Physical Barriers in First-Line Defenses: Mucous Membrane - Video Tutorials & Practice Problems

Mucous Membranes

In this video, we're going to begin our lesson on mucous membranes, which recall from our previous lesson videos is one of the physical barriers in the first line of defense in innate immunity. And so mucous membranes consist of an epithelial layer of cells and connective tissue that produces as its name implies mucus. And so mucus is a slightly viscous glycoprotein fluid that's going to be produced by goblet cells. And so these goblet cells are just cells that are going to produce components that are found in mucus. And the mucus itself can protect and prevent line tracks from drying out. Now, mucous membranes will line our digestive tract, including our mouths, our nose, our esophagus, our di you know, our entire digestive system, our respiratory tract, including our uh trachea and our lungs and our genitourinary tract as well. And so again, it will help to protect and prevent those line tracks from drying out. Now, although our bodies do have mechanisms to protect the mucus membrane, some of those mechanisms we'll get to talk about later in our course, it turns out that the mucous membranes are commonly used by pathogens to enter our bodies And so if we take a look at our image down below, over here, on the left hand side, notice that we're showing you our map of the first line of defense in innate immunity. And we're focusing in specifically on the physical barriers, specifically mucus membranes here in this video. And so on the right over here, we're showing you the mucous membranes uh diagram and notice that it consists of these epithelial cells and connective tissue. And notice that the goblet cells specifically are going to be the cells that produce the components found in the mucus. And so the notice that there is a mucus layer that is kind of lining uh these mucus membranes. And so uh the mucus here can trap microbes and uh the mucus can be washed out of the body and basically help to protect our uh membranes. And so here's a micrograph showing you an image of the mucous membranes as well. And so this here concludes our brief introduction to the mucous membranes. But as we move forward in our course, we'll be able to talk a little bit more about them and then apply the concepts that we've learned. And so I'll see you all in our next video.

Physical Barriers in First-Line Defenses: Mucous Membrane

In this video, we're going to talk a little bit about peristalsis and the mucociliary escalator. And so mucus membranes have mechanisms that can move microbes towards areas where they can be easily eliminated from our bodies. For example, moving microbes through our digestive tract towards the anus where they can be easily eliminated. Now, peristalsis specifically refers to the intestinal tract, muscle contractions that will contract and move food liquids and microbes that we've ingested towards the anus where they can be easily eliminated. Now, the mucociliary escalator refers to the synchronized movement of cilia, which recall from our pre previous lesson, videos are small hair like projections that move like ores and can move substances uh through a system. And so the mucociliary escalator is gonna be the synchronized movement of cilia that move microbes out of the respiratory tract and towards our mouth. And so the movement of uh these microbes is going to be once again away from our lungs, away from our respiratory tract and towards our mouth where those microbes can be easily expelled from the body via coughing or sneezing, or we could swallow those microbes into our digestive tract where peristalsis can eliminate those microbes through the anus. Now, microbes that enter the nasal cavity can actually get trapped in what we refer to as the mucociliary blanket. And the mucociliary blanket refers to ciliary cells in the nose and sinuses that are covered in mucus. And their job is to trap microbes that enter into our body and then to remove those microbes to make sure that they don't cause us any harm. And so if we take a look at our image down below, on the left hand side, notice that we're focusing specifically on the first line defense of innate immunity on the physical barriers. Uh specifically talking about the mucociliary escalator. And so once again, the mucociliary escalator here uh somewhat does resemble an escalator because uh what happens is microbes that are in the lungs can be moved uh towards the mouth and nose. So you can see the movement of the mucus is in this direction. And this is because we have cells that have cilia that can move the mucus and the microbes that are embedded within the mucus towards our mouth and nose where we can easily eliminate those microbes in our mucus, either through coughing, sneezing or again, swallowing the mucus into our digestive tract where those microbes can be eliminated. And so this over here is showing you uh in our uh trachea here. What you can see is the mucociliary escalator where we have mucus and we have foreign particles that are embedded within our mucus. And notice that these cells here have cilia and these cilia they can beat in a specific direction to move the mucus and move the foreign particles towards an area of interest. In this case, it's an escalator, moving the mucus uh towards the mouth area and the nose area where once again, they can be eliminated through sneezing or coughing or swallowing the mucus so that it can be eliminated uh through our digestive tract. And so this year concludes our brief lesson on peristalsis and the mucociliary escalator and how they can help to eliminate microbes that have entered into the body and been trapped in the mucous membranes. And so we'll be able to apply some of these concepts moving forward and learn more as well. And so I'll see you all in our next video.

Which physical, nonspecific host defense mechanism is associated with the respiratory tract and trachea?

• A. Water-repelling keratin proteins.
• B. Lysozyme enzymes.
• C. Mucociliary escalator.
• D. Salivary amylase.