells function is to transport oxygen to the tissues and transport carbon dioxide to the lungs. The RBC only live about 120 days because of the squeezing through the capillaries. It is then destroyed within the spleen and liver.

 

LEUKOCYTES

 

        Next, leukocyte or also known as white blood cell makes up about 1% of the volume in blood. Unlike the erythrocyte the leukocyte have nucleus and a bunch of other organelles but they do not have haemoglobin thus making it colourless. The white blood cell is either granular or agranular. Granular leukocyte are neutrophils, eosinophils and basophils where it contains granules. While agranular leukocytes are lymphocytes and monocytes where it does not contain granules. The function of leukocyte is as defence mechanism of the body and is part of the immune system to fight infections and diseases.

 

NEUTROPHIL

 

        Neutrophils are the most abundant type of granulocyte and makes up to 70% of white blood cells. They are smaller than the other granular leukocytes with the diameter of 12-15μm . The nucleus has up to two to five lobes that are connected by very thin strands of fine filament. Older neutrophils have different shaped nuclear lobes and more number of lobes. The cytoplasm of the cell is clear and contains pink coloured granules. Immature neutrophils have a horseshoe shaped nucleus and it is called a band cell. The functions of neutrophils are to fight against bacterial infection and inflammation. It is also the first responders to bacterial infection. Large number of cells are involved in combating foreign material and death of bacteria and cells causing pus formation.

  

 

EOSINOPHIL

 

        Eosinophils are also called acidophils. It is a specialised cell that is pretty rare in our blood.It has the same size as neutrophil. The structure of the eosinophil have two nucleus and it is a bilobed nucleus. The cytoplasm is filled with pink granules. The functions of the eosinophil are to combat effects of histamine in allergic reactions, phagocyte antigen and destroy parasitic worms. They are also able to modulate inflammatory process. Mostly they are important to deal with allergy. When there are many eosinophils in the blood it indicates that the body is having an allergic reaction.

 

BASOPHIL

 

        Basophil are the rarest of all leukocyte with only less than 1% in the blood count. The basophil has two nucleus with large cytoplasmic granules and they appear deep blue purplish. The nucleus is hard to see because it is overlapped with granules. A high count of basophil may indicate leukemias and cancers while a low count might indicate pregnancy and ovulation. The function of basophil are to deal with allergic reaction related to histamine.

 

MONOCYTE

 

        Monocyte is the biggest leukocyte in our blood.  The monocyte is about 12-20 micrometer in diameter twice the size of a red blood cell. The monocyte has a kidney-shaped nucleus with a transparent cytoplasm with ground glass appearance. The blood is just a temporary place for monocytes that will later go to the tissues where they will enlarge and become macrophages. A high count of monocyte may indicate bacterial infection, inflammation and stress. The functions of monocytes are for phagocytosis function to bind the pathogen and present them to T-cells. 

 

LYMPHOCYTE

 

        Lymphocyte commonly appear around 20% - 40% in our blood. The size is smaller than other leukocytes but larger than red blood cell. Lymphocytes have transparent cytoplasm, with round and large nucleus occupying most of cytoplasm. There are three types of lymphocyte firstly the T cells, they coordinate the immune system, defence against intracellular bacteria and kill virus infected cells. Other than that, B cells that make antibodies that bind to bacteria and destroy them. Finally, Natural Killer Cells (NKC), they kill cells that are infected with virus or becoming cancerous by nature.

 

THROMBOCYTES

 

        Another name for thrombocytes is platelet. Platelets break off from megakaryocytes in red bone marrow and enter the blood. In each microliter of blood there are between 150,000 and 400,000 platelets present. Each platelet is irregularly disc shaped around 2-4 μm in diameter. Mostly oval in shape and do not have nucleus. The function of platelet is to form platelet plug in homeostasis and release chemicals that promote vascular spasm and blood clotting. It is also a natural source of growth factor. 

Written by Muhammad Fariz

Reference :

 

1.     “Basophils: What They Are and What They Do.” WebMD, 8 Apr. 2021, www.webmd.com/a-to-z-guides/what-are-basophils.

2.     @ClevelandClinic. “Eosinophilia: Definition, Symptoms, Causes and Treatment.” Cleveland Clinic, my.clevelandclinic.org/health/diseases/17710-eosinophilia.

3.     “What Do Your Blood Platelets Do?” Verywell Health, 31 Aug. 2022, www.verywellhealth.com/thrombocyte-what-is-a-thrombocyte-797228.

4.     @ClevelandClinic. “Monocytes: A Type of White Blood Cell — What Are Normal Ranges?” Cleveland Clinic, my.clevelandclinic.org/health/body/22110-monocytes. 

5.     @ClevelandClinic. “What Are Neutrophils? What Can Cause High or Low Neutrophil Count.” Cleveland Clinic, my.clevelandclinic.org/health/body/22313-neutrophils.

6.     @ClevelandClinic. “Lymphocytes: Function, Definition, Levels and Ranges.” Cleveland Clinic, my.clevelandclinic.org/health/body/23342-lymphocytes. 

7.     https://www.kenhub.com/en/library/anatomy/erythrocytes