The Sources of Energy for Muscle Contraction

The initial burst of speed and subsequent 5 seconds in the 100m sprint, is fuelled by the Phosphagen ATP- PC system as there is 4-5 times more Phosphocreatine (PCr) readily available in the skeletal muscles compared to that of ATP (1). The initial ATP stored is used within 2 seconds of maximal activity by the Myosin ATPase enzyme to cleave energy, leaving Adenosine Diphosphate (ADP)

An increase in the strength of a muscle’s contraction is necessary to perform a task. Subsequently, the brain increases the number of simultaneously active motor units within the muscle by a process known as the motor unit recruitment. Physical muscle movement in humans involves movement of fibers which are hundreds of cylindrically shaped cells bound together by connective tissue. It is essential for individuals, mainly professionals who work to promote health, to understand the mechanisms in the body. Resting skeletal muscles in vivo exhibit a phenomenon known as tonus, a constant state of slight tension that serves to maintain the muscle by motor centers in the brain and spinal cord. However, muscle

Muscle contraction can be understood as the consequence of a process of transmission of action potentials from one neuron to another. A chemical called acetylcholine is the neurotransmitter released from the presynaptic neuron. As the postsynaptic cells on the muscle cell membrane receive the acetylcholine, the channels for the cations sodium and potassium are opened. These cations produce a net depolarization of the cell membrane and this electrical signal travels along the muscle fibers. Through the movement of calcium ions, the muscle action potential is taken into actual muscle contraction with the interaction of two types of proteins, actin and myosin.

muscular rigidity. Explain why a lack of ATP would cause the sustained muscle contraction of rigor mortis.

Smooth muscle contraction occurs when calcium is present in the smooth muscle cell and binds onto calmodulin to activate myosin light chain kinase (Wilson et al., 2002). Phosphorylation of myosin light chains result in myosin ATPase activity thus cross-bridge cycling occurs causing the muscle to contract (Horowitz et al., 1996). There are two known models of excitation and contraction in smooth muscle, electromechanical coupling (EMC) and pharmomechanical coupling

Metabolism comprises of a vital set of biochemical reactions that all living organisms require to sustain life. For a marathon runner, their physiological response to strenuous exercise depletes both their fats and carbohydrate storage in order to supply energy in the form of Adenosine Triphosphate (ATP). ATP is the energy form that the human body uses for biological processes such as movement and synthesis of biomacromolecules. In regards to running a marathon, the athlete is capable of using a combination of both anaerobic and aerobic pathways, but these different systems predominate at different intervals in order to increase the energy allowed for the muscles.

Introduction: According to the “Human Physiology Laboratory Manual “,BIOL 282 ,page 31 , the reason of performing this experiment is to learn how the muscle contraction occurs based on the molecular level and what kind of factors are involved .As a matter of fact, skeletal muscles contain a lot of nuclei because of the cell fusion while being developed and are made of cylindrical cells that have myofibrils. The myofibrils contain sarcomeres and the

For muscle to contract, actin and myosin filaments need to slide past each other, causing the sarcomere to shorten in length . Each myosin filament has a protruding bulbous head, which can bind with the binding sites on the

The power stroke is responsible for the contraction of the muscle and force generation. ATP binding to the myosin head detaches the myosin head from the actin filament and allows the cycle to repeat. The coordinated contraction and relaxation of many muscles in an antagonistic fashion is the basis for the kinematics of any movement.

The ATP-PC aka Phosphogen system is for high power/ short duration only. It is entirely anaerobic and can last up to 10 seconds. (Think sprinting, powerlifting, etc.) No carbohydrate or fat is used in this process, as creatine phosphate is the only thing involved in resynthesizing ATP. Once the limited supply of creatine phosphate runs out, the body must then call on other systems to sustain an activity.

The overall process of glycolysis is so fast that cells can produce thousands of ATP molecules in just a few milliseconds.

Uniquely, glycolysis is both anaerobic and aerobic. The end product pyruvate, from glycolysis, is anabolized to lactic acid when there is a need for energy without an adequate supply of oxygen available. This last step or reaction enables glycolysis to continue producing ATP without the need for oxygen, which is why it is called the anaerobic energy system (Fink, 2009).

Because there is not enough ATP being produced to allow the muscle to contract that many times and for the length of time.

This is because once a contraction has started, the action potential has already fired, stimularing the muscle fibers. Once they

Three different metabolic energy systems power your workouts — and your day. Here’s how each one works, and how to make the most of them all.