30 Questions
What is the resting potential of a neuron?
-70mV
What is the main role of axons in our vision?
Compensating for movement accuracy
What covers a neuron and is composed of 2 layers of phospholipid molecules?
Membrane
What provides the membrane of a neuron with a combination of flexibility and firmness?
Proteins
What is the role of electrical gradient (polarization) in a neuron?
Maintaining resting potential
What type of channels permit certain ions to cross through the neuron membrane at a controlled rate?
Protein channels
What is the main reason a neuron inside the membrane has a slightly negative electrical potential with respect to the outside?
Presence of negatively charged proteins inside the cell
How is resting potential in a neuron typically measured?
By inserting a very thin microelectrode into the cell body
What is the typical level of resting potential in a neuron?
-70 millivolts
What is the most common electrode used for recording activity of a neuron?
A fine glass tube filled with a concentrated salt solution
Which chemicals pass through a neuron membrane more freely because channels for them are always open?
Oxygen, carbon dioxide, urea, and water
What are the biologically important ions that cross membrane channels sometimes open or closed?
Sodium, potassium, calcium, and chloride
What happens to the resting potential when the neuron is stimulated?
It remains stable
What is the molecular basis of action potential regarding sodium and potassium ions?
Sodium ions are mostly outside and potassium ions are mostly inside
What happens at the peak of the action potential?
Sodium channels close
What is the function of a voltage-gate channel?
Regulating the permeability of sodium and potassium based on charge
During the resting potential, what is the state of potassium channels?
Almost closed
What does hyperpolarization refer to?
Increase in polarization
What happens to the sodium-potassium pump after an unusually rapid series of action potentials?
It accumulates sodium within the axon.
Under what conditions does excessive stimulation leading to the buildup of toxic sodium typically occur?
During a stroke or after using certain drugs.
What is the role of local anesthetic drugs like NOVOCAIN and XYLOCAIN on the sodium channels of the membrane?
Prevent sodium ions from entering.
What do action potentials require for their occurrence?
Movement of both sodium and potassium ions.
How do local anesthetic drugs like NOVOCAIN and XYLOCAIN affect the transmission of pain signals?
Prevent pain signal transmission to the brain.
What happens when a dentist administers NOVOCAIN before a dental procedure?
Axons cannot transmit pain signals to the brain.
What is the function of the sodium-potassium pump?
Transport three sodium ions out of the cell and two potassium ions into the cell
During rest, why do very few sodium ions cross the membrane?
Due to the closed sodium channels preventing sodium flow
What is the role of potassium channels during rest?
They allow slow potassium flow as they are nearly but not entirely closed
Which ions are more concentrated outside the neuron when the membrane is at rest?
Sodium ions
What happens to the electrical gradient across the membrane as potassium ions leak out slowly?
It increases
Why does the selective permeability of the membrane make the Sodium Potassium Pump (SSP) effective?
To prevent leaking back of sodium ions that are pumped out of the neuron
Test your knowledge on how cell membrane functions in maintaining ion concentrations through mechanisms like sodium channels and sodium-potassium pump. Understand the roles of these processes in creating concentration gradients for sodium and potassium ions.
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