When we usually talk about immunology, most of us think about white blood cells first. Recalling back to my previous post on the innate immune system, I stated that the innate immune cells are the front line of defence. However, let's not forget our epithelia.
Skin
Your skin is like an armour that protects your whole body from the environmental pathogens. It serves as a physical barrier, which blocks any pathogen from entering your system. The many layers of skin makes it much more difficult for any pathogen invasion. Also, in the epidermal layer, there are Langerhan's cells (epidermal dendritic cells) which will act to capture pathogens, and present it to T cells to activate them. Innate immune cells can be most commonly found in the skin, so that they are able to get rid of pathogen immediately.
Now, the skin usually protects the whole body from external pathogens. However, there are 2 openings which can increase the chance of pathogen invasion. The mouth and nosetrils, which serves as the opening for the Gastrointestinal and Respiratory tract respectively, often allows the pathogen entrance, so how do they prevent pathogen invasion?
Respiratory epithelial
As we know, there are pathogens in the air, and they can enter when we inhale. So that's why we have nose hair, and the respiratory tract produces mucus regularly. The hair and mucus trap the pathogens in the air, and act as a filter, so that the air that reaches the alveoli are cleaner.
The respiratory epithelial changes as air travels from the nose down to the bronchi, and then into the alveoli. Those changes in respiratory epithelial change according to the lungs' function (gas exchange). But what is consistent, is the presence of mucus producing cells (goblet cells), and specialised ciliated cells.
Cilia are microscopic structures found on the apical side of the respiratory tract, which has a brush-like structure. These cilia are motile, which means that they are capable of 'sweeping' any pathogen trapped on the cell surface, out.
Gastrointestinal (GI) epithelial
While respiratory tract allows passage of air, GI tract allows the passage of food and water. Again, the different segments of the GI tract have very different epithelia according to the GI tract function (digestion & nutrient absorption). Similar to the respiratory tract, mucus is also produced, but for lubrication and trapping pathogens as well.
Particularly in the stomach, where the main chemical digestion occurs, its extremely low pH environment makes it difficult for pathogens to survive. However, there is still one particular specie, Helicobacter pylori, which is still able to survive the acidic environment. Infection by H. pylori can cause gastric ulcer.
At the mouth, there is a structure known as the Waldeyer's ring, which 'guards' the entrance of food.
In the intestines, Gut-associated lymphoid tissues (GALT) and Peyer's patches are present, ready to capture any pathogen and activate the lymphocytes.
As we can see, there are many structures in the body which we often overlook, but play a huge role in pathogen defence. So the next time, you are paranoid about a little dust in your environment, remember the body is already 'equipped' and ready for combat. 💪
Now, the skin usually protects the whole body from external pathogens. However, there are 2 openings which can increase the chance of pathogen invasion. The mouth and nosetrils, which serves as the opening for the Gastrointestinal and Respiratory tract respectively, often allows the pathogen entrance, so how do they prevent pathogen invasion?
Respiratory epithelial
As we know, there are pathogens in the air, and they can enter when we inhale. So that's why we have nose hair, and the respiratory tract produces mucus regularly. The hair and mucus trap the pathogens in the air, and act as a filter, so that the air that reaches the alveoli are cleaner.
The respiratory epithelial changes as air travels from the nose down to the bronchi, and then into the alveoli. Those changes in respiratory epithelial change according to the lungs' function (gas exchange). But what is consistent, is the presence of mucus producing cells (goblet cells), and specialised ciliated cells.
Cilia are microscopic structures found on the apical side of the respiratory tract, which has a brush-like structure. These cilia are motile, which means that they are capable of 'sweeping' any pathogen trapped on the cell surface, out.
Gastrointestinal (GI) epithelial
While respiratory tract allows passage of air, GI tract allows the passage of food and water. Again, the different segments of the GI tract have very different epithelia according to the GI tract function (digestion & nutrient absorption). Similar to the respiratory tract, mucus is also produced, but for lubrication and trapping pathogens as well.
Particularly in the stomach, where the main chemical digestion occurs, its extremely low pH environment makes it difficult for pathogens to survive. However, there is still one particular specie, Helicobacter pylori, which is still able to survive the acidic environment. Infection by H. pylori can cause gastric ulcer.
At the mouth, there is a structure known as the Waldeyer's ring, which 'guards' the entrance of food.
In the intestines, Gut-associated lymphoid tissues (GALT) and Peyer's patches are present, ready to capture any pathogen and activate the lymphocytes.
As we can see, there are many structures in the body which we often overlook, but play a huge role in pathogen defence. So the next time, you are paranoid about a little dust in your environment, remember the body is already 'equipped' and ready for combat. 💪
Comments
Post a Comment