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.
Respuesta
True
False
Pregunta 4
Pregunta
Choose the correct statements about the NMJ.
Respuesta
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.
Pregunta 5
Pregunta
[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].
Respuesta
Ca++
Na+
ATP
K+
microfilaments
myofilaments
length
ionic mass
Pregunta 6
Pregunta
Choose the correct components of the motor unit:
Respuesta
Motor neuron and the muscle it innervates
Motor neuron
Motor neuron, and all the muscles it innervates
Pregunta 7
Pregunta
Myasthenia gravis is a neuromuscular disease which blocks the ACh receptors, meaning signals from the motor neuron do not reach the NMJ and muscle.
Respuesta
True
False
Pregunta 8
Pregunta
Muscle fibres display no intermediate activation, it is all or none.
Respuesta
True
False
Pregunta 9
Pregunta
Which of these does not effect force of contraction?
Respuesta
Size of motor units
Number of motor units
Rate of firing
Neurotransmitter used
Pregunta 10
Pregunta
Bones act as levers which can primarily...
(Choose all correct.)
Respuesta
stabilise a joint position
overcome loads
allow a large range of motion and give speed to movement
prevent stress on bone
Pregunta 11
Pregunta
A student lifts a textbook. Which action is this?
Respuesta
Concentric
Isometric
Eccentric
Pregunta 12
Pregunta
Which statement best describes isometric muscle action.
Respuesta
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.
Pregunta 13
Pregunta
If a muscle is active, developing tension, and lengthening, it is:
Respuesta
Eccentric
Concentric
Isometric
Pregunta 14
Pregunta
You stand with your weight on your left leg. What muscle role is the quadriceps taking?