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Musculoskeletal systems and physiology of exercise
There are cells called Mesenchymal cells, these cells are where ossification occurs. There are two methods of bone formation. Intramembranous ossification occurs with flat bones like the skull. The process begins at the site of development the mesenchymal cells group together to form the ossification centre and osteoblasts surround it in extracellular matrix of bone. The cell is known as osteocytes develop in all directions allowing calcium to collect and harden. It will develop into trabeculae which fuses with further trabeculae. The gaps in between allow blood vessels to grow. This all then forms red bone marrow. The edges of the mesenchyme condenses into periosteum. The other method of bone growth is endochondral ossification. This is the replacement of cartilage with bone, which starts in a similar way the mesenchymal cells group together this time form chondoblasts. This then forms the cartilage model. The cartilage model then forms and is coated once more in extracellular matrix, and then forms into periosteum once again. (principles of anatomy 2006)
The skeletal system has many functions that allow the body to continue working properly. It offers support, it allows soft tissues to connect and have a formation. It is the framework for other tissues. The skeletal muscles are connected to the bones meaning when they contract and relax bones are able to move and allow movement throughout the body. So it also helps with movement. It also is a form of protection. It encases the organs with it meaning it has to be penetrated before the organs are at risk. It is stronger and tougher than the more fragile organs that it protects. Another function of bones are to store minerals. These minerals help to stabilise a healthy balance throughout the body, and are released from the storing skeletal system into the blood stream as and when they are needed. These are chemical such as Calcium and phosphorus. The skeletal system also adapts as to continue to provide as it ages. It develops to store chemical energy. The red bone marrow can change into yellow bone marrow which can help with the chemical energy reserves so as the body ages it can still continue to function. The skeletal system also helps to provide blood cells within the bone marrow. Red blood cells, white blood cells and platelets are produce within the red bone marrow of some bones. (IvyRoses Online)
A pivot joint such as in the neck (vertebrae) allows the movement around one axis. It is when a rounded end of bone fits inside a circular gap of another. It allows rotation movement. A ball and socket joint as found in the shoulder is spherical end of a bone fitting into cup or socket. This joint system gives most movement as it can rotate in most direction on many axis. The hinge joint as found in the elbow, is a groove of one bone housing the ridge of another. This allows movement to only be open or close or bend or straighten. The ellipsoid joint as in the wrist is an oval shaped bone fitting into a oval hollow of another bone. This type of joint allows movement across two axis, rotation and pivoting combined. The next joint is the saddle joint which is the type of joint within the thumb. The saddle joint sees that both bones include a convex section and a concave section. This again allows similar movement as the ellipsoid joint but with a greater range. The next joint is the Gliding joint found in the foot. This type of joint has flat or slightly curved bone surfaces. It allows little movement when gliding across the surfaces, and no rotation movement is available from this type of joint. (Boundless Online)
The Ball and socket joint gives the most movement out all the joint types, it can rotate and pivot giving it huge variety of movement. A Ball and socket joint in the shoulder or hip comprises of a spherical end of the bone being encased in a cup or socket from another bone. The shoulder as stated is a ball and socket joint therefore the humorous has the ball end which fits into the socket of the scapula bone. There is cartilage around this joint to keep the bones in place and to offer some protection too. Within the shoulder there is an area called the glenoid cavity, this allows the shoulder the wide movement. This specific joint allows for several types of movement abduction of the arm away from the body, adduction of the arm back towards the body extension of the arm forwards flexion of the arm back and rotation around the shoulder. Movement with any joint would not be possible without synovial fluid. The synovial fluid is a thick liquid which lubricates the joints which allow the joints to move. Furthermore to help protect the joints there is a synovial membrane. This two layered membrane produces and contains the fluid inside and so enabling further protection. This complex joint is equivalent to two or three joints working together in other areas of the body. The hip is also a ball and socket joint allowing great movement in the legs.
The muscle system is a vast and complex system. Within this system there are voluntary (skeletal), Cardiac and smooth muscles. The voluntary muscles are intertwined with the skeletal system and help to move the body. The muscles are usually attached to bones by tendons. These voluntary muscles are connected to the bone at either end. One end is the origin the other is the insertion which is usually at a joint. The insertion end is the end that moves and help the body to move.
The Structure of the muscles and tendons is was gives them the strength and ability to perform their tasks. The bone and tendon are attach and the tendon is very durable giving the muscle a very strong base attachment. The muscle itself is then formed of tightly packed fascicles, which are tube like. Each of these fascicles are tightly packed with muscle fibres or muscle cells which in turn contain myofibril. The muscle fibres can contract in large groups meaning the muscles as a whole would contract. The muscle fibres are surrounded by Endomysium which is a protective sheet around them. Then surrounding a bundle of the fascicles is another protective layer of fibrous tissue is the epimysium. However around each individual fascicle is a layer called perimysium. This shows that there are layers upon layers of tissues and cells within each muscle.
The tendons are what attach the muscles to the bone. They are strong cords made of tissues. The tissues are attached to the bone and to the muscles so when the muscles contract or relax they pull the tendons which in turn manipulate the bones. Tendons need to be durable and strong, this is to maintain the structure and connection. Being durable is essential due to healing or mending of tendons is very difficult. The strands of tissue comprise of tightly woven tenocyte cells, water and collagen protein. The tendons and bone mineralise into a virtually unbreakable bond. (Wise Geek Online)
Type I Fibres (Slow Twitch-Slow Oxidative Fibres)
Slow twitch fibres are associated with endurance this is due to the long twitch duration the fibres can last lengthy periods without becoming fatigued. These fibres require a lot of oxygen to continue their function. This means that slow twitch fibres heavily rely on aerobic respiration to draw in the much needed oxygen. Without the oxygen these muscle fibres would fatigue quicker and therefore would not be able to endure. Aerobic respiration converts the Adenosine triphosphate ATP with the use of oxygen, this is effective yet long. This shows once more that the slow twitch fibres have the time to reap the benefits of aerobic respiration due to their long fatigue period. Therefore they would use a little fuel which would be replace over a period.
Type II B Fibres (Fast Twitch- Fast Glycolytic Fibres)
These fibres are associated with small powerful bursts. The requirement therefore for oxygen is needed far less than slow twitching fibres which would constantly need to refuel as continue their task. The Fast twitch fibres burn up their fuel quickly as to gain the most out of the explosive power. This means that the oxygen for the use of these fast twitch and so these fibres would use the anaerobic respiration, and would not use aerobic respiration. A quicker production of ATP is without oxygen but with glucose instead both the fast twitch type of fibres require the fuel quickly due to the intense use therefore the longer aerobic respiration would be of little use.
Type II A Fibres (Fast Twitch- Fast Oxidative Fibres)
The last type of fibre is less common then the other two and is a combination of them both, longer bursts of power. These fibres therefore require both anaerobic respiration and aerobic respiration. The fibres will burst with power and will use up their Glycogen fuel supplies however will continue to function therefore without aerobic respiration would seize up and stop functioning. The anaerobic starts the process with the aerobic continuing. Once more the fibres require an immediate influx of fuel and therefore would require anaerobic respiration however they continue to work over the time then for the aerobic respiration to assist in the refuelling.
EXERCISE WHAT IT CAN DO FOR YOUR BODY!
Exercise can have a great impact on your body whether it is on the heart and cardiovascular system to the bones and skeletal system.
The Cardiovascular system- Within the cardiovascular system great amount of changes occur during exercise, these changes put more pressure on the heart to perform and deliver the vital blood around the body to the other organs and systems. The heart will begin to beat quicker meaning that the blood will get to areas quicker, which therefore means the oxygen can refuel where it has been used up quicker. Through the system also hormones can be transported as into inform muscles and other organs to react or start doing something. The blood vessel will dilate as to allow more blood to flow to the needed areas. Through exercise the cardiovascular system can be trained and improved. The Heart will increase in volume and efficiency therefore, after exercise the rest heart rate will be lower due to the higher volume being pumped by a strong heart. This would result in less stress being placed on this system and therefore a better expected lifespan and a better quality.
The Respiratory system – This system once more changes during exercise which has an effect on it afterwards too. The body will use up oxygen quicker during exercise therefore the breathing rate will increase, to draw in more air. A slight in oxygen levels can impact on other systems performance greatly. Once trained the lung will become bigger and therefore be able to hold more oxygen this would mean that the reserve of oxygen would not be needed as much as before and therefore the body would be able to deal with more strenuous activities with greater ease. This would also help in day to day life meaning that menial task become even easier and the body would require less input to achieve such tasks. During exercise the respiratory rate can increase to almost three times the resting rate, this is due to the higher demand of oxygen and furthermore the increase of waste products needing to be exhaled. As well as the rate increasing the volume will also increase by the lungs expanding allowing more to flow in with each breathe.
The Muscular System – This system once more will develop and become more efficient with exercise. Over time the muscle cell production of energy will increase, prolonging fatigue. The muscles themselves will become strong and be able to endure greater challenges. With the development of the muscular system an increase of both glycogen and oxygen storage develops too. The increase of metabolism means that excess food is burnt of quicker and not stored within the body as fats, which would put greater pressure on the heart and even other systems. Once more the strength of the muscles and tendons are increased meaning other task once more become easier.
The Skeletal System – The skeletal muscles play a big part in the changes within the skeletal system, whilst exercising these muscles will put stresses on the bones. The bones will develop differently if stressed, they will be more dense and possibly longer or bigger, therefore care should be taken when the bones and muscles are developing in children. Overtime bones may begin to deteriorate and become brittle exercise can slow these effects and help keep the bones and body alike healthy.
Over time the body will deteriorate and become frailer and more fragile than before. Two examples of this are osteoarthritis and cruciate knee injuries.
Osteoarthritis is a condition where the joints of the body become stiffer and more painful. It can affect people in different ways some become unable to move joints as they would have before and others just find it difficult to perform the tasks as easily. The cause of this condition is when there is damage around the joint which is irreparable. This could be from wear and tear over many years. It could also be the effect of extra pressure brought on by excess strain by being overweight. Over an average lifetime there will be a constant level of minimal damage however this damage is usually repair throughout the body with the individual not noticing and continuing on their daily routine. With Osteoarthritis the damage is not repaired and therefore causes issues. The cartilage may be diminished and so the bone may begin to rub on other bones causing further discomfort or pain. Age and weight are just to factors that can aid in osteoarthritis developing. Other factors could be the over use of a joint, wearing down the cartilage causing the bones to damage themselves. Some other factors could impact years later would be gout and rheumatoid arthritis, both causing swelling around joints. It can also be passed down through family lines and inherited by the children who have the genes, this however is not found to be one specific gene more several genes contributing. Having osteoarthritis will reduce mobility and therefore help is often need to perform possible simple everyday tasks and more complex tasks may become extremely hard to complete. Everyone suffering from osteoarthritis may have different symptoms and different level of those symptoms. Some of these symptoms include tenderness of the joints effected and pain may develop in the joints. The joints may become disfigured and swelling may occur. When moving a grating sound may be heard where the bones are rubbing against each other. Mobility will be reduced which could also mean muscle wasting and a decreasing of strength. All of this can be somewhat helped with regular exercise. (NHS Online) Osteoarthritis can also be brought on through lack of exercise. Doing some regular exercise will increase the muscle strength and therefore the body strength it can increase in the flexibility of joints to allowing them to move more freely and be supported by the muscles. This means that the joint is more stable and therefore less likely to become awkward or stiffen. Like exercising can increase the balance throughout the body which would mean that some joints are not over compensating for other joints. This would put less strain and stress on these joints reducing the risk of osteoarthritis.
Another Condition that can have effects on the body is cruciate knee, however once again exercise can help deter it. There are four ligaments within the knee, being the Medial Collateral Ligament (MCL), Lateral Collateral Ligament (LCL), Anterior Crucial Ligament (ACL) and Posterior Crucial Ligament (PCL). The PCL and ACL stop the leg from over straightening and over bending. The ACL also keeps the femur and tibia in place and it sits just behind the knee cap. A tear in the Crucial Ligaments can be very devastating and could lead to surgery, but not necessarily always lead to it. These injuries may occur with damage to other parts of the knee. This can occur from a sudden rapid change of direction causing the ligament to be sprained. There are different degrees of sprain the lowest is mild damage to the ligament, it has been slight over stretched but can still function to some degree and keep the knee cap where it should be. The second degree of sprain is a partial tear, the ligament has been stretched so much that it no longer has elasticity and becomes loose. The third and most sever is a complete tear in the ligament causing an unstable knee cap. Other ways any of these could occur is a direct impact, stopping suddenly, jumping and landing incorrectly. These will have symptoms such as swelling, pain, loss of mobility, tenderness and discomfort when doing simple tasks such as walking. If a Crucial Ligament injury occurs immediate exercise may delay recovery or even worsen the situation, however most sprained crucial ligament would require reconstructive surgery, as to try and rebind the torn ligament. This would require extensive rehabilitation afterwards and the ligament would have to be strengthened once more. The process of returning to normal would normally be lengthy. The first couple of weeks great swelling would need to be reduced as to gain mobility back to the knee, some small very light exercises may be given to aid the recovery. Following this the swelling may go down but the knee may become weaker, not having all the swelling pushing on it and keeping it in place. Exercises may reduce now just so the graft can begin to build on strength and structure. The patient may begin to be able to once again walk normally. After two months the ligament should be on the mend and may be able to take slightly more stress, this is normally achieved through less weight bearing exercise. After three months the range of movement and some of the strength should be back to normal. Then finally from about six months, for athletes, a full return to normal. This is usually lengthened somewhat for non-sporting people due to the sports professions eagerness to return to their livelihood. (bbc Online)
Principles of anatomy 2006 written by Gerard J Tortora and Bryan Derrickson
IvyRoses Online found at http://www.ivyroses.com/HumanBody/Skeletal/Skeletal_System.php Accessed May 2015
Boundless Online found at https://www.boundless.com/biology/textbooks/boundless-biology-textbook/the-musculoskeletal-system-38/joints-and-skeletal-movement-217/types-of-synovial-joints-822-12066/ accessed may 2015
Wisegeek online found at http://www.wisegeek.com/what-is-an-extensor-muscle.htm accessed may 2015
Wise geek online found at http://www.wisegeek.org/what-are-tendons.htm accessed May 2015
BBC online found at http://news.bbc.co.uk/sport1/hi/front_page/4285970.stm accessed May 2015