Muscle Control Flashcards
What are the subdivisions of the nervous system?
- Topographical subdivisions
- Functional subdivisions
- Directional subdivisions
What is included in the topographical subdivisions?
- central NS - brain and spinal cord
- peripheral NS - cranial and spinal nerves
What’s included in functional subdivisions?
- somatic (voluntary)
- visceral (involuntary) also includes the sympathetic and parasympathetic subdivisions
What’s included in the directional subdivisions?
- Afferent = towards brain and spinal cord
- Efferent = away from the brain and spinal cord
what is a neuron?
- A type of nerve cell that transmits information quickly
What do dendrites do?
-Synapse with other neurones to receive information
What does and axon do?
- axon rapidly conduct action potential to distant site
- myelination enhances conduction speed
What is a motor neuron?
- Efferent nerve cell transmitting information from CNS to muscle to elicit contraction
- they are excitatory
Complete the sentence … each skeletal muscle fibre is innervated by …
- one motor neurone
- but each neurone can innervate few or many fibres
Skeletal muscle requires innervation from what to contract?
- motor neurons
The pattern of muscle contraction (strength, speed, duration) is determined by what?
- the pattern of activity in motor neurons
what is a motor unit?
- A motor neurone plus all the muscle fibres it innervates
Ratio of neurone to muscle fibres depends on what?
- the muscle function
If a muscle has fine control and low force what size motor unit would it have?
- small motor unit
If a muscle has less control and a large force what size motor unit would it have
- large motor units
What can muscle force be controlled by?
- number of motor units recruited
- altering pattern of activity within a motor unit
What is a neuromuscular junction?
- A specialised chemical synapse between motor neurone and muscle
Synaptic vesicles contain what neurotransmitter? and what does it do?
- acetylcholine which enforces one-way messaging
why is the sarcolemma folded at the neuromuscular junction
- to increase surface area
How do we ensure that there is only one action potential per nerve?
- Acetylcholinesterase rapidly degrades Ach left in the cleft
How can you detect muscle action potentials?
- electromyography can be used to detect electrical activity in muscles
What is the function of T-tubules?
- T-tubules conduct an action potential deep into the muscle fibre
- T-tubules surrounded by sarcoplasmic reticulum
What is the function of the sarcoplasmic reticulum?
- Store of calcium ions
What are coupled receptors?
- voltage-sensitive proteins in the T-tubules which are linked to calcium channels in the sarcoplasmic reticulum
