30 Questions
What happens when a weak stimulus is applied to a nerve trunk?
Only a proportion of the nerve fiber is excited
During the Absolute Refractory Period (A.R.P.), what occurs in the nerve fiber?
Excitability is completely lost due to complete depolarization
What is the main factor affecting the velocity of conduction in nerve fibers?
Type and diameter of the nerve
What is the process called where the nerve impulse jumps from node to node in a myelinated nerve fiber?
Salutatory conduction
How does the excitability change during the Relative Refractory Period (R.R.P.)?
Gradually increases to normal level
How does stimulation of a nerve affect the propagation of a nerve impulse in an unmyelinated nerve fiber?
Flow of electrical currents between active and inactive areas affect propagation
What is the preferred type of stimulus to stimulate a nerve fiber?
Electrical stimulus
What is the purpose of the strength duration curve?
To illustrate the reciprocal relation between strength and duration of stimulus
What does rheobase refer to in the context of nerve stimulation?
The minimum strength below which no response occurs despite stimulation duration
What does chronaxie represent in nerve stimulation?
The time taken for tissue excitation with double the rheobase strength
What is the resting membrane potential of a nerve cell typically?
-70 mV
How does the strength duration curve demonstrate the relationship between strength and duration of a stimulus?
By indicating that greater strength is needed for shorter durations to cause a response
What is the junction between a nerve and a muscle called?
Neuromuscular junction
What is the potential required to trigger the action potential in neuromuscular transmission?
$-40$ mV
What happens to acetylcholine after it triggers muscle contraction?
It is hydrolyzed into choline and acetate
How do Ca++ ions affect the release of acetylcholine at the neuromuscular junction?
Increase release of acetylcholine
What is the continuous state of localized subthreshold depolarization at the motor end plate during rest called?
End plate potential
What is the main component of a motor unit?
One anterior horn cell and its axon
During the -ve after potential, what happens to the excitability of nerve fibers?
It increases
Which type of nerve fiber has the highest velocity of conduction?
A Fiber
Which type of nerve fiber has very high excitability?
A Fiber
What is responsible for restoring the normal ionic distribution in a nerve fiber after an action potential?
Membrane pump
Which type of nerve fiber is involved in proprioception, such as muscle spindle la & Golgi tendon organs?
A Fiber
What happens during the +ve after potential in terms of excitability and conduction velocity?
Both excitability and conduction velocity are depressed
What is the main cause of the resting membrane potential according to the text?
High concentration of K+ inside the cell
Which ion does the cell membrane show high permeability to, contributing to the resting membrane potential?
K+ ions
What happens during depolarization of the cell membrane?
K+ ions influx into the cell
What is one of the properties of action potential mentioned in the text?
The magnitude and duration are constant obeying all-or-none law
What occurs at the end of depolarization during action potential changes?
Na+ permeability returns to normal
What is responsible for the movement of Na+ ions into the cell during depolarization?
Increased permeability to Na+ ions
Test your knowledge on action potential, membrane permeability, ionic distribution, and after potentials in neuron physiology.
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