How does the immune system know we catch a virus/disease? And how does it attack the virus/disease?

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How does the immune system know we catch a virus/disease? And how does it attack the virus/disease?

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The immune system is able to recognize and respond to viruses and other infectious agents because it has specialized cells and molecules that can detect and identify these foreign invaders. When a virus or other pathogen enters the body, it triggers an immune response in which the body’s immune cells and molecules work together to identify and attack the invader. The specific details of how this process works can vary depending on the type of pathogen and the specifics of the immune response, but in general, here’s how it works:

1. When a virus or other pathogen enters the body, it is typically first detected by specialized immune cells called antigen-presenting cells (APCs). These cells are able to recognize the pathogen and take it up into their own cells, where they begin to process it.
2. As part of this process, the APCs break the pathogen down into smaller pieces, called antigens. They then present these antigens on their surface, along with special proteins called major histocompatibility complexes (MHCs).
3. The presence of these antigens and MHCs on the surface of the APCs alerts the body’s immune system to the presence of the pathogen. This triggers the activation of other immune cells, such as T-cells and B-cells, which are specifically designed to recognize and attack the pathogen.
4. Once activated, these immune cells begin to proliferate and produce molecules and substances that can directly kill the pathogen, or that can help to neutralize it. For example, T-cells can release chemicals called cytokines that can directly kill infected cells, while B-cells can produce antibodies that can neutralize the pathogen and prevent it from spreading.
5. The combination of these immune responses ultimately leads to the elimination of the pathogen from the body, and the restoration of the body’s normal, healthy state.

In summary, the immune system is able to recognize and attack viruses and other infectious agents by using specialized cells and molecules that can detect and identify these foreign invaders, and then activate the appropriate immune response to eliminate them.

This is the job of the B-cells. These are cells which are made in the bone marrow. Each B-cell is encoded with a random antigen. Before the B-cell is formed this antigen is tested against all the possible proteins that the parent cell’s DNA can make and if anyone is a match the B-cell is not formed. The B-cell will be released into the blood stream where it will have the antigens sticking out of its cell wall. These antigens will try to attach to any protein but normally no protein fits its unique shape. However if a virus infects you it will create proteins which are not encoded in human DNA.

When this happens some of the antigens will detach the B-cell and start interacting with the other cells, making T-cells attack them, making hormones that cause more T-cells to come, hormones which trigger generic immune responses, etc. But some of the antigens will instead trigger the B-cell to multiply, something it normally never does. So you get more B-cells and more antigens to attack this virus.

Take a virus for example:

– Your body has two major defense systems: one is your outer layer, like the skin and mucosal cells in your mouth and nose that filter/block things from getting in your body + unspecific cells (afaik dendritic cells) plus your white blood cells that attack any intruder. The other defence system is what many refer to the immune system: b and t cells that answer to an attack

– your body cells have proteins on their outside that show stuff that got produced in the cells. Your immune cells check those proteins to see if the cells work as intended.

– If a virus intrudes a cell, it rewrites its dna so the cell has to produce more viruses, that automatically get shown on the proteins on the outside of the cell

– if your immune cells detect unordinary stuff on those cells, they activate a immune response (too advanced, but simplified:)-the immune cells activate t killer cells that order cells to deconstruct (apoptosis) and b cells that produce antibodys in your lymph nodes (thats why they hurt when you are sick, they basically turn into a antibody factory)-these antibodys stick to the viruses, disabling them so they cant function any more

– your white blood cells then “eat” all the waste produced and clean the body- HIV for example attack the immune cells, so that they cant function any more, thats why you can die of “small” deseases like a cold when you catch aids, because your immune system is compromised

– biology class was some time ago and also I learned all the technical terms in german, so take it with a grain of salt