Motor control Flashcards
(94 cards)
The activation of muscle fibres is ___ or ____.
The activation of muscle fibres is all or none.
A skeletal muscle is attached to the bone by a ______.
A skeletal muscle is attached to the bone by a tendon.
A skeletal muscle comprises of several what?
Muscle fasiculi.
Each muscle fasiculus comprises of several what?
Muscle fibres.
Each muscle fibre comprises of several what?
Myofibrils.
Name the protein filaments contained within myofibrils.
Actin and myosin myofilaments.
What is a motor unit?
An alpha motor neurone and all the extrafusal skeletal muscle fibres it innervates.
What is an alpha motor neurone?
A lower motor neurone.
The muscle fibres in a single motor unit are located in the…
same muscle and are distributed throughout the muscle.
What determines the variation of movement of a muscle?
The number of muscle fibres a single motor neurone innervates.
How does the number of muscle fibres a single motor neurone innervates affect variation of movement?
The less fibres innervated by the motor neurone, the greater the variation of movement.
Give examples of areas with a great variation of movement.
Finger tips and tongue.
What is the effect of the activation of an alpha motor neurone?
Depolarises and causes the contraction of all the fibres in that unit.
What determines the power of a motor unit?
The number of muscle fibres contracting, which is determined by the frequency a motor neurone fires.
Where in the spinal cord are alpha motor neurones controlling the distal muscles located?
Laterally in the spinal cord.
Where in the spinal cord are alpha motor neurones controlling the proximal muscles located?
Medially in the spinal cord.
What is a neuromuscular junction?
The junction between a motor neurone and a muscle fibre.
What does the axon terminal of a motor neurone contain?
Vesicles containing neurotransmitter.
Which neurotransmitter is used at a neuromuscular junction?
Acetylcholine.
The postsynaptic membrane of the neuromuscular junction is called what?
Motor end plate.
How does the arrival of an action potential in a motor neurone effect the plasma membrane?
The action potential depolarises the plasma membrane.
Describe the effect of depolarisation of the plasma membrane at a neuromuscular junction.
Voltage-gated Ca2+ channels open, allowing Ca2+ to diffuse into the axon terminal from the extracellular fluid.
How does the action of Ca2+ ions lead to the release of ACh from the axon terminal.
Ca2+ ions bind to proteins that enable to membranes of the vesicles containing ACh to fuse with the neuronal plasma membrane, and release ACh.
By which process is ACh released into the extracellular cleft at a neuromuscular junction.
Exocytosis.