Component of Blood, Morphology and Functions of Each Blood Cells

What does blood do? First of all, you need to know first what is basically a thing called blood. Blood is an essential fluid created in our body. It has a bit of a sticky texture and definitely thicker than the water, which contributes to 8% of the total body mass. Blood normally has a temperature of 38°C where it is usually one degree higher than normal body temperature and slightly alkaline where the average pH is 7.4. The volume of blood normally depends on each of our body size and weight but for a normal adult, the average volume of blood consisting in their body is 5 liters. The color of blood depends on its oxygen content. Blood that is full of oxygen is bright red in color but unsaturated with oxygen, it is dark red.

Blood Component

Going into deeper details about blood, you must know blood also has its components. The whole blood has two components where there are 55% blood plasma, a watery liquid extracellular matrix that contains dissolved substances, and 45% formed elements, consisting of red blood cell, white blood cell and platelets. In the formed elements, more than 99% is the red blood cells. The other less than 1% is contained with colorless white blood cells and platelets. These white blood cells and platelets create a thin buffy coat layer between the packed RBCs and plasma in centrifuged blood because they are less dense than red blood cells but more dense than blood plasma.

Tortora, G. J., & Derrickson, B. (2018). Principios de anatomía y fisiología (15th ed.). Editorial Médica Panamericana. S.A. De C.V.

Blood plasma has a pale yellow color that is composed of 92% water and 8% of solutes where most of it is the proteins. The plasma protein is majorly synthesized by the liver cells, which include the albumins, fibrinogens and globulins. Other than plasma proteins, there are other solutes in plasma which are electrolytes, nutrients, regulatory substances such as enzymes and hormones, gasses, and waste products like bilirubin.

As said earlier, the formed elements of the blood have three components which are red blood cells, white blood cells, and platelets. Red blood cells (RBCs) are also known as erythrocytes while white blood cells (WBCs) or its scientific name are called leukocytes. There are five types of WBCs, three of them which are neutrophils, basophils, and eosinophils are contained with granules while the other two, monocytes and lymphocytes are classified without granules. Please note that each of white blood cells have their own way to protect our body. Lastly, platelets or thrombocytes are cell fragments that do not have a nucleus. It assists in blood clotting by releasing chemicals when blood vessels are damaged to prevent blood loss. Detailed function of each blood cell will be discussed further below.

Why do we need healthy blood? In order to understand the importance of having healthy blood, we should be well aware of how each blood cell works in the human body.

Red Blood Cell

Starting with RBCs, they have a disc shape that is thinner in the middle. From the side view, it has a biconcave shape with a diameter of 7.2µm. Each red blood cell contains hemoglobin, a red pigment that makes up the RBCs color. It is very flexible, easily able to squeeze through the blood vessels.

The red blood cells main function is for transportation. How red blood cells could transport the oxygen and carbon dioxide is because of the hemoglobin. The hemoglobin binds with the oxygen, carries it through the body and releases oxygen, which diffuses first into interstitial fluid and then into the cell once it reaches its destination. The cells need oxygen for metabolism, which creates carbon dioxide as a waste product. Red blood cells also help in regulation of blood flow and blood pressure. The pH of the blood could become stable by releasing or picking up hydrogen. Besides that, hemoglobin releases nitric oxide that causes the smooth muscles in the vessel wall to relax which enhance the oxygen delivery to the cells.

Thrombocytes

leopharma. (n.d.). How blood clots go from good to bad. Www.cancerclot.info. 

Thrombocytes or blood platelets are tiny, colorless and spherical with rod shaped when active. It plays a vital role in blood clotting. For example, have you ever accidentally cut yourself with a sharp tools? Did you amaze on how the cut suddenly healed after some time?  It is actually your thrombocyte working hard to prevent your body from bleeding. When blood vessels are damaged, it will trigger the blood platelets to come and clump together at the damage sites in order to start the healing process. This process initiates plug to form which helps to close the wound temporarily. Then, in the meantime, strong protein threads that act as a mesh were made to hold the clump in place and attached to the wound.

Neutrophils

OpenStaxCollege. (2013). Leukocytes and Platelets. Pressbooks-Dev.oer.hawaii.edu.

Moving on to neutrophils, they are the most common white blood cells that can be found in our blood. The lifespan is usually minutes to days. It has a nucleus with 2-5 lobes increasing with age and connected by fine filament. The diameter is around 12 to 15µm and has transparent cytoplasm with pale lilac granules. The immature neutrophils have a band-shaped or horse-shoe shaped nucleus, thus called as band cells. Analogically, neutrophils act as street cop since it is the first responder to bacterial or fungal infection and trigger other leukocytes to take action. Do you know why acne occurs? This might be a new thing some people will know today, perhaps it might be you! Neutrophils actually are the ones who fight with bacteria in our face that causes pus formation called acne. It is phagocytic that releases toxins called cytotoxic from granules to kill and combat bacteria or fungi and recruits other immune cells to the infection site.

Eosinophils

OpenStaxCollege. (2013). Leukocytes and Platelets. Pressbooks-Dev.oer.hawaii.edu. ‌

Eosinophils have a lifespan of minutes to days, circulate in blood and migrate to tissues. The nucleus generally has two lobes and the cytoplasm filled with bright red-orange granules. It has the same size as neutrophils. Then, unlike neutrophils, eosinophils function like fumigators as they combat the parasitic infections and deal with allergy reactions. Eosinophil releases antihistamine, a chemical to slow down inflammation triggered by allergies.

Basophils

OpenStaxCollege. (2013). Leukocytes and Platelets. Pressbooks-Dev.oer.hawaii.edu.

Basophils is a bilobed nucleus but hard to see because of the presence of dense, heavy and dark purple granules that overlap the nucleus. It is the least common white blood cell which is less than 1%. Basophils play a role like fireman because they have the anti-inflammatory which help to defend the body from allergen. 

Lymphocytes

Humagain, S. (2017, September 5). Blood cells (Types and functions). Online Science Notes. 

‌Lymphocytes are spherical cells that contain a large nucleus that occupies most of the cytoplasm with purple stains. The size is larger than red blood cells but smaller than the other white blood cells. The lymphocytes are divided into 3 types which are T cells, B cells and Natural Killer cells. You know that B and T cells behave like special forces soldiers because they have specific targeted responses. T cells work in destruction of pathogenic microorganisms by directly attacking other cells and causing the activation of B cells. For B cells, it releases the antibodies that bind to bacteria and destroy them. Natural killer cells have similar functions to T cells but in a nonspecific way.

Monocytes

Humagain, S. (2017, September 5). Blood cells (Types and functions). Online Science Notes. ‌

We’ve gone through each cell until the last one which is Monocyte, the largest white blood cell with an indented or kidney-shaped nucleus and the cytoplasm is transparent with ground glass appearance. When monocytes are triggered to leave circulation, they are referred to as macrophages. Monocytes are very effective phagocytic cells that engulf pathogens or worn out cells. It also serves as antigen-presenting cells (APCs) for other components of the immune system.

By : Sabrina bt Ambok Malek