Neuroscience Chapter 11 - Membrane Potential

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Questions and Answers

What is the membrane potential primarily a result of?

The physical structure of the plasma membrane

The difference in concentration and charge of ions across the plasma membrane (correct)

The movement of ions in and out of the cell

Equal distribution of ions inside and outside the cell

How does the presence of an electrical gradient influence ion movement?

Ions are equally likely to move in any direction

Ions will not move until an external force is applied

Positively charged ions are attracted to negatively charged areas (correct)

Ions will move away from regions with similar charge

What is true about the charge inside and outside of most cells?

The inside is generally more positively charged than the outside

The outside is usually more negatively charged than the inside

The outside is typically more positively charged than the inside (correct)

The inside and outside have the same charge

What measurement technique could be used to assess the membrane potential?

An oscilloscope using both a reference electrode outside and a recording microelectrode at the cell surface Signup and view all the answers

What is created when there are higher amounts of particular ions on one side of the plasma membrane?

Concentration gradient Signup and view all the answers

Which statement best describes the characteristics of neurons in relation to membrane potential?

Neurons utilize their charge difference more effectively than most other cells Signup and view all the answers

What happens if the measurement electrodes are both placed outside the cell?

The voltage reading would be approximately zero Signup and view all the answers

Why do ions move towards areas of opposite charge?

Opposite charges create an attractive force Signup and view all the answers

What primarily establishes the resting membrane potential in a neuron?

Higher concentration of potassium inside the cell compared to sodium Signup and view all the answers

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

They increase the permeability of the membrane primarily to potassium Signup and view all the answers

At resting membrane potential, what is the approximate electrical charge difference across the membrane in neurons?

Negative 70 millivolts Signup and view all the answers

How do negatively charged proteins contribute to resting membrane potential?

They contribute to the small negative charge just inside the membrane. Signup and view all the answers

What happens when a potassium channel opens in terms of ion movement?

Potassium ions will primarily move in accordance with their concentration gradient. Signup and view all the answers

What is the primary ion that influences the resting membrane potential due to its higher permeability?

Potassium Signup and view all the answers

What establishes the balance between the influx and efflux of potassium ions in a resting neuron?

The opposing electrical gradient generated by negatively charged proteins Signup and view all the answers

Why is the concentration of sodium higher outside the neuron than inside?

The sodium-potassium pump actively transports sodium out. Signup and view all the answers

What is the primary focus of the lecture on resting membrane potential?

The creation of electrical signals Signup and view all the answers

Which component of the cell membrane is primarily responsible for controlling the movement of substances in and out of the cell?

Transport proteins Signup and view all the answers

What do the colored structures in the image represent?

Transport proteins Signup and view all the answers

Which of the following best describes the resting membrane potential?

The difference in electric charge on either side of the membrane when the neuron is not actively transmitting signals Signup and view all the answers

What effect does the phospholipid bi-layer have on the movement of substances?

It restricts movement of certain ions or molecules Signup and view all the answers

Why is controlling the movement of ions across the membrane important for neurons?

To establish and maintain resting membrane potential necessary for electrical signaling Signup and view all the answers

What is depicted in the blown-up version of the axon cell membrane?

Phospholipid bi-layer and transport proteins Signup and view all the answers

Where can key features of cell membranes be reviewed?

Chapter 3 of the textbook Signup and view all the answers

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

It becomes more negative because negatively charged proteins remain. Signup and view all the answers

What primarily establishes the resting membrane potential?

The balance between potassium ions moving in and out of the cell. Signup and view all the answers

How does the movement of potassium ions illustrate the concept of an electrical gradient?

Positive potassium ions are attracted to the negative charge inside. Signup and view all the answers

What role do negatively charged proteins play when potassium leaves the cell?

They create a negative charge inside that attracts potassium back. Signup and view all the answers

What will occur if more potassium ions begin to leave the cell?

The interior of the cell will continue to become more negative. Signup and view all the answers

What prompts potassium ions to move back into the cell despite a concentration gradient favoring their exit?

The attraction to the negative charge inside the membrane. Signup and view all the answers

What is the initial effect on the charge outside the cell when potassium ions exit?

The outside charge becomes net positively charged. Signup and view all the answers

What creates a concentration gradient for potassium ions inside the cell?

The activity of the sodium-potassium pump. Signup and view all the answers

What does a negative resting membrane potential indicate about the cell's interior compared to its exterior?

The inside of the cell is more negatively charged than the outside. Signup and view all the answers

How does the concept of potential difference across the membrane relate to values like positive 70 millivolts and negative 70 millivolts?

Both values represent the same potential difference across the membrane. Signup and view all the answers

What happens to membrane potential if potassium ion channels are increased?

The membrane potential increases due to enhanced movement of potassium out of the cell. Signup and view all the answers

What is the relationship between resting membrane potential and potassium's ability to diffuse out of the cell?

Resting membrane potential is proportional to the potential for potassium to diffuse, not to the flow rate. Signup and view all the answers

What misunderstanding do students often have regarding decreasing membrane potential?

They believe decreasing membrane potential means becoming more negative. Signup and view all the answers

What would a resting membrane potential of negative 90 millivolts signify for muscle tissues?

Muscle tissues have a resting potential that is more negative than most cells. Signup and view all the answers

What does the term 'equilibrium' refer to in the context of potassium movement at resting membrane potential?

A condition where the electrical and chemical gradients for potassium balance. Signup and view all the answers

What is the implication of a cell having a resting membrane potential significantly different from zero?

It necessitates a continuous input of energy to maintain that potential. Signup and view all the answers

What is the primary function of ATP in the sodium-potassium pump?

It provides energy to maintain the ion concentration gradients. Signup and view all the answers

What happens to the binding sites of the sodium-potassium pump after ATP is broken down?

They face towards the outside of the cell, allowing sodium to leave. Signup and view all the answers

What occurs immediately after sodium ions leave the sodium-potassium pump?

Potassium ions bind to the pump. Signup and view all the answers

How does the sodium-potassium pump counteract the leakage channels present in the cell membrane?

By using ATP to transport ions against their concentration gradient. Signup and view all the answers

What is the result when the inorganic phosphate detaches from the sodium-potassium pump?

It allows the pump to return to its original shape. Signup and view all the answers

Which statement accurately describes the concentration of sodium and potassium ions in a resting cell?

High potassium concentration inside the cell and low sodium concentration outside. Signup and view all the answers

What is the mechanism by which sodium ions move during the operation of the sodium-potassium pump?

They are actively transported out of the cell against their concentration gradient. Signup and view all the answers

Which of the following best describes the role of leak channels in a resting cell?

They allow potassium to leave and sodium to enter the cell. Signup and view all the answers

Study Notes

Introduction

Neurons create electrical signals, a process studied in membrane potential
Membrane potential defines the electrical charge difference across the neuron membrane
Initial study of neuronal structure followed by membrane potential creation

Slide 1

Lecture material in chapter 11 of the textbook, focusing on electrical signals and resting membrane potential
Key cell membrane features crucial for understanding
Membranes composed of phospholipid bilayers, with embedded transport proteins
Proteins control what enters/leaves cell, crucial for membrane potential
Review of chapter 3 for further details on cell membranes recommended

Slide 2

Neurons are electrically excitable; they transmit signals
Polarized membranes have different charges on either side
Ions with different charges (cations, anions) create a charge difference
The difference in ion concentration creates both concentration and electrical gradients across the membrane

Slide 3

Similar charges repel, opposite charges attract
Polarized membrane created by separating charges across the membrane
Separated charges create potential, a voltage, or electrical force

Slide 4

Neurons and other cells have charge differences across the membrane
Outside the membrane is positive, inside is negative typically
A microelectrode measures the difference in charge across the membrane: voltage or membrane potential
Voltage difference of negative 70 millivolts (mV) is the resting potential of a neuron

Slide 5

Describes resting membrane potential as the difference in voltage when not actively sending a signal
Explains the relationship between ion concentrations on either side of the cell membrane
Shows a table of ion concentrations (e.g., sodium, potassium, calcium, chloride, and proteins). Explains higher/lower concentrations

Slide 6

Explains the sodium-potassium pump, an active transport mechanism
Sodium-potassium pump actively moves sodium ions out and potassium ions in, maintaining concentration gradients
This process requires energy, using ATP, and plays a fundamental role in maintaining resting membrane potential

Slide 7

Describes leak channels, channels that are always open, allowing ions to diffuse down their concentration gradients.
Sodium and potassium leak channels are described
Concentration gradients are crucial to maintain the cell's resting state.

Slide 8

Explains how ion channels affect membrane permeability and maintain ion concentrations
Two main types of ion channels are explained: leak channels (always open) and gated ion channels (open/close based on signals).
Gated channels are crucial for changing the membrane potential

Slide 9

Demonstrates the structure of the plasma membrane, with sodium and potassium ion channels
Shows differing ion concentrations inside and outside the membrane
Highlights the resting membrane potential of -70mV as a result of these concentration imbalances
Explains that resting membrane potential is NOT determined by the rate of ion movement, instead results of ion separations across the membrane

Slide 10

Resting membrane potential characteristics are summarized
Ion concentration differences and leak channel permeability are key factors
Resting potential is a prerequisite for generating electrical signals in neurons
Summary of ion concentrations and their roles in setting up the resting potential

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Description

This quiz covers the essential concepts presented in Chapter 11 of your neuroscience textbook, focusing on the creation of electrical signals through membrane potential. It will test your understanding of neuron structure, membrane composition, and the roles of ions in establishing charge differences across membranes. Familiarity with Chapter 3 on cell membranes is also advised.