...INTRODUCTION: The skeletal muscle is an important organ in the human body that allows for movement and support of the skeleton, helping the body execute various tasks from precise control movements (writing a letter or picking up a chalk) to more abrupt, powerful movements (lifting weights or running). The skeletal muscle is one of the main types of muscle in the body (the other two being cardiac and smooth muscles) that allows movement by contraction of the muscles. When a motor unit, a single nerve that innervates all the muscle fibers, activates these muscles fiber, it causes a muscle contraction. These muscle contraction occurs when motor neurons from the spinal cord leaves and activates multiple muscle fibers, the number of muscle fibers depend on the type of muscle. According to the Hennemen size principle, muscles that react rapidly and exert fine control have smaller motor units than those with larger, weight-involving muscles, whose movements are less precise, will require larger motor units. The means of movement and force generation is based on the skeletal muscles contraction. Contractile units of the skeletal muscles include thick myosin and thin actin myofillaments or fillaments. Sarcomere is the smallest contractile unit of a muscle fiber. The repetition of the sarcomere structure make up myofibrils and hundreds to thousands of these myofibrils make up a single muscle fiber (Sherwood 258). Contraction is initiated by an increased in the intracellular calcium...
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...Broussard Exercise 2: Skeletal Muscle Physiology: Activity 2: The Effect of Stimulus Voltage on Skeletal Muscle Contraction Lab Report Pre-lab Quiz Results You scored 100% by answering 4 out of 4 questions correctly. 1. Skeletal muscle fibers are innervated (stimulated) by You correctly answered: c. motor neurons. 2. A single action potential propagating down a motor axon results in You correctly answered: d. a single action potential and a single contractile event in the muscle fibers it innervates. 3. In resting skeletal muscle, calcium is stored in You correctly answered: c. the sarcoplasmic reticulum. 4. During the latent period for an isometric contraction You correctly answered: c. the cellular events involved in excitation-contraction coupling occur. 11/10/14 page 1 Experiment Results Predict Question: Predict Question: As the stimulus voltage is increased from 1.0 volt up to 10 volts, what will happen to the amount of active force generated with each stimulus? Your answer : c. The active force will first increase and then plateau at some maximal value as the stimulus voltage increases. Stop & Think Questions: What do you see in the active force display when the stimulus voltage is set to 0.0, and why does this observation make sense? You did not answer this question. Correct answer: a. 0.00 g; there was no activation of skeletal muscle fibers by this stimulus. What is the lowest stimulus voltage that induces active force in the skeletal muscle? You did not answer...
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...Lyndsey Kessler English 4A 24th Nov. 2014 Mrs. Nills Biomedical Technology: Today’s Experiments Tomorrow’s Medicine I am sure you have heard of mammograms and MRIs, but did you know that they are a part of biomedical technology? Biomedical technology is any medical imaging device or a medical practice that involves biology or technology. Some people do not believe in biomedical technology because they say it had not been proven safe or effective, but it has already saved lives. This is why biomedical technology should be used in medical practices My first reason is that biomedical technology could help save many lives. This technology has the potential to cure many diseases, one example is that scientists have found that stem cells can become a wide variety of specialized cells, this could help cure Alzheimer’s. They also have the potential to help people that are paralyzed. Biomedical technology has already found ways to detect and cure many life threatening diseases. With mammograms and MRIs doctors can detect breast cancer along with other diseases much faster than they have been able to in the past. This could potentially help cure those who are diagnosed. My second reason is that biomedical technology can increase treatment options. Since mammograms and MRIs help detect diseases sooner there are many different ways to treat these diseases some of which may not be as severe. For example instead of doing radiation for cancer right away you could undergo surgery to...
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...Dr. Xu 2 March 2016 Frog Skeletal Muscle Lab Introduction A biologist by the name Jan Swammerdam performed the first experiments on muscle physiology between 1661 and 1665. Swammerdam demonstrated that an isolated frog muscle can contract if the sciatic nerve is irritated with a metal object. Almost a century later, a physician by the name Luigi Galvani demonstrated that frog muscle responds to electrical currents. In the late 1840s, either Carlo Matteucci or Carl Ludwig attributed to the invention of the kymograph, which is illustrated as a rotating drum powered by a clockwork motor. The invention of the kymograph changed experimental physiology by allowing muscle contractions, and other actions, to be recorded and analyzed for the first time ever. Muscle cells, or muscle fibers, are defined as the basic unit of a muscle. Therefore, complete muscles are constructed from bundles of muscle fibers, but there are no gap junctions between adjacent cells so each fiber performs independently. Myofibrils establish an ordered structure for single muscle fibers. Every myofibril is comprised of actin and myosin. Actin and myosin are contractile proteins that can slide past each other when Ca2+ and ATP are present. A motor unit is described as a single motor neuron and all of its innervating muscle fibers. Like nerve tissue, muscle fibers produce an all-or-none response to a stimulus, generating a twitch. A single motor neuron supplies numerous muscle fibers to make up a motor unit...
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...Introduction: Motor neurons and muscle fibers are the building blocks of motor units and where they intersect is called the neuromuscular junciton. The region where the flattened end of a motor neuron transmits neural impulses to a muscle is the motor end-plate. The end plate potentials depolarizes skeletal muscle fibers caused by neurotransmitters binding to the postsynaptic membrane in the neuromuscular junction. The process of contraction of the muscle cell is called excitation-contraction coupling. In this experiment, when we used a single electrical stimulus, it resulted in a muscle twitch with three phases: latent period, contraction phase, and the relaxation phase. Activity 1: Figure 1: Identifying the latent period ]The Latent Period of time that elapses between the generation of an action potential in a muscle cell and the start of muscle contraction. The length of the latent period was 2.78msec. When we increased the stimulus voltage from 3v to 9v and then to 10v, the latent period remained the same at 2.78msec. Thus, the latent period does not change with different stimulus. Activity 2: Figure 2: Identifying the Threshold Voltage The threshold is the minimal stimulus needed to cause a depolarization of the muscle plasma membrane. It is the point at which sodium ions start to move into the cell for membrane depolarization. When we stimulated the voltage of 0, the active force showed a straight line such as depicted in figure 2. We kept on increasing the...
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...As you increase voltage to the muscle describe how it responds to the increased stimulus. As the voltage was increased from threshold to maximum voltage, there was a greater force in the muscle contraction. Once the maximum voltage (2500 mv) was reached, even if there was an increase in voltage, the force of the muscle contraction remained the same. 2. What was the smallest voltage required to produce a contraction (the threshold voltage)? What proportion of the fibers in the muscle do you think were contracting to produce this small response? 0.2500V , a small contraction of all the muscle fibers 3. What was the smallest voltage required to produce the maximum (largest) contraction? What proportion of the fibers in the muscle do you think were contracting to produce this maximal response? 0.6500V, all muscle fibers contracted maximally. 4. What do you conclude happened to the number of fibers contracting as the voltage was raised from threshold to that required to produce a maximal contraction? As the stimulus voltage is increased past the muscle’s threshold voltage, the amount of force in the entire muscle increases. Each time the voltage was increased the force generated from the muscle also increased. This occurs because, as the voltage increases, and is delivered to the whole muscle, more fibers are activated. This causes the total force produced by the muscle to increase. 5. In light of the all or none law of muscle contraction, how can you explain...
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...Quarterly Journal of Experimental Physiology (1986) 71, 467-473 Printed in Great Britain FREE INTRACELLULAR MAGNESIUM CONCENTRATION IN FERRET VENTRICULAR MUSCLE MEASURED WITH ION SELECTIVE MICRO-ELECTRODES L. A. BLATTER AND JOHN A. S. McGUIGAN Department of Physiology, University of Berne, Buehlplatz 5, 3012 Berne, Switzerland (RECEIVED FOR PUBLICATION 2 AUGUST 1985) SUMMARY The free Mg concentration ([Mg]i) was measured in ferret ventricular muscle using singlebarrelled Mg-sensitive micro-electrodes. The electrodes were calibrated in solutions containing the [K]i and [Na]i measured in this tissue. In thirteen measurements from seven experiments conforming to strict criteria for calibration and penetration the estimated mean [Mg]i was 04 mmol/l. This is to be regarded as an upper limit since it was estimated by linear extrapolation of the calibration curve. INTRODUCTION Ionized Mg plays an essential role in the regulation of a large number of cellular functions. It is a co-factor in many enzymatic reactions, influences tension development in muscle and modulates amongst others the ionic transport systems in mitochondria (see reviews by Gunther, 1977; Shine, 1979; and Ackerman & Nicholls, 1983). Despite its importance in cellular mechanisms, estimations of the free Mg ([Mg]i) by various methods range from 0- 1 mmol/l to 6 mmol/l (reviews: Flatman, 1984; Gupta, Gupta & Moore, 1984) mainly because of the lack of a simple direct method for its measurement. Direct measurement of...
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...interpreting mechanical activity based on muscle contraction. The prediction of muscular tissue condition can be found using MMG, a technique that muscular mechanical waves produced during a fiber’s contraction and stretching that are sensed over skin surface [22]. The purpose of this research is to explore various methods of muscle activity through MMG signal to recognize multiple hand gesture. The evaluation of muscle condition can be known with mechanomyography (MMG), that registers intramuscular mechanical waves produced during a fiber’s contraction and stretching that are sensed or interfaced over skin surface [21]. The major focus is on mechanomyography, the measurements of mechanical response of muscle during activity. It is well documented that muscle produce low frequency vibrations (5-100Hz) during muscle activity. The mechanomyogram (MMG) signal is observable at the surface of the muscle due to the movement of the muscle...
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...Frog Skeletal Muscle Exercise 1: Twitch Recruitment Using the Horizontal Compression buttons and the scroll bar, display the data you wish to include in your report. 1. As you increase voltage to the muscle describe how it responds to the increased stimulus. A n s w e r A n s w e r Study Questions 2. What was the smallest voltage required to produce a contraction (the threshold voltage)? What proportion of the fibers in the muscle do you think were contracting to produce this small response? A n s w e r A n s w e r 3. What was the smallest voltage required to produce the maximum (largest) contraction? What proportion of the fibers in the muscle do you think were contracting to produce this maximal response? A n s w e r A n s w e r 4. What do you conclude happened to the number of fibers contracting as the voltage was raised from threshold to that required to produce a maximal contraction? A n s w e r A n s w e r 5. In light of the all or none law of muscle contraction, how can you explain the graded response? A n s w e r A n s w e r Exercise 2: Effects of Stretch 6. Describe how the isolated muscle behaved as it was stretched progressively. A n s w e r A n s w e r Study Questions 7. What effect does stretching the muscle have on contraction strength? Is this effect linear? A n s w e r A n s w e r 8. What stretch resulted in the highest contraction...
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...Portfolio Task: Module 3 (546 Words) “Give a detailed description of the theory that explains how a muscle fibre shortens” Sliding-Filament Theory proposes that a muscle shortens or lengthens because the thick and thin myofilaments sliding past each other without filament lengths being affected. Thus, muscle, fibre, and myofibrils change lengths, but not myofilaments. Processes of muscle contraction: First Stage: The first stage is when the impulse gets to the unit. The impulse travels along the axon and enters the muslcle through the neuromuscular junction. This causes full two to regulate and calcium channels in the axon membrane to the open. Calcium ions come from extra cellular fluid and move into the axon terminal causing synaptic vessels to fuse with pre synaptic membranes. This causes the release of acetylcholine (a substance that works as a transmitter) within the synaptic cleft. As acetylcholine is released it defuses across the gap and attaches itself to the receptors along the sarcolemma and spreads along the muscle fiber. Second stage: The second stage is for the impulse spreads along the sarcolemma. The action potential spreads quickly along the sarcolemma once it has been generated. This action continues to move deep inside the muscle fiber down to the T tubules and the action potential triggers the release of calcium ions from the sacroplasmic reticulum. Third Stage: During the thrd stage calcium is released from the sacroplasmic reticulum and actin...
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...anatomy/physiology of muscle contraction. Anatomy of Skeletal Muscle: A single skeletal muscle, such as the triceps muscle, is attached at its • Origin to a large area of bone; in this case, the humerus. • At its other end, the insertion, it tapers into a glistening white tendon which, in this case, it’s attached to the ulna, one of the bones of the lower arm. As the triceps contracts, the insertion are pulled toward the origin and the arm is straightened or extended at the elbow. Thus the triceps is an extensor. Because skeletal muscle exerts force only when it contracts, a second muscle a flexor is needed to flex or bend the joint. The biceps muscle is the flexor of the lower arm. Together, the biceps and triceps make up an antagonistic pair of muscles. Similar pairs, working antagonistically across other joints, provide for almost all the movement of the skeleton. The Muscle Fiber Skeletal muscle is made up of thousands of cylindrical muscle fibers often running all the way from origin to insertion. The fibers are bound together by connective tissue through which run blood vessels and nerves. Each muscle fibers contains: • An array of myofibrils that are stacked lengthwise and run the entire length of the fiber; • Mitochondria; • An extensive smooth endoplasmic reticulum (SER) • Many nuclei (thus each skeletal muscle fiber is a syncytium). The multiple nuclei arise from the fact that each muscle fiber develops from the...
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...BBE 517 - ERGONOMICS FOR CONSTRUCTION MAMAGEMENT CLASS ASSIGNMENT THE HUMANCAPABILITY AND LIMITATIONS IN LIFTING MATERIALS AT ACONSTRUCTION SITE 17TH NOVEMBER 2014 HUMAN LIFTING CAPABILITY AND LIMITATION ON CONSTRUCTION SITES 1.0 Introduction Ergonomics is the science and art of fitting the job to the workers. There are numerous activities that take place on site that enable realization of the structure being constructed. Generally construction involves the utilization of materials in undertaking the works. This will involve labour of the workers to put in place the materials as per the design are it mixing, lifting and placing them in place, installation, delivery and storage of the materials. Material handling can be by machines/equipment or directly by the workers themselves. Handling and storing materials involves many different activities such as hoisting, manually carrying bags or material and stacking supplies. Employees can be injured by improperly lifting materials (manually and by machine), falling objects and improperly stacked supplies. This paper concentrates on the human ability in the movement and placement of materials and other facilities as work progresses on site. An examination of activities on an active site have been undertaken to inform this paper on the practicability and applicability of researched theories relating to human lifting capability on site. The following sites have been examined and findings discussed later in this...
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...| Chapter 8 Muscular System | |The Muscles: Each muscle is an organ, comprised of skeletal __muscle__ tissue, several ___connective____ tissue coverings, __nervous_ tissue to cause it | |to contract, and __blood___ to nourish it. | | Connective Tissue coverings: | |The muscle has several dense connective coverings. | |Layers of dense connective tissue, called __fascia___, surround and separate each muscle. | |This connective tissue extends beyond the ends of the muscle and gives rise to cord like | |__tendons___ that are fused to the periosteum of bones. | |Sometimes muscles are connected to each other by broad sheets of connective tissue called | |___aponeuroses___ ...
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...disorder that causes a hypermetabolic state after administration of volatile anesthetics. When a patient is under anesthesia, the muscles are usually relaxed, but when a patient is experiencing Malignant Hyperthermia crisis, certain IV anesthesia causes the opposite effect. Most inhaled anesthetics other than nitrous oxide, cause or trigger Malignant Hyperthermia. More specifically, the anesthetic agents: Halothane, Chloroform, and Succinylcholine. The genic condition of Malignant Hyperthermia only becomes apparent when a patient is exposed to certain anesthetics such as halothane, which causes muscle rigidity. During the relaxed phase of muscle contraction, adenosine triphosphate and phosphate (ADP and Pi) are bound to the myosin S1 fragment, which is in a strained vertical position. Depolarization to the sarcoplasmic reticulum occurs followed by the depolarization of the triad region which initiates the release of calcium into the cytosol. This calcium then binds to troponin. A conformational change in the actin-tropomyosin interaction is induced by the troponin-calcium complex, which allows myosin to bind to actin. The binding allows the S1 to move to the unstrained position, causing muscle contraction. During this process, ADP and Pi are released. The muscle contraction results from the shortening of every sarcomere in every muscle fiber of the motor units that is recruited. ATP, if available, then binds to the S1. The ATP is then broken down to ADP and Pi...
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...1. Muscle spindles - Provide sensory information about changes in muscle length and tension of muscle fibres - They primarily respond to any stretch of a muscle and, through reflex response, initiate a stronger muscle action to reduce the stretch - Two sensory afferent fibres and one motor efferent fibre services the spindle 2. Golgi Tendon Organs - Golgi tendon organ connects up to 25 extrafusual fibres near the tendon’s junction to the muscle - Golgi tendon organs discharge impulses under two conditions: - 1: in response to tension created in the muscle when it shortens - 2: in response to tension when muscle is stretched passively - When stimulated the Golgi receptors conduct their signals rapidly into the spinal cord to elicit reflex inhibition of the muscles they supply -...
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