During class, I have become more aware of salmonella. Before taking this class, I did not exactly know what salmonella is. Salmonella are bacteria that can cause food poisoning. It can also cause diarrhea and typhoid fever. Salmonella infections are most commonly caused by contaminated food. After learning this, I started to eat less medium-rare cooked meat and more well-cooked meat. By cooking meat for a longer time, it kills off more of the bacteria and contaminants in the meat and greatly reduces the chances of being infected with salmonella.
Thursday, May 31, 2012
Anatomy and Physiology: The Humoral and Cell Mediated Immune Responses
Humoral (Antibody-Mediated) Immune Response
When there is a first exposure to an antigen, these free antigens activates B cells. The lymphocyte "switches on" and undergoes clonal selection, which is when the lymphocyte grow and multiplies rapidly to form many identical cells called clones. This clone formation is the primary humoral response. Most of the B cell clone members become plasma cells, which produce the same highly specific antibodies. The plasma cells die off after 4-5 days and the antibody level in the blood goes down. There are some B cell clone members that don't become plasma cells but instead, become memory cells that can respond to the same antigen later. As a result, in later immune responses or secondary humoral responses, the response to the presence of the antigen is more faster, prolonged, and effective.
Cellular (Cell-Mediated) Immune Response
In the cellular immune response, T cells are sensitized by binding to an antigen and a self-protein on the macrophage surface. After clonal selection, clone members differentiate into memory T cells and effector T cells. There are several different classes of T cells: cytotoxic (killer) T cells, helper T cells, memory T cells, and suppressor T cells.
Cytotoxic (killer) T cells: directly attack and kill infected and cancerous cells
Helper T cells: binds with specific antigen presented by a macrophage; stimulates production of other immune cells (cytotoxic T cells and B cells); acts directly and indirectly by releasing lymphokines
Memory T cells: descendant of a T cell; forms during initial immune response (primary response); may exist in the body for years to allow it to respond more quickly to later infections by the same antigens
Suppressor T cells: slows or stops activity of B and T cells when the infection or attack has been conquered
Sources:
Elaine N. Marieb's Essentials of Human Anatomy and Physiology, Eighth Edition
When there is a first exposure to an antigen, these free antigens activates B cells. The lymphocyte "switches on" and undergoes clonal selection, which is when the lymphocyte grow and multiplies rapidly to form many identical cells called clones. This clone formation is the primary humoral response. Most of the B cell clone members become plasma cells, which produce the same highly specific antibodies. The plasma cells die off after 4-5 days and the antibody level in the blood goes down. There are some B cell clone members that don't become plasma cells but instead, become memory cells that can respond to the same antigen later. As a result, in later immune responses or secondary humoral responses, the response to the presence of the antigen is more faster, prolonged, and effective.
Cellular (Cell-Mediated) Immune Response
In the cellular immune response, T cells are sensitized by binding to an antigen and a self-protein on the macrophage surface. After clonal selection, clone members differentiate into memory T cells and effector T cells. There are several different classes of T cells: cytotoxic (killer) T cells, helper T cells, memory T cells, and suppressor T cells.
Cytotoxic (killer) T cells: directly attack and kill infected and cancerous cells
Helper T cells: binds with specific antigen presented by a macrophage; stimulates production of other immune cells (cytotoxic T cells and B cells); acts directly and indirectly by releasing lymphokines
Memory T cells: descendant of a T cell; forms during initial immune response (primary response); may exist in the body for years to allow it to respond more quickly to later infections by the same antigens
Suppressor T cells: slows or stops activity of B and T cells when the infection or attack has been conquered
Sources:
Elaine N. Marieb's Essentials of Human Anatomy and Physiology, Eighth Edition
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