Histological Features of Skeletal Muscle

Histological Features of Skeletal Muscle Objectives The aim of this report is to describe the basic histological features of a skeletal muscle and the differences between type I and type II skeletal muscle fibres. I will also describe the motor neuron unit and explain Hennemans size principle of recruiting motor units. Observations The basic features of skeletal muscle General Structure   Ã‚   The main function of skeletal muscle is to provide support, maintain posture and provide movement. Skeletal muscles comprise of densely packed groups of elongated cells which are known as muscle fibres, which are held together by fibrous connective tissue. Many capillaries penetrate this tissue to enable muscles to be supplied with oxygen and glucose needed for muscle contraction. Skeletal muscle is comprised of bundles of long striated fibres; the striated appearance is caused by the repeated structure of the fibres inside the muscle cell (Page, 2001). Individual muscle cells are called myocytes and muscles are made up of bundles of individual muscle cells. These bundles are called fascicles. Each muscle cell is surrounded by a connective tissue cover called the endomysium, and each bundle is surrounded by a connective tissue covering called the perimysium. Fascicles form muscle which is surrounded by a connective tissue called the epimysium. Skeletal muscles are made up of three types of fibres. Type I (red/ slow fibres), type IIa (red/ fast fibres) and type IIb (white/ fast fibres). Type I fibres are slow-contracting muscle fibres and they have a very dense capillary network, because these fibres have a high capacity for ATP production and a low myosin ATPase activity compared to type II fibres; the main pathway for ATP production is aerobic cellular respiration. Type IIa fibres have a higher myosin ATPase activity than type I fibres, a high capacity for ATP production and a dense capillary network; because of this the main pathway for ATP production is aerobic cellular respiration. Type IIa also has high levels of intracellular myoglobin. Type IIb fibres have a higher myosin ATPase activity than type I fibres but a lower capacity for ATP production and a lighter capillary network; this means that the main pathway for ATP production is anaerobic glycosis, which is fast but not sustainable for as long as aerobic respirat ion which means muscle fatigue happens sooner. There is no intracellular myoglobin unlike type I and IIa, which means that it is white in colour (Types of skeletal muscle Fibres, 2016). The structure of the sarcomere The plasma membrane of the skeletal muscle fibre is the sarcolemma and contains cylindrical structures called myofibrils. The myofibrils practically fill the cells and push the nuclei to the edges of the cell. Each myofibril have light and dark bands and are aligned with each other so that the light and dark bands are next to each other; this gives the cells their striated appearance. The light bands are called I bandsand the dark bands are called A bands. In the middle of the I bands there is a line which is called the Z line and in the middle of the A bands there is a light zone called the H zone. In the middle of the H zone there is another line called the M line. The sarcomere consists of several individual protein elements and some of these proteins are thread-like proteins called myofilaments. There are two main types of myofilaments. The thick myofilaments which are made up of proteins molecules called myosin. The myosin molecules are shaped like golf clubs with long shafts. Myosin forms the thick myofilaments by forming bundles in which the heads of the golf clubs stick out at either end of the filament and the shafts form a bare zone in the middle of the filaments. The heads of the thick myofilaments form attachments with the other type of myofilaments, the thin actin myofilaments and these attachments are called cross bridges.The heads are the areas on the thick myofilaments that use the energy in the ATP molecule to power the muscle contraction. The second type are the thin myofilaments, which are made of the protein actin. They have binding sites to which the heads of the thick myofilaments attach (Hwang, 2015). The triad A triad is a structure that is formed from a T-tubule with a sarcoplasmic reticulum known as the terminal cisternae on either side. Each skeletal muscle fibre has many thousands of triads, visible in muscle fibres that have been sectioned longitudinally (Al-Qusairi Laporte, 2011). Table 1; Comparison of the different types of skeletal muscle fibres (Bushell, 2013) The structure of a motor unit A motor unit is made from a motor neuron and the skeletal muscle fibres innervated by that motor neurons axonal terminals (Purves, et al., 2001). A group of motor units is called a motor pool and the number of fibres in each unit can differ within muscles. This impacts precision and force generation. Differential initiation of single or multiple motor units with a motor pool can therefore control precision and force of movement. Hennemans size principle of motor unit recruitment Hennemans size principle states that; motor units are recruited from smallest to largest and as more force is needed, motor units are recruited in a certain order per the extent of their force output. This means that the smaller units are recruited first which means that it reduces the amount of fatigue an organism experiences by only using fatigue resistant muscle fibres, unless a higher force is needed and then fatigable fibres are used. This means that slow twitch, low-force, and fatigue resistance muscle fibres are activated before fast twitch, high-force, less fatigue resistant muscle fibres (Bawa, Jones, Stein, 2014). The motor unit and the Hennemans size principle of motor unit recruitment The structure of the motor unit A motor unit is constructed from a motor neuron and skeletal muscle fibres, they innervated by the axonal terminals (Purves, et al., 2001). The motor neuron and its muscle unit are inseparable in function, this is because the action potetial in the neurons activates the fibres of the muscle unit (Karpati, 2010). A group of motor unit are gathered in columnar, spinal nuclei and this is called motor neuron pools. The number of fibres in each unit can differ from another and this then affects the force generation and the precision of the movement (Present, 1997). The Hennemans size principle of recruiting motor unit The Hennemans size principle expresses that motor units that are recruited from the smallest to the largest, this is because if more force is needed, then are recruited in a certain order due to the extent of their force output. Therefore, this means that the smallest motor units are employed first and this reduces the amount of fatigue that an organism experiences, by only using fatigue resistant muscle fibres, unless a higher force is needed, then fatigable fibres are used (Bawa, Jones, Stein, 2014). References Al-Qusairi, L., Laporte, J. (2011). T-tubule biogenesis and triad formation in skeletal muscle and implication in human diseases. Skeletal Muscle, 1(1). doi:10.1186/2044-5040-1-26 Bawa, P., Jones, K., Stein, R. (2014). Assessment of size ordered recruitment. 8. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4112781/ Bushell, D. (2013). Muscle-specific hypertrophy: Chest, Triceps and shoulders. Retrieved from TheGymLifestyle: http://blog.thegymlifestyle.com/muscle-specific-hypertrophy-chest-triceps-shoulders/ Hwang, P. (2015). Targeting the sarcomere to correct muscle function. Nature Reviews Drug Discovery, 14(5). doi:10.1038/nrd4554 Page, M. (2001). Human body: An illustrated guide to every part of the human body and how it works. (A. Baggaley, Ed.) London: Dorling Kindersley Publishers. Purves, D., Augustine, G., Fitzpatrick, D., Katz, L., LaMantia, A.-S., McNamara, J., Williams, M. (2001). The Motor Unit. Sinauer Associates. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK10874/ Types of skeletal muscle Fibres. (2016). Retrieved from Ivy Roses: http://www.ivyroses.com/HumanBody/Muscles/types-of-skeletal-muscle-fibers.php

Assignment on the Contribution of Charles Babbage, Adam Smith and Robert Owen in the Field of Management Essay

Contribution of Charles Babbage in the field of Management Charles Babbage (1792–1871) is known as the patron saint of operations research and management science. Babbage’s scientific inventions included a mechanical calculator (his â€Å"difference engine†), a versatile computer (his â€Å"analytical engine†), and a punch-card machine. Babbage’s most successful book, On the Economy of Machinery and Manufacturers, published in 1832, described the tools and machinery used in English factories. It discussed the economic principles of manufacturing, and analyzed the operations; the skills used and suggested improved practices. He showed that reducing the tasks of manufacturing to their simplest activities increases the numbers of people who can do them and, thus, reduces the average wage which needs to be paid. According to him, a work should be divided into mental and physical efforts and a worker should be paid a bonus in proportion to his own efficiency and success of the business. Babbage emphasized the importance of division of labor, indicating that greater profit could be made by specializing. Babbage also emphasized the importance of balance in processes and the principle of optimum size of the manufacturing unit for each class of product. Contribution of Robert  Owen  in the field of Management Robert Owen (1771–1858) was a successful Scottish entrepreneur and a utopian socialist who sowed the first seeds of concern for the workers. He was repulsed by the working conditions and poor treatment of the workers in the factories across Scotland. Owen became a reformer. At New Larnark, in his factory he was trying to make different approaches to the workers. He reduced the use of child labor and used moral persuasion rather than corporal punishment in his factories. He chided his fellow factory owners for treating their equipment better than they treated their workers. In 1813 he proposed a factory bill to prohibit employment of children under the age of ten and to limit hours for all children to 103/4 hours per day with no night work. The bill became law six years later, but was limited to cotton mills, reduced the age limit to nine, and included no provision for inspections; therefore, the law had little impact. Owen was totally devoted to management as a profession. Under his direction, houses and streets were built, the minimum working age for children was raised, working hours were decreased, meal facilities were provided, schooling were introduced, and evening recreation centers were opened to meet the problem of leisure. He is the father of modern Personnel Management. Contribution of Adam  Smith  in the field of Management Adam Smith (1723–1790) was a Scottish political economist. His Wealth of Nations, published in 1776, established the â€Å"classical school† and with its publication, he became the father of â€Å"liberal economics. † Smith argued that market and competition should be the regulators of economic activity and that tariff policies were destructive. The specialization of labor was the mainstay of Smith’s market system. According to Smith, division of labor provided managers with the greatest opportunity for increased productivity. He gives three reasons for the increased output due to the division of labor: a) to the increased dexterity in every particular workman b) to the saving of time which is commonly lost in passing from one species of work to another c) to the invention of a great number of machines which facilitate and abridge labor, and enable one man to do the work of many. His idea about the division of labor is fundamental to modern work simplification and time study, and extends also into such areas as production simplification.

Effect of Force Majeure or Act of God Essay

If upon the happening of a fortuitous event or an act of God, there concurs a corresponding fraud, negligence, delay or violation or contravention in any manner of the tenor of the obligation as provided for in Article 1170 of the Civil Code, which results in loss or damage, the obligor cannot escape liability. It has been held that when the negligence of a person concurs with an act of God in producing a loss, such person is not exempt from liability by showing that the immediate cause of the damage was the act of God. To be exempt from liability for loss because of an act of God, he must be free from any previous negligence or misconduct by which that loss or damage may have been occasioned. Fortuitous Event – an event which could not be foreseen, or which, though foreseen is inevitable. Essential Characteristics of a Fortuitous Event 1. Cause is independent on the will of the debtor;  2. Impossibility of foreseeing or impossibility of avoiding it to be foreseen even if foreseen; 3. Occurrence renders it impossible for debtor to fulfill his obligation in a normal manner; and 4. Debtor is free from any participation in the aggravation of the injury to the creditor. General Rule: No liability in case of fortuitous event Exceptions: 1. By contrary stipulation in the contract;  2. Declared by law e.g. Art 552(2), 1268, 1942, 2147, 2148, 2159 of the New Civil Code; 3. Nature of the obligation requires assumption of risk when expressly declared by law; 4. When the obligor is in default or has promised to deliver the same thing to 2 or more persons who do not have the same interests (Art. 1165 (3)) Art. 1174. Except in cases expressly specified by the law, or when it is otherwise declared by stipulation, or when the nature of the obligation requires the assumption of risk, no person shall be responsible for those events which could not be foreseen, or which, though foreseen, were inevitable. If the performance of this Agreement, or any obligations hereunder is prevented, restricted, or interfered with by reason of: fire, flood, earthquake, explosion or other casualty or accident or act of God; strikes or labor disputes; war or other violence; any law,  order proclamation, regulation, ordinance, demand or requirement of any governmental authority; or any other act or condition whatsoever beyond the reasonable control of the affected party, the party so affected, upon giving prompt notice to the other party, shall be excused from such performance to the extent of such prevention, restriction or interference; provided, however, that the party so affected shall take all reasonable steps to avoid or remove such cause of non performance and shall resume performance hereunder with dispatch whenever such causes are removed.

Engineered For Strategic Advantage - Free Essay Example

Sample details Pages: 5 Words: 1517 Downloads: 1 Date added: 2017/06/26 Category Engineering Essay Type Narrative essay Did you like this example? Define Resistance and Compliance. What are the primary and secondary parameters that are affected by the changes in both Resistance and Compliance? Explain how these combinations of changes have an effect on the arterial parameters and why? Use results from windksimrun. Observe and state the changes in trends and use the theory discussed in class to justify these changes. Refer back to Wind KesIndiv Results. Resistance can quite simply be defined as the tendency of a particular item to oppose the blow flow going through or by it, and is usually dictated by the size and diameter of the different vessels. In other words, as the amount of resistance decreases, the amount of blow flow proportionally increases, regardless of the fact that the perfusion pressure goes down, since resistance is inversely related to the flow. It should always be remembered that blood ends up flowing through the cardiovascular system from areas of higher pressure to those of lower pressu re. (Silverthorn, 473) When dealing with the resistance element, there are three main parameters to take a look at. First, the radius of the tube (r), as that can have a direct impact on the flow rate to begin with. Next, the length of the tube (L), as this also important in dictating the parameters of the flow rate. Finally, the viscosity of the substance going through the tube can also have a large impact as well (represented by eta). The French physician Jean Leonard Marie Poiseuille came up with the relationship between these factors, known as Poiseuilles law. R=8L*(eta)/(pi)*r4. That being said, since 8/(pi) is a constant, it can accordingly be removed from the equation, leaving us with the relationship stating that R is inversely proportional to L*(eta)/r4. In English, this means to us that the resistance increases as the tube length increases, that the resistance increases as the viscosity increases, and the resistance decreases as the radius increases (473-474). In wha t can be considered to be an ideal situation, where there are no external factors such as elasticity involved, with a flow and resistance that is constant, the model can be seen in the following equation: Q(t) = DP(t)/R. Q(t) is the flow at time t measured in units of L/s and ÃÆ' ¢Ãƒâ€¹Ã¢â‚¬  Ãƒ ¢Ã¢â€š ¬Ã‚  P(t) is the difference in pressures (pressure upstream pressure downstream) in mmHg. However, it is relatively rare in life to encounter such ideal situations, and in true biological systems, arteries will show properties of compliance. Compliance, which is a relationship between pressure and volume, can be defined as a measure of the tendency of a hollow vessel to stretch in response to changes in pressure. Changes in resistance and compliance primarily affect the flow of the substance but also secondarily affect the pressure of the substance that is acting on the walls of the vessel. In summation, changes in resistance end up affecting the rate of flow of the substance a nd changes in compliance end up affecting the amount of volume that can be stored for a specific particular flow of a substance. Thus, the changed fluid flow rates can affect the severity of the compliances effects on both pressure and volume. The arterial parameters are defined as pressure, volume, and flow. Changes in the resistance and compliance will end up affecting them, as they are all inherently interlinked. Compliance dictates the amount of volume that can be stored in a particular vessel. On that token, if there is more volume that can be stored, the flow rate of the substance will go down, as will the pressure, and vice versa if there is less volume that can be stored in that vessel. As mentioned earlier, resistance can also affect substance flow. Figure . In this figure, differently colored lines are representative of vessels with different resistances. The figure itself is showing the max flow, min flow, mean flow, and fractional flow in systole change with change s in the arterial compliance and the arterial resistance in a series of vessels that have fixed resistances, and gives the ability to visually see the relationships. The top left sub-figure shows that as the compliance goes up, the max flow also increases at a constant resistance. In this simulation, the max flow models the blood flow during systole, and the max flow stays the same (constant) when the compliance is below the baseline, which is the compliance of a normal artery. This is consistent with what was expected, as less compliant leads it to behave like a lead pipe and store little to no volume. On the other hand, when the compliance goes above the baseline, the max flow goes down. This is not too surprising either, as it is known that the greater the compliance, the more the tendency of the vessel to expand in order to accommodate the increased volume, which results in a lower flow through output. In addition, it can be observed that when at a fixed compliance, higher re sistance means a lower max flow, since resistance essentially controls the flow rate. The top right sub-figure is essentially the inverse of the first situation, and it is showing the effects of the aforementioned conditions (resistance and compliance) on the min flow situation. The min flow happens during diastole, when the heart is in a fully relaxed state, and is driven by the volume of substance that is stored in the artery during systole. This makes the min flow extremely close to zero until the baseline is reached, and when the compliance goes over the baseline, the min flow increases as well, since more volume is being stored, resulting in a higher min flow. Min flow can also be seen in this sub-figure to decrease as resistance increases in equally compliant vessels. The bottom left sub-figure helps to analyze the situation further by showing the average of the min and max flows. As long as the compliance is below the baseline, the mean flow essentially behaves akin to the max flow. However, once the compliance goes past the baseline, it now models the min flow. The rationale here is that vessels that are more compliant have the ability to store more volume, which lowers the max flow (and resultantly increases the min flow) and vice versa. Finally, the bottom right sub-figure shows the fractional flow during systole (max flow) while changing the resistance and compliance factors. As resistance increases, the fractional systolic flow decreases, since the resistance essentially regulates how much substance can flow during systole, and thus a higher resistance allows for less substance flow. Figure .This figure displays the changing relationship between the pressure and volume as there are changes in the compliance and the resistance. When the resistance is fixed, the maximum pressure goes down as the compliance goes up, and when the compliance is fixed, the maximum pressure goes down as the resistance decreases. The differently colored lines r epresent different resistances. The top left sub-figure shows max pressure against compliance, and it can be observed from this that as the compliance is increased, the max pressure decreases. That being noted, another observation from this graph is that with a higher resistance, there is accordingly a higher initial and final max pressure, which shows that there is a relationship that exists between the resistance and the max pressure. As would be expected, the max pressure happens during systole. The top right sub-figure shows min pressure versus compliance, and shows that min pressure increases as compliance increases, and also that the greater the resistance, the greater the min pressure. As was the case with the min flow, the min pressure happens during diastole since the lowest pressure happens when the heart is in a relaxed state. The bottom left sub-figure shows arterial volume versus time. The arterial volume can be described as a combination of the min and max vol umes of increasing compliance. The dashed lines are representative of the max values, and likewise the solid lines of the min values. When looking at these two with relation to the other, the min values have a higher slope, and as the compliance goes up, so does the volume. The bottom right graph is the change in volume against the compliance, and is done essentially to be able to visualize the arterial volume versus time graph in a way that makes it give more information. The distance between the max and min is taken for each of the points for each individual resistance, and is plotted in a new graph. For each resistance, there is a maximum change in volume. From this, it can be seen that when the resistance is lower, the larger the compliance when it reaches its maximum. Furthermore, lower resistance means a greater change in volume. What physiological conditions cause such a change in resistance and compliance? Of the quantities that vary in time (i.e., variables as opposed to those that are fixed (called parameters), which quantities do we need to know to give a complete description of the state of the systems? Use results from SimpWind.mdl. Don’t waste time! Our writers will create an original "Engineered For Strategic Advantage" essay for you Create order