 The muscular system and the skeletal system are important for many different types of movement in our body. So you can imagine when any part of these systems is affected how it will affect our movements, right? So this is what our video is about, different disorders in these two types of systems. First, we will look at a disorder that affects the neuromuscular junction. So here is a neuromuscular junction. The green things, they are nerve endings, parts of neurons. And the neurons, where are they coming from? From the CNS, central nervous system. So this is the central nervous system. In fact, it's the cross-section of the spinal cord. And this is a neuron. The green thing is a neuron. And this is a muscle. So what we are interested in is this. The contact point between the neuron and the muscle, which is called the neuromuscular junction. So what happens is in a disease called myasthenia gravis, the neuromuscular junction is attacked by our own antibodies. So that is an autoimmune disorder. So our antibodies go and attack the neuromuscular junctions. And so what do you think will happen? What happens in a neuromuscular junction? Do you remember? The nerve transmits a signal to the muscle and tells it to contract. So we can contract our muscles and we can do different kinds of movement. When the antibodies affect this neuromuscular junction, this communication is not happening very effectively. The neuron is sending the signal, but the muscle is somehow not receiving it well. So what happens is the muscle does not contract as efficiently and it gets weakened and that may result in tiredness, fatigue, or even in some cases paralysis. So let's break down this name. Myas means muscle. Asthenia means weakness, which is what we see in this disease. And gravis means serious. So it is a serious muscle disease is what the name tells us. But we'll see later how it's not as serious as it sounds usually. So what are the symptoms? So the symptoms are muscles are weekend, fatigued and in some cases paralyzed. I said it's not as serious as it sounds it can be managed. There is no cure for this disease, but there are certain medications which improve the transferring of the signal between the neuron and the muscle. Then there are some medicines which reduce the immunity. They are immunosuppressants. So management, treat the neuromuscular junction, immunosuppressants. So these make sure that the person is able to manage the regular movements that he wants to do. Another disease which on the face of it might look similar is muscular dystrophy. Dystrophy means degeneration. So the symptoms are kind of similar like myasthenia gravis. So weak muscles, you know paralysis. But the reason is very, very different. The neuromuscular junction is not affected. The muscles themselves are affected. You can see the difference. This is normal. It's a normal muscle, biceps in our arm. Whereas this has the diseased muscle. You see how thin it is. It's degenerated and the cause is genetic. There are many types of muscular dystrophy. Each of them is caused by a genetic reason. Actually this is more serious than myasthenia gravis. It can be not necessarily. Most people can live a healthy life with some kind of management. Again, this disease has to be managed. It can't be cured. So management by certain drugs like steroids. And then there is physiotherapy. Most people will live for quite a while. But sometimes the disease spreads too soon and a person lives for only let's say 20 or 30 years. So yeah, this is more serious. Although the disease myasthenia gravis has the word gravis in it, which means more serious. Muscular dystrophy is actually a more serious disease. Another disease of muscles is called titani. In this disease, the muscles spasm or contract uncontrollably. You have no control on it. So for example, in these hands, you see these hands have peculiar postures, right? Why is the person holding their hand in such a way? Well, not on purpose. They just can't move their fingers. So they have more normal postures. Their fingers are stuck in these poses. That's because they are contracting uncontrollably. Sounds painful, doesn't it? In fact, it is. And the cause is low blood calcium levels. So the symptom is uncontrolled spasm of muscles and the cause is low blood calcium and it often results from hyperparathyroidism. So what is the treatment? Calcium supplementation and also vitamin D supplementation. Do you know why? Because vitamin D is absolutely essential for us to absorb calcium ions from our gut. Let's say you have a lot of calcium rich food. If you don't have vitamin D in your body or not enough of it, then your body can't absorb the calcium from your gut. So both calcium and vitamin D are necessary. So these three were muscle diseases. Now let's move on to bone and joint diseases. So this here, again it looks kind of painful. It's called arthritis. So here what happens is joints are inflamed. So you see this is a healthy joint and this one is inflamed. So symptom, inflamed joint. So what are the causes? Old age. What happens in old age is because of wear and tear for a long period of time, you see this blue thing. This is the cartilage between the bones and that gets worn out. See here it's worn out and that means the bones are constantly grating against each other and hence are getting injured. Hence the inflammation. Then there is another kind of arthritis which is again an autoimmune disease. So there are different kinds of arthritis and what are the treatments? There are steroids. There are NSAIDs. I'm not going to go into the detail of what these are. You don't have to know. Just know that they help reduce inflammation and then there is physiotherapy. And one thing the doctors keep telling, especially the old people, is walk, walk and walk. So if you see any of your grandparents or any other old person that you know who is suffering from arthritis, just tell them take a walk every day. Your arthritis will be in control. Another bone disease which also affects older people more than others is called osteoporosis. So osteo means bone and porosis as the name suggests means pores. So if you see here this is a normal bone, the cross section of a normal bone and this is diseased, osteoporosis bone. So can you tell me the difference? You can maybe pause the video and then study these carefully and then think about the difference between them. So I'm sure you have noticed that there are more black regions in here than here. This bone, the normal bone is more solid because it has more bone mass, minerals and proteins and other things than the osteoporotic bone. So the symptoms are reduced bone mass. So that weakens the bones and what happens is fractures happen very easily. So what are the causes? One is old age. In old age what happens is bone is broken down quicker than it can be reformed. So that's one cause. And the second cause is low estrogen in women which often happens after menopause. So what can you do to treat it? Calcium supplementation again and of course vitamin D as well and then hormone replacement therapy. This is often done in older women who have undergone menopause so that they have enough estrogen and osteoporosis by the way is not only the disease of old women. It also affects older men. Although it affects men at a greater age than women, nevertheless older men should also be careful. They should take enough calcium so that their bones are not brittle. Another bone disease or rather joint disease is gout. This is another type of arthritis actually. So you can see here what is happening in gout. You see this foot here, this joint here, it's swollen, it's inflamed. So it's an inflammation of joint. And why is the inflammation happening? That has a very specific reason in gout. You see these yellow crystals over here. These are uric acid crystals. So symptoms are joint inflammation. Cause is uric acid deposition in the joints. How do you think gout can be treated? Medications which reduce uric acid levels in the blood and anti-inflammatory drugs such as steroids. So to summarize, myasthenia gravis affects the neuromuscular junction so that the muscles can't function properly. They can contract properly and become weakened and finally paralyzed. Then in muscular dystrophy, the muscles degenerate because of genetic causes. This is tetany where the muscles spasm uncontrollably because of low blood calcium levels. This is arthritis in which the joints are inflamed because of old age or because of an autoimmune disease. This is osteoporosis where the bones are brittle because there is less deposition of minerals and other material. And then finally, this is gout which is another type of arthritis because of uric acid deposition in the joints.