Some research suggests that optimism can actually make our immune system work better. “I don’t know if it’s a direct cause,” Tran says, “but the happier, or more positive you are, the more likely you are to eat right and be less <a href="https://www.everydayhealth.com/stress/guide/">stressed </a>, which will help your immune system.”

5. Positive emotions + healthy lifestyle may boost your immunity

Though it may not be pleasant to think about, countless microbes live on and in our bodies, and they are actually necessary to maintain good health. “Good bacteria in our body provides us with nutrients we need and also provides a defense against bad bacteria and infection,” Tran says. A balance needs to be maintained because when good bacteria is reduced, bad bacteria can take over, making us feel sick, he says.

3. Every day, we encounter billions of germs, but all aren't bad

Autoimmune diseases affect about 8 percent of the population in the United States, making up the third most common category of disease after cancer and heart disease, according to the <a href="https://wwwnc.cdc.gov/eid/article/10/11/04-0367_article">U.S. Centers for Disease Control and Prevention </a>. Women make up nearly 80 percent of those living with autoimmune diseases. While the cause of autoimmune diseases is unknown, it is generally believed to have a strong genetic component, and women in their child-bearing years are at the highest risk.

9. Women are more likely to be diagnosed with autoimmune disease

Vaccines work by stimulating the immune system to produce antibodies against a foreign invader without actually infecting the individual with the disease. As a result, when the body encounters that infection in the future, it knows how to fight it off, and you face minimal symptoms.

2. Vaccines play an important role to educate your immune system

Stress can lead to increased <a href="https://www.everydayhealth.com/cortisol/guide/">levels of cortisol </a>, a steroid hormone that is important for overall function of our body; but too much of it can lead to a number of health problems, including decreased immunity. “The high level of steroids can blunt your immune system,” Tran says.

4. Stress can affect the way your immune system works. 

<a href="https://www.everydayhealth.com/autoimmune-disorders/managing-your-weight-with-an-autoimmune-disorder.aspx">Autoimmune diseases </a>occur when the immune system destroys its own healthy tissues. In such cases, white blood cells in the body cannot distinguish between pathogens and the body’s normal cells, setting off a reaction that destroys healthy tissues.While there are over 80 different types of autoimmune disorders, common ones include rheumatoid arthritis, <a href="https://www.everydayhealth.com/psoriasis/guide/">psoriasis </a>, and <a href="https://www.everydayhealth.com/crohns-disease/guide/">Crohn’s disease </a>.

8. Your immune system can attack itself. 

Cleaning and disinfecting may seem like the best way to avoid infection, but this is a case where there can be too much of a good thing.“When you make your environment so clean, you minimize so many foreign pathogens that you actually minimize the development of the immune system,” Tran says. This is especially the case with young children, since if they’re not exposed to harmful microbes at all, their bodies won’t be able to develop the proper antibodies to fight them off.

10. Being too clean can inhibit your immune system functioning 

Not getting enough sleep can wreak havoc on the body, and the immune system is no exception. <a href="https://www.cmu.edu/homepage/health/2009/winter/not-sleeping.shtml">Studies show </a>that a lack of sleep may make you more likely to catch a cold and also makes it more difficult to fight off infection.

6. Sleep deprivation can impact immunity. 

“Think of the immune system like the military, each part has a different role"The first line of defense is the white blood cells, who are first to recognise pathogens and fight off infection. Lymphocytes, a specific type of white blood cell, work to allow the body to remember the invading microbes to fight them faster in future infections. Other parts of the immune system include the bone marrow, where white blood cells are produced; lymph nodes, which produce and store infection-fighting cells throughout the body; and the spleen, which helps control and clean the amount of blood in the body.

1. Each part of the immune system has a unique function.  

When you experience an <a href="https://www.everydayhealth.com/allergies/">allergic reaction </a>, your immune system is responding to a harmless <a href="https://www.everydayhealth.com/allergies/">allergen </a>that it perceives as a threat. Symptoms of an allergic reaction, which can range from a runny nose to breaking out in <a href="https://www.everydayhealth.com/hives/">hives </a>to fainting, are a result of the body’s misguided attack.

7. Allergies are when your immune system reacts to a false alarm

Was learning about communicable diseases in biology, and found the process of immunity really interesting in the context of the COVID 19 pandemic.

There are surprising things you may not know about your body’s natural defense system.