The human body is extremely vulnerable to germs from bacteria and viruses in the air. Sneezing, sniffling, and incessant coughing are external tell-tale signs the body is fighting to eliminate infection, but what exactly happens internally when foreign invaders attack the immune system? In Life Noggin’s video “What Happens When We Get Sick?” host Patrick Graziosi explains although the immune system combats thousands of bacteria and viruses inhaled from the air, the occasional germ or two sneaks into the body and spreads infection.

Infections with viruses and bacteria can easily be transmitted from person to person, especially in the workplace. A recent survey from Staples found 60 percent of people still show up to work sick, putting their co-workers at risk with their symptoms. A person with a cold can spread infection by coughing and/or sneezing; bacteria or viruses can be passed on by touching or shaking hands with another person.

These foreign bodies have the ability to sneak into the body and get you sick. This leads the mucus membrane to become infected and inflamed, which causes the body to respond by sending more blood to these areas. The increase in blood flow lets loose a greater amount of antibodies and white blood cells that attack anything unusual, according to Life Noggin. As a result, the blood vessels begin to swell to allow this influx of blood.

For example, when you get a sore throat, they press up against nerve endings, which cause soreness. This is a sign that the body is healing itself. The same can be seen when you have a stuffy nose. Before you blow your nose, the mucus membrane secretes mucus to protect the body. This helps trap the bacteria and viruses and provides a good way for them to exit the body through your nose.

Lastly, when we’re sick we're susceptible to fevers caused by pyrogens. Although they can come from outside the body, they are more often than not triggered inside as part of the immune system’s response to invading germs. They cause the hypothalamus to raise the body’s overall temperature, which helps inhibit many viruses and bacteria.

Remember, the next time you get infection symptoms, they are just your immune system’s way of fighting off foreign invaders.