What Are Mucous Membranes? - Definition & Explanation

Lesson Transcript
Instructor: Kelly Robson

Kelly has taught High School Science and Applied Communications. She holds an Education Specialist Degree in Ed. Leadership.

Mucous objects create the slimy substance we often prefer not to think about, also known as mucus. In this lesson, you will learn how mucous objects and mucus are vital to the human body, though they can have negative effects as well.

Mucous vs. Mucus

Mucous is the adjectival form of the more familiar noun, mucus. In other words, mucous is actually the action or ability to make mucus, the yucky stuff we blow into Kleenex. There are mucous cells, mucous fluid, mucous membranes, and mucous glands. They are all different objects that can secrete mucus. Mucus is the slimy substance that can be found in our respiratory system, digestive system, and reproductive system. Although it has a tendency to be highly annoying - especially during changes in weather - mucus is actually used to protect our bodies from the outside world.

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  • 0:01 Mucous vs. Mucus and Functions
  • 1:28 Respiratory System
  • 2:31 Digestive System
  • 3:09 Reproductive System
  • 3:31 When Mucus Goes Bad
  • 4:48 Lesson Summary
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Mucous membranes are found where outside invaders are able to get into our bodies. They secrete mucus as protection from potentially harmful invaders such as bacteria, viruses, or outside matter that can mess up our systems. The mucus from these layers can trap and remove invaders. Some mucus even contains antibodies that help to detect the different viruses and bacteria and send for back up from the rest of the body's immune system.

The mucus that is secreted by mucous objects lies on top of the tissues to not only protect it from invaders but also to keep the underlying tissue from drying out. If the tissue becomes dry, it becomes more fragile and can cause the organ to malfunction. Each system that produces mucus also uses mucus for its own purposes.

Respiratory System

The main function of the respiratory system is to make an exchange between the air we breathe and our blood. We breathe in air, and our lungs take oxygen from it and deliver it into the blood. At the same time, our lungs also pick up waste from the blood and release it back to the outside world.

The air that enters our lungs can come with invaders that could do harm to the respiratory system. Therefore, mucus in that system has a huge job to keep harmful objects out of our lungs. The mucus acts like a sticky piece of fly paper that the invaders get stuck on. The mucus will then drain and take the invaders with it.

The lung tissue is also very thin. The thinnest part of the tissue is actually at the site of the exchange. Mucus plays a vital role of protecting this tissue not only from the invaders but from drying out. At normal function, the lungs feel kind of like a slimy moist sponge that expands and contracts smoothly. They would not be able to function properly as a dry sponge because they would not be able to expand and contract.

Digestive System

The digestive system is connected to the outside world through the food we eat. The mucus in our esophagus helps the food slide down easily. This helps to prevent the food from scratching our esophagus and also helps to prevent chocking.

The mucus in the digestive system also protects itself from its own dangerous elements. The digestive system uses very powerful chemicals to break down our food into usable nutrients. Without the layer of mucus created by the mucous membranes, these chemicals would eat right through the organs such as the stomach or the small intestines. So, the mucus is there to act as a barrier to prevent the chemicals from damaging the internal lining of the organs.

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