Answers
T-Lymphocytes: white blood cells, develop in the bone marrow and then thymus, includes helper T-cells and cytotoxic (killer) T-cells, helper T-cells stimulate the cell-mediated response and the humoral response, cytotoxic T-cells kill cells infected with a pathogen and kill cancerous cells
B-Lymphocytes: white blood cells, develop in the bone marrow, produce antibodies, involved in humoral response only
Antibodies: substances created by B-lymphocytes, highly specific, mark pathogens in the blood stream or interstitial fluid to be engulfed by macrophages
Interferons: substances produced by virus infected cells that make surrounding, noninfected cells to become more resistant to the virus
Cell-Mediated Response: involves helper T-cells and cytotoxic T-cells. First cytotoxic T-cells are alerted by helper T-cells or cell membrane proteins that body cells are infected with a pathogen, next the cytotoxic T-cells check body cells for pathogen proteins on their cell membranes (searches for foreign material). If the cell is infected, the cytotoxic T-cell uses perforin to lyse the cell's membrane, therefore killing the cell and releasing the pathogen into the blood stream where it can be marked by an antibody
Humoral Response: involves B-Lymphocytes and helper T-cells, involves antibodies. First B-Lymphocytes are alerted by pathogens in the bodily fluids or helper T-cells that free pathogens are present. Next, specific B-Lymphocytes produce an antibody that can attach to the pathogen's membrane proteins, therefore marking it to be killed by a macrophage
Note: in both the cell mediated response and the humoral response, the T and B cells that react to the pathogen make long living copies of themselves which can react to the pathogen quickly the next time the body is exposed to the pathogen.
These are memory cells.
.Humoral Response: involves B-Lymphocytes and helper T-cells, involves antibodies. First B-Lymphocytes are alerted by pathogens in the bodily fluids or helper T-cells that free pathogens are present. Next, specific B-Lymphocytes produce an antibody that can attach to the pathogen's membrane proteins, therefore marking it to be killed by a macrophage
inflammatory response
When a bacterial infection is established in the body, the purpose of the immune system is to control or eradicate it. The initial reaction of the immune system to an infection varies, depending on the site which has been invaded and on the nature of the invader. There can be many "triggers", that can spur the immune system into action.
Here are some of the ways in which the immune system can be activated.
- If the invasion is in an area of the body that is primarily defended bymacrophages, such as the lungs or intestines, then these macrophages will be the first immune cells on the scene. They begin to digest the invading organism, and by presenting antigens (proteins from the destroyed bacteria), they stimulate other cells of the immune system into action.
- Some bacteria, for example Staphylococcus Aureus and Salmonella Typhi, produce chemotaxins when they enter the body, which betray their presence to the immune system, by acting as "breadcrumbs" which reveal the location of the invader. Chemotaxins are chemicals that activate phagocytes, the immune cells whose function it is to consume and destroy the invading bacteria.
- Some bacteria first encounter, and are recognised by, the complement system, which in turn produces chemical messengers (cytokines) that warn other cells of the immune system that the body has been invaded.
- The invader may be recognised by the acquired immune system, i.e. thelymphocytes. These cells either directly fight the infection themselves, or control other cells to do so.
The immune system protects the body from possibly harmful substances by recognizing and responding to antigens. Antigens are substances (usually proteins) on the surface of cells, viruses, fungi, or bacteria. Nonliving substances such as toxins, chemicals, drugs, and foreign particles (such as a splinter) can also be antigens. The immune system recognizes and destroys substances that contain antigens.
When the body is first invaded
When a bacterial infection is established in the body, the purpose of the immune system is to control or eradicate it. The initial reaction of the immune system to an infection varies, depending on the site which has been invaded and on the nature of the invader.
There can be many "triggers", that can spur the immune system into action. Here are some of the ways in which the immune system can be activated.
- If the invasion is in an area of the body that is primarily defended bymacrophages, such as the lungs or intestines, then these macrophages will be the first immune cells on the scene. They begin to digest the invading organism, and by presenting antigens (proteins from the destroyed bacteria), they stimulate other cells of the immune system into action.
- Some bacteria, for example Staphylococcus Aureus and Salmonella Typhi, produce chemotaxins when they enter the body, which betray their presence to the immune system, by acting as "breadcrumbs" which reveal the location of the invader. Chemotaxins are chemicals that activate phagocytes, the immune cells whose function it is to consume and destroy the invading bacteria.
- Some bacteria first encounter, and are recognised by, the complement system, which in turn produces chemical messengers (cytokines) that warn other cells of the immune system that the body has been invaded.
- The invader may be recognised by the acquired immune system, i.e. thelymphocytes.
These cells either directly fight the infection themselves, or control other cells to do so.
Effects of the inflammatory response.
The primary physical effect of the inflammatory response is for blood circulation to increase around the infected area. In particular, the blood vessels around the site of inflammation dilate, permitting increased blood flow to the area. Gaps appear in the cell walls surrounding the infected area, allowing the larger cells of the blood, i.e. the immune cells, to pass. As a result of the increased blood flow, the immune presence is strengthened.
All of the different types of cells that constitute the immune system congregate at the site of inflammation, along with a large supply of proteins, which fuel the immune response. There is an increase in body heat, which can itself have an anti-biotic effect, swinging the balance of chemical reactions in favour of the host. The main symptoms of the inflammatory response are as follows.
- The tissues in the area are red and warm, as a result of the large amount of blood reaching the site.
- The tissues in the area are swollen, again due to the increased amount of blood and proteins that are present.
- The area is painful, due the expansion of tissues, causing mechanical pressure on nerve cells, and also due to the presence of pain mediators.
Humoral Response: involves B-Lymphocytes and helper T-cells, involves antibodies. First B-Lymphocytes are alerted by pathogens in the bodily fluids or helper T-cells that free pathogens are present. Next, specific B-Lymphocytes produce an antibody that can attach to the pathogen's membrane proteins, therefore marking it to be killed by a macrophage
The term "humoral" refers to the non-cellular components of the blood, such as plasma and lymphatic fluid.
The humoral immune response denotes immunologic responses that are mediated by antibodies. However, both B and T lymphocytes, as well as dendritic cells and other antigen presenting cells, are necessary for the formation of antigen-specific antibody.
Humoral immunity includes the primary and secondary immune responses to antigen. During the primary immune response, an antigen is encountered by the host for the first time. Virgin B cells need to be activated and proliferate before an effective immune response can be generated. This primary response may be too slow to protect against many pathogens, therefore polyspecific natural antibodies with low affinity and the innate immune system may be utilized to limit microbial replication at the onset of infection.
By comparison, the secondary antibody response, which results from the activation of a memory B cell, is faster and more effective in halting the progress of infection due to increased antibody binding affinities.
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