Myasthenia Gravis: Thymus Gland (Nursing)

00:00 Now look at this thymus gland.

00:02 It's located in the chest behind the breastbone.

00:06 Now it's the biggest in little kids.

00:08 Now when you're first born, it's pretty good size, compared to the rest of the size of your body.

00:12 It keeps growing gradually until you reach puberty, and then it gets smaller.

00:17 Yeah, but here's the bad news.

00:18 One more thing that gets replaced by fat in your body.

00:22 So a thymus gland, it's biggest when I'm a little kid, keeps growing gradually until puberty, and then it gets smaller and is replaced by a fat.

00:31 Okay, that's normally what happens with a thymus gland.

00:35 But throughout childhood, it plays an important role in helping the immune system develop.

00:40 So the thymus gland is a good guy, because it's responsible for helping make T lymphocytes or T cells.

00:48 So when you're looking at the white cell count, these are our fighters, these are our defenders.

00:54 Because they're a very specific type of white blood cell that protects us from viruses and infections.

01:00 When a patient is HIV positive or then develops AIDS, that means I've got an opportunistic infection and a low CD4 T cell count less than 200.

01:11 So this is where these very specialized white cells come from, the thymus gland.

01:16 And, thankfully, that's why we call them the T cells because that's a little easier to remember.

01:21 Okay, that's a lot of talk about a thymus gland.

01:25 Pause the video for just a second and I want you to write down three quick facts that you remember about the thymus gland without looking at your notes.

01:39 Okay, welcome back.

01:41 Remember, pause, and reflect, and writing things down really help you gain mastery of that information.

01:48 Now we're going to talk about the thymus gland in adults because many adults with myasthenia gravis, their thymus gland didn't gradually get smaller and replaced by fat, it remains large.

02:00 So people with this disease, typically have these clusters of immune cells in their thymus gland, similar to lymphoid hyperplasia.

02:08 Now, usually, that only happens in the spleen and the lymph nodes when someone has some super active immune response.

02:14 But people with myasthenia gravis sometimes have the same kind of activity in their thymus gland.

02:21 Now some individuals with myasthenia gravis develop a thymoma, and I really have to think before I say that word because it's a tongue twister.

02:30 But a thymoma is a tumor of the thymus gland.

02:34 Okay, so right away you've got the idea that the thymus gland in adults with myasthenia gravis is different.

02:42 Now how is it different? It didn't become smaller and replaced by fat and sometimes it has this hyperplasia, it gets really big.

02:50 Much like our spleen and lymph nodes do in an active immune response.

02:55 Well, that's kind of starting to make sense, isn't it? Because we know this is a autoimmune disorder, we know that thymus gland isn't working like it normally does.

03:03 It's doing some kind of different things, going a little bit rogue.

03:06 And that's why the patient is having a problem.

03:09 Now the thymomas are usually harmless, but it's something your healthcare provider will keep a close eye on because they can become cancerous.

03:18 So in myasthenia gravis, the thymus gland gets bigger, much like other organs do in an acute immune response.

03:26 Some people with myasthenia gravis develop thymomas and these should be benign, but they could actually turn cancerous.

03:34 So before we move forward, make sure you have straightened your mind what a normal thymus gland does as you age, and how it's different in a patient with myasthenia gravis.

03:47 So we're gonna view that one more time.

03:49 The thymus gland plays a role in myasthenia gravis, but we're not exactly sure what.

03:54 We just kind of laid down for you that, look, it's different, we know it looks different, its size is different and we're pretty sure it plays a key role in myasthenia gravis.

04:04 See, here's what the theory is, scientists think the thymus gland may give some incorrect instructions to the immune cells, meaning-- Remember that thymus gland makes those really specialized white cells, those T cells, and we think the thymus gland in the case of myasthenia gravis patients is giving some bad instructions to those developing immune cells that causes their immune system to attack its own cells and its tissues, and gives those acetylcholine receptor antibodies.

04:34 And that sets you up for the stage for attack on neuromuscular transmissions.

04:38 So we told you what we kind of think is happening, right? That thymus gland is telling these developing cells or giving them some bad instructions, and that's what ends up-- At the end, the body misunderstanding what those cells are and attacking them, creating antibodies that blocks the transmission and the patient's ability to move their muscles.