Cellular Respiration in Skeletal Muscles
Every day we use our skeletal muscle to do simple task and without skeletal muscles, we will not be able to do anything. Szent-Gyorgyi (2011) muscle tissue contraction in rabbit’s muscles and discovered that ATP is a source for muscle contraction and not ADP. He proposed a mechanism to cellular respiration and was later used by Sir Hans Krebs to investigate the steps to glucose catabolism to make ATP. In this paper, I will be discussing the structure of muscle fibers and skeletal muscles, muscle contraction, biomechanics, and how glucose and fat are metabolized in the skeletal muscles.
Muscle fibers are cylindrical. They have a diameter around ten to one hundred micrometers and are generally a few centimeters long. Within each muscle cells, contains basal lamina of collagen and glycoproteins. Each fiber contains a structure called excitation-contraction coupling, which is used to make sure the each contractile stimulus is quickly and equally communicated throughout the muscle fiber.
The four different type of fiber types are: slow, fast and fatigue resistant, fast fatigable and fast intermediate. Slow muscle fibers have a long twitch time, which means that they have low peak forces, and have a high resistance to fatigue. These fibers are high in oxidative enzymes and are low in glycolytic markers and ATP activity.
Fast and fatigue resistant fibers are faster in contractions. Fast and fatigue resistant fibers maintains force production after contractions. These fibers are the opposite of slow fibers, instead they have a high ATP and glycolytic activity and have a low oxidative capacity. The fast fatigable have high contractions rates and large forces, but they cannot maintain tensions...
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...st the sacrolemma will depolarized, thus activation potentials along the T-tubules. This signal will transmit from along the T-tubules to sarcroplasmic reticulum's terminal sacs. Next, sarcoplasmic reticulum will release the calcium into the sarcroplasm leading to the next second event called contraction. The released calcium ions will now bind to troponin. This will cause the inhibition of actin and mysoin interaction to be released. The crossbridge of myosin filaments that are attached to the actin filaments, thus causing tension to be exerted and the muscles will shorten by sliding filament mechanism. The last event is called Relaxation. After the sliding of the filament mechanism, the calcium will be slowly pumped back into the scaroplasmic reticulum. The crossbridges will detach from the filaments. The inhibition of the actin and myosin will go back to normal.
The data collected during this experiment has shown that a relationship likely exists between the rate of muscle fatigue and the time spent performing vigorous exercise prior to the set of repetitive movements. This is likely due to a build-up of lactic acid and lactate as a result of anaerobic respiration occurring to provide energy for the muscle cell’s movement. As the pH of the cell would have been lowered, the enzymes necessary in the reactions would likely not be working in their optimum pH range, slowing the respiration reactions and providing an explanation to why the average number of repetitions decreased as the prior amount of exercise increased.
While DOMS does have a negative effect on strength performance, the factors that are associated with DOMS are also potentially important in stimulating muscle hypertrophy. Researchers believe thought that DOMS most likely reflects the body’s response to maximize the training response. Due to the wear and tear on the muscle fibers during exercise, muscle damage happens to be the causing factor for muscle hypertrophy. After exercise, the damage and repair process involves calcium, lysosomes, connective tissue, free radicals, energy sources, and the inflammatory response. Healing process steps that go along with DOMS are important steps in muscle hypertrophy (Kenney et al.,
This report will explore the structure and function of skeletal muscle within the human body. There are three muscle classifications: smooth (looks smooth), cardiac (looks striated) and skeletal (looks striated). Smooth muscle is found within blood vessels, the gut and the intestines; it assists the movement of substances by contracting and relaxing, this is an involuntary effort. The heart is composed of cardiac muscle, which contracts rhythmically nonstop for the entire duration of a person’s life and again is an involuntary movement of the body. The main focus of this report is on skeletal muscle and the movement produced which is inflicted by conscious thought unless there is a potentially harmful stimulus and then reaction is due to reflex, as the body naturally wants to protect itself. Skeletal muscle is found attached to bones and when they contract and relax they produce movement, there is a specific process that the muscle fibers go through to allow this to occur.
Muscle is a very specialized tissue that has both the ability to contract and the ability to conduct electrical impulses. Muscle fiber generates tension through the action of actin and myosin cross-bridge cycling. The muscle may shorten, lengthen or remain the same under tension. Skeletal muscle has an impressive ability to regenerate itself, which it does on a daily basis as well as in response to injury [1].
Muscle activity, including generating force and moving limbs through lengthening and shortening, is an important influence on beneficial tissue stress. Muscles adapt quickly to periods of lower or higher stress and demonstrate obvious visual and functional changes. At a tissue level, the Physical Stress Theory (PST) states that muscle adaptations are consistent with other high and low strain tissue adaptation models. Low stress/activity associated with immobilization results in decreases in contractile protein, fiber diameter, peak tension and power. Evidence supports the idea that tissues within the musculoskeletal system atrophy and become less tolerant of physical stress if stress on the tissue diminishes below a baseline level.3 In addition,
On average, approximately 60% of people have fast muscle fiber and 40% slow-twitch fiber (type I). There can be shifts in fiber composition, but fundamentally, we all have three types of muscle fiber that need to train (Kenney, 2011).
...e myelin sheath helps making it faster by keeping it insulated and warm by covering it with fat. After this the nerve reaches the end of the nerve which is to synaptic knob this is the last part of the nearby after this the impulse goes to our muscles where we contract. If this never happens then we wouldn’t be able to move so quickly during steady state exercising we need the nerve impulses to be quick and to work effectively. Without it there would be a little chance that out muscles contracts at all then we wouldn’t be able to move all.
The source expands on three major groups of muscular systems. They are skeletal muscle, Cardiac muscle and smooth muscle. Skeletal muscles are made up of muscle tissue, connective tissue, nerves and blood vessels that is attached to tendons and bones. Cardiac muscles are small with short wide T-tubules and is only found in heart. Smooth muscles are long, slender and spindle shaped with no T tubules, myofibrils or sarcomeres that arrange the blood vessels in some organs. All these three types of muscles are grouped together with fibers that
Cardiac muscle is a type of involuntary muscle found only in the walls of the heart, specifically the myocardium. Cardiac muscles contract automatically to tighten the walls of the heart in a rhythmic fashion. The heart beats nonstop about 100,000 times each day. Smooth muscle is a type of involuntary muscle found within the walls of blood vessels such as in small arteries and veins. Smooth muscle is also found in the urinary bladder, uterus, male and female reproductive tracts, gastrointestinal tract, and the respiratory tract. Skeletal muscles are voluntarily controlled and are attached to bones by tendons. Skeletal muscles also vary considerably in size and shape. They range from extremely tiny strands such as in the muscle of the middle ear as large like in the muscles of the thigh. The three individual muscle types also serve five main functions. The five basic functions are movement, organ protection, pumping blood, aiding digestion, and ensuring blood flow.
Sarcopenia is considered to be the degenerative loss of skeletal muscle mass and it’s functioning due to aging (Waters, Baumgartner & Garry 2000). It is linked to muscle atrophy which is shortening of the muscle. It can be mostly noticed in fast twitch fibres which usually fatigue easily and provide a larger amount of force in comparison to slow twitch fibres. Sarcopenia is usually ...
The contraction of a muscle is a complex process, requiring several molecules including ATP and Cl-, and certain regulatory mechanisms [1]. Myosin is motor protein that converts chemical bond energy from ATP into mechanical energy of motion [1]. Muscle contraction is also regulated by the amount of action potentials that the muscle receives [2]. A greater number of actions potentials are required to elicit more muscles fibers to contract thus increasing the contraction strength [2]. Studied indicate that the larger motor units, which were recruited at higher threshold forces, tended to have shorter contraction times than the smaller units [3]. The aims of the experiment were to reinforce the concept that many chemicals are required for skeletal muscle contraction to occur by using the rabbit muscle (Lepus curpaeums) [2]. In addition, the experiment was an opportunity to measure the strength of contraction and to observe the number of motor units that need to be recruited to maintain a constant force as the muscles begin to fatigue [2]. Hypothetically, the rabbit muscle fiber should contract most with ATP and salt solution; and the amount of motor units involved would increase with a decreasing level of force applied until fatigue stage is reached.
Then, rigor mortis occurs. Rigor mortis is the stiffening of the muscles due to the disappareance of ATP (adenosin triphosphate). The proteins responsible for muscle contraction, actin and myosin, need ATP to create crossbridges and make the muscles contract, and then relax. When ATP is no longer produced by the cells, the cycle of contraction cannot be completed and the muscles remain contracted. [3]
The first fibre type is a slow oxidative. Slow oxidative muscle, as the name suggests contract slowly, and they depend on aerobic metabolism for energy. These fibres take three times as long as fast fibres to reach peak contraction, hence the term 'slow twitch.' Slow fibres are specialized to maintain prolonged contraction, as we need for standing or sitting. Human postural muscles, along with the chicken leg, contain a lot of slow fibres. These slow fibres have relatively low force, or contraction strength, and high endurance.
Cardiac muscle is a type of involuntary muscle found only in the walls of the heart, specifically the myocardium. Cardiac muscles contract automatically to tighten the walls of the heart in a rhythmic fashion (pp.212-216). The heart beats nonstop about 100,000 times each day (p.18). Smooth muscle is a type of involuntary muscle found within the walls of blood vessels such as in small arteries and veins. Smooth muscle is also found in the urinary bladder, uterus, male and female reproductive tracts, gastrointestinal tract, and the respiratory tract. Skeletal muscles are voluntarily controlled and are attached to bones by tendons. Skeletal muscles also vary considerably in size and shape. They range from extremely tiny strands such as in the muscle of the middle ear as large like in the muscles of the thigh (Martini, 2000). The three individual muscle types also serve five main functions. The five basic functions are movement, organ protection, pumping blood, aiding digestion, and ensuring blood flow.
There are three different types of muscles in the body, and the first to be talked about are skeletal muscles. The body consists of about 640 skeletal muscles and they just so happen to be the only voluntary or (controlled) muscles. Their main function is to contract and expand so that your bones are able to move. Most skeletal muscles are attached to bones or joints so that the muscle can either expand or contract to create motion. They consist of band like fibers attached and bundled together that run along the bone. These fibers are held together by connective tissue called epimysium, which also protects the muscle. Skeletal muscle is what makes the body able to walk and move, without these skeletal muscles the body could not function properly because it would have nothing to rely on for stabilization and strength. They contain what is called striated cells, which is cells that are shaped like bands and are individual, they stretch out the length of the muscle so that they are able to contract with it and these cells are also what give the muscle energy through respiration of proteins fats and glucose which is the energy supplement for all muscles. For example refer to figure 1-1 1-4 and1-5 for the cell