[05] Motor Units and Muscle Tone Flashcards
What is a “Motor Unit”?
A single motor neuron and all the muscle fibers it innervates
What is the “All-or-None Law” in relation to motor units?
If a motor neuron fires, all the muscle fibers it controls will contract
What is “Muscle Tone”?
The constant, low-level contraction of a muscle
How is muscle tone maintained?
By alternating activation of different motor units
Why is muscle tone important?
- Maintains posture
- Helps keep muscles ready for action
What is a “Motor Neuron”?
A nerve cell that controls muscle contraction
What is a “Muscle Fiber”?
An individual muscle cell
How does the size of a motor unit relate to precision of muscle control?
Smaller motor units allow for more precise control
What is the process of “Recruitment” in motor units?
Activating more motor units to increase the strength of muscle contraction
What happens when all motor units in a muscle are activated?
The muscle contracts maximally
How does the nervous system control the force of muscle contraction?
By varying the frequency of motor neuron signals and recruiting more or less motor units
What is a “Twitch” in muscle physiology?
A single, brief contraction and relaxation cycle in a muscle fiber
What is the “Summation” of twitches?
When a second twitch occurs before the muscle has fully relaxed from the first twitch, increasing the strength of contraction
What is “Tetanus” in muscle physiology?
When the muscle fiber is stimulated so rapidly it doesn’t have a chance to relax at all between stimuli, leading to a sustained contraction
What is “Isotonic Contraction”?
Muscle contraction where the length of the muscle changes
