Mighty Motor Units
This principle describes how motor neurons are recruited from smallest to largest, and it must remain accurate even when translated for international audiences, meaning the scientific term must not change across languages.
What is the size principle?
This process occurs when surviving axons grow new branches to reinnervate abandoned muscle fibers.
What is collateral sprouting?
This part of a muscle fiber contains the contractile units known as sarcomeres.
What is a myofibril?
This type of synapse uses gap junctions to allow direct electrical coupling between cells and is extremely fast.
What is an electrical synapse?
This ion is the primary contributor to the resting membrane potential because of its high membrane permeability at rest
What is potassium (K+)?
A single action potential produces this minimal force response from a motor unit.
What is a twitch?
This autoimmune disorder attacks the myelin of the peripheral nervous system, often after an infection.
What is Guillain-Barré syndrome?
These two proteins regulate the position of actin binding sites and must move when calcium binds.
What are troponin and tropomyosin?
In a chemical synapse, the influx of this ion into the presynaptic terminal triggers vesicle fusion and neurotransmitter release.
What is calcium (Ca2+)?
These channels are always open and allow passive movement of ions, contributing to the baseline membrane potential.
What are leak channels?
According to the Burke Protocol, a reduction in force during an unfused tetanus indicates this motor unit type.
What is a fast-twitch (type F) motor unit?
This term describes long-lasting strengthening of synapses and is the most studied mechanism of learning.
What is long-term potentiation (LTP)?
This type of contraction occurs when muscle torque is less than the load, causing the muscle to lengthen.
What is an eccentric contraction?
These receptors on the postsynaptic cell open ion channels when neurotransmitters bind, producing either EPSPs or IPSPs.
What are ligand-gated receptors (channels)?
This pump restores ion concentration gradients after activation by moving sodium out and potassium in using ATP.
What is the sodium-potassium pump (Na+/K+ ATPase)?
This term describes how motor units increase force by firing action potentials more rapidly.
That is rate coding?
Rats raised in enriched environments show increased dendritic branching in the cortex, demonstrating this type of plasticity.
What is structural neuroplasticity?
This structure increases a muscle's movement arm at the knee and improves torque production.
This disorder occurs when the immune system destroys acetylcholine receptors at the neuromuscular junction, causing muscle weakness.
What is myasthenia gravis?
This equation is used to calculate the equilibrium potential for a single ion, such as potassium or sodium.
What is the Nernst equation?
This property explains why small motor neurons reach threshold first - they have high resistance and therefore a large change in voltage for a given input.
What is low conductance (or high input resistance)?
These four key factors determine the magnitude of LTP: intensity, timing, repetition, and this meaningful quality of a task.
What is salience?
This genetic disorder results from a lack of dystrophin, leading to progressive muscle degeneration.
What is Duchenne Muscular Dystrophy?
This neurotoxin blocks synaptic transmission by disabling the vesicle fusion proteins at the neuromuscular junction, leading to temporary paralysis.
What is botulinum toxin (Botox)?
This term refers to the combined influence of chemical and electrical forces that determine the direction and magnitude of ion movement across the membrane.
What is the net driving force (NDF)?