What Blood Contains
Blood consists of a suspension of cells in a special fluid called plasma. In a grown man, is the blood of body weight 1 / 12vo corresponding to 5.6 liters. Blood consists of 55% plasma and 45% formed by cells called elements.Blood performs many important functions. At the hemoglobin in red blood cells that carry oxygen to tissues and accumulates carbon dioxide (CO2). It also transports nutrients (amino acids, sugars, minerals), and collect the separated material is excreted by the kidneys filter. Blood also transports hormones, enzymes and vitamins. He keeps the defense of the body by phagocytic activity of leukocytes, the bactericidal effect of serum and immune cells are the main characters.
serum or cell-free plasma can be obtained by centrifugation. The liquid plasma is slightly alkaline, with a distinct yellow color. It consists of 90% water and 10% solids. Nine Parts of it are made of organic substances, while some are composed of minerals. These organic substances are composed of carbohydrates (glucose), lipids (cholesterol, triglycerides, phospholipids, lecithin, fats), proteins (immunoglobulins, albumin, fibrinogen), glycoproteins, hormones (gonadotropin, erythropoietin, thrombopoietin), amino acids and vitamins. Minerals dissolved in ionic form, which dissociates into positive and negative ions.
In certain blood cells are present, which are classified as erythrocytes and leukocytes. Platelets are not considered true cells. Then we will discuss the different types of blood cells.
Red blood cells (corpuscles) contain hemoglobin (a substance that is able to bind to oxygen). Oxygen from the lungs is transported by red blood cells to all tissues in the body. A person who has anemia, a condition caused by too few red blood cells in the blood may show a weakness, fatigue and lack of red blood cells are breath.The blood cells are most likely to know about 4-6 million / mm3. They are also called red cells.
In the hall of red blood cells in mammals, does the absence of the base more hemoglobin and biconcave shape of these cells increases the surface area and cytoplasmic volume ratio. These properties make it more efficient diffusion of oxygen by these cells .. In the so-called "sickle cell anemia, red blood cells usually sickle-shaped electron microscopy, the biologists have seen the red blood cells can have different forms: normal (discocyte ), berries (teeth), strawberries (echinocytes), white (codocyte), anemia, oat hulls, is tight, sharp, bleeding, poikilocytes, etc. The half-life of erythrocytes is about 120 days. When you reach the end of their lives, they are retained by the spleen, where they are phagocytosed by macrophages.
Leukocytes (white blood cells)
leukocytes, or white, is responsible for defending the body. In the blood, which is much smaller than many red blood cells. The density of leukocytes in the blood is 5000-7000 / mm3. The leukocytes are divided into two categories: granulocytes and lymphoid cells or agranulocytes. The ANC is due to the presence of granules in the cytoplasm. In various types of granulocytes, the granules are different and help us to distinguish. In fact, these granules have a different affinity for acidic or basic neutral spots and give the cytoplasm in different colors. Thus, neutrophils are separated, eosinophils (or acidophilus) and basophils. Lymphoid cells, but differ in lymphocytes and monocytes. As we shall see, helps even the shape of the kernel's in recognition of leukocytes.
There are five types of white cells in the body, including the following:
These cells fight viruses, bacteria, and others and participate in hypersensitivity reactions seen in allergic reactions.
Neutrophils, basophils, and eosinophils are (white blood cells that destroy bacteria). Granulocytes are characterized by small particles or granules, found in every cell, and contains substances that fight infections. Granulocytes undergo several developmental stages before becoming mature neutrophils, basophils, eosinophils o. The most immature myeloid series of cells called granulocytes are myeloblasts, promyelocytes, myelocytes, metamyelocytes, band forms (cells with a dagger), and polymorphonuclear leukocytes (PMN).
Neutrophils are very active in the trailer and bacteria are present in large numbers in the pus of wounds. Unfortunately, these cells are not able to renew their lysosomes used in digesting microbes and killed after consuming any of them.
Eosinophils attack parasites and phagocyte antigen-antibody complex.
Basophils differ anticoagulant and vasodilator substances such as histamine and serotonin. Although they have a phagocytic capacity, its main function is to secrete substances that are involved in the hypersensitivity reaction.
Lymphocytes are cells which, in addition to being present in the blood, fill the lymphoid tissues and organs, and lymph flow through lymphatic vessels. lymphoid organs are the heart of the thymus, bone (in birds storage), spleen, lymph nodes, tonsils, Peyer's patches and lymphoid tissues of the respiratory tract and stomach.
Most lymphocytes circulating in the blood is in a state of rest. They look like small round cells with a compact core that takes up almost the entire volume of the cell. Consequently, the cytoplasm is very low. Lymphocytes in lymphoid tissues and organs can be activated by a different amount of antigen stimulation. In blood, lymphocytes are 20-40% of all leukocytes soft and larger than red blood cells.
Lymphocytes are the main components of the immune system is a defense against attack by pathogens such as viruses, bacteria, fungi and protists. performance and cell antibodies in their membranes. An antibody is a molecule that can bind to a form of complementary molecules, called antigens, and recognition. Like all proteins, although antibodies are encoded by genes. On the basis of a mechanism for the recombination of some of these genes, each cell produces antibodies specifically.
Therefore, cells that perform a specific action called each additional recognize antigen only. Although all cells are highly selective recognition of a molecule, the number of circulating lymphocytes so large that they are able to detect almost all substances in the body, both domestic and foreign. It's about recognizing hundreds of millions of different molecules.
immune cells, mainly lymphocytes, cooperate to activate, stimulate and make more precise the immune system. To reach this area, there are different types of cells with different functions: T-cells and B when B cells are activated, they reproduce rapidly (clonal selection) and become plasma cells that secrete large amounts of antibodies in the blood (humoral response) . When antibodies without complying with further micro-organisms (epitopes), join them and form complexes immobilized microorganisms. Later, other cells that are not specific, but can recognize the antibodies, phagocytes these complexes.
In turn, T cells are divided into three categories: Tc (cytotoxic), Th (helper), Ts (suppressor). Although cytotoxic lymphocytes reproduce quickly when it is activated. They do not release antibodies in the blood, but to maintain the antibodies in their membranes and cells use to detect, especially its own body cells infected with viruses or tumor. Cytotoxic lymphocytes kill cells by substances perforin, which produces lesions in the membrane of the target cell and cause death by osmotic lysis (cell response). Lymphocytes of the aid is necessary to activate B cells and Tc which, although they recognize foreign agents, rarely direct action. Suppressor lymphocytes reduce the severity of the immune response.
But does not the immune system attacks the body's cells that autoimmune reaction can damage the body and cause death. How does the immune system between itself and not me? We have seen that B cells and Tc recognize an antigen, do not do anything, but must be activated by an additional cell. A couple of times after the birth of the organization, some of the new cells pass through the thymus where T-cells are cells then were compared with all antigens of the organism (auto-anti-gens). It appears that lymphocytes that recognize an antigen, as they are still immature, he will die. Thus, the autoreactive Th cells are dead, only B cells and Tc have recognized foreign antigens can be activated. The system of cellular cytotoxicity mediated by Th cells is developed as a defense against the infected cells, altered, or deviant. Indeed, B cells and Tc turned against bacteria, even without the consent of the participants.
The B and Tc lymphocytes activated in addition to the production of antibodies and kill foreign cells, multiply rapidly. During cell division, rearrangements often occur in the sequence of genes coding for antibodies. Thus, the antibody in the new cell a little bit different compared to his father mitotic. If the new form is better suited to the antigen, this cell will be persuaded to share more. The next generation of clones is more efficient and, in turn, can lead to more selective variants. This process of clonal selection and more effective immune response. Finally, immune memory cells, ie lymphocytes off ready to be reactivated on the occasion of the meeting with the same antigen.
In addition to Th cells and B, a third population of lymphocytes in the blood and peripheral lymphoid organs have receptors for antigens. These cells have a non-specific defense function is not activated by Th cells, these cells are the oldest part of the immune system and is characterized by cytotoxic activity. For these reasons, called NK, natural killer. In addition to killing viruses, bacteria, infections and neoplastic cells, these cells also regulates the production of other blood cells, red blood cells and granulocytes.
Monocytes are precursors to macrophages. Blood pieces are larger, which, after reaching maturity in the bone marrow into the bloodstream, where they remain in 24-36 hours. Then migrate into the tissues where they become macrophages and move into tissues. In the presence of an area of inflammation, monocytes migrate rapidly from the blood vessels and begin an intense phagocytic activity. The role of these cells is not only in phagocytosis, and also an intense activity of secretion. They produce substances that have defensive functions, such as lysozyme, interferon and other substances that modulate the function of other cells. Macrophages cooperate in the immune system. They expose the body to digest the molecules in the membrane, and present them to more specialized cells such as B and Th lymphocytes.