Myasthenia Gravis: Causes (Nursing)

by Rhonda Lawes, PhD, RN

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    00:00 Now myasthenia gravis is a lack of communication.

    00:03 And we have some really cool pictures to help you understand this.

    00:08 So this is what it looks like normally.

    00:11 And a patient with acetylcholine and it's working the signal, goes down to the receptors, and the muscles contract and move.

    00:17 In myasthenia gravis, we've got a problem there.

    00:21 The nerves aren't connecting or communicating with the muscles as they do in a normal setup, so you end up with the paralysis.

    00:30 Now don't worry, we're gonna break that down a little bit more.

    00:33 See, there's this error in the transmission of the nerve impulses to the muscles.

    00:38 Remember, that's what makes our neuromuscular system neuromuscular.

    00:43 It's the nerves and the muscles.

    00:46 So when they aren't communicating well, when the transmission of the nerve impulse isn't working, that's why the muscles aren't working.

    00:53 Because that normal communication just gets interrupted at the neuromuscular junction.

    00:58 Now I know I keep saying those things slowly.

    01:02 But sometimes we use words we don't really think about what they mean.

    01:05 That's what neuromuscular is.

    01:07 We're talking about neuromuscular junction.

    01:09 That's the little space in between your nerves, which you see represented up there by the kind of yellowy form, and the muscles, kind of the more flesh colored there.

    01:19 So when the communication is interrupted where the nerve cells connect with the muscles that they control.

    01:25 So neurotransmitters are these chemicals.

    01:27 They communicate with the neurons.

    01:30 That's how they send a message from the nerves to the muscle to tell it what to do.

    01:34 So that's what communicates the information.

    01:36 Normally, when these electrical signals or impulses, these neurotransmitters travel down a motor nerve.

    01:42 The nerve endings release this neurotransmitter called acetylcholine.

    01:47 Okay, so look at our picture.

    01:49 This is a normal nerve and muscle connection and communication.

    01:53 So those electrical signals are traveling down that, right? And it causes it to release the acetylcholine into the neuromuscular junction.

    02:02 Now it will keep on progressing.

    02:04 It's going to connect to those receptors, the little green, almost tree-like things with their arms out.

    02:10 So the neurons will release the acetylcholine.

    02:14 It will travel down to the receptors.

    02:16 So when acetylcholine travels from the nerve ending and it binds to the acetylcholine receptors on the muscle, then that action should cause a contraction of the muscle, allowing the patient to move it.

    02:28 There is so much in our body that is controlled by transmitters and receptors.

    02:34 This is just one more example.

    02:36 In myasthenia gravis, it got these antibodies.

    02:40 There's this immune proteins and they alter or destroy the receptors for acetylcholine at the neuromuscular junction.

    02:46 So a neurotransmitter without a functioning receptor, it's not going to work.

    02:52 That's where the problem is and that's why the patient experiences paralysis.

    02:56 Most people with myasthenia gravis, if it's caused by antibodies to the acetylcholine receptor itself, so their bodies have decided to kind of attack or block those actual acetylcholine receptors.

    03:09 Antibodies to other proteins like MuSK.

    03:11 That sounds like a weird one, isn't it? But it's muscle-specific kinase protein can also lead to impaired transmission at the neuromuscular junction.

    03:19 Okay, so you don't need to memorize a lot of different things.

    03:23 We just want you to get the concept.

    03:25 Acetylcholine, right? Squirts out of that nerve and its job is to attach to acetylcholine receptor.

    03:33 In autoimmune disease, that patient's body is turned on itself, and it started kind of attacking those receptors, so they're not workable.

    03:40 That's why the patient is paralyzed.

    03:43 So where do these nasty things come from? Where do antibodies come from? Well, it's from their own system.

    03:51 So the antibodies are good things.

    03:52 We need those in our immune system to protect us from most infections.

    03:55 But in an autoimmune, that means self-checking.

    04:00 That's when we start to have a problem.

    04:03 Myasthenia gravis is an autoimmune disease because the immune system, which normally protects the body from foreign organisms, mistakenly attacks its own self.

    04:13 Now we're going to talk about a gland that we don't talk about a whole lot, but it's the thymus gland.

    04:19 That's the one that controls the immune function and we think it might be associated with myasthenia gravis.

    04:24 See, there's still a lot to learn about myasthenia gravis, but I'm gonna share with you what we do know so far.

    About the Lecture

    The lecture Myasthenia Gravis: Causes (Nursing) by Rhonda Lawes, PhD, RN is from the course Chronic Neurological Disorders (Nursing).

    Included Quiz Questions

    1. The client's own immune system
    2. A foreign body that activates them
    3. An infection from an opportunistic pathogen
    4. A systemic antihistamine response
    1. Muscle contractions are inhibited by blocked or damaged acetylcholine receptors.
    2. Muscle cells respond too sensitively to nerve impulses resulting in an exaggerated response.
    3. Nerve cells are unable to release signals to the muscle cells.
    4. Nerve impulses generate a muscular response that is too overwhelming to generate proper muscular functioning.

    Author of lecture Myasthenia Gravis: Causes (Nursing)

     Rhonda Lawes, PhD, RN

    Rhonda Lawes, PhD, RN

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