Summary Muscle Contraction

As result, the bonding causes the sodium and potassium gates to open. As result, end plate potential is formed and excites areas of muscle tissue. Action potential is created and the muscle moves or contracts.

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.

-Sarcoplasmic Reticulum (SR) then releases Calcium which binds to troponin in the thin filament, exposing myosin-binding sites;

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

How is contraction ended? Ach is released and binds to receptors on the motor end plate, then an action potential is produced which releases Ca+. The Ca+ binds to troponin, then myosin binds to actin to form crossbridges. The myosin pulls the actin then releases from actin and ADP is bound to the myosin.

As a result of the contractions in the Muscle- Skeletal Longitudinal Section cells and the Muscle- Skeletal Cross Section cells, it allows your muscle to be able to contract in response to nerve stimuli. This means that the movements of most of these muscles are not involuntary, you can control them. Therefore, once the stimulation stops, the muscles relax.

Muscles contract through an action potential moving along a motor neuron toward the skeletal muscle and they connect to a neuromuscular junction  acetylcholine vesicles being released  binding on the sarcolemma  causes Na+ influx in the muscle fiber generating an action potential within the muscle fiber  action potential moves through the T-tubules Calcium channels open calcium is released into the cytoplasm  actin-myosin binding sites and cross-bridges are activated by calcium ions between the actin/ myosin heads  ATP is hydrolyzed to flex myosin head  this flexion makes the actin filaments move close to the middle of the sarcomere  The length of the sarcomere becomes shorter  contraction. I would like to define a few terms discussed within this

Smooth muscle cells of the ileum spontaneously contract due to the presence of pacemaker cells, called Cajal cells (Widmaier et al., 2014d). However, these smooth muscle they are also innervated by autonomic nerves, which can be stimulated to change contraction rates by stimulating. Figure 1, shows the effect of nerve stimulation of 17volts on isolated ileum tissue. Stimulating sympathetic (sympathetic nerves was stimulated for this particular tissue), causes release of noradrenaline, which inhabits contraction of smooth muscle cells. Furthermore, according to table 1, there is a -58.83% change in contraction amplitude. It can be extrapolated that fewer smooth muscles are contracting. At lower voltages, a weaker response was observed, as voltage is increased a stronger response was observed. Increasing the voltage, means more neurons are being recruited (Widmaier et al., 2014b). In this particular experiment, stimulation of nerves around the mesenteric artery caused an inhibitory response, therefore at higher voltages, more smooth muscles are being inhibited.

The termination of muscle contraction is followed by muscle relaxation, which is a return of the muscle fibers to their low tension-generating state. OBJECTIVE: To become familiar with the skeletal

Simple movements strengthen the muscles that protect the joints in the legs. These five types of activities you can every day to practice at home.

The introduction of this lab report discussed and elaborated how muscle contraction is an intricate and precise step-by-step process in the body. The concepts outlined at the introduction intertwine with the experiments performed in this lab. The experiments aimed to showcase the physiological cause and effect of skeletal muscle responses towards various situations. For instance, the first experiment demonstrated spatial summation through the form of muscle recruitment. The cause of this reaction was due to the increased voltage input on the sciatic nerve. Furthermore, the second case study exhibited temporal summation, where constant stimulus exposure led to a fusion of twitches called a tetanic contraction. As for the third experiment, the

2. What occurs in the muscle during this apparent lack of activity? Ca++ is being released from the sacroplasmic reticulum and filament movement is taking up slack.

The dose-response curve in the presence of antagonist shows it effect on the ileum smooth muscle contraction which increases rapidly after 5 minutes exposure to atropine at a constant concentration of 3 x 10-7 M. The dose-response curve in the absence of antagonist shows it effect on the ileum smooth muscle contraction which increases rapidly on 3 minutes exposure to acetylcholine with the interval of 20 seconds between all doses at the concentration of 1 x 10-8 M to 1 x 10-4 M for every 3-2 doses. Also, as shown in figure 1, dose-response curve in the absence of antagonist has a higher contraction than the dose response curve in the presence of antagonist.

While most people associate muscles with strength, they do more than assist in lifting heavy objects. The 650 muscles in the body not only support movement — controlling walking, talking, sitting, standing, eating and other daily functions that people consciously perform — but also help to maintain posture and circulate blood and other substances throughout the body, among other functions.

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