Muscle Contraction Lab

Six different subjects all between the age of 21-25 from all different physical levels performed four experiments. Each experiment consisted of two sessions a warm-up and lifting both a 10 lbs and 15 lbs dumbbell with a two-minute break between the two loads. The warm-ups were bicep stretches, which involve three different stretches and lasted for about 30 seconds each for a two-minute stretch, cardio, which included step up until max heart rate was

This activity is the critical driving force of muscle contraction. The stream of action potentials along the muscle fiber surface is terminated as Acetylcholine at the neuromuscular junction is broken down by acetyl cholinesterase. The release of Calcium ions is ceased. The action of the myosin molecule heads is obstructed because of the change in the configuration of troponin and tropomyosin due to the absence of calcium ions. This will eventually cause the contraction to be ceased. Together with these physical processes, an external stretching force such as gravity pulls the muscle back to its normal length.

It compares three specific muscles in the human body that vary in muscle tissue type in terms of:

Martini, F. H., Nath, J. L., and Bartholomew, E. F. “Muscle Tissue.” Anatomy & Physiology. 9th

Szent-Gyorgyi discovered that contraction occurs in the presence of adenosine triphosphate (ATP) and KCI. The rate of the contraction is capable of increasing by the presence of MgCI2. [1] KCI consists of salt, which is capable of causing muscles to contract in considerable dosages. The dosage given to the rabbit muscle was a fairly adequate amount, resulting in the muscle contraction of muscle strand #2 (which received treatment B). The MgCI2, also known as magnesium chloride solution, is used frequently as a ready-to-go reaction mixture to increase the reaction of experiments and lab studies.

First, we measured each fiber, and then added 2 drops of one of the solutions, Solution A; .25% & ATP in distilled water, Solution B; .25% ATP solution in water, .05M KCI, .001 M MgC12 in distilled water, and Solution C; .05 M KC1, .001 M MgC12 in distilled water. We waited 30 seconds after adding the solution and we measured the fiber again to see if there was any muscle concentration after adding the solution. Our hypothesis was not supported, because the fiber size did not change. Purpose:

We will examine and measure the tension and contractile forces of different responses of the skeletal muscle, tetanus and fatigue, at different pulse frequencies. 2 Methods To investigate the properties of skeletal muscle, we used bullfrog (Lithobates catesbeianus) as our model organism. As for the treatment we had saline Ringer solution and Ringer solution with 30 mM nicotine. Each treatment was used in 3 exercises to examine the properties of muscle during muscle recruitment, muscle tetanus, and muscle fatigue. Experimental Protocol:

-Muscles contract in a repeated pattern of binding and releasing between the two thin and thick strands of the sarcomere. ATP is critical to prepare myosin for binding and to recharge the myosin. The source

In order to stimulate all muscle fibers in an area, the stimulus must have a high voltage. However, there are a limited number of muscle fibers within each muscle, so there is a limit on how great the force of the contraction can be (Sedava et al, 2014). I hypothesized that if the stimulus applied to the muscle increases in voltage, then the force of the contraction will increase in strength until it reaches its maximal force where all individual muscle fibers will be recruited. This hypothesis was tested by delivering stimuli of increasing voltages to the muscle and recording the corresponding contraction forces (Holbrook et al, 2017). Through observation of the contraction and graphing the recorded values, it was possible to determine whether the results followed the

It was hypothesized that the highest tension would be observed at the equilibrium length as observed in peer-reviewed sources. (3,4,5) The independent variable was the length of the muscle and the dependent variable was the muscle tension. This experiment was done on one rana pipiens. The tetanic muscle contraction was observed by stimulating it with a current of 1.5 amps at a frequency 20 hz at various muscle lengths.

The more muscle fibers recruited for an exercise the greater the extent of potential remodeling process in the whole muscle.

In order for us to move, our bodies utilize its muscles to create movement. Muscles help with maintaining body temperature, supporting of soft tissue and skeletal movement. To do this, muscles must be able to contract during each movement. This lab session was completed in order for us to have a greater understanding of how muscles function and to find the relationship between muscle length and force. To better understand what events occur during muscle contraction, an electromyogram (EMG) was used to record the electrical activity of contracted forearm flexors at different angles of the wrist.

The muscular system is fundamental to human life, without the skeletal muscles mobility and balance would be impeded. The purpose of this lab is to study the physiological properties of the skeletal muscle by isolating the gastrocnemius of a frog and running it through a series of tests. These tests will help us identify the minimum and maximum strength of stimulation (threshold and plateau values) that will evoke a muscle twitch. The force generated by muscles is dependent on the total number of muscle fibers, the number of activated fibers also depend on frequency and stimulation.

Thеrе 'ѕ a low percentage оf fаѕt-twitсh (FT) fibers in the mеdiаl dеltоid, averaging 36% FT аnd 57% ѕlоw-twitсh (ST). (25, 4) And, ассоrding tо Tеѕсh аnd Larsson, "Fiber-type diѕtributiоn pattern in рrеѕеnt bоdуbuildеrѕ tends tо resemble thе muscle ѕtruсturаl рrоfilе оf endurance аthlеtеѕ. Thе bodybuilders did еxhibit rеlаtivеlу high muscular endurance, whiсh iѕ соnѕiѕtеnt with thе оbѕеrvеd low percentage оf high-glусоlуtiс, fаtigаblе FTb fibers."

The isometric phase of muscle contraction occurs when the length of the muscle body is constant, with no visible shortening, as the tension increases (Kroeker, 2017). Isometric tension is the first phase of the SEC model of contraction, in which the cross-bridges formed by actin and myosin filaments shorten, but add tension only to SEC (Kroeker, 2017). The isotonic phase of muscle contraction occurs when the tension remains constant, but the muscle body begins to shorten (Kroeker, 2017). In regard to SEC, the isotonic shortening phase occurs when the actin/myosin cross-bridges cause visible shortening after tension when PEC=SEC=Load, as for the muscle to visibly shorten as a unit the tension in SEC must be equal to the load (Kroeker, 2017). The muscle must shorten as an outcome of the elastic elements already being stretched (Kroeker, 2017). The latent period represents the force generated by the sarcomeres of each filament that is transmitted through the connective tissues and tendons prior to movement, but will cause movement (Kroeker, 2017). Therefore, the latent period is the time between the stimulus and contraction, as it occurs during the isometric tension phase during the time between stimulus application and isotonic shortening (Kroeker, 2017). When a load is higher, the latent period will be longer as more tension is needed for the muscle to generate a force large enough to move the weight (Kroeker, 2017). A longer latent period allows for muscle tension to