First-Line Defenses: Normal Microflora - Online Tutor, Practice Problems & Exam Prep

The normal microbiota, or microbiome, serves as a crucial first line of defense in innate immunity, protecting against pathogenic microbes by blocking attachment sites and producing toxic chemicals. Disruption of this microbiota, often due to antibiotics, increases susceptibility to infections. Probiotics, live microbial cultures, and prebiotics, substances that promote beneficial microbes, can help restore and support a healthy microbiome. Understanding the role of the microbiome is essential for maintaining immune health and preventing infections.

Normal Microflora

This video, we're going to discuss the normal microbiota as a first line defense mechanism of innate immunity. And so the normal microbiota is also sometimes referred to as the microbiome. And this is referring to the population of resident microbes that grow in and on our bodies, and they are representative of healthy humans. And so healthy humans have a healthy microbiome. Now the normal microbiota or the microbiome is part of the first line of defense in innate immunity, and it is essential to the immune development during and after childbirth. And so humans will acquire their microbiota during childbirth as well as after childbirth.

Now some of the members of the microbiota will protect us by blocking attachment sites that pathogenic microbes use to cause harm. And so by blocking these attachment sites, it's helping to protect us from these pathogenic microbes. Now other members of the microbiota are able to produce chemicals that are actually toxic to pathogenic bacteria. Once again, helping to protect us against pathogenic bacteria. And so these, are ways that our normal microbiota can really protect us from these pathogenic microbes.

Now the normal microbiota can be disrupted, and when it is disrupted, when, we use antibiotics, antibiotics can disrupt our normal microbiota. And when that happens, that makes a person more susceptible to various infections. Because our normal microbiota plays a huge role in protecting us from pathogenic microbes. Now the term probiotics refers to live microbes, live microbe cultures that are actually applied or ingested, thereby benefiting the normal microbiota. And the term prebiotics specifically refers to chemicals that are used to promote the growth of the beneficial, consumed microbes. And so, those will be consumed with probiotics. So probiotics are going to be live microbe cultures, and prebiotics are going to be chemicals that benefit those, probiotics.

And so if we take a look at this image down below, notice the left hand side, we have this image that's focusing on the first line of defense, and focusing specifically on the microbiome. And so here we're showing you the normal microbiota or the microbiome, which again, is really just, talking about those microbes that live on and in us. And so here we're showing you a bunch of microbes living on and in our bodies. And so we refer to this as our normal microbiome, or normal microbiota. And so notice here in this little cartoon, we're showing you our normal microbiome here. It says you are not welcome here to these pathogenic microbes. And the microbes here are saying, well, you're not really a good host. And so, this is just a cartoon just showing you how the normal microbiome that we have is important for protecting us, and it does serve as a first line of defense.

This here concludes our brief lesson on the normal microbiota as a first line defense mechanism, and we'll be able to get some practice applying these concepts as we move forward in our course. So I'll see you all in our next video.

Normal microbiota:

• A. Are the organisms that typically reside on and in your body.
• B. Protect against infection by pathogens.
• C. Enhance infection by pathogens.
• D. Play no role in affecting pathogen growth.
• E. A and B.
• F. C and D.

Here’s what students ask on this topic:

What is the role of normal microbiota in innate immunity?

The normal microbiota, also known as the microbiome, plays a crucial role in innate immunity by serving as a first line of defense against pathogenic microbes. These resident microbes inhabit various parts of our bodies and help protect us in several ways. Firstly, they block attachment sites that pathogens use to establish infections. Secondly, some members of the microbiota produce chemicals that are toxic to pathogenic bacteria, thereby inhibiting their growth. This protective role is essential for maintaining immune health and preventing infections. Disruption of the microbiota, such as through antibiotic use, can increase susceptibility to infections.

How do antibiotics affect the normal microbiota?

Antibiotics can significantly disrupt the normal microbiota, which is the community of beneficial microbes residing in and on our bodies. While antibiotics are effective at killing pathogenic bacteria, they can also eliminate beneficial microbes. This disruption can lead to an imbalance in the microbiome, making individuals more susceptible to infections. The loss of beneficial microbes means fewer defenses against pathogenic bacteria, as there are fewer microbes to block attachment sites and produce toxic chemicals against pathogens. Therefore, maintaining a healthy microbiota is crucial for immune health, and the use of antibiotics should be carefully managed.

What are probiotics and how do they benefit the normal microbiota?

Probiotics are live microbial cultures that are ingested or applied to benefit the normal microbiota. These beneficial microbes help restore and maintain a healthy balance of the microbiome, especially after it has been disrupted by factors like antibiotic use. Probiotics can enhance the population of beneficial microbes, which in turn helps block pathogenic attachment sites and produce chemicals toxic to harmful bacteria. By supporting the normal microbiota, probiotics play a vital role in maintaining immune health and preventing infections.

What are prebiotics and how do they support probiotics?

Prebiotics are substances that promote the growth and activity of beneficial microbes, particularly probiotics. These are typically non-digestible fibers that serve as food for the beneficial bacteria in the gut. By providing a nutrient source, prebiotics help sustain and enhance the population of probiotics, thereby supporting a healthy microbiome. This symbiotic relationship between prebiotics and probiotics is essential for maintaining a balanced microbiota, which in turn plays a crucial role in immune defense and overall health.

How does the normal microbiota protect against pathogenic microbes?

The normal microbiota protects against pathogenic microbes through several mechanisms. Firstly, it competes with pathogens for attachment sites on the host's cells, effectively blocking the pathogens from establishing infections. Secondly, some members of the microbiota produce antimicrobial substances that are toxic to pathogenic bacteria, inhibiting their growth. Additionally, the microbiota can stimulate the host's immune system, enhancing its ability to respond to infections. These combined actions make the normal microbiota a vital component of the body's first line of defense in innate immunity.