Objectives:
• Describe a motor unit and how it is involved in skeletal muscle contraction.
• Describe the attachments of muscles and how this affects muscle action.
• Define the actions of muscles.
• Describe the roles a muscle can play.
• Understand that the same muscle can have different actions and roles.
A nerve cells innervates from the distal end of a muscle so as to innervate the entire area of the muscle.
Answer
True
False
Question 4
Question
Choose the correct statements about the NMJ.
Answer
The axon coming to the NMJ is commonly unmyelinated.
The NMJ can have multiple motor end plates.
The synaptic cleft utilises chemical transmission methods.
A NMJ endplate always situates beside the nucleus of the myocite.
Question 5
Question
[blank_start]Ca++[blank_end] and [blank_start]ATP[blank_end] allow the myosin and actin [blank_start]microfilaments[blank_end] to interdigitate without losing any of their [blank_start]length[blank_end].
Answer
Ca++
Na+
ATP
K+
microfilaments
myofilaments
length
ionic mass
Question 6
Question
Choose the correct components of the motor unit:
Answer
Motor neuron and the muscle it innervates
Motor neuron
Motor neuron, and all the muscles it innervates
Question 7
Question
Myasthenia gravis is a neuromuscular disease which blocks the ACh receptors, meaning signals from the motor neuron do not reach the NMJ and muscle.
Answer
True
False
Question 8
Question
Muscle fibres display no intermediate activation, it is all or none.
Answer
True
False
Question 9
Question
Which of these does not effect force of contraction?
Answer
Size of motor units
Number of motor units
Rate of firing
Neurotransmitter used
Question 10
Question
Bones act as levers which can primarily...
(Choose all correct.)
Answer
stabilise a joint position
overcome loads
allow a large range of motion and give speed to movement
prevent stress on bone
Question 11
Question
A student lifts a textbook. Which action is this?
Answer
Concentric
Isometric
Eccentric
Question 12
Question
Which statement best describes isometric muscle action.
Answer
The muscle is active and develops tension, but does not move.
The muscle is active and develops tension, keeping a constant length and constant joint position.
The muscle is inactive but developing tension, keeping a constant length and constant joint position.
Question 13
Question
If a muscle is active, developing tension, and lengthening, it is:
Answer
Eccentric
Concentric
Isometric
Question 14
Question
You stand with your weight on your left leg. What muscle role is the quadriceps taking?