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

Mucous membranes are vital physical barriers that produce mucus, a glycoprotein fluid from goblet cells, protecting and preventing drying in the digestive, respiratory, and genitourinary tracts. They trap pathogens, which can enter the body, and utilize mechanisms like peristalsis and the mucociliary escalator to eliminate microbes. Peristalsis moves substances through the digestive tract, while the mucociliary escalator uses cilia to transport trapped microbes from the lungs to the mouth for expulsion. Understanding these processes is crucial for grasping innate immunity and pathogen defense mechanisms.

Mucous Membranes

This video, we're going to begin our lesson on mucus membranes, which recall from our previous lesson videos is one of the physical barriers 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 tracts from drying out. Now mucus membranes will line our digestive tract, including our mouths, our nose, our esophagus, our digestive system, our respiratory tract, including our trachea and our lungs, and our genitourinary tract as well. And so again, it will help to protect and prevent those line tracts 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 the mucus 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 specifically on the physical barriers, specifically mucus membranes here in this video. And so on the right over here, we're showing you the mucus membranes 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 notice that there is a mucus layer that is kind of lining, these mucus membranes. And so, the mucus here can trap microbes, and, the mucus can be washed out of the body and basically help to protect our membranes. And so here's a micrograph showing you an image of the mucus membranes as well.

And so this here concludes our brief introduction to the mucus 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.

Peristalsis & Mucociliary Escalator

This video, we're going to talk a little bit about peristalsis and the mucociliary escalator. Mucous 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 contract and move food, liquids, and microbes that we've ingested towards the anus where they can be easily eliminated.

The mucociliary escalator refers to the synchronized movement of cilia, which, recall from our previous lesson videos, are small hair-like projections that move like oars and can move substances through a system. The mucociliary escalator is the synchronized movement of cilia that move microbes out of the respiratory tract and towards our mouth. The movement of 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.

Microbes that enter the nasal cavity can actually get trapped in what we refer to as the mucociliary blanket. 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.

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 of defense of innate immunity on the physical barriers, specifically talking about the mucociliary escalator. The mucociliary escalator, somewhat does resemble an escalator, because what happens is microbes that are in the lungs can be moved towards the mouth and nose. You can see the movement of the mucus is in this direction. 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.

This here 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 mucus membranes. We'll be able to apply some of these concepts moving forward and learn more as well. 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.

Answer: (C)

Here’s what students ask on this topic:

What are mucous membranes and what role do they play in the body's first line of defense?

Mucous membranes are physical barriers that line various tracts in the body, including the digestive, respiratory, and genitourinary tracts. They produce mucus, a slightly viscous glycoprotein fluid secreted by goblet cells. This mucus helps to trap pathogens and prevent the underlying tissues from drying out. By trapping microbes, mucous membranes play a crucial role in the body's first line of defense, preventing pathogens from entering deeper tissues and causing infections. Additionally, mechanisms like peristalsis and the mucociliary escalator help move trapped microbes towards areas where they can be expelled from the body, further enhancing their protective function.

How does the mucociliary escalator function in the respiratory tract?

The mucociliary escalator is a mechanism in the respiratory tract that involves the synchronized movement of cilia, which are small hair-like projections on the surface of epithelial cells. These cilia beat in a coordinated manner to move mucus, along with trapped microbes and particles, upwards towards the mouth and nose. This movement helps to clear the respiratory tract of potential pathogens. Once the mucus reaches the mouth or nose, it can be expelled from the body through coughing or sneezing, or swallowed into the digestive tract where peristalsis can eliminate the microbes. This process is essential for maintaining respiratory health and preventing infections.

What is peristalsis and how does it contribute to the elimination of microbes?

Peristalsis refers to the wave-like muscle contractions in the intestinal tract that move food, liquids, and ingested microbes towards the anus. These contractions help to propel the contents of the digestive tract forward, ensuring that any trapped pathogens are moved along and eventually expelled from the body. By facilitating the movement of microbes through the digestive system, peristalsis plays a critical role in the body's first line of defense, preventing pathogens from colonizing and causing infections in the digestive tract.

What are goblet cells and what is their function in mucous membranes?

Goblet cells are specialized epithelial cells found in mucous membranes that produce and secrete mucus. This mucus is a slightly viscous glycoprotein fluid that serves several protective functions. It traps pathogens and particles, preventing them from reaching and infecting underlying tissues. Additionally, mucus helps to keep the mucous membranes moist, preventing them from drying out and becoming more susceptible to damage and infection. By producing mucus, goblet cells play a vital role in maintaining the integrity and protective function of mucous membranes in the digestive, respiratory, and genitourinary tracts.

How do mucous membranes prevent pathogens from entering the body?

Mucous membranes prevent pathogens from entering the body through several mechanisms. Firstly, they produce mucus, which traps microbes and particles, preventing them from reaching deeper tissues. Secondly, the mucus can be moved by mechanisms like the mucociliary escalator in the respiratory tract, where cilia transport the mucus and trapped pathogens towards the mouth and nose for expulsion. In the digestive tract, peristalsis moves the mucus and trapped microbes towards the anus for elimination. These combined actions help to ensure that pathogens are trapped and removed from the body, reducing the risk of infection.