Muscle cells play a very important role in movement of our body. There are three types of muscle cells in vertebrates: skeletal, cardiac and smooth. We are mainly going to be concerned with skeletal muscle for this particular experiment. The skeletal muscle is responsible for the voluntary movement of whole body or body parts, manipulation of external objects, support for our skeleton (Sherwood, 2010, p257). Skeletal muscles have a striated structures of alternating light and dark bands (Sherwood, 2010, p258). A bands, which are dark and primarily composed of myosin, and I bands, that are light are primarily composed of actin filaments (Sherwood, 2010, p258). The interaction of these bands is responsible for muscle contraction.
Muscle cells, …show more content…
This causes the release of acetylcholine in the vesicles into neuromuscular junction. Acetylcholine is an excitatory neurotransmitter that binds to the acetylcholine receptors on the muscle, This opens the sodium channels that depolarize the muscle fiber. Depolarization of the muscle continues along the membrane and then down into the T-tubules, which is continuous with muscle fiber’s membrane. The depolarization activates dihydropyridine receptors on T-tubule and causes calcium release from the linked ryanodine receptors on sarcoplasmic reticulum. Calcium is released from ryanodine receptors and triggers muscle contraction by exposing the binding site on actin to allow cross bridges to form between actin and myosin (Sherwood, 2010, …show more content…
One of them was to understand how nerve stimulation endues muscular contraction and to explore this idea we stimulated the sciatic nerve of the subject and we were able to analyze how changes in stimulus intensity and stimulus frequency affected twitch tension of the gastrocnemius muscle. Another goal, was to observe the changes in contraction after injecting the muscle with tubocurare, a poisonous competitive inhibitor of acetylcholine receptors.( source) Finally, we wanted to discover whether neuronal input was needed to elicit muscle activity by directly stimulating the gastocnemius with an electrode. In this experiment, we hypothesized that increasing stimulus voltage would lead to greater number of motor units being activated which in turn will increase the number of motor units recruited. A motor unit is a single motor neuron and all the muscle fibers it innervates. Therefore, we should see an increased contraction force in the gastrocnemius producing a graded response. This phenomenon is known as spatial summation. Next we proposed that increasing the frequency should lead to greater number of action potentials being generated in the gastrocnemius in a smaller time that will cause muscle contractions to occur before previous ones have relaxed. This results in tetanus and this phenomenon is known as temporal summation. After the injection of Tubocurare, we expected the twitch tension to decrease slowly over time. However, as
Muscle cells, …show more content…
This causes the release of acetylcholine in the vesicles into neuromuscular junction. Acetylcholine is an excitatory neurotransmitter that binds to the acetylcholine receptors on the muscle, This opens the sodium channels that depolarize the muscle fiber. Depolarization of the muscle continues along the membrane and then down into the T-tubules, which is continuous with muscle fiber’s membrane. The depolarization activates dihydropyridine receptors on T-tubule and causes calcium release from the linked ryanodine receptors on sarcoplasmic reticulum. Calcium is released from ryanodine receptors and triggers muscle contraction by exposing the binding site on actin to allow cross bridges to form between actin and myosin (Sherwood, 2010, …show more content…
One of them was to understand how nerve stimulation endues muscular contraction and to explore this idea we stimulated the sciatic nerve of the subject and we were able to analyze how changes in stimulus intensity and stimulus frequency affected twitch tension of the gastrocnemius muscle. Another goal, was to observe the changes in contraction after injecting the muscle with tubocurare, a poisonous competitive inhibitor of acetylcholine receptors.( source) Finally, we wanted to discover whether neuronal input was needed to elicit muscle activity by directly stimulating the gastocnemius with an electrode. In this experiment, we hypothesized that increasing stimulus voltage would lead to greater number of motor units being activated which in turn will increase the number of motor units recruited. A motor unit is a single motor neuron and all the muscle fibers it innervates. Therefore, we should see an increased contraction force in the gastrocnemius producing a graded response. This phenomenon is known as spatial summation. Next we proposed that increasing the frequency should lead to greater number of action potentials being generated in the gastrocnemius in a smaller time that will cause muscle contractions to occur before previous ones have relaxed. This results in tetanus and this phenomenon is known as temporal summation. After the injection of Tubocurare, we expected the twitch tension to decrease slowly over time. However, as