Blood Cells

The typical human adult has more than 5 liters of blood in his or her body. The function of the blood is to carry oxygen and nutrients to living cells and takes away waste products from these cells. It also delivers immune cells and makes the body capable to fight against infections. It also contains platelets that can form a plug in a damaged blood vessel to avoid blood loss and thus help in blood coagulation.  There are three main types of blood cells which are RBC, WBC, and platelets.



Through the circulatory system, blood adapts to the body’s needs. When you are exercising, your heart pumps harder and faster to provide more blood and hence supply more oxygen to your muscles. During an infection, the blood delivers more immune cells to the site of infection, where they accumulate to destroy harmful pathogens.

All of these functions make blood a precious fluid. Blood is deemed so precious that it is also known as “red gold” because the cells and proteins it contains could be sold for more than the cost of the same weight in gold.

Red Blood cells

Every second, 2-3 million RBCs are produced in the bone marrow and released into the circulation. Also called erythrocytes, RBCs are the most typical kind of cell found in the blood, with each cubic millimeter of bloodstream containing 4-6 million cells. Using a diameter of only 6 µm, RBCs are small enough to squeeze through the tiniest arteries. They circulate throughout the body for up to 120 days, of which point the old or harmed RBCs are taken out of the circulation by specialized cells in the spleen and liver.

the mature RBC lacks a nucleus that gives special features to the blood. This allows the cell more room to store hemoglobin, the oxygen-binding proteins, allowing the RBC to transport more oxygen. RBCs are also biconcave in form; this shape boosts their area for the diffusion across their areas. In non-mammalian vertebrates such as birds and seafood, mature RBCs do have a nucleus.

If an individual has a minimal level of hemoglobin, a problem called anemia, they may appear pale because hemoglobin gives a red color to the blood. They could also tire easily and may suffer from shortness of breath because of the primary role of hemoglobin in transporting oxygen from the lungs to the body cells.

White blood cells

WBCs come in many different shapes and sizes. Some cells have nuclei with multiple lobes, whereas others contain one large, rounded nucleus. Some contain packets of granules in their cytoplasm and are also known as granulocytes.

Despite their variations in appearance, all of the numerous kinds of WBCs have a job in the immune response. They circulate in the bloodstream until they get a signal from the damaged area of the body. Impulses include interleukin 1 (IL-1), a molecule secreted by macrophages that contribute to the fever of infections, and histamine, which is released by circulating basophils and structure mast cells and contributes to allergies. In response to these signals, the WBCs leave the bloodstream vessel by squeezing through holes in the blood vessel wall. They migrate to the source of the signal and help get started the healing process.

Individuals who’ve low degrees of WBCs may have significantly more and worse attacks. Depending upon which WBCs are absent, the patient reaches risk for different kinds of infection. For instance, macrophages are especially proficient at swallowing bacteria, and insufficiency in macrophages brings about recurrent transmissions. In contrast, T cells are particularly skilled in fighting viral microbe infections, and a lack of their function results in increased susceptibility to viral infections.

Neutrophils are also called polymorphonuclear cells because they include a nucleus whose condition (morph) is irregular possesses many (poly) lobes. In addition, they belong to several WBCs known as granulocytes because their cytoplasm is dotted with granules that contain enzymes that help them absorb pathogens.

Monocytes are young WBCs that circulate in the bloodstream. They become macrophages once they have gone the blood and migrated into tissues. There they provide an immediate defense because they can engulf (phagocytose) and break down pathogens before other types of WBCs reach the area.

In the liver, tissue macrophages are called Kupffer cells, plus they specialize in removing harmful agents from the blood that has remaining the gut. Alveolar macrophages are in the lungs and remove dangerous agents that may have been inhaled. Macrophages in the spleen remove old or damaged red blood cells and platelets from the blood circulation.

Macrophages are also “antigen-presenting cells”, presenting the antigens to other immune cells, triggering an immune response.

Lymphocytes are round cells that contain an individual, large circular nucleus. You will discover two main classes of cells, the B cells that mature in the bone marrow, and the T cells that mature in the thymus gland.

Once activated, the B cells and T cells trigger different kinds of immune responses. The turned on B cells, also called plasma cells, produce highly specific antibodies that bind to the agent that brought about the immune response. T cells, called helper T cells, secrete chemicals that recruit other immune cells and help organize their invasion. Another group, called cytotoxic T cells, attacks virally contaminated cells.


Platelets are irregularly shaped fragments of skin cells that circulate in the bloodstream until they can be either activated to create a blood clot or are removed by the spleen. Thrombocytopenia is a disorder of low degrees of platelets and bears an increased threat of bleeding. Conversely, a high level of platelets (thrombocythemia) holds an increased risk of forming improper blood clots. These could deprive essential organs such as the heart and brain, of these blood supply, causing heart disorders and strokes, respectively.

Much like all the cells in the bloodstream, platelets result from stem cells in the bone marrow. The stem cells develop into platelet precursors (called megakaryocytes) that “shed” platelets into the bloodstream. There, platelets circulate for approximately 9 days. If indeed they encounter ruined blood vessel surfaces during this time period, they adhere to the broken area and are activated to create a blood coagulum.

This plugs the hole. Normally, by the end of their lifetime, they are taken off from the circulation by the spleen. Inside a diverse quantity of diseases where in fact the spleen is overactive, e.g. arthritis rheumatoid and leukemia, the spleen removes way too many platelets, resulting in increased bleeding.