Skeletal Muscle Contraction And Relaxation Is Vital For

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

Smooth muscle: contractions are involuntary movements. They are triggered by impulses that travel through the autonomic nervous system to the smooth muscle tissue. This allows organs to expand and relax as needed.

Skeletal muscle which is responsible for locomotor movement is under voluntary control. Skeletal muscles lack an ion channels that are responsible for the depolarization of membrane, such as voltage-gated sodium channels. That means they have no intrinsic activity. That is why the nerve impulse is the source of stimulation for skeletal muscle activity (Philip M., 2006). When an action potential travels to the skeletal muscle along the motor neuron, the neuromuscular junction releases acetylcholine that binds to the sarcolemme receptor. The sarcomere, which is composed of contractile units, is consist of alternating thick (myosin) and thin (actin) filaments. A sliding mechanism happens between the thin and thick filaments, where the myosin pulls

Summation and recruitment together can produce a sustained contraction. This means that simultaneous twitches, combined with recruitment, can produce the powerful sustanced contraction.

Muscle contraction requires ATP, ATP is required to separate myosin from actin and re-cycle. Several cycle cycles in many myosin heads lead to a reduction in sarcomere. The decomposition of ATP releases energy that allows the myosin to pull the threads of actin inward and thus contract the muscles. This occurs along the entire length of each myofibril in the muscle cell.(2)

There are many steps involved in muscle contraction. The first being where the action potential starts in the brain and travels to the muscle where it meets at the neuromuscular junction. This is where a chemical synapse is formed. The motor neuron from the brain connects with the muscle fiber. Acetylcholine is a chemical neurotransmitter used at the neuromuscular junction that the motor neurons of the nervous system release in order to activate muscles causing contraction. There are diseases that wreak havoc on the connection at the neuromuscular junction; tetanus, botulism, and myasthenia gravis.

Gamma motor neurons are a type of lower motor neuron that take part in the process of muscle contraction. Their cell bodies are located in the anterior horn of the spinal cord. Gamma motor neurons innervate intrafusal fibers, which contract only slightly. The function of intrafusal fiber contraction is not to provide force to the muscle; rather, gamma activation of the intrafusal fiber is necessary to keep the muscle spindle taut, and therefore sensitive to stretch, over a wide range of muscle lengths. If a resting muscle is stretched, the muscle spindle becomes stretched in parallel, sending signals through the primary and secondary afferents. A subsequent contraction of the muscle, however, removes the pull on the spindle, and it becomes

In order to effectively study the mechanics of the frog muscle contraction, it is important to understand the physiology of that particular muscle. The gastrocnemius muscle of the frog is attached to the heel bone by the Achilles tendon and runs up the tibiofibular bone to the knee. The calf muscle is an example of a muscle tissue type known as skeletal muscle. Skeletal muscle is capable of contracting because of the proteins actin and myosin binding together, pulling the muscle. This process begins with the body receiving a stimulus. That stimulus is transferred into action potentials that travel to the muscle via the motor neuron attached to the muscle fiber. These action potentials initiate the release of Calcium in the axon terminal of

Acetylcholine increases the muscle contraction of the skeletal muscle , however, is reduces that the contraction of the cardiac muscles.

Smooth muscle founded in the gastrointestinal tract of the Northern leopard frog, Rana pipiens, contracts through myogenic activity. However, neurotransmitters from the parasympathetic and the sympathetic branches of the autonomic nervous can influence the strength of these myogenic contractions. To explore myogenic activity under the influence of the autonomic control, we examined the contractile activity with and without additions of chemical compounds associated with the autonomic nervous system. We also wanted to observe contractile activity under the influence of mechanical stimulus by manually stretching the gastrointestinal smooth muscle. With the addition of acetylcholine and eserine a significant increase in contraction amplitude and

One activity that most people perform daily is exercising/walking. Exercise help with anyone health who isn’t in good health, and it help to relax the body and mind. Skeletal muscle is the muscle we normally attached to the moveable parts of the skeleton. They are capable of rapid, powerful contractions and long states of partially sustained contractions, allowing for voluntary movement. Skeletal muscle is striated having transverse bands that run down the length of muscle fiber. The muscle is under conscious control; and skeletal, because these muscles are attached to the skeleton. We can be alternating light bands of the thin protein filaments of action and dark bands of the thick protein filaments myosis muscle makes up about 40% of our

The difference in factors between stimuli are that visual stimulants are processed in a far more complex manner that takes time; auditory stimulants are processed quickly as their distance is proximate to the cortex; and cutaneous stimulants are processed with a lower level of complexity and number of synapses that can vary in their reaction time depending on their proximity to the cortex. These differences exist because of the different types of somatic senses, and the need of the spinal cord and brain to discern different impulses such as heat or sharp pain than they would need to discern an itch or dull pain. Muscle spindle fibers are sensory receptors that are found within the extrafusal fibers, and they transmit information about muscle stretch to the central nervous system (CNS). The stretch reflex pathway is monosynaptic and stimulates a muscle spindle to excite intrafusal fibers, 1a afferent sensory neurons to generate an action potential that travels to the spinal cord and synapses with an extrafusal motor neuron and triggers a contraction in the desired muscle. Two possible ways that the Jendrassik maneuver could alter this pathway are reducing the inhibition of alpha moroneurons, and the activation of gamma motor neurons as the responds to the change in activity of the 1a fibers. Psssmore, et. al (2012), also observed a reduced inhibition of the 1a afferent fibers with the use of the Jendrassik maneuver, and concluded that this inhibition was due the physical and not mental aspect of the maneuver. These possibilities affect the pathway and the ability of the neurons to fire an action potential by averting the subject

The spinal cord gets the message that the muscle is stretched, where there is a direct connection to a motor neuron that contracts the muscle. “Neurons pass messages to each other using a special signals in which they bring information to the brain from outside of your body, such as things you see, hear, and smell while other signals are instructions for your organs, glands and muscles. ( Arizona Board of Regents).” But there are also connections to other muscles, which inhibit the contraction so that you don't react too hard. Detection of the stimulus, the process in which a stimulus is received by a cell and converted into a molecular signal, is thus a class of stimulus response. Kinetic energy takes place in reflexes as

‘Red’ muscles are innervated by small motor neuron of the S type and the muscles slowly contract producing fairly minute force compared to the fast-twitch fibres because S has small and few contractile filaments. S motor unit has large amount of mitochondria and sufficient blood supply to maintain aerobic metabolism because of extensive network of capillaries. Moreover, they are rich of myoglobin that stores oxygen

Fig. 6. This is a typical record from an experiment in which a train of 5 identical dual-pulses were applied to the nerve. The CT interval for the above recording was 120 ms; Fig. 2B was taken from a portion of this record, specifically, the twitches produced by the 5th stimulus. In the actual experiment, a series of trains were applied. There was a 2 min rest between trains, and each train corresponded to a different CT interval.! !Visual inspection of the 5 sequential contractions suggests a !dynamic interplay of factors affecting transmitter release: !! !!The conditioning twitches trend downward, indicating ! !depression.! !!Concomitantly, the test twitches trend upward, as do the ! !resultant T/C ratios, indicating facilitation.! !Control measurements, using the same series of stimulus !trains, revealed T/C ratios that were close to unity. ! ! !! Using relatively simple muscle twitch measurements, we have observed increases in synaptic efficacy in frog sciatic nerve/ gastrocnemius muscles that have undergone synaptic fatigue in the presence of curare. A new stimulus protocol is described in which