Introduction to Resting Membrane Potential
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Questions and Answers

What is the membrane potential at rest in a neuron?

  • +70 millivolts
  • -70 millivolts (correct)
  • 0 millivolts
  • -90 millivolts

What does a negative resting membrane potential indicate about the inside of a neuron compared to the outside?

  • The inside is less negatively charged than the outside
  • The inside has no charge compared to the outside
  • The inside is more negatively charged than the outside (correct)
  • The inside is more positively charged than the outside

Which ions play a critical role in establishing the resting membrane potential?

  • Sodium and potassium ions (correct)
  • Phosphate and sulfate ions
  • Calcium and chloride ions
  • Magnesium and bicarbonate ions

What happens to the voltage difference across the membrane when a neuron is activated?

<p>It becomes less negative (C)</p> Signup and view all the answers

What is the primary function of the plasma membrane in relation to ions?

<p>To separate charges and create a potential difference (A)</p> Signup and view all the answers

What is meant by the term 'resting membrane potential'?

<p>The voltage difference when the cell is not activated (B)</p> Signup and view all the answers

How is the voltage difference across the membrane actually measured?

<p>By inserting a microelectrode close to the membrane (A)</p> Signup and view all the answers

Which type of ion is designated as negatively charged?

<p>Anion (C)</p> Signup and view all the answers

What happens when two similarly charged ions approach each other?

<p>They repel each other (B)</p> Signup and view all the answers

Which of the following statements about resting membrane potential is accurate?

<p>It reflects the charge imbalance due to ion distribution. (A)</p> Signup and view all the answers

Why is it important to create a polarized plasma membrane?

<p>To create an electrical force through charge separation (C)</p> Signup and view all the answers

What is the primary cause of the charge difference across the plasma membrane in neurons?

<p>Unequal distribution of ions on either side of the membrane (D)</p> Signup and view all the answers

In which state is the outside of a typical body cell membrane usually found?

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

What analogy is used to describe the separation of charges in a plasma membrane?

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

What would occur if positive and negative ions were allowed to move freely across the plasma membrane?

<p>They would neutralize the voltage difference (C)</p> Signup and view all the answers

What is a key feature of the membranes of neurons compared to other body cells?

<p>They can separate charges more effectively (B)</p> Signup and view all the answers

What is the role of ATP in the sodium-potassium pump?

<p>It powers the active transport mechanism of the pump. (C)</p> Signup and view all the answers

What happens to the sodium ions after they are released from the pump?

<p>They are released to the extracellular space. (B)</p> Signup and view all the answers

What occurs after inorganic phosphate detaches from the sodium-potassium pump?

<p>The pump returns to its original shape allowing potassium to enter. (D)</p> Signup and view all the answers

How do leak channels impact the sodium-potassium pump's function?

<p>They create a need for the pump to maintain ion gradients. (C)</p> Signup and view all the answers

During the operation of the sodium-potassium pump, what is created when ATP is cleaved?

<p>Inorganic phosphate and ADP are produced. (B)</p> Signup and view all the answers

What is the primary ion concentration maintained by the sodium-potassium pump inside the cell?

<p>High potassium concentration. (C)</p> Signup and view all the answers

What is a consequence of the sodium-potassium pump functioning correctly?

<p>The cell can prevent excessive sodium influx. (B)</p> Signup and view all the answers

What mechanism allows potassium ions to enter the sodium-potassium pump when it is facing outward?

<p>Binding sites becoming available after sodium release. (D)</p> Signup and view all the answers

What effect does a higher number of gated channels have on membrane potential?

<p>Enhances the ability to change the membrane potential. (D)</p> Signup and view all the answers

Which of the following correctly describes the sodium-potassium pump's activity?

<p>It consumes ATP to pump 3 sodium ions out and 2 potassium ions in. (A)</p> Signup and view all the answers

What is the primary reason for the higher concentration of potassium ions inside the cell compared to sodium ions?

<p>There are more potassium leak channels than sodium leak channels. (A)</p> Signup and view all the answers

How does the concentration gradient affect potassium ions in the cell?

<p>Potassium is drawn outside the cell through its concentration gradient. (A)</p> Signup and view all the answers

What role do leak channels play in establishing resting membrane potential?

<p>They contribute to ion flow based on concentration gradients. (B)</p> Signup and view all the answers

What is the relationship between the sodium-potassium pump and basal metabolic rate?

<p>The pump's activity is a major ATP consumer, influencing energy expenditure. (D)</p> Signup and view all the answers

What dual forces are responsible for the movement of ions across the plasma membrane?

<p>Concentration gradient and electrical gradient. (A)</p> Signup and view all the answers

Which of the following correctly characterizes the ion distribution across the membrane at resting potential?

<p>Proteins are more concentrated inside the cell than outside. (C)</p> Signup and view all the answers

What happens to the net charge inside the cell as potassium ions leave?

<p>It becomes more negative due to the presence of negatively charged proteins. (B)</p> Signup and view all the answers

What is the primary driving force for potassium ions to move back into the cell?

<p>The electrical gradient created by negatively charged proteins. (D)</p> Signup and view all the answers

How does the concentration gradient affect the movement of potassium ions during resting membrane potential?

<p>It balances by allowing equal movement of potassium in and out. (A)</p> Signup and view all the answers

What is established when the flow of potassium ions in equals the flow of potassium ions out?

<p>Resting membrane potential. (C)</p> Signup and view all the answers

What role do negatively charged proteins play in the dynamics of potassium ion movement?

<p>They draw potassium ions back into the cell due to electrostatic attraction. (C)</p> Signup and view all the answers

Which statement best describes the relationship between the concentration gradient and electrical gradient for potassium ions?

<p>Both gradients influence potassium movement, leading to equilibrium. (C)</p> Signup and view all the answers

Why do potassium ions initially leave the cell despite their attraction to the negative charge inside?

<p>Their concentration inside the cell is higher than outside. (D)</p> Signup and view all the answers

What does a negative resting membrane potential indicate about the charges inside and outside the cell?

<p>The inside of the cell is negative relative to the outside. (D)</p> Signup and view all the answers

How does increasing the number of potassium ion channels affect membrane potential?

<p>It increases the membrane potential by allowing more potassium to diffuse out of the cell. (C)</p> Signup and view all the answers

What is crucial to understand about the comparison of positive 70 millivolts and negative 70 millivolts?

<p>Both values represent the same potential difference of 70 millivolts from zero. (C)</p> Signup and view all the answers

What does the rate of flow of potassium ions at resting membrane potential indicate?

<p>There is minimal movement of potassium ions due to equilibrium. (D)</p> Signup and view all the answers

Which statement correctly describes the relationship between membrane potential and potassium diffusion?

<p>Membrane potential is proportional to the potential for potassium to diffuse but not to the actual rate of potassium flow. (A)</p> Signup and view all the answers

If the resting membrane potential is around negative 90 millivolts in muscle tissue, what does this imply?

<p>Muscle cells have a more significant potential difference across their membranes. (B)</p> Signup and view all the answers

What does it mean to decrease membrane potential as indicated in the content?

<p>The magnitude of the voltage value gets closer to zero. (A)</p> Signup and view all the answers

Which characteristic is true about the resting membrane potential in relation to potassium ion distribution?

<p>Potassium ions predominantly influence resting membrane potential due to their potential to diffuse out. (B)</p> Signup and view all the answers

Flashcards

Plasma membrane and Ion Separation

The plasma membrane can separate not only molecules but also charges, specifically ions.

Membrane Permeability and Proteins

The ability of the plasma membrane to allow ions to pass through depends on the types of proteins embedded within it.

Ion Interactions

Ions with the same charge (both positive or both negative) repel each other. Ions with opposite charges attract each other.

Anion and Cation

A negatively charged ion is called an anion, and a positively charged ion is called a cation.

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Polarized Plasma Membrane

Creating a polarized plasma membrane involves separating positive and negative charges, creating a voltage difference.

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Electrical Force

The separation of charges in a polarized membrane creates an electrical force, where the charges want to move back towards each other.

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Voltage Generation

The separation of charges across the plasma membrane generates a voltage or electrical potential.

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Charge Difference in Cells

Most body cells maintain a charge difference across their membranes, typically positive on the outside and negative on the inside.

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Resting Membrane Potential

The difference in electrical charge across the plasma membrane of a neuron when it is not actively sending a signal.

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Membrane Potential at Rest

The voltage difference across the plasma membrane of a neuron, normally around -70 millivolts.

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Microelectrode

A specialized electrode used to measure the electrical potential inside a cell.

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Intracellular Fluid

The fluid inside a cell, containing dissolved ions and other molecules.

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Extracellular Fluid

The fluid outside a cell, containing dissolved ions and other molecules.

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Cations

Positively charged ions, such as sodium (Na+) and potassium (K+).

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Anions

Negatively charged ions, such as chloride (Cl-) and proteins.

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ATP's role in the sodium-potassium pump

ATP binds to the sodium-potassium pump, providing energy for its active transport function.

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How does ATP breakdown affect the pump?

When ATP is broken down into ADP and inorganic phosphate, the pump changes shape, moving sodium ions out of the cell.

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Potassium binding and pump's shape change

Potassium ions bind to the pump as sodium ions are released, and this allows the pump to return to its original shape.

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Role of leak channels in ion movement

Leak channels allow potassium ions to move out of the cell, and sodium ions to move in, causing a natural tendency towards equilibrium.

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Maintaining ion concentration gradients

The sodium-potassium pump actively moves sodium ions out and potassium ions in, maintaining concentration gradients.

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Active transport of sodium ions

The pump requires energy (ATP) to move sodium ions out of the cell against their concentration gradient.

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Sodium and potassium concentration gradients

The concentration of sodium ions is higher outside the cell than inside, and potassium is higher inside.

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Defining the sodium-potassium pump

The sodium-potassium pump is a protein embedded in the cell membrane, responsible for moving sodium and potassium across it.

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Concentration Gradient

The movement of ions across a cell membrane due to the difference in their concentration between the inside and outside of the cell.

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Electrical Gradient

The force that pushes positively charged ions towards negatively charged areas and vice versa.

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Leak Channel

A protein embedded in the cell membrane that allows specific ions to pass through passively, following their concentration and electrical gradients.

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Sodium-Potassium Pump

A protein pump that uses energy from ATP to move sodium ions out of the cell and potassium ions into the cell.

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Potassium Efflux

The tendency for potassium ions to move out of the cell through leak channels due to both concentration and electrical gradients.

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Negative Interior

The net negative charge inside the cell compared to the outside, contributing to the resting membrane potential.

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Basal Metabolic Rate

The level of metabolic activity required to maintain the ion concentration gradients and the resting membrane potential.

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Membrane Potential

The difference in electrical charge between the inside and outside of the cell membrane. It is normally negative on the inside due to the presence of negatively charged proteins.

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Electrochemical Gradient

The net movement of ions across the membrane due to both the concentration and electrical gradients.

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Polarization

The accumulation of positive charges outside the cell membrane and negative charges inside the cell membrane.

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Excitable Cell

The potential for a cell to generate an electrical signal, based on the difference in charge across its membrane.

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Why is the membrane potential negative?

The inside of the cell is typically negative relative to the outside, despite the actual values changing.

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Increasing membrane potential

Increasing the membrane potential means the difference across the membrane is becoming larger, moving further away from 0 millivolts.

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Decreasing membrane potential

Decreasing the membrane potential means the difference across the membrane is becoming smaller, moving closer to 0 millivolts.

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Greater resting membrane potential

A greater resting membrane potential means a larger difference in electrical charge across the membrane.

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Resting potential and potassium movement

The resting membrane potential is dependent on the potential for potassium to move out of the cell, not the actual rate of flow.

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Potassium channels and resting membrane potential

Increasing the number of potassium channels in the membrane increases the potential for potassium to move out, which increases the resting membrane potential.

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Resting membrane potential in muscle

Muscle tissue has a greater resting membrane potential than many other cells, usually around -90 millivolts.

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Study Notes

Introduction to Resting Membrane Potential

  • Neurons create electrical signals, and this lecture explains membrane potential
  • Membrane potential is defined first, followed by resting membrane potential creation
  • Textbook chapter 11, section 11.5 discusses electrical signals
  • Cell membrane structure and protein transporters are important concepts

Membrane Structure Review

  • Cell membranes are composed of a phospholipid bilayer
  • Phospholipid bilayer structure prevents easy movement of substances
  • Transport proteins facilitate specific ion movement across membranes
  • Proteins and ions are present on either side of the membrane

Ionic Concentration Differences

  • Ions (positively and negatively charged molecules) create an electrical gradient
  • The different ion concentrations (chloride, sodium, potassium, proteins) between inside and outside vary
  • Unequal ion distribution across the membrane generates a charge difference

Membrane Polarity

  • A polarized membrane refers to a charge difference across the membrane
  • Positive charge on the outside and negative charge on the inside is crucial
  • Repulsion of like charges and attraction of opposite charges contribute to this difference

Membrane Permeability

  • The membrane's permeability to various ions influences their movement
  • Different ion permeabilities influence membrane potential
  • Permeability changes are crucial for electrical signaling

Slide 3: Ion Interactions

  • Positively charged ions repel each other
  • Negatively charged ions repel each other
  • Positively and negatively charged ions attract each other
  • Separating charges creates a potential difference between ions

Slide 4: Electrical Nature of Neurons

  • Most cells have a charge difference (polarity)
  • Neurons utilize this difference for electrical signaling
  • Reference and recording electrodes measure voltage differences

Slide 5: Ion Concentration and Electrical Gradients

  • Intracellular and extracellular fluids have different ion concentrations
  • Chloride, sodium, and calcium concentrations are higher outside
  • Potassium and protein concentrations are higher inside
  • Ions move from high to low concentrations, attracted to opposite charges

Slide 6: Sodium-Potassium Pump

  • Active transport moves sodium out and potassium in
  • The pump utilizes ATP (energy) to maintain concentration gradients
  • Maintains concentration differences necessary for membrane potential

Slide 7: Leak Channels and Resting Membrane Potential

  • Leak channels are always open, allowing ions to diffuse
  • Ions move following their concentration and electrical gradients
  • Ions move until their concentrations and electrical gradients equilibrate

Slide 8: Gated Ion Channels

  • Gated ion channels open or close based on triggers
  • They control ion movement across the membrane
  • Different gated channels respond to different triggers

Slide 9: Resting Membrane Potential

  • Sodium and potassium leak channels and the sodium-potassium pump are key
  • The membrane maintains equilibrium across the concentration and electrical gradients

Slide 10: Summary of Resting Membrane Potential

  • The differences in ion concentrations across the plasma membrane establish the resting membrane potential. The inside is negative to the outside.
  • The relatively high concentration of potassium inside the cell and relatively low concentration of sodium inside, combined with higher concentrations of Na+ and Cl- outside, creates a membrane potential around -70mV.

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Description

This quiz covers the fundamentals of resting membrane potential as discussed in textbook chapter 11, section 11.5. It explores the structure of cell membranes, the role of transport proteins, and the ionic concentration differences that lead to electrical signals in neurons. Test your understanding of these critical concepts in cellular physiology.

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