Artem has a doctor of veterinary medicine degree.
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.
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.
One reason cachexia occurs in chronic disease states is because an inflammatory mediator, known as tumor necrosis factor alpha, is released for too long a time. One thing this inflammatory compound does is that it basically causes your body to improperly utilize and absorb fat from your diet. Meaning, there may be enough food to go around, but the body just can't use it properly due to chronic inflammation and the person ends up losing a lot of weight.
Another terrible consequence of too many inflammatory mediators being released at once is known as anaphylactic shock. This is a systemic inflammatory reaction to an allergen that causes the blood pressure to drop to dangerous levels in conjunction with problematic breathing, itching, and vomiting, among other signs and symptoms. One major component of anaphylactic shock is a compound called histamine that is released by mast cells and basophils during a reaction, directly causing many of the problems I just mentioned. While mast cells and basophils are important components in inflammation, their overstimulation or overreaction may lead to death, as in anaphylactic shock, due to a sudden, massive, and systemic inflammatory response to something your body perceives as a threat, whether real or not.
Sometimes, this reaction can occur because of an innocent substance that wouldn't cause the body nearly as much harm as anaphylactic shock does. I liken this reaction to a person who worries way too much about nothing important. It's like that mother who hands you rubber boots, an umbrella, and a waterproof coat when there's one tiny cloud in the sky. Could it theoretically rain because of that one cloud? Yes. Will it really cause that big of a problem? No.
Well, now I hope you can appreciate how important and how dangerous systemic inflammatory responses can be!
Two important components of a solid inflammatory response we went over were leukocytosis, which is an abnormally high white blood cell count in the blood, and pyrexia, or fever.
The major internal initial trigger of fever, a pyrogen in our body is a protein known as IL-1 or Interleukin-1. This 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.
While fever is usually a good thing, unless it gets out of hand, and leukocytosis usually indicates a normal response to a foreign invader in your body that needs to be killed, the systemic inflammatory response can go haywire. Two notable examples of this are cachexia, which is the wasting away of body fat and muscle as a result of a chronic disease process or inflammation, and anaphylactic shock, which is a systemic inflammatory reaction to an allergen that causes the blood pressure to drop to dangerous levels in conjunction with problematic breathing, itching, and vomiting among other signs and symptoms.
When this lesson is over, you should be able to:
- Understand the components of solid inflammatory response
- Explain how fever affects the body
- Identify what triggers internal fevers
- Recognize how certain fevers can be dangerous
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