The Inflammatory Response's Effect on the Entire Body

Lesson Transcript
Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

This lesson will discuss two important roles systemic inflammation is involved in: fever and leukocytosis. It will also discuss the flip-side, two bad components of systemic inflammation: cachexia and anaphylactic shock. Updated: 01/15/2020

Inflammation Not Kept in Check

In another lesson, I mentioned the importance of realizing that most inflammatory mediators are made and inactivated at the local site of injury in order to try and minimize deleterious body-wide effects of inflammation. While this is true, it's often harder to achieve the latter point than not, since your body isn't an isolated series of compartments. Everything interacts everywhere all of the time and sometimes this is actually necessary.

A case in point is the flu. It's a respiratory infection, but the inflammation induced by the flu virus makes your entire body feel terrible. However, that terrible feeling may actually be important for your recovery, as you'll soon learn.

In this lesson, we'll discuss the body-wide, or systemic, effects of inflammation, why they occur, and what may happen in extreme cases.

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  • 0:07 Inflammation Not in Check
  • 1:00 What is Pyrexia?
  • 3:17 What is Leukocytosis?
  • 4:15 Cachexia & Anaphylaxis
  • 6:42 Lesson Summary
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What Is Pyrexia?

One very well-known component of systemic inflammation is known as pyrexia, or fever. The way I recall this definition is by thinking about the fact that a pyromaniac is someone who loves to set things on fire. The first three letter of each word match, fire is hot, and I know you've felt very hot when you've had a bad fever.

As a general rule, you must recall that fever is usually associated with an infection. But you can impress your teacher by telling them that people can have a fever due to many other things, such as cancer.

Anyway, there are two important reasons for the fever:

  • A high temperature is great for killing off pathogens
  • A high temperature speeds up important protective chemical reactions

Therefore, while the fever may make you feel bad when you've got the flu, you should actually thank it effusively for helping you kill off whatever it is that's trying to hurt you.

However, you surely know that a fever can be a bad thing, since a prolonged high temperature can cause a person to feel miserable, may cause seizures and, in serious cases, even death!

What's also critical for you to know is that the major internal initial trigger of fever in our body is a protein known as IL-1 or Interleukin-1. It is mainly secreted by white blood cells called macrophages in response to a foreign pathogen. This trigger of fever, or pyrogen, IL-1, then causes the synthesis and release of a compound known as prostaglandin E. This is a lipid compound that ultimately tells the hypothalamus to raise our body's temperature. The hypothalamus is the structure in our brain that regulates our body's temperature.

As you can tell, there's a whole sequence of events that leads to a fever. The IL-1 is like a match that is sparked. This spark then lights up the tissues, prostaglandin E. The little flames of prostaglandin E then trigger the firewood, our hypothalamus, to light up and produce powerful heat all over the place.

What Is Leukocytosis?

Besides causing fever, another major systemic response to inflammation is known as leukocytosis. This is an abnormally high white blood cell count in the blood. This occurs as a result of compounds called epinephrine and corticosteroids. In short, they cause an increase in the white blood cell count by forcing mature white blood cells, called neutrophils, to enter the circulation from storage pools inside of the body. By forcing the neutrophils to get out there and get going, so to speak, they have a much higher chance of encountering whatever it is that's causing you inflammation, destroying it, and getting you back to normal ASAP.

Basically, epinephrine and corticosteroids act as a swift kick in the butt to a lazy teenage son, the neutrophils, who needs to stop lying around on the couch and should go outside and save the world like Batman!

Cachexia and Anaphylactic Shock

Now, while I did mention two important systemic effects of inflammation, I don't want to leave this lesson alone without mentioning the fact that systemic inflammation can also be a bad thing if it's not kept in check.

One of these bad effects is known as cachexia. Cachexia is the wasting away of body fat and muscle as a result of a chronic disease processes or inflammation.

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