Our head is structure organization of skeletal muscle total number of skeletal muscles So my body will present with a vote and you have my past for 34 I mean muscles who they have my first appears my present with a mostly right or left You can notice the amary right limb kibasa. Oster my left mid limb kibasa. I'm doing We have 75 pairs of muscles. These are the muscles that are responsible for posture and movements of our limbs.
The remaining muscles are used for swallowing. or controlling the movements of our eyes, the rest of the muscles are not used. Now we will cover the main things in the heading of this topic. In that we will learn about muscle fibers, motor units, types of fiber and fiber architecture.
In this video, we will mainly cover muscle fibers in detail. Now what is muscle fiber? Basically any tissue is made by joining cells.
This is a muscle fiber. The cells that make up the skeletal muscle are called muscle fibers. It is called fiber because the cells are thread-like. That's why we call it muscle fiber.
Every muscle fiber has a membrane called sacroiliac. Now, like a muscle has a nucleus, like we have a fluid, which is called cytoplasm. In the case of muscles, the name given to it is called sarcoplasm. And what is this sarcoplasm?
it has nutrients and mitochondria like normal cells so you understood what is muscle fiber what is sacroplasm and what is sacrolemma now every muscle fiber has are present in the myofibrils. What are myofibrils? Myofibrils are, which we will see in detail in the next structure, it contains different proteins.
We have two types of proteins which are present in our body. Those proteins are organized in such a way that because of them the skeletal muscles get striations. On the basis of those striations, the skeletal muscles are also called striated muscles.
This was the introduction, so I hope you understood. That is. As I told you that we have muscle fibers One membrane has covered it which is called sacroilema Now the membrane of the sacroilema is a surround of the connective tissue membrane which we call endomyosin First of all we have muscle fibers Now when we get the number of muscle fibers and collect it and make a bundle We call it as fascicle Now when we get the number of fascicles and collect it This is endomysium and when we wrap the physical then it becomes perimyosin.
When number of physicals meet then they make a muscle and the muscle that covers it is epimyosin. You understood that the membrane around the muscle fiber will be called endomyses. When the muscle fibers will meet in different places, they will make the physicals.
So the one which covers the physical is called perimycin. When the bundle of physicals are found, then what happens? The whole muscle is formed. and the membrane that covers it is called epimyosome so this is what we have discussed about membranes now you understood that first of all we have muscles inside muscles we have physicals and what are physicals? they are fibers Now what is present in this muscle fiber?
In this we have units present Which are important for contraction They are sarcomeres Now we have to see the structure of these sarcomeres in detail Now you should know First you should know some terminology I will tell you that first And then we will go to its organization Now you have to keep in mind We have bands One is eye band one is A band and one is M band and H-zone why we call it I-band because it is named because of its isotropic nature means this band is independent in any direction This band is called asisotropic but A band is called as anisotropic When we see from one direction then it is different and when we see from other direction then it will have different determination So they are named on this basis Now I band, I you have to remember from I Thin plus it contains protein actin So I, I and I You have to remember I band from these Thin bands and in them the filaments of protein filaments are of actin protein. Now opposite of this is coming. A band is thick and if actin is there then what will happen in this? It will be myosin.
So, we have understood that I band which is thin and they have filaments of actin protein. A band is thick in nature and they have filaments of myosin protein. What is M band?
M band is called because it has an intermediate disc. It is between I band and A band. It is at the first initial of the name of the person who discovered it. So you understood these terms.
Now we will go to the structure of our sacro-mer. One sacro-mer is between two z-lines. This is one z-line and this is one z-line.
And in the center we have M-band. Always remember that the band that is adhered to the z line is the eye band. If it is adhered to the z line here, then the eye band will also be adhered to the z line here. So this is the eye band.
I have already told you that I band is thin and it contains active protein. Now whatever we have left, this is A band. Now we have A band which leaves a hollow space in the center This is M line so there is a hollow space on both sides of M line and this space between these two is called H zone Now what happens is that we have two types of proteins one is actin protein and the other is actin Now on myosin there are heads When contraction happens The z line The eye band comes towards the H zone When they move here What is there near the eye? Actin So actin moves and comes on myosin And this zone disappears the length of the muscle gets short and it contracts. We have read this phenomenon in detail.
If you watch any animation video, you will be able to understand this phenomenon very well. Here you should understand what are the things present in the muscle fibers. We have seen that we have two z-lines.
In the center of the two z-lines, we have the M-band and the adhere band with the z-line is the I-band. And we know what is the I-band? It is thin and active present in it.
Then we said that the adhare band is connected to the M-band. we have a vent but in between these there is an area which is hollow space I am saying to remember that it is hollow space so it is called as H zone of your callus I hope that you have understood this is the structure of sarcomere it is like this and what all things are present in it apart from these we have two things one is sarcoplasmic reticulum and the other thing that we have is transverse tribules these are present because they are providing channels because whenever muscles are activated, what is needed? electrolytes are moved inside and action potential is generated if there is no way for electrolytes to come So how will you activate the eyes? So they are providing the way They are making channels So that the electrolytes come, their movement action potential is generated and this phenomenon of contraction happens here So this happens We have muscles Now we should know that the number of fibers we have is determined at the time of birth and it is genetically variant. It is not necessary that the number of fibers in a person is the same but the number of fibers in him is maintained throughout his life.
The exception is that if a muscle is cut in an injury or something like that, then we do not have that much but it is determined and it does not increase. Now what do people do when they are increasing muscle mass? they are increasing the diameter of their fibers they are gaining mass of their fibers and the number of fibers doesn't increase at all because they are determined at the time of birth they don't increase again so hopefully you have understood all the details of muscle fibers let's take a small overview of what we have studied what are muscle fibers then we saw how membranes are covered and our muscle is divided into compartments then at the end when we reached myofibril we said that the muscles are not visible and sacomeres are present in it then we saw the structure of sacomeres then we said two more things are present sacoplasmic reticulum and transverse tubules which give channels to the electrolytes to come and activate and contract then we said that the number of muscle fibers is never high Ding!