34 Questions
What type of ion channels are NOT present in the myelinated areas where action potential/refractory period occurs only at Nodes of Ranvier?
Calcium channels
What is the function of myelination in relation to axons?
Allow axons to have small diameters while transmitting action potentials rapidly
What is the role of the synapse in neural communication?
Integration of signals between neurons
What determines whether inputs from another axon are excitatory or inhibitory at the synapse?
Ion channels opened at the synapse
What occurs when a chemical messenger binds to receptors on the postsynaptic cell at a synapse?
Opening of ion channels
What is the state of the sodium channel during the hyperpolarization phase?
m gate open, h gate closed
Which phase sees the potassium channel activated by Na+ entering the cell and changing the membrane potential?
Repolarization Phase
What must happen before an action potential can be generated in terms of sodium channel inactivation?
The h gate opens
Which channel must be open for the repolarization phase to occur?
Potassium channel - h gate
What is the role of the inactivation (h) gate in returning to the resting potential?
Opens the h gate
What type of channels are generally considered inhibitory in the context of neuronal signaling?
Cl channels
What is the principle that describes the phenomenon where once the electrical impulse reaches a certain level of intensity, it fires and moves all the way down the axon without losing any intensity?
All or nothing principle
Which ion's influx increases the membrane potential and favors the formation of an action potential?
Na+
What term is used to describe when the action potential becomes more negative?
Hyperpolarization
What type of presynaptic neurons favor depolarization and generating a new action potential?
Excitatory Presynaptic Neurons
In the Hodgkin and Huxley Experiment, what did they find happens when an electrical stimulation is introduced to a region of the axon?
It causes major depolarization
Which type of presynaptic neurons make it more difficult for an impulse to cross the synapse?
Inhibitory Presynaptic Neurons
Which of the following channels is responsible for the inactivation of sodium channels during an action potential?
Delayed-Rectifier Potassium Channel
What is the main effect of opening Na+ or Ca+ channels at a synapse?
Stimulate depolarization
What happens to the membrane potential after there is a massive increase due to depolarization?
It briefly drops below the resting potential
What is the membrane potential level of a typical action potential after depolarization?
+50 mV
What type of event are action potentials classified as?
All-or-none events
What is the period called during which it is impossible to cause another action potential to be produced?
Refractory period
What triggers action potentials in neurons?
Depolarization
What type of ion channels are stimulated by excitatory presynaptic axons?
Sodium channels
What happens to the depolarization after it occurs in an axon?
It quickly returns to its resting potential
If sodium is removed from the system, what effect does it have on action potential?
It decreases the height of the action potential
Which stage of action potential involves a massive spike in depolarization?
Depolarization
What is the function of voltage-gated sodium channels?
They are gated by depolarization of the membrane
What is the role of the Delayed-Rectifier Potassium Channel in the recovery of membrane potential?
It helps recover the membrane potential to the starting level.
During the refractory period, what is the status of the m gate in sodium channels?
Closed
What happens to the h-gate of sodium channels 5 ms after depolarization?
Closes
How do One Gates m gate and h gate differ in their response to membrane potential changes?
m gate opens immediately, h gate opens with a delay
What characterizes the refractory period of an axon in terms of sodium channel opening?
The channel remains closed regardless of membrane potential.
Test your understanding of the action potential threshold and the all or nothing principle. Explore how inactivation of sodium channels and the increase in membrane potential play a role in the firing of electrical impulses along the axon.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
