From the common cold to COVID-19, our immune systems play a large role in helping us stay healthy. When an unknown substance enters our body, the immune system will respond in a specific way. We will often receive physical symptoms characteristic of that disease, and behind the scenes, our immune systems will work to eliminate it. So how does this process occur? I have wondered the same thing, especially with the COVID-19 pandemic being so prevalent as of now.
Innate vs. Adaptive Immunity
Our immune system responds in two ways to a pathogen. Firstly, through innate immunity. To enter the body, pathogens must first contend with our skin and mucous membranes. Other than preventing pathogens from entering the body, our skin also prevents the growth of bacteria. Due to the oil and sweat on our skin, the pH of our skin is quite low, or acidic. Many bacteria cannot survive in such an environment. However, there are other openings that pathogens can enter our body, like our mouths or eyes. There are enzymes in our saliva or tears that destroy bacteria.
If a pathogen tries to enter the body, they are subject to several other immune system functions. Firstly, phagocytosis, where phagocytic cells will trap pathogens and lead to their deaths. Natural killer cells release chemicals that also lead to cell death. This way, further spread of the disease can be prevented. The immune system also has an inflammatory response. Common to this response is pain and swelling. For example, when you have a splinter, the immune system will send signals to your body for help in the area of the splinter.
Compared to innate immunity, adaptive immunity is much slower. Special white blood cells called lymphocytes will work to combat the pathogens that are detected. Many of these cells work together to protect the body fluids and cells. However, this type of immunity is unique because it allows the system to remember diseases it has encountered. If your body has contacted the cold, it will remember how to deal with this pathogen in the future. Next time the same pathogen appears, your body will be able to respond more quickly.
In the 1700s, Edward Jenner noticed that people who became infected with cowpox did not contract smallpox. By exposing a test patient to cowpox, allowing them to recover, then smallpox, he noticed that the patient stayed healthy. This method has prevented diseases all around the world, and vaccines continue to be developed today for their effectiveness. A major method of combat for the ongoing pandemic is the COVID-19 vaccine.
Vaccines can also provide herd immunity. If many people in the population are vaccinated, it is less likely for a breakout to occur. This also protects high-risk individuals, such as seniors or young children.
How can we Stay Healthy?
While our immune system will independently work to keep us healthy, there are also steps we can take to boost it. For example, not smoking, eating fruits and vegetables, regularly exercising, and getting enough sleep. Staying up to date with vaccines is also helpful. Now that you know more about the immune system, make sure you return its favour by keeping it healthy too!