Investigating The Relationship Between Motor Neurons And Their Associated Muscle 's Electrical Activity Via Neuromuscular Junctions

Directions: Label the neuromuscular (myoneural) junction. Then, read the case study below and answer the questions. Each question should be answered with FIVE or more sentences.

* Electromyogram- Measures electrical activity of muscles at rest and during contraction. These studies measure how well and fast the nerves can send electrical signals.

Encyclopedia of Nursing & Allied Health. Bioelectricity: Transmission of nerve impulses to muscle. Retrieved on 26 June 2011 from http://www.enotes.com/nursing-encyclopedia/bioelectricity

The results in Figure 2. show that increasing the stimulus strength (V) from 0 to o.40V will result in an increase of Active Muscle force generated by the gastrocnemius muscle in the Buffo Marinus, confirming the hypothesis. The force generated plateaus when the stimulus is beyond o.40V.

Purpose: What is the purpose of this exercise? Are there any safety concerns associated with this exercise? If so, list what they are and what precautions should be taken. To understand the structure and function of multipolar neuron,unipolar and bipolar neurons. Also to identify the structures of a nerve. There are no safety concerns for this lab.

In this exercise, you examined the effect of increasing stimulus intensity on the nerve. What other stimulus parameter

Rationale, Significance and Hypothesis. An extrinsic factor, which exerts a dominant influence on skeletal muscle fiber phenotype, is the nervous system. Buller et al. (1960) elegantly demonstrated the plastic nature of skeletal muscle fibers in response to changes in innervation type. Later, Lφmo and Westgaard (Lφmo and Westgaard, 1974; Westgaard and Lφmo, 1988) demonstrated that depolarization of muscle with specific patterns and frequencies of electrical activity are sufficient to cause changes in mature muscle fiber phenotypes. However, how myofibrillar gene expression and structural organization is affected by the frequency of impulses during activity, the amount of activity over time, or other characteristics of patterned activity is essentially unknown. To answer these questions will require the isolation and study of subsets of muscle-specific proteins in relation to different electrical activation patterns in vivo, an issue that cannot be easily addressed in preparations currently used in the study of muscle development and maintenance. However, using novel in vivo approaches can, in part, circumvent this difficulty.

• Nerve conduction studies. These record muscle activity and check how well your muscle nerves send signals.

The EMG signal that is observed through the placement of electrodes on the skin is closely coupled with the generation of muscle force. In normal conditions, the force-EMG relationship is either linear or the increase in EMG at low force levels is less than proportional (Semmler 2014). However, a different force-EMG relationship was observed following eccentric exercise,

Review Sheet Results 1. Describe how increasing the stimulus frequency affected the force developed by the isolated whole skeletal muscle in this activity. How well did the results compare with your prediction? Your answer: When the stimulus frequency was at the lowest the force was at its lowest level out of all of the experiments. As the stimulus frequency was increased to 130, s/s the force increased slightly but fused tetanus developed at the higher frequency. When the stimulus frequency was increased to the amounts of 146-150 s/s, the force reached a plateau and maximal tetanic tension occurred, where no further increases in force occur from additional stimulus frequency. 2. Indicate what type of force was developed by the isolated skeletal muscle in this activity at the following stimulus frequencies: at 50 stimuli/sec, at 140 stimuli/sec, and above 146 stimuli/sec. Your answer: At 50- Unfused

1. As you increase voltage to the muscle describe how it responds to the increased stimulus.

The control group received only standard physical therapy treatments (stretching and strengthening exercises). There were three experimental groups. One group received estim to the intensity of stimulating only sensory nerves. The next group received estim with an intensity that minimally stimulated motor neurons. The final group received “full movement neuromuscular electric stimulation,” which was an estim intensity to the maximum tolerated intensity to receive maximum muscle movement. All three experimental groups also received standard PT interventions (stretching and strengthening exercises).

Post-lab Quiz Results You scored 50% by answering 2 out of 4 questions correctly. 1. Which of the following is not one of the ways that the body can increase the force produced by a skeletal muscle? Your answer: b. application of high-frequency stimulation by a motor neuron Correct answer: d. application of higher voltages to the whole muscle 2. When a muscle receives a stimulus frequency that causes non-overlapping twitches to follow each other closely in time such that the peak tension of each twitch rises in a stepwise fashion up to a plateau value, the result is known as You correctly answered: c. treppe. 3. In this experiment the isolated skeletal muscle was repetitively stimulated such that individual twitches overlapped with each other and resulted in a stronger muscle contraction than a standalone twitch. This phenomenon is known as You correctly answered: c. wave summation. 4. Wave summation is achieved by Your answer: c. summating action potentials so that their depolarizing magnitude is greater. Correct answer: a. increasing the rate of stimulus delivery (frequency)

The final element that was tested against the baseline reflex was the influence of fatigue on the strength of the reflex response. This was achieved by having the subject run up and down three levels of stairs three times in the Frost building stairwell of Holyoke Community College. The subject immediately came back to the original sitting position on the edge of the lab bench with legs dangling freely, and the patellar tendon was tapped once more.

Reaction time is the time between the presentation of a stimulus and the initiation of the muscular response to that stimulus ( the free dictionary [26/07/14].The purpose of this test was to identify what happens to reaction times as different independent variables are applied. The nervous system helps all parts of the body to communicate with each other, it is responsible for making sure all of the body’s parts coordinate properly. The nervous system is the centre of all the body’s activity (better health channel [26/07/14]). The brain and spinal cord make up the central nervous system and all the other nerves in the body part of the peripheral nervous system. Inside nerves lie neurons, neurons are found in the brain, spinal cord and the peripheral nerves (PubMed Health [26/07/14]). They are also known as nerve cells. These neurons have the same structure as plant and animal cells (differencebetween.net [27/07/14]). Neurons are made up of a cell body, dendrites, a nucleus, an axon and a myelin sheath (the nervous system [27/07/14]). The myelin sheath surrounds the nerve fibre of axon and protects the body from the electrical charge that nerves have (GCSE Bite size [27/07/14]). There are two types of neurons: sensory neurons and motor neurons. Sensory neurons send signals to the brain and spinal