Microbiology

Microbiology Study Guide

©2018 of 132 to neutralize the effect of a foreign substance, kill it, and eliminate it from the body. One of the actions is a non-specific resistance exercised by the immune system against these infection-causing organisms. It may also be possible that the action taken by the immune system damages the bodily tissues and may lead to allergy and hypersensitivity issues. The nature of the action taken by the immune systemdepends on the ability of the system to recognize and differentiate between the proteins and the protein-linked components of the foreign agents. Once the difference has been recognized, the immune system directs certain lymphocytes to generate antibodies that work against the foreign substances. Some lymphocytes are even sensitive to the foreign agents and react against them. Cells of the Immune System The lymphatic system and its cells make up the major cells of the immune system. The lymphatic system has lymphocytes, which are derived from the stem cells of bone marrow. The roles of these cells are to flourish these undifferentiated precursor cells and eliminate the cells that are maturing in the immune system. The stem cells in the immune system generate two kinds of cells: B-lymphocytes and T-lymphocytes. The B-lymphocytes are known as B-cells because these cells are produced in the bursa of fabricius, which are considered to be absent in human beings and thus, considered as a part of the bonemarrow. In contrast, the T-lymphocytes, also known as T-cells, get converted in the tissues of the neck near the trachea and thyroid gland, which is the thymus gland. In any organism, the stem cells begin to develop into B-lymphocytes and T-lymphocytes soon after five months post-fertilization, and the entire conversion is completed a few months after birth. Once the entire set is formed, they are ready to transfer to the lymphoid organs in the body including tonsils, adenoids, and lymph nodes. When microorganisms attack the human body system, the immune system is initiated, which signals the organisms to process the antigen’s phagocytic cells like macrophages. The determinants of the antigenic get displayed on the phagocytic cell’s surface and become visible to the cells of the immune system; this helps to inflame the response from the immune system. The immune system has two branches: antibody-mediated immunity, or humoral immunity (centered in B-lymphocytes), and cell- mediated immunity (centered in T-lymphocytes). Cell-Mediated Immunity T-lymphocytes are responsible for causing cell-mediated immunity. The lifespan of these cells is longer than that of the B-cells, even though both types of cells reside in the same lymphatic tissues. The T-cells become immunologically committed after they react with the antigenic determinants. This leads to a partial conversion of cells to cytotoxic T-lymphocytes. Achieve Page 59