Blood Cell, Types and Functions
Blood:
One of the most important components of life is blood. Blood is found in almost every mammal with a circulatory system. Blood was thought to have evolved from a sort of cell that was involved in feeding and phagocytosis from the perspective of evolution. Blood and the circulatory system have played a major role in the evolution of more complex lifeforms billions of years later.
What is Meant by Blood?
Blood is a fluid connective tissue made consisting of platelets, plasma, and blood cells. It circulates throughout our body, giving different cells and tissues oxygen and nutrients. It makes up 8% of our total body weight. An adult normally has between 5 and 6 liters of blood in them.
Blood Cell:
The cells that are produced during hematopoiesis and are mostly present in blood are known as blood cells. Blood is composed of up of plasma, the liquid component of blood, which makes up the remaining 55% of the volume. Blood cells make up 45% of the blood tissue by volume.
Blood cells come in three distinct types. These are:
1-Red blood cells ( Erythrocytes )
2-White blood cells ( Leukocytes)
3-Platelets (Thrombocytes )
1-Red blood cells (Erythrocytes):
- The most prevalent blood cell kind.
- Make up between 40 and 45 percent of the blood.
- Biconcave disc: a flat, spherical disc that is like a shallow bowl.
- Disk diameter ranging from 6.2 to 8.2 µm.
- Nucleus Absent.
- They have a thick rim and a thin sunken center.
- Can change its shape without breaking.
- Erythropoietin is the hormone that controls RBC production.
- 33% of RBCs are made of hemoglobin.
- The red color of blood is attributed to the iron present in hemoglobin.
- RBCs are not self-repairing.
- 120-day life span.
- Adult humans create 4 million new erythrocytes every second.
- At any given time, 20–30 trillion red blood cells.
- 4.3-5.9 million/mm3 for men and 3.5-5.5 million/mm3 for women.
Functions:
- RBCs, also referred to as erythrocytes, are human biconcave cells without a nucleus. Blood is red because haemoglobin, an iron-rich protein found in red blood cells, is present in them. RBCs are the most abundant blood cells that bone marrow produces. Their main function is to move oxygen to and from various tissues and organs.
- Pick in and release carbon dioxide into the lungs from other tissues.
2-White blood cells (Leukocytes):
- Account for only 1% of the blood.
- 4500- 11,000/mm3
- The bulk of the immune system is made up of these cells.
- It is the area of the body that protects against impurities and various types of infections.
- They are made in the bone marrow from multipotent hematopoietic stem cells.
- They are found in the bloodstream, lymphatic system, and connective tissue, among other areas of the body.
- Low white blood cell counts, is a leukopenia, that can result from treatments like chemotherapy, radiation therapy, or medication-induced bone marrow destruction.
- A high white blood cell count, or leukocytosis, can result from a variety of illnesses, such as inflammatory diseases of the body and various types of infections.
- Blood cells called leucocytes are colorless. They lack hemoglobin, which is why they are colorless. They are divided into two more classified as granulocytes and agranulocytes. WBCs primarily support defense and immunity mechanisms.
Types of White blood cells:
WBCs come in five primary varieties:
- Neutrophils (Granulocytes).
- Eosinophils (Granulocytes).
- Basophils (Granulocytes).
- Lymphocytes (A-granulocytes).
- Monocytes (A-granulocytes).
1-Neutrophils (Granulocytes):
- Most prevalent kind of white blood cells.
- Makes up 62% of leukocytes.
- There is a multilobed nucleus.
- Contain very tiny particles of cytoplasm.
- 2,500–7,500 cells/mm3
- Medium-sized white blood cells.
- Due to their various nuclear forms, they are also known as polymorphonuclear (PMN) systems.
- 10–12 μm in diameter.
- Lifespan of a few days to 6 hours.
Functions:
- Uses the phagocytosis mechanism to kill bacteria.
- They release a burst of superoxides, which can at the same time kill a large number of bacteria.
2-Eosinophils (Granulocytes):
- 40–400 cells/mm3
- Possess big granules.
- The nucleus has two lobes (a bi-lobed nucleus) and a diameter of 10–12 μm.
- Accounts for 2.3%
- That life span is 8–12 days.
Functions:
- Has a part in allergic reactions and kills parasites.
- Releases toxins that kill pathogens from their granules.
3-Basophils (Granulocytes):
- 0–100 cells/mm3
- Colorful when stained and viewed under a microscope.
- Their pale nucleus usually gets covered with granules.
- There is a present bi- or trilobed nucleus.
- Diameter: 12–15 μm.
- Accounts up 0.4%
- Life span, which is a few hours to a few days.
Functions:
- Plays a role in allergic responses.
- Secrete antibodies and anticoagulants that protect the circulation from hypersensitivity reactions.
- Histamine, which is found in basophils, causes blood vessels to enlarge, attracting more immune cells to the site of injury.
- Release heparin, an anticoagulant that encourages the movement of additional white blood cells by preventing coagulation.
4-Lymphocytes (Agranulocytes):
- Tiny, rounded cells
- Present Nucleus
- 1300–4000/mm3 with a small diameter of 7-8 μm and a large diameter of 12–15 μm.
- Contributes 30%
- Life span of years for memory cells and weeks for else.
Functions:
- The cells responsible for cell-mediated immunity are called T lymphocytes, or T cells.
- The generation of antibodies or humoral immunity is carried out by B lymphocytes.
- They can identify and remember invasive viruses and bacteria.
- Aid in eliminating cancerous cells.
- They expose other immune system cells to antigens to stimulate them.
5-Monocytes (Agranulocytes):
- The largest variety of white blood cells.
- With a nucleus and a kidney shape.
- 200–800 monocytes/mm3
- After they exit the bloodstream, they turn into macrophages.
- Dimensions: 15-30 μm.
- Makes up 5.3% of the life span, which is a few hours to a few days.
Functions:
- Enters the tissue, grows larger, and turns into macrophages.
- Destroy the body's aging, damaged, and dead cells.
3-Platelets (Thrombocytes):
- Nucleus Absent.
- Don't make reproduce.
- Small fragments of bone marrow cells.
- Each microliter of human blood contains between 150, 000 and 400, 000 platelets.
Functions:
- The parts of cells called platelets.
- Promotes additional blood clotting mechanisms. For instance, to encourage blood clotting, secrete procoagulants, or clotting factors.
- Vasoconstrictors, which they release, cause blood vessels to contract, leading to vascular spasms in broken blood vessels.
- Specialized blood cells called thrombocytes are produced from bone marrow.
- In situations where there is bleeding or hemorrhage, platelets are useful.
- They help blood coagulation and clotting. After a cut or wound, platelets help in the coagulation process.
- They secrete substances that attract monocytes and neutrophils to inflammation sites.
- When blood clots are no longer required, dissolve them.
- Digest down and destroy bacteria.
- To keep the linings of the blood vessels intact, they release growth factors.
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