Examples of 1st line defenses to infection which are components of the innate immune system include all of the following except?

Phagocytosis of a pathogen by an immune cell.

Examples of 1st line defenses to infection which are components of the innate immune system include all of the following except?

Okay, everyone. Examples of first line defenses to infection, which are components of the innate immune system include all of the following except which of these answers? Okay. So we're talking about first line defenses of the innate immune system. Remember that these are going to be barriers to infection. First line is to stop the infection from ever happening. While second line of defense is is dealing with the infection once you've already been infected. But that first line of defense is like a barrier, It's like walls making sure nothing gets in. So we're looking for which of these is not an example of a first line defense to infection. Acer choice a says unbroken skin. Absolutely. This is a first line defense. This is going to be a physical first line defense, physical barrier to the outside world. So that's not the answer we're looking for. Answer choice B says phagocytosis of a pathogen by an immune cell. So if a pathogen is interacting with an immune cell, that's telling me that the pathogen is already within the body and within the tissues, which makes me think that this person has already been infected and now their immune cells are having to phagocytose or consume that pathogen. So this is actually going to be a second line of defense that happens after the person's already infected. So that's probably our correct answer. Let's rule out the other answers. Answer choice C says digestive enzymes in saliva. Yes. This is going to be a chemical first line of defense against infection. That's going to try to kill the microbes or slow down their growth. The enzymes in saliva are not very strong, but they can slow or inhibit the growth. So this is gonna be a first line defense and not what we're looking for. Answer choice d says, destructive acids of gastric juices. Yes. This is another chemical first line defense And the acids in your stomach, which are also known as the gastric juices, are very, very acidic and can kill most microbes before they enter your body. So, yes, a great first line defense. So now we're looking for. Answer choice e says, naturally occurring human microbiome. Exactly. Yes. Remember when we talked about the first line defenses, there were 3 types, physical barriers like skin, chemical barriers like your stomach acid, and your normal microbiome, which are gonna be all those microorganisms that already live on your body, and they don't want the competition. So they're not going to allow pathogens to infect your body because it's competing with the microbiome organisms. So, yes, this is also a first line defense, so it's not the answer we're looking for. The correct answer here is answer choice b. Phagocytosis of a pathogen by an immune cell is not a first line defense but a second line defense of the innate immune system. Okay, everyone. Let's move on to our next video.

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Examples of 1st line defenses to infection which are components of the innate immune system include all of the following except?

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