Download >>> https://tinurli.com/28144v
The immune system is the body’s natural defense against infection, injury, and even cancer. It is made up of a network of cells, tissues, and organs that are able to detect an enemy invasion both inside the body or on its surface. A new form of immunology that employs cell biology is transforming our understanding of how immunity functions. This field has given us new insights into the cellular molecular mechanisms underlying immune responses to chronic inflammation and autoimmunity as well as protective immunity against infections. Cellular immunology may also explain the many other mechanisms by which the body's cells communicate with one another. Cellular immunology has transformed our understanding of how immunity functions. It has given us new insights into the cellular molecular mechanisms underlying immune responses to chronic inflammation and autoimmunity as well as protective immunity against infections. Immunologists are beginning to understand that many aspects of immune responses are controlled, not by a single cell or system, but by a set of cells and systems that work together in a highly orchestrated fashion. Cellular immunologists have been able to identify a number of important cell types, including B cells, T cells, dendritic cells (DC), macrophages and neutrophils. Each of these cells is found within specialized tissues (lymph nodes, spleen, lymphatics, tonsils), which are organized into “nodules” of tissue that contain specific immune cells. This cellular organization also allows for the existence of non-immune cells that play an integral role in the formation and function of the immune system. For example, epithelial cells form portions of blood vessels and lymphatic vessels. These epithelial cells are joined by tight junctions that do not allow for the passage of most fluids or solutes through the paracellular space between these cells. As a result, molecules or proteins delivered to immune tissue must be passed across tight junctions via transcellular transport. In some cases, the epithelial cells may transport molecules or proteins to immune cells while they complete their task of forming a vessel. Perhaps more importantly, epithelial cells secrete a variety of factors that impact the activity of immune cells. These factors can be involved in several ways within the body. For instance, they can be involved in initiating or terminating an immune response, or they can participate in interactions between different cell types that regulate these processes. Many of these factors function by acting on specific receptors present on various immune cell types. Some of these molecules are secreted by non-epithelial cells within the body and delivered to nearby lymphoid tissue via lymphatic vessels or blood vessels. Others are secreted by the epithelial cells of the oropharyngeal, intestinal, and respiratory tract. Of course, whether immune cells respond to a given molecule depends on a number of factors including the receptor used by a particular cell type and its position within a tissue or organ. For instance, different types of lymphocytes have been shown to respond to signals from different types of receptors. In addition, certain immune cells can be activated by multiple pathways at once. This might be because one pathway is inhibiting another pathway that is needed for activation. In other cases it might be that there are multiple pathways that activate or inhibit each other in an asymmetric manner when one pathogen invades the body (hypersensitivity). cfa1e77820
Comments