In this video, we're going to begin our lesson on the steps of the inflammatory response. And so really a series of just 4 events or 4 steps occur in the inflammatory response during tissue damage and infection of a microbe. In this video, we're only going to focus on the very first event, or the very first step of the inflammatory response, which is tissue damage and infection. But later in other videos, we'll talk about the other steps of the inflammatory response. In the first step of the inflammatory response, we have tissue damage and infection. Damage to the tissues allows microbes to bypass the first line of defense of innate immunity. So it can bypass our skin, mucus membranes, antimicrobials, and things of that nature. When they bypass the first line of defense, they can enter into the surrounding tissue cells. Immediately after the injury, blood vessels will briefly constrict via vasoconstriction. Vasoconstriction is the constriction or narrowing of the blood vessels. It does this in order to prevent blood loss. If we take a look at our image down below, we're showing you the very first event of the inflammatory response, which is tissue damage and infection by the microbe. Notice in this image, it is an image showing you our skin. You can see the epidermis layer is at the top here and the dermis layer is right here. Down below, notice that the blood vessel is at the bottom. When there is damage, like for example when a sharp object penetrates into your tissues, some of our immune system cells are already going to be present in the tissues. For example, mast cells can be present in the tissues. But, when there is penetration by a sharp object like this, it creates the opportunity for microbes to infect the tissues. This tissue damage can lead to infection by a microbe. Once again, the blood vessels are going to briefly constrict to prevent a large amount of blood loss. This here concludes our lesson on the first event of the inflammatory response, and we'll get to talk about the other events of the inflammatory response as we move forward. I'll see you all in our next video.
Steps of the Inflammatory Response - Online Tutor, Practice Problems & Exam Prep
1) Tissue Damage & Infection
Video transcript
2) Release of Inflammatory Mediators & Other Cytokines
Video transcript
In this video, we're going to talk briefly about the second step in the inflammatory response, which is the release of inflammatory mediators and other cytokines. In response to a microbe invasion or tissue damage, local mast cells, which recall are very similar to basophils but reside in the tissues, will release cytokines and inflammatory mediators. These mast cells are already residing within the tissues, as you can see here in this image. They will begin to release cytokines and inflammatory mediators upon an infection. Inflammatory mediators refer to messenger molecules specifically involved in the inflammatory response. For example, histamine is an example of an inflammatory mediator, and the release of histamine will promote inflammation.
The release of inflammatory mediators will help to regulate changes in local blood vessels, potentially causing the local blood vessels to dilate, as we'll discuss in the next step. It will also signal immune system cells from the blood to the infected site, attracting immune system cells to the area of infection.
If we take a look at this image down below, we're focusing on the second step of the inflammatory response: inflammatory mediators and cytokines being released. These mast cells that are present in the tissues and reside there will begin to release cytokines and inflammatory mediators. These cytokines and inflammatory mediators will cause changes to the local blood vessels and also signal immune system cells to travel from the blood vessels to the area of infection to help eliminate the microbes.
This concludes our brief lesson on the second step of the inflammatory response, and we will be able to talk about the third and fourth steps of the inflammatory response as we continue to move forward. I'll see you in our next lesson video.
In the inflammatory response, which immune cells are the first to begin the immune response to an injury?
3) Vasodilation
Video transcript
In this video, we're going to talk briefly about the 3rd step of the inflammatory response, which is vasodilation. Vasodilation is the dilation or the enlargement of the blood vessels that increases the permeability of those blood vessels. The increased permeability allows for cells of the immune system to leave the bloodstream and enter the site of infection. This increased permeability is in response to inflammatory mediators. Inflammatory mediators that are released by mast cells lead to vasodilation, the enlargement of the blood vessels, and the increased permeability of those blood vessels.
The term diapedesis refers specifically to the migration of immune system cells through the intact walls of the blood vessels into the infected tissue. The term exudate refers specifically to the fluid mix of blood plasma, proteins, and immune cells that exit the bloodstream to the infected site. Recall from some of our previous lesson videos that neutrophils are the very first type of cells to be recruited to the site of infection. They are the first phagocytes that are recruited. Taking a look at our image down below, we have the 3rd step of the inflammatory response, which is vasodilation and diapedesis. What you'll notice here is that the cells in the infected area are battling many microbes. The mast cells, upon releasing those inflammatory mediators, lead to vasodilation. Here we have dilated blood vessels. These dilated blood vessels increase the permeability of the blood vessels, allowing for diapedesis. Diapedesis, again, is the migration of blood of immune cells from the blood into the site of infection. Macrophages and neutrophils can be recruited, and again, it's the neutrophils that are the first to be recruited to the site of infection.
This concludes our brief lesson on the 3rd step of the inflammatory response, vasodilation, and we will be able to get some practice applying these concepts and talk about the 4th and final step of the inflammatory response as we move forward in our course. I'll see you all in our next video.
Which of the following is needed for vasodilation and diapedesis to occur at an infection site?
4) Removal of Invading Microbes
Video transcript
This video, we're going to talk about the 4th and final step of the inflammatory response, which is the removal of the invading microbes. The phagocytic cells that migrated from the blood into the infected area are going to destroy or eliminate those invading microbes. Now the neutrophils are going to remove microbes through degranulation or through phagocytosis, and macrophages are going to perform phagocytosis and engulf the cells, the dead cells in the area to help destroy and eliminate all of the microbes that have invaded. Taking a look at this image down below, the 4th and final step of the inflammatory response is phagocytosis of the invading microbes, and removal of those invading microbes. Notice in this image we have neutrophils and we also have macrophages. Together, they will work to eliminate these microbes and remove those microbes. This here concludes our lesson on this 4th and final step of the inflammatory response. Moving forward, we'll be able to get practice on these concepts and also continue to talk more about the innate immune responses. So I'll see you all in our next video.
Which immune cells are responsible for removing dead or damaged host material at an injury site?
Match the scenario to the step of the inflammatory response it belongs in.
1. Tissue Damage & Infection.
2. Release of Inflammatory Mediators & Cytokines.
3. Vasodilation and Diapedesis.
4. Removal of Invading Microbes and Damaged Tissue.
_____ Local mast cells release histamines and cytokines when encountering an invading microbe.
_____ Neutrophils destroy the invading microbes found in the injury site.
_____ Peter accidentally cuts his finger with a kitchen knife.
_____ Fluid full of plasma, proteins and immune cells exits the blood stream at injury site.
_____ Macrophages remove the epidermis and dermis cells damaged by the injury.
_____ The blood vessels in the region of the injury dilate releasing immune cells and proteins.
_____ Pathogenic bacteria enter the host's body.
Problem Transcript
Damaging Effects of the Inflammatory Response
Video transcript
This video, we're going to talk a little bit about the damaging effects of the inflammatory response. And although inflammation is designed to eliminate microbes and protect us from microbes, sometimes inflammation can result in significant damage to the host. This is really accidental damage because the inflammatory response is supposed to be eliminating microbes. The inflammatory response can be somewhat similar to a sprinkler system in a building, where the sprinkler system is designed to project water and eliminate and prevent fires. However, sometimes, the sprinkler system can also cause accidental damage to electrical equipment. That's why the inflammatory response can be an analogy to a sprinkler system because it's designed to eliminate microbes, but sometimes it can cause accidental damage to the host.
Depending on the location of where inflammation occurs within the host, inflammation can actually be life-threatening. For example, if inflammation occurs in the brain, it can be very life-threatening. The suffix -itis is found in many disease names and it specifically means inflammation. You can find that suffix in terms like meningitis or encephalitis. That suffix -itis means inflammation. Below, we're showing you just an image of rheumatoid arthritis, which is basically inflammation that occurs in the joints. Meningitis and encephalitis are basically just inflammation of the meninges or the membranes of the brain, or inflammation of the brain itself, which again can be life-threatening. It's important to keep in mind about the inflammatory response that occasionally it can have some damaging effects.
This concludes our brief lesson on the damaging effects of the inflammatory response. Once again, we'll be able to get some practice applying these concepts as we move forward. I'll see you all in our next video.
Which of the following statements about the inflammatory response is false?
Rheumatoid arthritis is an autoimmune disease, meaning that the body's immune system attacks the body's joint tissues. Why are many autoimmune diseases associated with chronic inflammation?
Which of the following is FALSE in regards to inflammation?
Do you want more practice?
Your Microbiology tutor
- Why are vascular changes in early inflammation considered central to generating inflammation’s cardinal signs?
- Which of the following would you not expect to see in the first stage of inflammation?a. Histamineb. Kininsc. ...
- Which of the following shows a correct chronological order of events in inflammation?a. Neutrophil recruitment...