In: Biology
The process of movement requires and interaction
between muscle fibres and bone tissue to pull about a joint.
Construct an information leaflet that can be used at a local Gym to
explain the processes involved in muscular contraction and movement
of the skeleton. In this leaflet ensure that the following points
are addressed: you need to do it in a leaflet I will do it.
1) explain the mechanical process of contraction (there is no need
to address nerve impulses here)
2) Analysis the roles of antagonist, agonist and synergist muscles
and their contractions. This should be linked to specific examples
in the body.
3) The different types of fibres that make up muscle tissue and how
they work together to produce movement relating to their
properties.
4) The components of skeletal muscle fibres and a comparison
between them
The steps are involved in muscle contraction:
The cycle of actions leading to contraction is initiated someplace in the central nervous system which is either as voluntary action from the brain or as reflex action from the spinal cord. Activation of motor neuron in the ventral horn of the spinal cord while an action potential passes away from in a ventral root of the spinal cord.The axon branches to make available a numeral of muscle fibers known as motor unit while the action potential is conveyed to a motor end plate on every muscle fiber.Then at the motor end plate, the action potential releases of packets of acetylcholine into the synaptic clefts which are on the exterior of the muscle fiber.Acetylcholine initiates the electrical resting potential beneath the motor end plate to vary which then initiates an action potential that passes in both directions all along the surface of the muscle fiber. Upon the opening of every transverse tubule onto the muscle fiber surface, action potential spreads within the muscle fiber.At each point where a transverse tubule touches part of the sarcoplasmic reticulum, it causes the sarcoplasmic reticulum to discharge Ca++ ions. Then the calcium ions result in progress or movement of troponin and tropomyosin on their thin filaments which enables the myosin molecule heads to “grab and swivel” their way all along the thin filament, which is the driving force of muscle contraction.
Contraction is turned off by the following of events:
The Acetylcholine at the neuromuscular junction is broken down by acetylcholinesterase which terminates the flow of action potentials all along the muscle fiber surface. Then sarcoplasmic reticulum stops to liberate calcium ions, and without delay starts to resequester all the calcium which have been released. When there is a absence of calcium ions, a alteration in the configuration of troponin and tropomyosin stops or blocks the action of the myosin molecule heads while the contraction ceases. In living animal external stretching force, as gravity or an antagonistic muscle, pulls the muscle back to its original length.
a). Agonist: The agonist in a movement is the
muscle(s) which gives the main force in order to complete the
movement. It is due to this agonists are called as the ‘prime
movers’. The biceps muscle, agonist in the bicep curl produces
flexion at the elbow.
The agonist is not for all time the muscle which is shortening. In
a bicep curl the bicep is the agonist on the way up as it contracts
concentrically while on the way down as it contracts eccentrically.
It is as it is the prime mover in both cases.
b). Antagonist: The antagonist in a movement refers to the muscles which combat the agonist. All through elbow flexion where the bicep is the agonist and the tricep muscle is the antagonist. As the agonist contracts causing the movement to happen while the antagonist typically relaxes so as not to obstruct the agonist.
The antagonist doesn’t for all time relax though, an additional
role of antagonist muscles can be to slow down or to stop a
movement. We can see this if the weight involved in the bicep curl
is extremely heavy, when the weight is lowered from the top
location the antagonist tricep muscle produces a adequate amount of
tension to have power over the movement as the weight lowers.
This helps to make sure that the gravity doesn’t speed up the
movement causing injury to the elbow joint at the bottom of the
movement. While the tricep becomes the agonist and the bicep the
antagonist as the elbow extends in opposition to gravity as in a
push up, a bench press or a tricep pushdown.
c). Synergist: The synergist in a movement is the
muscle(s) which stabilizes a joint in the region of which movement
is occurring, that helps the agonist function efficiently.
Synergist muscles also help to produce the movement. In the bicep
curl synergist muscles are the brachioradialis and brachialis.
These muscles help the biceps to produce a movement and stabilize
the elbow joint.