Microbiology Semester 2 Week 12

              Assalamualaikum and hi everyone... how are you all? I hope everyone will be fine as well... On Tuesday, before our class start, my classmates do their Pecha Kucha about a microbe based on topics provided to them. Later on, Dr. Asilah taught us about the introduction to immunology. Basically, Immune system  is includes various cells, tissues and organs, working collectively and defend against harmful pathogens, cells and substances. Primary lymphoid organs is production sites of immune cells and maturation sites for immune cells in the absence of antigen such as bone marrow, and thymus. Secondary lymphoid organs is maturation sites for antigen-driven immune cells, sites where immune cells encounter, bind with antigen which is proliferate and differentiate into fully mature, antigen specific effector cells.Innate Immune Response is non-specific, immune components are preformed, response magnitude is similar during the first and subsequent encounters and no memory is stored.

             On Friday, Dr Asilah continue about the introduction to immunology. Adaptive Immune Response u Specific is immune components are fully activated only after infection starts, response magnitude is higher in the second and subsequent encounters compared to the first and immunological memory is stored. Development of T and B cells is lymphocyte development diverges into two cell lines u T cells and B cells. This antigen-independent maturation occurs in two sites which is T cells in thymus and B cells in bone marrow. They have surface markers or receptors, which function to bind to receptors on other cells, bind to antigens and transmit and receive messages. The common receptor molecules which is major histocompatibility complex (MHC), cluster of differentiation (CD) and antigen-specific receptors. Antigenicity of a substance is determined by a combination of factors size, complexity and foreignness. Antigens are presented by professional antigen presenting cells (APCs), such as: Macrophages, Dendritic cells and B cells.

           Antigens presented on APCs will activate T and B cells. For T cells, this activation stimulates their differentiation into subtypes of T helper cells (Th), memory T cells, regulatory T cells (Treg) and cytotoxic T cells (Tc). T helper cells stimulate or activate other cells, including macrophages, B cells, Tc cells. Memory T cells store immunological memory. Regulatory T cells regulate other cells to prevent excessive inflammation and autoimmunity. Sometimes, B cells can be activated without the help of T helper cells. Referred to as T-independent activation. Most of the time, B cells require activation by of T helper cells. Following activation, B cells differentiate into memory B cells, regulatory B cells and plasma cells. Memory B cells store immunological memory. Regulatory B cells regulate other cells to prevent excessive inflammation and autoimmunity. Plasma cells launch billions of antibodies to attack the invaders. Antibodies disable the targets through neutralisation which block the receptor on a surface or the targets, neutralising them. Opsonisation is coat the targets, helping phagocytes to recognize them. Agglutination is link the targets with one another into large clumps, immobilizing them and enhancing their phagocytosis. Antitoxin action is bind to toxins produced by the targets, rendering them harmless.