The Causes and Significance of Tissue Swelling

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  • 0:08 The Real Meaning of…
  • 0:52 Reversible Swelling
  • 2:10 Inflammation
  • 3:36 Hormones, Infections, and More
  • 6:00 Other Types of Tissue…
  • 7:00 Lesson Summary
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Lesson Transcript
Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

This lesson will discuss the different types of swelling and growths that may appear in or on your organs and tissues. We'll cover everything from hematomas and seromas to cancer and splenomegaly.

The Real Meaning of the Word Tumor

I know that some science lessons can be a bit boring. So, to lure you in this time around, I'm going to promise you some money. Well, sort of. I mean, I won't give you any money directly, but I can show you a way how you can win a bar-bet and make some money.

Ask someone at the bar, someone preferably really drunk and not in the scientific realm, what the word tumor really means. They'll probably say something along the lines of cancer. But, that's wrong and that's when you'll win $20. The word tumor actually means swelling. The swelling on the body can be a result of cancer, as in its modern usage, but more technically does not have to be. This lesson will delve into some of the reasons why tissue and organs in your body can swell.

Reversible Swelling

Another lesson pointed out that, during an injury to the body, a cell can swell as a result of the accumulation of water. This cell swelling is a potentially reversible change if the injury isn't severe enough or the cell can quickly compensate for the swelling. However, if that cannot occur, the cell will undergo necrosis, or cell death as a result of traumatic injury.

Necrosis is a pretty bad thing, it causes inflammation, which can cause further swelling, and it implies the cell is dead and therefore unable to function or do its job at all, whereas non-lethal cell swelling, or hydropic degeneration, means the cell may still be able to do some of its job. The problem is, this term of non-lethality is very relative. For instance, a collection of cells that form a tissue or organ may swell as a result of an injury and may still be alive, but the person may die anyways.

One simple example of this is the heart. If the cells of the myocardium swell due to an injury, even if they are still alive, the cell swelling may interfere with their ability to allow the heart to beat. If your heart stops, even though the cells aren't dead, you'll be dead anyways.


Another cause of tissue or organ swelling is inflammation. One really good way to picture this is to think of a dog bite. If a dog ever bit you in the arm, then your arm almost certainly swelled up like crazy. That's because of inflammation. When a dog's teeth cut into your flesh, two main things happened.

First, the cutting and crushing force of the dog's teeth and mouth ripped apart your skin cells. When the cells are ripped apart, they release their guts, or insides, in addition to a bunch of molecules. These molecules are sensed by neighboring cells and cells of the immune system, called white blood cells. These white blood cells rush into the area of the injury as a result of that injury and release other chemical signals that cause the blood vessels in the area to swell and engorge with blood so that other white blood cells and reparative molecules can stream into the area.

Furthermore, the dog's mouth was almost certainly not very clean, meaning all sorts of bacteria got into your flesh as a result of the bite. That's why all of those white blood cells rushed into the area in order to kill off the bacteria. When the battle between the bacteria and immune system rages on, it causes more leakage and accumulation of fluids, cells, and molecules that further cause the tissue surrounding the area of the bite to swell as a result of the inflammatory process.

Hormones, Infection, and More

Besides inflammation, other tissues can swell due to a myriad of reasons. For example, when an infection, due to something like the flu or perhaps from the same dog bite as before, sets in, then you may experience lymphadenopathy, or swollen lymph nodes. Your lymph nodes swell as the cells in your lymph nodes, called lymphocytes, multiply in response to an infectious agent. They multiply in number so they can help fight off the infection. As soon as the infection is fought off, the lymph nodes decrease back down to a normal size.

Unfortunately, however, the swelling of the lymph nodes need not always be transient and a more permanent swelling of a lymph node, or any other part of your body, may indicate neoplasia, or the abnormal growth and proliferation of abnormal cells or abnormal amounts of cells due to a benign or malignant process.

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