Beale's Blogs : Assessment 2 - The Muscular System

Function of the muscular system

There are four main functions of the muscular system, these are movement, maintenance of posture and thermoregulation. The main function of the muscular is movement, this is because muscles allow the body to move from area to area and also perform involuntary movements. Muscles also help the body to maintain itself, this is done by helping the body with the digestive system and aid the bodies breathing.

Types of muscles

There are three types of muscle. These are Cardiac, Skeletal and smooth.

Cardiac

The Cardiac muscle is only found in the heart and is very smooth. The job of the Cardiac muscle is to pump blood through the whole the body and is an involuntary muscle.

Skeletal

The Skeletal muscles are found attached to the bones at both of the ends by tendons. The job of the Skeletal is to perform all body movements and also to sustain heat within the body and provide stability to allow movements such as standing up or sitting in a seated position. This muscle is voluntary and has a stripey texture which is why it is known as striated.

Smooth

The smooth muscles are responsible for moving the food through the digestive system, it also has the responsibility of dilating and constructing blood vessels. The smooth muscle is innervated by the nervous system and is an involuntary muscle.

Muscle Roles

There are four types of muscle roles, these are agonist, antagonist, fixator and synergist.

Agonist and Antagonistic

The agonist is the one that provides the movement as it is the prime mover whereas on the other hand the antagonistic is the one which relaxes, it also can slow down movement. The agonist and antagonistic muscles work in pairs. As one muscle contracts the other muscle relaxes, this occurs in many scenarios for example when kicking a ball and the knee bends and the hamstring relaxes whilst the quadriceps contracts.
Fixator
The fixator muscle prevents the scapula muscle which allows full movement at the radius area. Not only this but the fixator is basically the movement in the muscle. The fixator stabilises the agonistic and the joint that moves over when the movement is performed. For example if someone was performing a bicep curl at the gym, the fixator will work around the shoulder to help the agonist work correctly.
Synergist
The synergist helps the overall movement which overall helps the agonist work correctly. It stabilises the joint around the working area. For example when bending the legs to do a squat the synergist supports the knee in which allows the full movement with ease.

Muscle fibre types

The different types of fibres are Type I (slow-twitch muscle fibres) which have a low speed and force but a high level of mitochondria which means high fatigue resistance (moderate fast-twitch fibres) which have a medium level of force and speed and a high level of oxygen and glucose which provides energy and finally Type IIa and Type IIx (fast-twitch fibres) which has extremely high levels of glucose which produces masses amount of energy and therefore allows very quick twitches which means a high level of force and speed.

Type l

Type I fibres are small in diameter, they also have a high resistance to fatigue; this means that during aerobic events such as a marathon that the runner won’t fatigue easily allowing them to run for a longer period of time. Type I also has high oxidative capacity, this allows more oxygen to be pumper around the body which proves more energy to the muscles to then go for long periods of time.

Type lla

Type IIa fibres are better for anaerobic events for example, because they are large in diameter which therefore means low in oxidative capacity, this suits anaerobic better because you are only doing the exercise for a short period of time which means only a small blast of oxygen is needed to perform the task. For example a sprint, this is only short and therefore needs a quick burst of energy.
Type llb

Type llb fibres contain a low content of myoglobin, not many mitochondria, few blood capillaries and a vast amount of glycogen, this means that the fibres fatigue very easily and have fast contractions. Type llb fibres are commonly found in the biceps and triceps, these fibres fit perfectly for anaerobic activity because the fast twitched mean quick bursts of energy. Sports like sprinting are relevant.

Type I - walking, jogging and aerobics
Type IIa - mile run, swimming and cycling
Type IIx – weight lifting and swimming

Types of contractions

Isotonic

This is where there is the concentric and eccentric contractions occur. Eccentric contractions are the opposite to concentric contractions as when the muscle contracts it lengthens for eccentric but shortens for concentric. A good sporting example of this is the bicep curl as when the bicep curl action is performed the concentric and eccentric contraction actions occur when the arm straightens and bends.

Isometric

Isometric contractions happen when there is no change in the length of the contracting muscle, for example when picking up something like a tennis racket and gripping it in your hand, the joints have no movement but the muscles still continue to contract. The plank is an example of an isometric contraction.

Isokinetic

Isokinetic contractions occur when the muscle changes length, isokinetic contracts produce movement at a constant speed unlike isometric. A sporting example of an isokinetic contraction is a wall sit as it speeds up the muscle contraction quickly.

Muscle Movement

When striking/kicking a ball the bones used are the Ferra, Fibia and Tibia. The hip which is a ball and socket joint and the knee which is a hinge both work together to create the kicking action. Muscles that enable the contraction to occur are the Quad which contains the Vastus Latendia, Vastus Medias, Vastus imedas and the Rectus femoris. It also uses the hamstring which includes theBicep femious, Semitendousus and the semmenbraneous. The roles of the muscles are when the leg bends (flexion) the agonistic is the hamstring and the antagonistic is the quad but when the leg extends (extension) the agonistic is the quad and the agonstic is the hamstring. The contractions that occur when the leg bends are the hamstring is concentric and the quad is eccentric and when the leg extends they are the opposite way round.

When throwing a javelin the bones used are the lluna, scapula, humerous and the radius. The joints used are the shoulder which is a ball and socket joint and the elbow which is a hinge joint. Muscles that enable the contraction to occur are the bicep which involves the teres major and the tricep which involves the trapizus, posteria deltoid, rectoras major and anterior deltoid. The roles of the muscles are when the arm bends (flexion) the agonistic is the tricep and the antagonist is the bicep, when the arm extends (extension) the bicep is the agonsit and the tricep is the antagonist. The contractions that occur are when the arm is bent the concentric contraction is the bicep and the eccentric contraction is the tricep and the opposite way round when the arm is extended.

When performing the high jump the bones used are the pelvic gurdle, femur, tibia and also the tarsals. The joints used are the ball and socket joint which is the hip and the hinge joint which is at femur which joins the femur, radius and tibia. The muscles used in high jumping are the glute maximus, hamstring, quadricepts, bicep femoris, gastrocnemius, semimembranosus and the semitendinosus. The roles of the muscle are when the leg bends the quads are the antagonsitic and the amstring is the agonstic. The movement performed is when the knee bends the leg is in flexion and when the leg straightens they are extended. The contractions that occur when the leg bends are the hamstring is concentric and the quads are eccentric but when the legs straighten the contractions that occur are the hamstring becomes the eccentric and the quadricep becomes the concentric because the muscle is now getting shorter wheres as before it was getting longer.