Lecture 23. Motor and Sensory Systems Flashcards
How many pairs of spinal nerves are there in humans?
31
Where do motorneuron cell bodies lie?
In the ventral horn of the spinal cord
What controls the lower motorneurons?
The upper motorneurons
What is a neuromuscular junction?
Synapse between nerve and muscle
What makes up a single motor unit?
Neuromuscular junctions or motor end-plates attached to muscle fibres
What happens when a motor neuron is activated?
All the muscle fibres that it innervates contract
What are the different types of skeletal muscle?
Type I (Slow oxidative (ATP oxidative phosphorylation))
Type II (Fast oxidative (ATP oxidative phosphorylation) or Fast glycolytic (ATP through glycolysis)
How can the force of contraction be increased?
- Recruitment
- Temporal summation (tetany or taranus)
Why do muscles show fatigue?
Protective/defensive mechanism
What are the causes of muscle fatigue?
Depletion of glycogen
Accumulation of extracellular K⁺
Accumulation of lactate
Accumulation of ADP + Pi
Central fatigue (fatigue in brain)
What is the Golgi tendon reflex?
Monitors tension in the muscle
Protects muscle to prevent damage
Tendon reflex less sensitive than stretch reflex but can override it
How does sensory transduction occur?
Stimulus (touch, pressure, hot, cold, pain, etc)
Receptor
Change in permeability of nerve ending
Change in membrane potential of nerve ending (generator potential)
Generation of action potentials in nerve ending Propagation of action potentials to the CNS Integration of information by the CNS
What do generator potentials do that action potentials do not?
Generator potentials decrement during conduction Action potentials do not decrement
What are receptive fields?
Area of skin where neurone activates
