Structure of a Skeletal Muscle & Muscle Fibre Types
What colour are slow twitch muscle fibres?
Red
Name the two protein filaments in a sarcomere.
Actin & Myosin
Complete this statement:
The smaller the _________ ________ (innervates a small number of muscle fibres), the more precise the action of the muscle, the _______ the size of the action ________. E.g. the eye.
The smaller the motor unit (innervates a small number of muscle fibres), the more precise the action of the muscle, the lower the size of the action potential (AP). E.g. the eye.
The inverted U looking graph is representing which relationship?
Force-Length
True or False:
The greater the weight, the more motor units are required. The brain sends messages to more motor units to fire by decreasing the size of the stimulus.
FALSE
The greater the weight, the more motor units are required. The brain sends messages to more motor units to fire by increasing the size of the stimulus.
What is the structure that contains a chain of sarcomeres, which are composed of actin and myosin filaments responsible for creating movement?
Myofibrils
A neurochemical stimulation results in __________ being released by the sarcoplasmic reticulum into the sarcomere.
Calcium
The nervous system can be divided into two parts, what are they?
1.Central Nervous System
2.Peripheral Nervous System
In a Concentric muscle contraction, if maximum force is wanting to be achieved, what happens to the velocity?
It must be low
Identify the fibre diameter for Type I, Type IIA and Type IIB.
Type I - Small
Type IIA - Intermediate
Type IIB - Large
Name the three connective muscle tissues that make up skeletal muscles.
Epimysium
Perimysium
Endomysium
According to the sliding filament theory, when a muscle fibre shortens, which of the following also shortens?
(a) actin
(b) myosin
(c) sarcomere
(d) Z-line
(c) sarcomere
List the 4 structures that make up a motor neuron
Dendrites
Cell Body
Axon
Motor End Plates or Axon Terminals
Define Force-Velocity Relationship
Describes the relationship between force production and the velocity of movement
If an athlete is competing in the 800m track event, what muscle fibres would need to be recruited?
Type 1 & Type IIA
Type IIb fibres – ___________ force, ___________ time to exhaustion
Type IIb fibres – largest force, shortest time to exhaustion
For the statements below, identify the correct order of events for the Sliding Filament Theory of muscle contraction.
i calcium leaves the sarcomere
ii actin reveals binding site for myosin head to connect
iii breakdown of ATP releases energy to stimulate cross bridges
iv calcium enters the sarcomere
v Z line is pulled closer together
(a) i, ii, iii, v, iv
(b) i, iii, ii, v, iv
(c) iv, ii, iii, v, i
(d) iv, iii, ii, v, i
(c) iv, ii, iii, v, i
Define Motor Unit
The motor neuron and the muscle fibres it activates / innervates is called a motor unit.
When the muscle is fully lengthened, only a small force can be generated due to.....
Insufficient overlap of actin and myosin filaments, reducing potential to contract
Identify in order the structures of the neuromuscular system from identifying a stimulus to completing a movement and providing feedback.
Sensory Neuron
Brain
Spinal Cord
Motor Neuron
Sensory Neurons
Brain
In skeletal muscle, which is the correct order from superficial (closest to the skin) to deep?
(a) epimysium, fascicle, perimysium, muscle fibre, myofibril
(b) epimysium, perimysium, fascicle, myofibril, muscle fibre
(c) epimysium, perimysium, fascicle, muscle fibre, myofibril
(d) perimysium, epimysium, fascicle, muscle fibre, myofibril
(c) epimysium, perimysium, fascicle, muscle fibre, myofibril
Draw and label a sarcomere in the Sliding Filament Theory
Z Line
H Zone
Actin
Myosin
Crossbridges
Define All or None Principle
When a motor unit receives stimulation/impulse/action potential to threshold, all the muscle fibres associated with that motor unit will contract to their maximum potential.
Why is it that during a concentric muscle contraction, the greater the force required, the slower the speed of contraction?
This is due to the number of cross bridges that can be attached between the myosin and actin
There are 3 types of muscle contraction, identify what each type of muscle contraction does.
Concentric
Isometric
Eccentric
1.Concentric - muscle shortens
2.Eccentric - muscle lengthens
3.Isometric - muscle does not change length