'Identify the link between motor units, motor neural firing patterns and the sliding filament theory.'
Compare the energy systems used in team, racket and individual sports to illustrate your answer.
The deadline for you essay is Monday 3rd November.
If you have any questions or aspects you are not sure about please raise them so you are in a position to provide the best answer possible.
9 comments:
Keywords you will need to include are:-
Axon
Electrical impulse
Synoptic knobs
Wave summation
Gradation of contraction
Synoptic bulb
Calcium ions
Transverse tubules
Sarcoplasmic reticulum
ATP regeneration
ATP breakdown – energy releases Crossbridges
Glycolosis
Krebbs cycle
Electron transport chain
Please share your thoughts and ask for definitions if you are not sure.
http://hwspe.blogspot.com
/2007/10/
scientific-priciples
-of-exercise-and.html
This will take you to websites used by last years A2.
Mr I
Hi sir, are we meant to be focusing on our PEPs at the moment? Also do you have like some kind of gideline for it because im not whats meant to go where! thank you
http://www.shelfieldpeonline.co.uk/html/motor_units_and_motor_neurone_.html
http://www.shelfieldpeonline. co.uk/html/motor_units_ and_motor_neurone_.html
Think i am done with the essay. I havent included anything about the Krebbs cycle or the electron transport chain. Struggling to see how they come into it.
Get back to me if i should change parts before monday.
Joe
Identify the link between motor units, motor neural firing patterns and the sliding filament theory.
A motor unit is a single motor neuron. A single muscle can consist of hundreds of motor units depending on the size. The quadriceps, which is one of the biggest muscle groups in the body, would contain more motor units than the four small muscles beneath your shoulder called the rotator cuffs.
One motor nerve can branch into tens, hundreds or even a thousand branches, each one terminating at a different muscle fibre.
Therefore motor units are the start of the process for when a muscle wants to move.
A muscle can contract only when a nerve ending is stimulated by outgoing impulses from the central nervous system. Once an electrical impulse has been recognised and is carried towards the muscle bed by the axon, the neurone divides into several branches. These branches called synoptic knobs connect the motor neurone to the muscle fibres by specialised structures known as motor end plates.
This is where the impulse reaches the motor end, which initiates the sliding filament theory.
The Sliding filament theory can be divided into 5 stages. In stage 1 of the sliding filament theory the action potential reaches the axon terminal causing acetylcholine to be released. When the motor end is activated depolarization occurs which means the motor end attaches to the muscle bed. Calcium ions are transmitted to the T-tubules into deep muscle fibres via the sarcoplasmic retuculum which surrounds each myofibril. These myofibrils are thread like structures which combine to make up a muscle fibre.
The basic unit of a myofibril is sarcomere. Sarcomere is divided into four different categories; the I-Band which is made of thin actin filaments; the H-Band which is made of thick myosin filaments; the A-Band which is made up of thick myosin and thin actin filaments and the Z-Line which marks the end of one sarcomere and the beginning of another.
At stage 2 Troponin-Tropomyosin surrounds the active sites on the actin filament. The calcium ions which were taken to deep muscle fibres earlier on now bind to Troponin-Tropomyosin to reveal binding sites. These enable myosin heads to attach to actin to form a cross-bridge.
At stage 3 the contraction takes place. For this contraction to occur the actin cross bridge needs to be energised. This form of energy comes from Adenosine Tri-Phosphate (ATP) being broken down from ATPase.
This causes the myosin to pull the actin inward in order to shorten the muscle. The H-Band disappears as the muscle shortens and the I-Band shortens as actin is pulled to the centre, closer to the Z-Line.
The power of the contraction created depends on the number of motor neurons that were stimulated, a phrase which means gradation of contraction. Gradation of contraction refers to the ability of muscles to produce forces varying from very light to maximal force or tension. These forces can range from fine, delicate precision controlled movements such as snooker or gymnastics to strong, dynamic powerful movements like the 100m or shot put. The rate at which a muscle fibre contracts to produce these varying contractions is called wave summation.
Stage 4 is about what happens as the contraction is nearing its finish. The ATP molecules cause the myosin head to detach from the actin and relax. ATP can be broken down continually if there are enough ATP molecules which results in a continual power-stroke of the cross-bridge. The contraction is ended as soon as there is a decrease in calcium ions.
At stage 5 the contraction is over. The myosin releases from the actin filaments and the contraction is ended as the cross-bridge detaches itself. Binding sites in actin filaments are covered, the muscle relaxes and sarcomere returns to its original state of rest. Furthermore the sarcoplasmic reticulum is replenished with calcium ions ready for next time.
Without motor units there is no sliding filament theory, without the sliding filament theory there is no motor neural firing patterns. Each three parts are individually crucial to muscle movement but without all three together our muscles would not be able to move as efficiently and varied as they do. They allow us to do simple things such as pick up a cup of tea to more complicated actions such as scoring a 30 yard free kick in football. Muscle contraction is the key link.
im acually having too much confusion doin this - im just plain up lost! ive got research printed out i just dont know how to go about piecing it together ?
jack m.
sir i researched the relevent information but i cant really put it into my own words.
i upload what ive researched, what i mainly found is that the motor unit and the firing patterns are connected by the The Neuromuscular Junction?
Identify the link between motor units, motor neural firing patterns and the sliding filament theory.
A motor unit is a single motor neuron and all of the corresponding muscle fibres it innervates. When a motor unit is activated, all it’s fibre’s that it is connected to contract. Groups of motor units often work together to coordinate the contractions of a single muscle.
Muscle can contract only when a nerve ending is stimulated by outgoing impulses from the central nervous system (CNS), which consists of the brain and spinal cord. The contractile system for muscles is organised into a number of distinct parts, each of which is controlled by a single motor neurone and each motor neurone controls a large number of muscle fibres.
Motor-Neural Firing Patterns
A Muscle Twitch
Stimuli received by the motor neurone pools are transmitted to the different motor units, which do not necessarily work in unison. The strength of the stimulus must be sufficient to activate at least one motor unit to produce any contraction at all. Once activated, all the muscle fibres (within a single muscle fibre block) in that motor unit will contract maximally to produce a muscle twitch that lasts a fraction of a second. This is known as the ALL-OR-NONE LAW as neurones and muscle fibres either respond completely (all) or not at all (none) to a stimulus.
Sliding filament theory
Stage 1
This is done as the action potential reaches the axon terminal causing acetylcholine to be released. When the motor end is activated depolarization occurs which means the motor end attaches to the muscle bed. Calcium ions are transmitted to the T-tubules into deep muscle fibres via the sarcoplasmic retuculum which surrounds each myofibril.
Stage 2
Troponin-Tropomyosin surrounds the active sites on the actin filament. The calcium ions which were taken to deep muscle fibres earlier on now bind to Troponin-Tropomyosin to reveal binding sites. These enable myosin heads to attach to actin to form a cross-bridge.
Stage 3
The contraction happens. For this contraction to occur the actin cross bridge needs to be energised. This form of energy comes from Adenosine Tri-Phosphate (ATP) being broken down from ATPase.
This causes the myosin to pull the actin inward in order to shorten the muscle. The H-Band disappears as the muscle shortens and the I-Band shortens as actin is pulled to the centre, closer to the Z-Line.
Stage 4
The ATP molecules cause the myosin head to detach from the actin and relax. ATP can be broken down continually if there are enough ATP molecules which results in a continual power-stroke of the cross-bridge. The contraction is ended as soon as there is a decrease in calcium ions.
Stage 5
The contraction has finished. The myosin releases from the actin filaments and the contraction is ended as the cross-bridge detaches itself. Binding sites in actin filaments are covered, the muscle relaxes and sarcomere returns to its original state of rest. Furthermore the sarcoplasmic reticulum is replenished with calcium ions ready for next time.
The Neuromuscular Junction
A typical motor neurone divides into several branches as it reaches the muscle bed.
These branches connect the motor neurone to the muscle fibres by specialised structures known as motor end-plates or neuromuscular junction. For each skeletal muscle fibre there is usually only one neuromuscular junction The transmission of neural messages along a neurone is an electrochemical process. When a neurone is not conducting an impulse it has a resting potential brought about by the outward diffusion of potassium ions (K) along a concentration gradient.
An action potential occurs at the point along the axon where the neural impulse is being propagated. It is initiated when sufficient numbers of sodium ions (Na+) are allowed to diffuse into the neurone. This depolarises the axon to a critical threshold level.
Action potentials occur in an “all-or-none fashion”. If an action potential occurs at all, it is of the same magnitude and duration no matter how strong the stimulus.
Repolarisation is the return of the membrane potential towards the resting membrane potential because of K movement out of the cell and because Na+ movement into the cell slows to resting levels. The after potential is a short period of hyperpolarisation.
The resting potential is restored by the sodium/potassium exchange pump, which returns ion concentrations to their resting values. An action potential initiated in one part of the cell membrane stimulates action potentials in adjacent parts of the membrane and so on.
The speed of propagation along neurones varies greatly from cell to cell.
Neurones that have large-diameter myelinated axons conduct action potentials faster than small-diameter unmyelinated axons.
A myelin sheath offers increased conduction velocity as a result of the action potential jumping from node to node.
Transmission of an impulse between sensory and relay, and relay and motor neurones occurs at specialised junctions called synapses.
The wave of depolarisation is unable to jump across the synaptic cleft; however,the problem is solved by the release of transmitter substances, such as acetylcholine, from the synaptic knobs. This transmitter substance diffuses across the synaptic cleft to bind with postsynaptic receptors.
The sodium gates in the membrane open, allowing sodium to enter the axon and initiate the action potential. The electrical impulse can now pass directly from one cell to another. Once the action potential is completed, the enzyme acetylcholinesterase breaks down the acetylcholine, thus clearing the gap in readiness for the arrival of the next impulse
Each whole muscle consists of a large number of motor units.
In muscles such as those in a leg or arm, there are about a thousand muscle fibres serviced by one motor unit; whereas, on smaller, more sensitive muscles such as those in fingers, there are fewer fibres per motor unit.
The nerve cell bodies of all motor units are, for a given muscle, bound together at an appropriate level in the spinal cord to give the nearest access point to that specific muscle and leave as a concentrated bundle from the ventral root of the spinal cord.
These concentrated bundles or patches are called motor neurone pools and there is a motor neurone pool for each muscle in the body.
The nature of the stimuli received at the muscle bed will determine the type of muscular response.
Davoud Qauyumi
An example of a sport that i would give would be football.
the type of fittness tranning that you would have do would be surkits.
And in the sirkit u would have to do running,wheight lifting to help grow the leg muscels, and swimming.
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