Introduction to Inflammation - Online Tutor, Practice Problems & Exam Prep

Inflammation is a coordinated immune response to infection or tissue damage, characterized by five cardinal signs: swelling, heat, altered function, redness, and pain, remembered by the acronym SHARP. There are two types of inflammatory responses: acute inflammation, a short-term response marked by neutrophils, and chronic inflammation, a long-term response involving macrophages and T lymphocytes, which can lead to granuloma formation. Understanding these processes is crucial for recognizing how the body defends itself against pathogens and manages tissue repair.

Inflammation

This video, we're going to begin our introduction to inflammation. And so first, we need to recall from some of our previous lesson videos that we already briefly defined inflammation as a coordinated set of events that occurs when the body detects an infection or tissue damage. Now there are five cardinal signs of inflammation that you can remember by using this acronym SHARP: swelling, heat, altered function, redness, and pain. If you can remember SHARP, then you'll be able to remember the five cardinal signs of inflammation: swelling, heat, altered function, redness, and pain.

Over here, we have a little cartoon just to help you remember this SHARP acronym. Notice here we have Doctor Clutch Prep over here and he says, "Wow, this sword is so sharp." Notice he had a little accident here, and Doctor Clutch is now feeling the five cardinal signs of inflammation just by remembering this SHARP acronym right here.

As we move forward in our course, we'll be able to talk a lot more about the steps of inflammation and different types of inflammation as well. But for now, this here concludes our brief introduction to inflammation, and I'll see you all in our next lesson video to learn more.

Types of Inflammatory Response

In this video, we're going to briefly introduce 2 types of inflammatory responses. And so once again, there are 2 types of inflammatory responses, and they are acute inflammation and chronic inflammation. Now, acute inflammation is characterized by being a short-term immune response. And, the symptoms are going to develop very rapidly and they're going to last only a short period of time. For example, just a few days. And so examples of acute inflammation include inflammation that's due to the common cold, flu, headache, and joint pain, all associated with inflammation that only lasts a short period of time, just a few days. Now, chronic inflammation, on the other hand, is characterized by a long-term immune response. And so the symptoms of chronic inflammation develop very slowly rather than developing rapidly, and they last a long period of time, for example, many many years, or perhaps even the entire lifespan of the organism. And so examples of chronic inflammation include inflammation due to heart disease, cancer, Crohn's disease, or arthritis.

If we take a look at our image down below, notice on the left-hand side we're showing you a table that's comparing acute and chronic inflammation. And so notice on the y-axis we have the severity of the inflammation and on the x-axis what we have is time. And what you'll notice is the red curve that you see here is corresponding with acute inflammation because notice that it is lasting just a short period of time, with the x-axis just being a few days. And notice that the purple curve that you see here corresponds with chronic inflammation. And once again, chronic inflammation is characterized by being a long-term inflammation that can last years, perhaps even the entire lifespan of the organism. Now on the right over here, we're showing you our map of the lesson on Innate immunity. And, in this video, we're specifically focusing on the second line of defense and the innate effectors, specifically inflammation. And here in this video, we're distinguishing between acute inflammation and chronic inflammation. And as we move forward in our course, we're going to talk even more details about acute inflammation and even more details about chronic inflammation. But for now, this here concludes our brief introduction to these two types of inflammatory responses, acute inflammation and chronic inflammation, and we'll be able to learn more about them as we move forward. So I'll see you all in our next video.

Acute Inflammation

This video, we're going to talk a little bit more about acute inflammation. And so recall from our previous lesson video that acute inflammation is characterized by a short-term immune response where symptoms develop very quickly and last a short period of time. For example, just a few days. Now, acute inflammation is characterized by an abundance of neutrophils. And so these neutrophils are going to be in the infected and damaged area. And so the goal of acute inflammation is to quickly recruit immune cells to the location of damage or infection. Once again, neutrophils are going to be recruited first. And so these neutrophils are the first to arrive at the site of infection.

If we take a look at our image down below on the left-hand side, we're focusing on our map of the lesson showing the innate effector actions. We've already discussed phagocytosis, so here in this video, we're focusing on acute inflammation. Here we have a little cartoon that's focusing on acute inflammation. And notice that we have a person outside, and then a bug lands on this person, like a mosquito. Then notice that this person is saying, "Ow, a bug bit me," and the mosquito bit them and notice that acute inflammation is resulting from the bug bite. Just a few days later, notice that the inflammation is gone. And so, notice that acute inflammation only lasts a short period of time, again just a few days.

This here concludes our brief lesson on acute inflammation, characterized by an abundance of neutrophils. Again, we'll be able to apply these concepts as we move forward, and then we'll talk a little bit about chronic inflammation. So I'll see you all in our next video.

Which of the following answers is an inflammatory mediator that stimulates vasodilation allowing immune cells to enter the site of infection?

• A. Collagen.
• B. Serotonin.
• C. C3b protein.
• D. Histamine.

Which of the following scenarios would not result in an episode of acute inflammation?

• A. An individual having rheumatoid arthritis, an inflammatory disease that degrades the joints over a lifetime.
• B. An individual having a painful sensation around a vaccine injection site for a few days after vaccination.
• C. An individual having a swollen ankle for a week after falling down a set of stairs.
• D. An individual having a painful, red wound for a few days after being scratched by a cat.

Chronic Inflammation

In this video, we're going to talk some more details about chronic inflammation. And so first, we need to recall from some of our previous lesson videos that we already chronic inflammation as a long-term immune response, where symptoms are going to develop slowly and they are going to last a long period of time. For example, several years. Now, unlike acute inflammation, which is characterized by an abundance of neutrophils, chronic inflammation is characterized by an abundance of macrophages, giant cells, and T lymphocytes or T cells. Now recall that giant cells are the fusion of 2 macrophages, and T lymphocytes or T cells are cells that are part of adaptive immunity. Now these macrophages, giant cells, and T lymphocytes can accumulate to form what is known as a granuloma. And so a granulomas or granulomas are really just concentrated groups of cells that are important for retaining or walling off microbes that cannot be easily destroyed.

And so if we take a look at our image down below, notice on the left-hand side we're showing you our map of the lesson on these innate effector actions, and we're specifically focusing on inflammation and chronic inflammation here. And so once again, chronic inflammation is characterized by a long-term immune response. And so notice in this cartoon on the left over here we have a person whose knee is displaying some inflammation through rheumatoid arthritis. And notice that several years later, a long period of time later, this arthritis and inflammation are still occurring. And so this is an example of chronic inflammation, long-term inflammation that can last a long period of time. Now down below what we're showing you is, once again, chronic inflammation and the granulomas that can form during chronic inflammation. And so over here what we have is the Mycobacterium tuberculosis which is the bacteria that causes tuberculosis. And then, we have the image of the macrophage, B cells, and T cells. And what you'll notice is that these granulomas are going to consist of a bunch of immune system cells that are gathering to create a structure to wall off and block and retain the bacteria so that the bacteria are not capable of spreading. And this really only occurs during severe chronic long-term inflammation.

And so here's an image of the granuloma in the lymph node. And so this here concludes our brief lesson on chronic inflammation, as well as granulomas. And we'll be able to get some practice applying these concepts as we move forward, so I'll see you all in our next video.

A scientist is analyzing the cells from a granuloma tissue sample. Which type of immune cell is the scientist least likely to find in this sample?

• A. T cells.
• B. Macrophages.
• C. Neutrophils.
• D. Giant cells.

The disease tuberculosis (TB) is a serious bacterial infection characterized by granulomas typically found in the lungs. What characteristics would a TB granuloma have?

• A. A large mass of immune cells surrounding the Mycobacterium tuberculosis thus stopping the spread of bacteria.
• B. A region of scar tissue created by Mycobacterium tuberculosis.
• C. A region of tissue growth to heal the damage caused by Mycobacterium tuberculosis.

Here’s what students ask on this topic:

What are the five cardinal signs of inflammation and how can they be remembered?

The five cardinal signs of inflammation are swelling, heat, altered function, redness, and pain. These can be remembered using the acronym SHARP. Swelling refers to the accumulation of fluid in tissues, heat is the increase in temperature due to increased blood flow, altered function indicates a loss or change in the normal function of the affected area, redness is caused by increased blood flow, and pain results from the release of chemicals that stimulate nerve endings. Remembering the acronym SHARP can help you recall these signs easily.

What is the difference between acute and chronic inflammation?

Acute inflammation is a short-term immune response where symptoms develop rapidly and last for a few days. It is characterized by an abundance of neutrophils. Examples include inflammation from a common cold or a bug bite. Chronic inflammation, on the other hand, is a long-term immune response where symptoms develop slowly and can last for years or even a lifetime. It involves macrophages, giant cells, and T lymphocytes, and can lead to granuloma formation. Examples include inflammation from heart disease or arthritis.

What role do neutrophils play in acute inflammation?

Neutrophils play a crucial role in acute inflammation. They are the first immune cells to arrive at the site of infection or tissue damage. Their primary function is to quickly respond to and neutralize pathogens through processes like phagocytosis, where they engulf and digest harmful microorganisms. The rapid recruitment and action of neutrophils help to control and resolve the inflammation within a short period, typically a few days.

How do macrophages and T lymphocytes contribute to chronic inflammation?

In chronic inflammation, macrophages and T lymphocytes play significant roles. Macrophages are responsible for engulfing and digesting pathogens and dead cells. They can fuse to form giant cells, which help in containing persistent infections. T lymphocytes, part of the adaptive immune system, help in recognizing and responding to specific antigens. Together, these cells can form granulomas, which are concentrated groups of immune cells that wall off and contain microbes that cannot be easily destroyed, thereby preventing their spread.

What is a granuloma and how does it form during chronic inflammation?

A granuloma is a concentrated group of immune cells that forms during chronic inflammation to wall off and contain pathogens that cannot be easily destroyed. It consists mainly of macrophages, giant cells (formed by the fusion of macrophages), and T lymphocytes. Granulomas are important for preventing the spread of persistent infections, such as those caused by Mycobacterium tuberculosis, the bacteria responsible for tuberculosis. The formation of granulomas helps to isolate the pathogen and limit tissue damage.