What are types of skeletal fibers - Pathskills

              Types of skeletal muscles fibers

skeletal muscle is a type of muscle found in the human body that is responsible for voluntary movement for movements such as walking running riding a bicycle swimming and so forth now there are three different types of skeletal muscles as we'll see in just a moment and although all these different types of skeletal muscle have their differences they are all controlled by the somatic nervous system and they all consist of the same type of general structure now what exactly are these muscles what are their differences and similarities and what is their function

slow oxidative 

          so let's begin with type 1 skeletal muscle also known as slow oxidative or slow twitch muscle now slow simply means the breakdown rate of ATP is slow so these types of muscles break down ATP very slowly and that means the contraction speed of these muscles the velocity at which these muscles contract is low so these muscles basically contract relatively slowly now the oxidative portion of slow oxidative simply means they use oxygen to basically form ATP and that means the pathway of ATP production is aerobic so they use not only glycolysis but these also use the Krebs cycle and the electron transport chain to actually produce our ATP now because they have a lot of oxygen that means they have a high concentration of myoglobin because myoglobin is the protein carrier that actually carries that oxygen in our muscle tissue so that means we have a high amount of myoglobin and these muscles appear red and that's exactly why these are also known as red muscles now how exactly does oxygen actually get to our slow oxidative muscle well it's carried by the blood and that means because these muscles have a lot of oxygen they also have men the capillaries that actually carry the oxygen to those particular muscles now because these have a low contraction speed and because they break down ATP slowly they also have a high amount of triglycerides and they have a high amount of triglycerides means our major source of fuel our major source of ATP is our fatty acids so these muscles use predominantly triglycerides to break down the fatty acids you know anaerobic respiration into ATP so that also means that they have a low fatigue rate that means we can use them for hours and hours before they actually run out of that fuel source so we can continually use our fats as our major storage fuel to form ATP and that's exactly why these are the muscles that are used when we carry out very long activities such as running a marathon so if we're running a marathon that basically means we have to use muscles that will not fatigue very quickly and that's why we use the type 1

muscles

fast oxidative 

               now these are the muscles that also have a relatively low diameter so the thickness is low and that's exactly why the force that is produced by these muscles is also low so when we're running a marathon we don't actually have to exert a very strong force we exert a very low force over a very long distance so that our muscles don't fatigue very quickly so these are the muscles that are used in that case what about our type 2 a muscles known as fast oxidative or fast twitch muscles so fast simply means the breakdown of ATP is quick so we break down ATP very quickly and that means the muscle contraction is high now just like slow oxidative fast oxidative also uses aerobic respiration that means it also contains a high supply of oxygen it also contains a lot of myoglobin so these muscles also appear red but they also appear pink so that means the amount of myoglobin is lower and fast oxidative then in slow oxidative  now the major supply of fuel is not fatty acids but it's glycogen so the polymer version of sugar where we break down glycogen into glucose and then the glucose goes into the process of glycolysis then into the Krebs cycle and onto the electron transport chain so these also contain many mitochondria and many capillaries now it also uses a type of molecule known as creatine phosphate creatine phosphate itself is not actually used directly as an energy source we use creatine phosphate to pass down the phosphate group onto ADP to form our ATP now the thickness of our muscle fiber for fast oxidative is higher than the thickness in our slow oxidative and so these produce a slightly higher force then in the case of the slow oxidative so we have a low diameter of muscle fiber in this case and a medium in this case so that's why we produce a higher force now if these muscles can last less hours these muscles basically last us minutes so these are the muscles that are used in long distance events such as running a marathon these are used in middle distance events such as for example running a 400 meter distance run and these are the muscles so type 2 B or fast glycolytic are used in sprint events so for example if we're diving or sprinting let's say 100 meters or swimming 50 meters these are the muscles that are basically used

fast glycolytic

 so let's discuss the fast glycolytic so fast simply means these also have a fast contraction speed and that's because they break down ATP quickly now unlike these two muscles these muscles basically do not use oxygen so that means we have a low concentration of oxygen so we do not have too many capillaries and we use anaerobic respiration that means we only use glycolysis to form our ATP and we also use creatine phosphate so these have a large diameter that means they produce the greatest contractile force out of all these three muscles and these basically fatigue very quickly so that means when we're sprinting and that requires let's say ten seconds these are the muscles that we're going to use so because we don't have too many capillaries we don't have too much oxygen that means we don't have too many myoglobin carrier proteins and so these muscles will appear white so these are known as the white muscles but these two muscles are known as the red muscles because these have a fast contractile rate that means these two are known as fast twitch muscles but this which has a low contracting speed this is known as a slow twitch muscle so once again these are the muscles that are found predominantly in the back and the legs because these muscles are the muscles that are have a low fatigue rate they can be used to basically support our body to give it posture now these are the muscles that are used in middle-distance events for example if we're running let's say 400 or 800 meters these are the muscles that we're going to use these are the muscles that are used when we basically need to exert a very large force for example when we're lifting a very heavy weight and that only requires several seconds these are the muscles that we're going to use predominantly so we have three different types of muscles we have slow oxidative type one fast oxidative type 2a and fast and fast glycolytic type 2b and these basically have many different similarities but they're all skeletal muscle and that means they're controlled by the somatic nervous system and they all have the same type of contraction and they have the same type of structure they're all composed of sarcomere units