How does the immune system work?
The immune system is a complex network of cells, tissues, and organs that defend the body against harmful invaders like bacteria, viruses, fungi, and parasites. This system operates on two levels: innate immunity and adaptive immunity, which work together to protect the body.
Innate Immunity: The Body's First Line of Defence
The innate immune system is the body’s first line of defence. It acts quickly to combat invading pathogens before they can establish an infection. This system includes:
- Physical barriers: such as skin and mucous membranes, which block invaders.
- Chemical barriers: such as stomach acid and natural germ-killing substances that destroy pathogens.
Innate immunity doesn’t target specific invaders, making it a general defence mechanism.
Adaptive Immunity: The Body's Targeted Defence
The adaptive immune system is your second line of defence, responding to specific invaders. When a pathogen breaches the innate immune system, the adaptive immune system steps in by producing antibodies. It identifies specific antigens on the foreign substance, then creates a targeted response.
The adaptive immune system also builds a memory of past infections, enabling a faster response to future attacks from the same pathogen. This immunological memory is crucial in preventing repeat infections.
T-Cells and Their Role in Immunity
A key component of the adaptive immune system is T-cells, which play a significant role in recognising and attacking infected cells. There are two main types:
- Helper T-cells: These release chemicals that alert the rest of the immune system.
- Killer T-cells: These directly destroy cells carrying foreign peptides (antigens).
Both types work together to eliminate pathogens and protect the body.
B-Cells and Antibody Production
B-cells are another critical part of the immune system. They are responsible for producing antibodies. Once a B-cell encounters an antigen, it transforms into a plasma cell, which produces large amounts of antibodies. These antibodies bind to the antigen, marking it for destruction by other immune cells.
Autoimmune Response
Occasionally, the immune system can mistakenly attack the body’s own tissues. This is called an autoimmune response. It happens when antibodies are produced to target self-antigens, leading to inflammatory conditions such as arthritis and inflammatory bowel disease.
The Role of Lymphocytes
Lymphocytes are a type of white blood cell that play a pivotal role in the immune response. These cells make up 20-40% of the body’s circulating white blood cells. They are produced in the bone marrow and include both B-cells and T-cells.
As people age, the number of B-cells and T-cells in the bone marrow decreases, which can weaken the immune system and increase susceptibility to infections.
Secondary Lymphoid Organs
Secondary lymphoid organs like lymph nodes, the spleen, and tonsils are vital for detecting and responding to infections. These organs collect and filter lymph fluid, removing pathogens before they can spread throughout the body.
- Lymph nodes filter lymph fluid and house white blood cells that destroy pathogens.
- The spleen can detect pathogens and respond more quickly than lymph nodes.
- Tonsils help trap pathogens entering through the mouth or nose.
These organs contain specialised cells that recognise and destroy foreign invaders, forming an essential part of the immune system.
Conclusion
In summary, the immune system is a highly organised network that protects the body from harmful invaders. Its two main components, innate and adaptive immunity, work together to identify and destroy pathogens. As people age, changes in immune cell numbers may affect overall immune function, but the system continues to defend the body from illness and disease.
Understanding how the immune system works is crucial for maintaining good health and preventing diseases. Regular exercise, a healthy diet, and vaccinations can help strengthen your immune system.
