The integrated EMG tells us that the motor neuron recruitment increases the more an activity is performed which supported our hypothesis.
Experiment 2: Skeletal Muscle ABSTRACT Frog skeletal muscle is used as an animal model to study muscle contraction. The objectives of this experiment is to demonstrate the physiological responses of skeletal muscle to electrical stimuli using frog gastrocnemius, to understand twitch, summation, tetanus and fatigue, to investigate the relationship between initial tension and force of contraction, to explore the differences between human and frog skeletal muscle. The threshold voltage is 0.4V. The minimum voltage required to give a maximal response is 5V. Stimulus voltages and muscle response shows a linear relationship from 0.4V to 5V and reaches plateau at 6V. The optimal initial tension at which maximum force of contraction could be
Introduction: According to the “Human Physiology Laboratory Manual “,BIOL 282 ,page 31 , the reason of performing this experiment is to learn how the muscle contraction occurs based on the molecular level and what kind of factors are involved .As a matter of fact, skeletal muscles contain a lot of nuclei because of the cell fusion while being developed and are made of cylindrical cells that have myofibrils. The myofibrils contain sarcomeres and the
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.
9th Ed. Boston: Benjamin Cummings, 2012. Martini, F. H., Nath, J. L., and Bartholomew, E. F. “Muscle Tissue.” Anatomy & Physiology. 9th
Lyndsie Cox 09/09/15 EXS – 1000 Personal Health Anatomy and Physiology Worksheet Use the internet, reliable resources only, to explore and source your responses. No Wikipedia, please. What do each of the following contribute to body’s motion or stability: How ? Why? Be complete in your answers. Muscle – Muscles pull on the joints that
Lightly myelinated Aδ fibers and unmyelinated C fibers have thinner axons and a higher threshold of activation. Nociceptors of Aδ fibers can be either mechanosensitive or thermosensitive. Polymodal nociceptors (of C fibers), may respond to both mechanical and thermal stimuli, as well as chemicals [261-263]. When nociceptors are activated, the fibers transmit action potentials along the axon to the spinal cord [264, 265]. The spinal cord mediates sensory and motor communication between the periphery and the brain, and is organized into four regions; cervical, thoracic, lumbar, and sacral. The gray matter contains cell bodies of neurons and glia and is divided into the dorsal horn, intermediate column, lateral horn, and ventral horn. The dorsal horn is comprised of sensory nuclei that receive and process incoming sensory information , and like the rest of the spinal gray matter, is organized histologically into parallel laminae based on the size and density of neurons . In general, laminae I to IV are involved in exteroceptive sensation whereas laminae V and VI are involved in proprioceptive sensations . Nociceptors terminate in the dorsal horn laminae in a
The spinal motor neurons undergo an aging-related gradual loss due to the interaction of multiple factors; the neurons undergo a programmed cell death along with a decrease in signaling by growth factors and protein uptake. This process leads to the denervation of muscle fibers. The surviving motor axons or motor end plates can send some collaterals to innervate the denervated muscle fibers which explains the formation of enlarged motors end
Although the cause of fibromyalgia is unknown, there are many explanations for what occurs in the nervous system of people afflicted with fibromyalgia. Specific to this are the various reasons for the intense perception of pain. A change to the myofascia surrounding the muscles has been found to be one of the leading causes of pain and other muscular symptoms of fibromyalgia in the majority of cases. Myofascia is the thin, whitish membrane comprised of a material called 'ground substance' that envelopes and protects the muscle like a sack and which is responsible for supporting and connecting all of the body's muscles together. Normally, neurotransmitters pass easily from the interneurons on one side of the myofascia to create action potentials in the motor neurons attached to the muscles. In the case of people with fibromyalgia, however, often the myofascia has lost its elastic properties and hardened. The ground substance within the myofascia, which is usual in a fluid state, has become more like a solid gel. This change in the myofascia hinders or entirely prevents the neurotransmitters from reaching the motor
Facilitation occurs when postsynaptic potentials evoked by a stimulus are increased when that stimulus closely follows a pervious stimulus. Five stimulus pulses were given at decreasing interpulse intervals. The data for this experimenet displays that when the interpulse interval changes from 10msec to 8 msec, the number of pulses needed to reach the maximum MAP increases rather than the expexted outcome. This is most likely due to movement of the muscle in the chamber, causing the recordings to be reading different areas of the muscle. Different neuromuscular junctions in the muscle require different amounts of Ach in order for muscle action potentials to reach threshold.
Introduction Annie is a swimmer who has started to suffer from sever muscle fatigue. Muscle fatigue is a decrease in force during lengthy contractions. Skeletal Muscle is made out of fascicles, which are then made up of muscle fiber cells and those cells are made of micro fibrils (Stanfield, C, 2017). All of these items make up a motor unit, which cause muscle units to contract due to the startup of the action potential that release neurotransmitters that depolarizes the muscle membrane (Stanfield, C, 2017). The neurotransmitters are released in an area known as the neuromuscular junction (Stanfield, C, 2017). In this junction. In the junction action potentials that are entering the axon terminal starts the free movement of acetylcholine that then goes into the synaptic cleft (Stanfield, C, 2017). The acetylcholine then travels through a cleft which binds to a nicotinic receptor on the motor end plate that then opens the ion channels that leads to the freedom of calcium from the sarcoplasmic reticulum (Stanfield, C, 2017). In order to determine why she was beginning to have muscle fatigue Annie had to face a series of test. One of the tests that Annie could have taken was an Electromyography, also known as an EMG.
In the gastrocnemius muscle of the B. Marinus used, there are two types of myofilaments that are inside the muscle fibres. These myofilaments are thick filament protein called myosin, and a thin filament containing three different proteins; actin, tropomyosin and troponin. These myofilaments are arranged in myofibrils in a structure known as a sarcomere (Hopkins. M, P. 2006). The muscle in this experiment was stretched and forced to contract through an ATP-driven interaction between myosin and action called crossbridge cycling. In this process, the head of the myosin molecule extends laterally and binds with an actin molecule to form what is known as the crossbridge. The contraction of the muscle in this experiment occurs through a process called a power stroke (Hopkins.
1- According to the data of measuring EMG activity from antagonistic muscle, anterior muscles were more active during flexion than posterior muscles. Also, muscles were more activated when the hand is closed as opposed to open. Muscle flexion without a weight requires more force; however, muscle extension with a weight requires more force. Moreover, the muscle active increase in the heteronymous muscle during relaxation, which add stabilization and control to the movement. Doing the same experiment while a subject is running will increase the muscles force.
Motor imagery (MI) is defined as cognitive process in which the subjects imagine that they perform movements without actually performing movement and muscle contraction . MI has been shown to improve various motor functions in healthy subjects. Specifically, Yue et al.  suggested that MI of little finger abduction under
Introduction: The body consists of three different kinds of muscles: skeletal, cardiac and smooth muscle. Skeletal muscle, which is the primary focus of this lab, is made up of much smaller muscle fibers. These muscle fibers have smaller units called myofibrils followed by the smallest contractile unit of a muscle fiber called the sarcomere. Furthermore, the sarcomere is composed of two filament types- thick filaments, called myosin and thin filaments called actin. In order for muscle contraction to occur, these two filaments must bind to form cross bridges. These cross bridges are formed through the interaction of the actin and myosin head along with calcium ions and ATP molecules. The formation and reformation of these cross bridges is what is known as cross bridge cycling and is what is responsible for repeated muscle contraction in the same sarcomere.