Blog, Immune

An Introduction to the Immune System


There are a few experiences every individual has gone through before such as getting a cut or developing a fever. When these injuries and illnesses occur, how does your cut heal or how does your fever disappear?

The immune system is our defense against intrusions to our bodies such as bacteria, viruses, or parasites. It is the mechanism that fights the bacteria that enters your skin after getting a cut. This is the same entity that causes a fever in response to fighting a disease, virus or bacteria in order to kill it.

What is the Immune System?

The immune system is a response that works against pathogens; pathogens are organisms that replicate and cause disease. The immune system attacks bacterial, parasitic, or viral disease and infections in order to eliminate them.

Important Cells in the Immune System:

  • White blood cells are cells that circulate the blood and other fluids that respond against pathogens
  • There are two important types of white blood cells: phagocytes and lymphocytes
    o Phagocytes engulf and chew up foreign pathogen through phagocytosis
    o Lymphocytes provide cell memory to fight reoccurring infections

Important Immune Organs:

  • Bone Marrow: where all blood cells are produced
  • Thymus: where T cells (a specific type of lymphocyte) mature and develop in order to actively fight pathogens
  • Spleen: filters the blood
  • Lymph nodes: filters lymph fluid and acts as a bridge from the lymphatic system to the blood stream

How are pathogens eliminated by the Immune System?

There are two types of immune response:

Innate Immunity

It is a quick response (takes hours) in which cells are produced to investigate and eliminate the pathogen that triggered the immune response. The innate immune response causes inflammation that is visual seen as symptoms such as heat or redness, increased fluid to flush out the pathogens. The innate immune response is responsible for an increase of immune cells (like phagocytes) to fight the pathogen.

Adaptive Immunity

It is a longer, slower response (takes days to develop); however, it is a stronger and more vigorous response. Lymphocytes produce antibodies, which are proteins that are made to respond to and target a particular pathogen. After an adaptive immune response, the lymphocytes have memory cells that will allow these cells to respond faster and stronger if infected by the same disease or infection subsequent times.

Next week we’ll address a deeper overview of these responses and other great information about the immune system. Let us know your thoughts in the comments section!

Check out our book about The Immune System.

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