Nervous System Lecture 2: Electric Properties
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Questions and Answers

What is the electrical potential of a resting nerve cell?

-70mV

Which of the following is NOT a reason why the inside of a resting nerve cell has a negative electrical charge?

  • The Sodium-Potassium pump pumps more positive charge out of the cell than it pumps into it.
  • Ion channels allow movement of ions to the inside of the cell. (correct)
  • Positively-charged Potassium ions leak out through the cell membrane.
  • The cell membrane is selectively permeable, allowing only certain types of ions to pass through.
  • There are lots of negatively-charged proteins inside the nerve cell.

What is the name of the protein embedded in the cell membrane that helps maintain the resting membrane potential?

Sodium-Potassium pump

Ion channels are ion-specific.

<p>True (A)</p> Signup and view all the answers

Which type of ion channel is always open?

<p>Ungated ion channels (C)</p> Signup and view all the answers

What is the function of a gated ion channel?

<p>To allow ions to pass through when triggered by a specific stimulus.</p> Signup and view all the answers

What type of gated ion channel is responsible for the rapid depolarization of the cell membrane during an action potential?

<p>Electrically-gated (C)</p> Signup and view all the answers

At rest, sodium channels are open.

<p>False (B)</p> Signup and view all the answers

Potassium channels are always open.

<p>False (B)</p> Signup and view all the answers

How does the movement of potassium through ungated channels contribute to the resting membrane potential?

<p>Potassium ions are more concentrated inside the cell than outside. Because ungated potassium channels are always open, they allow a continuous flow of potassium ions out of the cell, contributing to a negative charge inside the cell.</p> Signup and view all the answers

Flashcards

Resting Membrane Potential

The electrical potential difference across the membrane of a neuron when it is not actively transmitting a nerve impulse.

Inside Negative?

The inside of a resting nerve cell is typically more negative than the outside.

Phospholipid

A type of lipid molecule that forms the structural basis of cell membranes.

Negative proteins

Large, negatively charged molecules found within the cell.

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Na+/K+ Ion Exchange Pump

A membrane-bound protein pump that actively transports sodium (Na+) ions out of the cell and potassium (K+) ions into the cell, using energy from ATP.

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ATP

Energy currency of the cell, used by Na+/K+ pump to move ions across the membrane.

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Pump Ratio

The Na+/K+ pump transports 3 sodium ions out of the cell for every 2 potassium ions it transports into the cell.

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Ion Channels

Channels in the cell membrane that allow specific ions to pass through.

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Ungated Ion Channels

Ion channels that are always open, allowing a continuous flow of ions.

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Gated Ion Channels

Ion channels that can be opened or closed by a specific stimulus.

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Electrically-Gated Ion Channels

Ion channels that are opened by a change in the electrical potential across the membrane.

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Chemically-Gated Ion Channels

Ion channels that are opened by the binding of a specific neurotransmitter molecule.

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Mechanically-Gated Ion Channels

Ion channels that are opened by a mechanical stimulus, such as pressure or stretch.

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Sodium Channels

Sodium (Na+) channels are mainly electrically-gated. They are closed at rest and open when the membrane potential depolarizes.

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Potassium Channels

Potassium (K+) channels can be both electrically-gated and ungated.

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Ungated Potassium Channels

Potassium channels that are always open, allowing a constant flow of potassium ions out of the cell.

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Potassium Leak

The movement of positively charged potassium ions (K+) out of the cell through ungated potassium channels contributes to the negative charge inside the cell.

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Depolarization

A change in the membrane potential of a neuron that makes it more positive.

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Hyperpolarization

A change in the membrane potential of a neuron that makes it more negative.

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Action Potential

The process by which a neuron generates a nerve impulse.

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Refractory Period

The period after an action potential during which the neuron is less likely to fire another action potential.

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Motor Neuron

A type of neuron that transmits signals from the central nervous system (CNS) to muscles and glands.

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Sensory Neuron

A type of neuron that transmits signals from sensory organs to the CNS.

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Synapse

Specialized junctions where one neuron communicates with another neuron or muscle cell.

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Neurotransmitters

Chemical messengers released by neurons at synapses to transmit signals across the synaptic cleft.

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Excitatory Neurotransmitter

A type of neurotransmitter that is excitatory.

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Inhibitory Neurotransmitter

A type of neurotransmitter that is inhibitory.

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Synaptic Transmission

The process by which neurotransmitters are released from the presynaptic neuron and bind to receptors on the postsynaptic neuron.

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Neurotransmitter Removal

The process by which neurotransmitters are removed from the synaptic cleft after they have been released.

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Neural Integration

The process by which a neuron integrates signals from multiple other neurons.

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Net Excitatory Postsynaptic Potential (EPSP)

The sum of excitatory and inhibitory postsynaptic potentials at a neuron.

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Seizure

A disorder characterized by the disruption of electrical activity in the brain.

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Epilepsy

A condition characterized by seizures.

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Study Notes

Nervous System Lecture 2: Electrical Properties of a Resting Nerve Cell

  • Nerve cells communicate electrically. The electrical signal travels from the cell body down the axon. Chemical communication also occurs, but this lecture focuses on the electrical properties.
  • A resting nerve cell's interior is more negatively charged than its exterior. This difference is measured in millivolts (mV) and typically is -70mV.
  • The inside of the cell is more negative, while the outside is more positive.
  • Three reasons for the negative electrical charge of a resting nerve cell include
  • A higher concentration of negatively charged proteins inside the cell
  • The sodium-potassium pump
  • The behavior of ion channels

Sodium-Potassium Pump

  • The sodium-potassium pump actively moves sodium ions (Na+) out of the cell and potassium ions (K+) into the cell. This process is critical in maintaining the cell's negative resting potential.
  • This pump requires energy in the form of ATP to function.
  • The pump actively moves 3 sodium ions out of the cell and 2 potassium ions into the cell; this creates an electrochemical gradient (difference in concentration on either side of the membrane).

Behavior of ion channels

  • Ion channels are proteins that allow ions to pass through the cell membrane.
  • Channels can be either gated or ungated. Ungated channels are always open. Gated channels can open and close.
  • Several types of gated channels exist:
  • Voltage-gated channels: Open or close in response to changes in the membrane potential
  • Ligand-gated channels: Open or close in response to a specific chemical signal (ligand)
  • Mechanically-gated channels: Open or close in response to mechanical pressure or stretching
  • Ions move from areas of high concentration to low concentration.
  • At rest, sodium channels are mostly closed, allowing little sodium to cross the membrane; gated potassium channels usually allow some passive movement of potassium to maintain resting potential.
  • Ungated potassium channels allow potassium ions to leak out of the cell, contributing to the negative charge inside the cell.
  • Sodium channels are predominantly closed, keeping sodium ions outside of the cell.

Nerve Cell Activation

  • When the nerve cell is activated, the membrane potential changes. This results in a rapid reversal of the electrical charge across the cell membrane.
  • This change in charge allows an electrochemical signal to travel along the axon.

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Related Documents

Nervous System Lecture 2 PDF

Description

Explore the electrical properties of a resting nerve cell in this lecture quiz. Learn about the mechanisms behind the negative charge of the cell and the crucial role of the sodium-potassium pump. Test your understanding of nerve cell communication.

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