Muscle structure and Functions of the muscular system
In this assignment I will look at the structure of the muscular system and the functions of it.
There are 3 types of muscles which are:
· Skeletal muscles
· Smooth muscle
· Cardiac muscle
Skeletal muscles are the muscles that move and support the skeleton. They make up fifty percent of your body weight. There are 640 individually named skeletal muscles. A skeletal muscle links two bones across its connecting joint. When these muscles contract or shorten, your bone moves. This type of muscle is a voluntary muscle which means it is under conscious control.
Smooth Muscle: This is an involuntary muscle that is moved with out thinking about the movement, These muscles work by functioning under the control of the nervous system which is located in the walls of the digestive system and blood vessels.
Cardiac Muscle: This muscle is found in the wall of the heart. It works continuously. This muscle is involuntary, which means it is not under conscious control. This muscle is made up of it’s own tissue which has it’s own blood supply.
Function of the muscular system
Muscle must cross the joint they move. When a muscle contracts it exerts a pulling force on the bone s causing them to move together around a joint.
In normal circumstances, muscles are in a state of partial contraction, ready to react to a stimulus from the nervous system, but without this muscle tone, the body would collapse and when a stimulus from the nerve supply occurs, muscle fibres work an all or nothing basis .
The strength of muscle contraction in response to the stimulus depends on the number of muscle fibres brought into use, a process known as muscle fibre recruitment . During exercise the muscles of an individual uses energy at a rate that is directly proportional to the intensity of the exercise . If the energy does not get replaced as it gets used up, the muscles are unable to maintain their work rate and you have to reduce the intensity of the activity or stop it.
Antagonist muscle pairs
Muscles do not work in isolation, They are assembled in groups and work together to bring about movement, they act only by contracting and pulling.
They are able to contract without shortening so hold a joint form and fixed in position.
When the contraction is over the muscle becomes soft but do not lengthen until stretched by the contraction of the opposite muscle.
Agonist: The muscle that shortens to move a joint is called the AGONIST or “Prime Mover”
Antagonist: The muscle that relaxes in opposition to the agonist is called the antagonist. This muscle is responsible for the opposite movement and the one that relaxes as the agonist works. If it did not relax, movement would not be able to take place. Antagonists exert a control over the movement .
Synergist- These muscles work together to enable the agonists to operate more effectively. They work with the agonists to control and direct movement by modifying or altering the direction of pull on the agonists to the most advantageous position.
Fibre types
All skeletal muscles contain a mixture of fibre types , each individual has a mix of fibre types and these varies from muscle groups to muscle groups in the individual .
There are two main type of striated skeletal muscle can be distinguished on the basis of the speed they conract, type 1 ( slow twitch and type 2 ( fast twitch).
Type 1 muscle fibres
Type 1 ( slow twitch) fibres contract slowly with less force. They are slow to fatigue and suited to longer duration of aerobic activities, theyt have a rich blood supply and contain many mitochondria to sustain aerobic respiration. An example of an activity that uses these fibres is a marathon runner and a long distance swimmer
Type 2a muscle fibres ( fast twitch fibres) are fast contracting and able to produce a great force, but are also resistant to fatigue , These fibres are suited to middle-distance events.
Type 2b muscle fibres also called fast twitch fibres contract rapidly and have the capacity to produce large amounts of force, but they fatigue more readily, making them better suited to anaerobic activity. These depend mostly on anaerobic metabolism and are recruited for high intensity and short duration activities such as a 100 metre sprint.
All types of muscle fibre are used in all types of activities although type 1 fibres are particularly adapted to low intensity aerobic endurance work, They are usually used at the beginning of exercises regardless of the intensity of the activity an example of an athlete with these fibres is Paula Radcliffe .
Type 2 fibres adapt to high intensity anaerobic exercise involving explosive or powerful movements but are increasingly employed as fatigue sets during low- intensity endurance work.
Structure of the heart complete
functions fin
Structure of the respiratory system
Functions of the respiratory system (4.2)
The lungs has many functions and in this assessment I will examine the functions and how the functions are possible due to the structure of the respiratory system.
Mechanisms of breathing: Breathing is the process were air is transported into and out of the lungs, this process is considered to have 2 phases, Breathing is operated regularly by the respiratory centres located in the brain and receptors in the air passages and lungs. Breathing requires the thorax to increase in size to allow air be brought in, whilst the decrease in size will allow air to be forced out. Adams, Barker, Gledhill, Lyndon, Mulligan, phillippo, Sutton (2010)
Inspiration: This is when the intercostal muscles contract and lift the rib cage upwards and outwards , while this happens the diaphragm is forced downwards and the sternum forwards. These movements means that the expansion of the thorax in all directions result in a drop in the pressure below that of atmospheric pressure, Adams, Barker, Gledhill, Lyndon, Mulligan, phillippo, Sutton (2010) this helps air to fill up the lungs and at this time oxygen is exchanged for carbon dioxide in the blood through capillary wall this is called gaseous exchange.
Expiration: This happens follows inspiration when the intercostal muscles relax, the diaphragm will start to expand upwards and the ribs and sternum will collapse. At this point, pressure within the lungs starts the increase and air is expelled from the lungs. When the body is in action large amounts of oxygen are required, as a result the intercostal muscles and diaphragm work harder. Adams, Barker, Gledhill, Lyndon, Mulligan, phillippo, Sutton (2010)
Gaseous exchange: This occurs by diffusion between the air situated in the alveoli and blood that is situated in the capillaries that surround the alveoli’s walls. The diffusion occurs between oxygen which is leaving the alveoli and entering the red blood cells and diffusion of carbon dioxide which leaves from the red blood cells and into the alveoli and the CO2 is then passed out of the body via exhaling. Before the diffusion occurs the blood travelling through the pulmonary artery has a low content of oxygen and a high content of carbon dioxide once the diffusion occurs this is reversed. Adams, Barker, Gledhill, Lyndon, Mulligan, phillippo, Sutton (2010)
This function will be an advantage during exercise or sporting activities because the oxygenated blood will travel back through the muscles which mean they can gain more oxygen and last longer without getting fatigued. This function is easily done with the pulmonary artery running beside the alveoli which means that the diffusion an take place directly which means that the oxygen that is diffused in to the blood is fresh in the lungs once inhaled and the carbon dioxide can leave quickly through exhaling.
Lung Volumes: A humans respiratory rate is the amount of air that the an individual inhales in one minute. For a typical 18 year old the lung volume is around 12 breathes per minute at rest which can allow around 6-7 litres of air to pass through the lungs. During exercise the amount will increase with breaths rising up to 30-40 breathers per minute. Adams, Barker, Gledhill, Lyndon, Mulligan, phillippo, Sutton (2010)
Tidal volume: This is the amount of air breathed in and out with each breath. In normal conditions it is usually around 500cm3 of air both inhaled and exhaled. Out of the 500cm3 about 350cm3 will reach the alveoli and be part of gaseous exchange and the 150cm3 left will fill up the pharynx,larynx,trachea,bronchi and bronchioles. Adams, Barker, Gledhill, Lyndon, Mulligan, phillippo, Sutton (2010)
Excise affects tidal volume as it increases and allows more air to pass through the lungs. The volume of air passing through the lungs each minute is known as the minute volume. It is made up of the breathing rate and how much air is in taken each breath.
Inspiratory reserve volume : By breathing in deeply it is possible to take in more than the usual 350cm3 of fresh air that reaches the alveoli. This is an advantage during exercise, In addition to the tidal volume, you can breathe in an additional 3,000cm3 of fresh air. This helps during exercise because more air can go in to the blood so that more oxygenated blood can go to the muscles whilst still having air in the lungs. Adams, Barker, Gledhill, Lyndon, Mulligan, phillippo, Sutton (2010)
Expiratory reserve volume: This can be up to 1,500cm3 and is the amount of additional air that can be breathed out after more expiration.
At the end of a normal breath the lungs will contain the volume plus the expiratory reserve volume.
Vital capacity: This is the amount of air that the lungs can force out after maximum inspiration. The capacity is around 4,800 cm3
Residual volume: The lungs are never completely emptied of air, if they were this would result in them collapsing, The air that stays in the lungs after maximal expiration is referred to as the residual volume. The volume is around 1,200cm3 for a normal male. Adams, Barker, Gledhill, Lyndon, Mulligan, phillippo, Sutton (2010)
Total lung capacity: This is the total lung capacity after an individual has inhaled as deeply as possible, After this the total capacity is normally around 6,000cm3 for an un-average-sized male. Adams, Barker, Gledhill, Lyndon, Mulligan, phillippo, Sutton (2010)
Control of breathing
Neutral control: Breathing seems simple but its control is complex, It involves neurones, cells that conduct nerve impulses, both parts of the brain stem, neurones in two parts of the medulla are critical in respiration. This is the dorsal respiratory group and the ventral respiratory group (DRG and VRG) .
Chemical control: There are other factors that control breathing which is the changing levels of oxygen and carbon dioxide. Sensors responding to such chemical fluctuations are called chemoreceptors. Adams, Barker, Gledhill, Lyndon, Mulligan, phillippo, Sutton (2010)
Know the Different Types of Energy Systems Finished
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