Neuroscience: Resting Potential and Action Potential

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Questions and Answers

What is the primary role of glial cells in the nervous system?

Transmit information to other neurons

Support and maintain neuronal health (correct)

Regulate blood flow to neurons

Protect the nervous system from infections

Which of the following cells are types of glial cells?

Erythrocytes

Myocytes

Astrocytes (correct)

Oligodendrocytes (correct)

What is the function of the blood-brain barrier?

Transport neurotransmitters across synapses

Facilitate communication between neurons

Keep most chemicals and pathogens out of the brain (correct)

Enhance the replication of neurons

Why is the blood-brain barrier essential for brain health?

It minimizes the risk of irreparable brain damage Signup and view all the answers

How do small uncharged molecules cross the blood-brain barrier?

By diffusion through the capillary wall Signup and view all the answers

What occurs when the endothelial cells of the blood-brain barrier shrink?

Increased susceptibility to harmful substances Signup and view all the answers

What is the typical resting membrane potential of a neuron?

-70 millivolts (mV) Signup and view all the answers

What maintains the resting potential in a neuron?

The active transport of potassium ions out of the cell Signup and view all the answers

Which mechanism does the sodium-potassium pump use to function?

Active transport Signup and view all the answers

During the resting potential, which channels primarily restrict potassium from crossing the membrane?

Potassium channels Signup and view all the answers

What happens when a virus enters the nervous system?

It likely remains in the body for life Signup and view all the answers

What occurs during hyperpolarization of an axon?

The internal charge becomes more negative. Signup and view all the answers

What happens if the threshold for an action potential is not met?

No action potential occurs. Signup and view all the answers

What is the threshold of excitation?

The level of depolarization required to trigger an action potential. Signup and view all the answers

Why is the resting potential significant for neurons?

It allows neurons to respond quickly to stimuli. Signup and view all the answers

What regulates the opening of sodium and potassium channels during an action potential?

Voltage-gated channels Signup and view all the answers

Which phase of the action potential involves the closing of sodium channels?

Repolarization Signup and view all the answers

Which ions are primarily affected by the sodium-potassium pump?

Sodium and potassium ions Signup and view all the answers

What happens to the internal charge of an axon during depolarization?

The internal charge becomes positive. Signup and view all the answers

What occurs during the relative refractory period?

A new action potential can occur with a stronger stimulus. Signup and view all the answers

What role do local anesthetic drugs have in relation to action potentials?

They block voltage-activated sodium gates. Signup and view all the answers

Where does the action potential begin in a neuron?

Axon hillock Signup and view all the answers

What causes hyperpolarization during an action potential?

Potassium ions exiting the neuron beyond normal levels Signup and view all the answers

What is the percentage of sodium ions that cross the membrane during an action potential?

Approximately 1 percent Signup and view all the answers

Study Notes

Resting Potential

Neurons maintain a resting electrical gradient, slightly more negative inside than outside.
This difference is the resting potential, typically -70 millivolts (mV).
Ion channels and pumps control ion movement across the membrane.
Sodium-potassium pump actively transports 3 sodium ions out and 2 potassium ions in.
This maintains a higher concentration of sodium outside the cell and potassium inside.
Electrical and concentration gradients affect ion movement.
The electrical gradient attracts positively charged sodium ions into the negatively charged cell.
The concentration gradient pushes sodium ions into the cell as they are more concentrated outside.
Potassium faces counteracting forces; the electrical gradient pulls it in, while the concentration gradient pushes it out.

Nerve Impulse - Action Potential

Action potentials are messages sent by axons.
They are rapid changes in membrane voltage.
Hyperpolarization occurs when the negative charge inside the axon increases (e.g., -70 mV becomes -80 mV).
Depolarization occurs when the negative charge inside the axon decreases, closer to zero (e.g., -70 mV becomes -55 mV).
The threshold of excitation is the depolarization level needed for an action potential to occur.
Action potentials follow the all-or-none law, their amplitude and velocity are independent of the stimulus intensity.

Glial Cells

Glia (neuroglia), are the other major components of the nervous system.
They don't transmit signals like neurons.
They are smaller and slightly more numerous than neurons.
There are several types of glia cells with different functions.
Astrocytes, oligodendrocytes, microglia, radial glia, and Schwann cell.

Blood-Brain Barrier

The Blood-Brain Barrier (BBB) prevents most chemicals from entering the brain.
This is because the brain doesn't have an immune system.
It protects the brain from harmful substances and viruses by forming a wall.
Endothelial cells form tight junctions in brain capillaries, creating a barrier.
Small uncharged molecules (like oxygen, carbon dioxide) and lipid-soluble molecules can passively cross.
Active transport systems move necessary chemicals across the barrier (e.g., glucose).
For example, in Alzheimer's disease, the lining of brain blood vessels shrinks, allowing harmful substances to enter.

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Description

This quiz explores the concepts of resting potential and action potential in neurons. Learn about how neurons maintain electrical gradients and how action potentials facilitate nerve impulses. Understanding these principles is essential for grasping the fundamentals of neurobiology.