Prepare for NEET Biology Neural Control And Coordination with MCQs & PYQs on NEET.GUIDE. Enjoy free practice, previous year questions, and expert guidance on neurons and synapses.
A neuron poisoned with tetrodotoxin (TTX) is stimulated. Which of the following would be observed?
Normal action potential generation
Delayed action potential generation
No action potential generated due to blocked channels
Hyperexcitability and spontaneous action potentials
Which statement BEST describes the role of the Nodes of Ranvier in saltatory conduction?
They insulate the axon, preventing ion leakage.
They synthesize neurotransmitters for synaptic transmission.
They allow for faster action potential propagation by concentrating voltage-gated channels.
They slow down action potential propagation, allowing for greater control.
In a demyelinating disease like multiple sclerosis, which characteristic of nerve impulse conduction is MOST directly affected?
Resting membrane potential
Threshold potential
Conduction velocity
Neurotransmitter release
The absolute refractory period of a neuron is primarily caused by:
Delayed closing of potassium channels
Inactivation of voltage-gated sodium channels
Hyperpolarization of the membrane
Depletion of neurotransmitter vesicles
During an action potential, the rapid depolarization phase is primarily caused by the:
Influx of ions
Efflux of ions
Influx of ions
Efflux of ions
A specific neurotoxin selectively blocks voltage-gated potassium channels in a neuron. What is the most likely effect on the action potential?
Increased rate of depolarization
Delayed repolarization and prolonged action potential
Prevention of action potential initiation
Hyperpolarization beyond the resting membrane potential
The absolute refractory period is primarily due to:
Increased potassium permeability
Inactivation of voltage-gated sodium channels
Hyperpolarization of the membrane
Depletion of neurotransmitter vesicles
During the relative refractory period, a stronger than normal stimulus can initiate another action potential because:
The membrane is hyperpolarized
Potassium channels are closed
Some voltage-gated sodium channels have recovered from inactivation
Neurotransmitter release is enhanced
A neuron is experimentally stimulated at multiple points along its axon. Action potentials are recorded downstream from the stimulation points. Which observation BEST supports the all-or-none principle of action potentials?
The amplitude of the action potential increases with increasing stimulus strength.
The speed of the action potential increases with increasing stimulus strength.
The amplitude of the action potential is the same regardless of the strength or location of the stimulus, as long as threshold is reached.
The frequency of action potentials increases with increasing stimulus strength, but their amplitude remains constant only at the axon hillock.
The absolute refractory period is crucial for the unidirectional propagation of action potentials. Which molecular mechanism primarily underlies this period?
Opening of voltage-gated potassium channels
Inactivation of voltage-gated sodium channels
Activity of the sodium-potassium pump
Binding of neurotransmitters to postsynaptic receptors
