أسئلة المحاضرة 13 فسيولوجي (قبل التعديل)
128 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary function of motor neurons?

  • Facilitate reflex responses in sensory organs.
  • Conduct motor information from the CNS to effector organs. (correct)
  • Conduct sensory information to the CNS.
  • Integrate signals within the CNS.

What characterizes the RMP (Resting Membrane Potential) in a neuron?

  • It is a potential difference with inside negative relative to the outside. (correct)
  • It is constant and does not change.
  • It exists only in nerve fibers.
  • The inside is positively charged relative to the outside.

Which type of neurons are classified as afferent?

  • Interneurons.
  • Sympathetic neurons.
  • Motor neurons.
  • Sensory neurons. (correct)

What is the term used to describe the ability of nerve fibers to respond to stimuli?

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

What is a characteristic of a nerve trunk?

<p>It contains a larger number of nerve fibers. (C)</p> Signup and view all the answers

Which property of nerve fibers describes their ability to conduct nerve impulses?

<p>Conductivity. (D)</p> Signup and view all the answers

What type of neuron functions primarily as small integrative neurons located in the CNS?

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

What is the resting membrane potential (RMP) of nerve tissue?

<p>-70mV (A)</p> Signup and view all the answers

What component covers each nerve fiber?

<p>Myelin sheath. (D)</p> Signup and view all the answers

Which ion has the highest concentration outside the nerve cell?

<p>Na+ (D)</p> Signup and view all the answers

Which type of ion channels are responsible for maintaining the resting membrane potential (RMP)?

<p>Leak or passive channels (C)</p> Signup and view all the answers

What is the main reason for the unequal distribution of ions inside and outside nerve cells?

<p>Active transport mechanisms (D)</p> Signup and view all the answers

How many times greater is the concentration gradient of K+ inside compared to outside the nerve cell?

<p>30-40 times (B)</p> Signup and view all the answers

What ions primarily enter the nerve cell due to their concentration gradient?

<p>Na+ and Cl- (D)</p> Signup and view all the answers

What is the ion concentration of Protein- inside a nerve cell?

<p>16 gm/dl (B)</p> Signup and view all the answers

What type of channels act as receptors for signaling molecules in cells?

<p>Ligand gated channels (A)</p> Signup and view all the answers

What is the main cause of the resting membrane potential (RMP)?

<p>Passive diffusion of K+ ions (B)</p> Signup and view all the answers

What happens to an ion when it diffuses across a selectively permeable membrane?

<p>It creates an electric charge separation. (A)</p> Signup and view all the answers

What defines the equilibrium potential of an ion?

<p>The balanced diffusion and repulsion forces. (A)</p> Signup and view all the answers

What is the role of diffusion force in ionic movement?

<p>It directs ions from high concentration to low concentration. (A)</p> Signup and view all the answers

What prevents Na+ ions from easily diffusing into the cell?

<p>Negative charges inside the cell creating repulsion. (B)</p> Signup and view all the answers

When is the resting membrane potential equal to the equilibrium potential?

<p>When a cell is only permeable to K+ ions. (A)</p> Signup and view all the answers

What occurs when the diffusion force and the electrical gradient are equal in magnitude?

<p>Net diffusion of the ion ceases. (A)</p> Signup and view all the answers

What happens to the concentration of ions on either side of the membrane during diffusion?

<p>It creates an unequal distribution of charges. (B)</p> Signup and view all the answers

What is the purpose of the sodium-potassium pump?

<p>It maintains high Na concentration outside and high K concentration inside the cell. (C)</p> Signup and view all the answers

How does cooling affect ion concentrations in the cell?

<p>It causes Na+ ions to accumulate inside the cell. (B)</p> Signup and view all the answers

What percentage of the resting membrane potential (RMP) is due to passive processes?

<p>90-95% (D)</p> Signup and view all the answers

What is the primary function of the Nernst equation?

<p>To determine the equilibrium potential for different ions. (B)</p> Signup and view all the answers

What occurs during a graded potential?

<p>It is a local change with variable magnitude and duration. (A)</p> Signup and view all the answers

Which ion's valence requires the division of 61 by +2 in the Nernst equation?

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

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

<p>They facilitate passive diffusion of ions across the membrane. (C)</p> Signup and view all the answers

What type of stimulus is the graded potential associated with?

<p>Sub-minimal stimulus (C)</p> Signup and view all the answers

What is the primary factor that contributes to the resting membrane potential (RMP) of excitable tissues?

<p>The selective permeability of the cell membrane to different ions (A)</p> Signup and view all the answers

Which ion has a significantly higher concentration inside the nerve cell compared to outside?

<p>K+ (D)</p> Signup and view all the answers

What mechanism primarily enables the diffusion of ions through leak channels in nerve tissues?

<p>Concentration gradients of ions across the membrane (B)</p> Signup and view all the answers

Which type of ion channels is specifically responsible for generating an action potential?

<p>Voltage-gated channels (D)</p> Signup and view all the answers

How does the concentration gradient of Na+ ions influence their movement into the nerve cell?

<p>The concentration gradient favors Na+ ions moving from outside to inside the cell (A)</p> Signup and view all the answers

What is the primary role of the sodium-potassium pump in excitable tissues?

<p>To establish the resting membrane potential through ion balance (C)</p> Signup and view all the answers

In terms of ion movement, what effect does the diffusion of K+ ions through leak channels have on the resting membrane potential?

<p>It contributes to the net negativity of the resting membrane potential. (B)</p> Signup and view all the answers

What is the expected membrane potential for a skeletal muscle fiber at rest?

<p>-90 mV (C)</p> Signup and view all the answers

What is the effect of potassium ions (K+) on the resting membrane potential (RMP)?

<p>They are primarily responsible for maintaining RMP. (C)</p> Signup and view all the answers

What occurs when the repulsion force equals the diffusion force across a selectively permeable membrane?

<p>Net diffusion of the ion ceases. (D)</p> Signup and view all the answers

What is the definition of equilibrium potential?

<p>The potential difference resulting from charge separation due to ionic diffusion. (C)</p> Signup and view all the answers

Which statement best describes the role of Na+ ions in relation to the resting membrane potential (RMP)?

<p>They are repelled by the negative charges inside the cell. (B)</p> Signup and view all the answers

What change occurs to potassium ions (K+) when metabolic activity decreases in a cell?

<p>K+ ions will escape from the outside surface of the cell. (B)</p> Signup and view all the answers

What best describes the gradient driving the movement of K+ ions across a membrane?

<p>Concentration gradient towards low concentration. (C)</p> Signup and view all the answers

How do ions behave when they diffuse through a selectively permeable membrane?

<p>Their diffusion is stopped by accumulated ionic charges. (D)</p> Signup and view all the answers

Which of the following ions has a valence of +1, thus resulting in 61 being omitted in the Nernst equation?

<p>Sodium (Na) (D)</p> Signup and view all the answers

Which factor contributes to the difficulty of Na+ ions passing through passive channels?

<p>Negative charge accumulation inside the cell. (B)</p> Signup and view all the answers

What percentage of the resting membrane potential (RMP) is attributed to the active process of the Na-K pump?

<p>5-10% (A)</p> Signup and view all the answers

In the context of the Nernst equation, what must be done to the 61 when calculating the equilibrium potential for calcium (Ca)?

<p>Divide by +2. (D)</p> Signup and view all the answers

What happens to the resting membrane potential (RMP) of a cell that is only permeable to Na+?

<p>It will equal the equilibrium potential for Na+. (A)</p> Signup and view all the answers

What defines the primary mechanism for the negative resting membrane potential?

<p>Passive diffusion of multiple ions through leak ion channels. (C)</p> Signup and view all the answers

Which statement accurately describes the action potential in neurons?

<p>It involves electrical changes that propagate when stimulated by an effective stimulus. (C)</p> Signup and view all the answers

What happens to the resting membrane potential when Na+ ions accumulate inside the cell?

<p>The RMP becomes progressively lost. (D)</p> Signup and view all the answers

Which ion plays a critical role in the generation of graded potentials in neurons?

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

Which property of nerve fibers allows them to change their membrane potentials in response to stimuli?

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

Which type of neuron is responsible for conducting impulses from peripheral receptors to the central nervous system?

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

What structure envelops each individual nerve fiber, providing insulation and supporting impulse conduction?

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

Which characteristic of the resting membrane potential describes the difference in charge across the cell membrane?

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

What is the primary factor that prevents sodium ions from diffusing freely into the neuron?

<p>Active transport mechanisms (B)</p> Signup and view all the answers

What best defines the role of nerve trunks in the conduction of nerve impulses?

<p>They comprise multiple nerve fibers grouped together. (B)</p> Signup and view all the answers

Which factor contributes significantly to the resting membrane potential being more negative inside the cell compared to the outside?

<p>Presence of negatively charged proteins inside the cell (D)</p> Signup and view all the answers

How do interneurons primarily contribute to the nervous system?

<p>They connect sensory and motor pathways within the CNS. (A)</p> Signup and view all the answers

Explain the role of the myelin sheath in nerve fiber function.

<p>The myelin sheath insulates the axon, enhancing the speed and efficiency of nerve impulse conduction.</p> Signup and view all the answers

What is excitability in the context of nerve fibers?

<p>Excitability is the ability of nerve fibers to respond to stimuli and generate an action potential.</p> Signup and view all the answers

Describe the structure of a nerve trunk.

<p>A nerve trunk is composed of numerous nerve fibers, each consisting of an axon covered by a myelin sheath and Schwann sheath.</p> Signup and view all the answers

How does conductivity differ from excitability in nerve fibers?

<p>Conductivity refers to the ability to transmit nerve impulses, while excitability pertains to the response to stimuli.</p> Signup and view all the answers

What establishes the resting membrane potential (RMP) in nerve cells?

<p>RMP is established by the uneven distribution of ions, primarily sodium (Na+) and potassium (K+), across the cell membrane.</p> Signup and view all the answers

Which type of neuron is responsible for conducting impulses to effector organs?

<p>Motor neurons (efferent neurons) conduct impulses from the CNS to effector organs.</p> Signup and view all the answers

What is the significance of potassium (K+) ions in relation to the resting membrane potential?

<p>K+ ions contribute to the negative charge inside the cell, which is essential for maintaining the resting membrane potential.</p> Signup and view all the answers

What effect does the sodium-potassium pump have on resting membrane potential (RMP)?

<p>The sodium-potassium pump actively maintains RMP by transporting 3 Na+ ions out and 2 K+ ions into the cell.</p> Signup and view all the answers

What phenomenon occurs when the diffusion force equals the repulsion force for a specific ion?

<p>Equilibrium is reached.</p> Signup and view all the answers

How does the concentration gradient impact the movement of potassium ions (K+) across the cell membrane?

<p>K+ ions diffuse from an area of high concentration to low concentration.</p> Signup and view all the answers

What role does charge separation play in the establishment of the equilibrium potential?

<p>Charge separation creates an electrical potential that opposes the concentration gradient.</p> Signup and view all the answers

What is the primary characteristic of a selectively permeable membrane in relation to ion diffusion?

<p>It allows specific ions to pass through based on their concentration gradients and charges.</p> Signup and view all the answers

Which force opposes the diffusion of an ion toward its area of lower concentration when the ion is charged?

<p>The repulsion force caused by electrical gradient opposes diffusion.</p> Signup and view all the answers

What happens to the movement of Na+ ions when they encounter repulsion from negative charges inside the cell?

<p>Na+ ions face difficulty diffusing through passive channels due to the repulsive force.</p> Signup and view all the answers

Define equilibrium potential in the context of ion movement across a membrane.

<p>Equilibrium potential is the electrical potential that balances the concentration gradient for that ion.</p> Signup and view all the answers

How do permeabilities of K+ and Na+ ions influence the resting membrane potential (RMP)?

<p>High permeability to K+ compared to Na+ establishes a negative RMP.</p> Signup and view all the answers

What ions have unequal concentrations inside and outside the nerve cell, contributing to the resting membrane potential?

<p>Sodium (Na+), Potassium (K+), Chloride (Cl-), and Proteins (Protein-).</p> Signup and view all the answers

What is the role of leak channels in the resting membrane potential?

<p>Leak channels allow specific ions, primarily K+, to move according to their concentration gradients, which helps establish the RMP.</p> Signup and view all the answers

Explain how the sodium-potassium pump contributes to the resting membrane potential.

<p>The sodium-potassium pump actively transports three Na+ ions out and two K+ ions into the cell, maintaining the concentration gradients essential for RMP.</p> Signup and view all the answers

What influence does the selective permeability of the cell membrane have on the distribution of ions?

<p>Selective permeability allows only certain ions to pass through, which affects the concentrations and, consequently, the resting membrane potential.</p> Signup and view all the answers

How does the concentration gradient of K+ ions impact their movement across the cell membrane?

<p>The high concentration of K+ inside the cell drives K+ ions to diffuse outward through leak channels.</p> Signup and view all the answers

Identify the main ions that contribute to the differences in resting membrane potential among various excitable tissues.

<p>Potassium (K+) predominantly contributes to negative RMPs, while Sodium (Na+) influences depolarization during action potentials.</p> Signup and view all the answers

What is the typical resting membrane potential of a nerve cell?

<p>The typical resting membrane potential of a nerve cell is approximately -70 mV.</p> Signup and view all the answers

How does the equilibrium potential relate to the resting membrane potential of K+ ions?

<p>The equilibrium potential for K+ is more negative than the resting membrane potential, reflecting K+'s tendency to diffuse out of the cell.</p> Signup and view all the answers

What is the role of the sodium-potassium pump in maintaining resting membrane potential?

<p>The sodium-potassium pump actively transports 3 Na+ ions out of the cell and 2 K+ ions into the cell, helping to maintain high Na+ concentration outside and high K+ concentration inside.</p> Signup and view all the answers

How does the Nernst equation determine equilibrium potential for an ion?

<p>The Nernst equation calculates equilibrium potential by using ion concentration gradients inside and outside the membrane along with the valence of the ion.</p> Signup and view all the answers

What happens to the resting membrane potential when the metabolic activity of a cell decreases?

<p>Decreased metabolic activity causes Na+ ions to accumulate inside the cell and K+ ions to escape, leading to a loss of resting membrane potential.</p> Signup and view all the answers

What percentage of resting membrane potential is attributed to passive ion diffusion, and what is primarily responsible for this?

<p>90-95% of resting membrane potential is due to passive ion diffusion through leak ion channels.</p> Signup and view all the answers

Which ion's concentration gradient is primarily responsible for the resting membrane potential in excitable cells?

<p>The concentration gradient of K+ ions is primarily responsible for establishing the resting membrane potential in excitable cells.</p> Signup and view all the answers

Why is the Nernst equation divided by 2 when calculating equilibrium potential for calcium ions (Ca+)?

<p>The Nernst equation is divided by 2 for calcium ions because Ca2+ has a valence of +2, which requires adjustment in the equation.</p> Signup and view all the answers

Explain the difference between graded potentials and action potentials.

<p>Graded potentials are local changes in membrane potential due to sub-minimal stimuli, while action potentials are large, propagated changes in membrane potential triggered by effective stimuli.</p> Signup and view all the answers

What is the significance of the 4-5 mV contribution of the Na-K pump to resting membrane potential?

<p>The 4-5 mV contribution of the Na-K pump signifies its active role in reinforcing the resting membrane potential despite being a smaller percentage compared to passive processes.</p> Signup and view all the answers

How does the structure of a nerve trunk contribute to its function?

<p>The nerve trunk, composed of many axons covered by myelin and Schwann sheaths, facilitates faster impulse conduction by insulating individual nerve fibers.</p> Signup and view all the answers

Explain the significance of excitability in nerve fibers.

<p>Excitability allows nerve fibers to detect stimuli and convert them into action potentials, which are essential for signal transmission.</p> Signup and view all the answers

Why is the inside of a neuron negative relative to the outside during resting membrane potential?

<p>The negativity inside the neuron is primarily due to higher concentrations of negatively charged proteins and the selective permeability of the membrane.</p> Signup and view all the answers

What is the role of the sodium-potassium pump in maintaining resting membrane potential?

<p>The sodium-potassium pump actively transports 3 Na+ ions out of the cell and 2 K+ ions into the cell, maintaining the negative internal environment.</p> Signup and view all the answers

Describe the difference between conductivity and excitability in nerve fibers.

<p>Conductivity refers to the ability to transmit action potentials along the nerve, while excitability is the ability to generate an action potential in response to stimuli.</p> Signup and view all the answers

What happens to the resting membrane potential (RMP) when potassium ion concentrations increase inside the cell?

<p>An increase in internal potassium concentrations would likely depolarize the cell, reducing the negativity of the resting membrane potential.</p> Signup and view all the answers

How does the permeability of the cell membrane to K+ ions affect the resting membrane potential?

<p>Increased permeability to K+ ions allows more K+ to leave the cell, enhancing the negative charge inside and stabilizing the resting membrane potential.</p> Signup and view all the answers

Why do nerve fibers exhibit a variable resting membrane potential (RMP)?

<p>The variable RMP is due to differences in ion concentrations and permeability among different types of neurons and their ionic environments.</p> Signup and view all the answers

What ion gradient significantly contributes to the resting membrane potential (RMP) by being more concentrated inside the nerve cell?

<p>K+ ions.</p> Signup and view all the answers

In relation to resting membrane potential (RMP), explain the significance of leak or passive channels.

<p>They are responsible for maintaining the RMP by allowing specific ions to diffuse across the cell membrane.</p> Signup and view all the answers

What is the primary reason Na+ ions have a low concentration inside the nerve cell compared to outside?

<p>The selective permeability of the cell membrane restricts Na+ ions from diffusing freely into the cell.</p> Signup and view all the answers

Describe the role of the sodium-potassium pump in maintaining the resting membrane potential (RMP).

<p>It actively transports Na+ out of the cell and K+ into the cell, counteracting ion leakage.</p> Signup and view all the answers

How does the concentration of Cl- ions impact the resting membrane potential (RMP)?

<p>Cl- ions have a higher concentration outside the cell, contributing to the negative charge inside.</p> Signup and view all the answers

What is the equilibrium potential, and how does it relate to ion movement across the membrane?

<p>The equilibrium potential is the voltage at which the force of diffusion and electrical gradient are equal for an ion.</p> Signup and view all the answers

Identify the effect of diffusion forces in ionic movement and their significance for nerve function.

<p>Diffusion forces drive ions from areas of higher concentration to lower concentration, crucial for generating action potentials.</p> Signup and view all the answers

Explain why K+ ions predominantly move out of the cell even though they are more concentrated inside.

<p>K+ ions move out of the cell due to their concentration gradient, which outweighs the electrical gradient acting on them.</p> Signup and view all the answers

What is the effect of the Na-K pump on the concentration of Na+ and K+ ions inside and outside the cell?

<p>The Na-K pump maintains high Na+ concentration outside the cell and high K+ concentration inside the cell.</p> Signup and view all the answers

How does cooling affect the resting membrane potential (RMP) through ion concentration changes?

<p>Cooling leads to the accumulation of Na+ ions inside the cell and the escape of K+ ions from the outer surface, reducing RMP.</p> Signup and view all the answers

What is the contribution of passive and active processes to the resting membrane potential (RMP), including their percentage?

<p>90-95% of RMP results from passive processes due to ion diffusion, while 5-10% is from the active process of the Na-K pump.</p> Signup and view all the answers

Why must 61 be divided by +2 when calculating the Nernst potential for calcium ions?

<p>It is divided by +2 because calcium (Ca) has a valence of +2, affecting the Nernst equation calculation.</p> Signup and view all the answers

Describe the role of graded potentials in neuronal signaling.

<p>Graded potentials result from stimulation by ineffective stimuli and cause local changes in membrane voltage with variable duration and magnitude.</p> Signup and view all the answers

What two key processes are involved in resting membrane potential (RMP) maintenance?

<p>The RMP is maintained by passive ion diffusion through leak channels and active transport via the Na-K pump.</p> Signup and view all the answers

What is the significance of the ion concentration gradient for Na+ ions in relation to their movement into the nerve cell?

<p>The concentration gradient for Na+ ions drives their movement into the nerve cell, promoting depolarization when channels open.</p> Signup and view all the answers

How does the permeability of a membrane to K+ affect the resting membrane potential?

<p>The high permeability of a membrane to K+ causes K+ to diffuse out, resulting in a negative charge inside the cell and contributing to a lower resting membrane potential.</p> Signup and view all the answers

When does the resting membrane potential equal the equilibrium potential for an ion?

<p>The resting membrane potential equals the equilibrium potential for an ion when the diffusion force and electrical gradient are equal.</p> Signup and view all the answers

What happens when the diffusion force and the repulsion force are balanced?

<p>When the diffusion force equals the repulsion force, net diffusion of ions stops and equilibrium is reached.</p> Signup and view all the answers

Explain the significance of equilibrium potential in relation to RMP.

<p>The equilibrium potential reflects the electrical potential that balances the concentration gradient for a specific ion, which equals the resting membrane potential when only that ion can cross the membrane.</p> Signup and view all the answers

Describe the role of the sodium-potassium pump in maintaining resting membrane potential.

<p>The sodium-potassium pump actively transports Na+ out and K+ into the cell, helping to maintain the concentration gradients essential for the resting membrane potential.</p> Signup and view all the answers

How does the electrical gradient affect the movement of K+ ions across the membrane?

<p>The electrical gradient tends to pull K+ ions back into the cell due to the negative charge inside, opposing the diffusion force that drives K+ out.</p> Signup and view all the answers

Why is it difficult for Na+ ions to pass through passive channels despite their concentration gradient?

<p>Na+ ions encounter repulsion from the negative charges inside the cell, making it difficult for them to pass through the passive Na+ channels.</p> Signup and view all the answers

What defines the concentration gradient of K+ ions across a selectively permeable membrane?

<p>The concentration gradient of K+ is defined by its higher concentration inside the cell compared to outside, driving K+ to diffuse out.</p> Signup and view all the answers

Discuss how charge separation contributes to equilibrium potential.

<p>Charge separation occurs during the diffusion of ions, leading to an accumulation of charges that results in an electrical potential opposing further ion diffusion, defining equilibrium potential.</p> Signup and view all the answers

Flashcards

Membrane Potential

The difference in electrical charge across a cell membrane, particularly important in nerve and muscle cells.

Resting Membrane Potential (RMP)

The electrical charge difference across a cell membrane when the cell is not actively transmitting a signal.

Sensory Neuron

A nerve cell that transmits information from sensory receptors to the central nervous system (CNS).

Motor Neuron

A nerve cell that transmits signals from the central nervous system (CNS) to muscles or glands.

Signup and view all the flashcards

Interneuron

Connects sensory and motor neurons in the central nervous system (CNS).

Signup and view all the flashcards

Nerve Trunk

A bundle of nerve fibers (axons).

Signup and view all the flashcards

Excitability

The ability of nerve fibers to respond to stimuli and create a nerve impulse.

Signup and view all the flashcards

Conductivity

The ability of a nerve fiber to transmit a nerve impulse down its length.

Signup and view all the flashcards

Resting Membrane Potential (RMP)

The electrical charge difference across a cell membrane when the cell is not actively transmitting a signal.

Signup and view all the flashcards

Ion Distribution (nerve cells)

Different ion concentrations inside and outside of nerve cells influence membrane potential.

Signup and view all the flashcards

Selective Permeability

Cell membranes only allow specific ions to pass through.

Signup and view all the flashcards

Leak Channels

Channels that allow ions to passively diffuse across the membrane.

Signup and view all the flashcards

Voltage-gated channels

Channels that open or close in response to changes in membrane potential.

Signup and view all the flashcards

Concentration Gradients

Differences in ion concentration between inside and outside the nerve cell.

Signup and view all the flashcards

Microelectrodes

Tiny electrodes used to measure electrical potential differences in cells.

Signup and view all the flashcards

High Permeability to K+

Potassium ions (K+) cross the cell membrane 100 times more easily than sodium ions (Na+).

Signup and view all the flashcards

Electric Gradient (Inside is Negative)

The inside of the cell membrane has a negative electrical charge compared to the outside.

Signup and view all the flashcards

K+ and RMP

Potassium (K+) is the primary ion responsible for the resting membrane potential (RMP).

Signup and view all the flashcards

Passive Na Channels

Sodium (Na+) ions can pass through the membrane through channels, but it's not as easy as it is for K+.

Signup and view all the flashcards

Equilibrium Potential

The electrical potential needed to stop an ion's diffusion across a membrane down its concentration gradient.

Signup and view all the flashcards

Diffusion Force

The force pushing ions from high concentration to low concentration.

Signup and view all the flashcards

Repulsion Force

The force pushing ions away from the same charges.

Signup and view all the flashcards

RMP Calculation

The resting membrane potential is determined by the balance between the diffusion and repelling forces of ions.

Signup and view all the flashcards

Nernst Equation

Calculates the equilibrium potential for an ion across a membrane.

Signup and view all the flashcards

Equilibrium Potential

Membrane potential at which the net movement of an ion is zero.

Signup and view all the flashcards

Sodium-Potassium Pump

Active transport protein that maintains ion gradients.

Signup and view all the flashcards

Resting Membrane Potential

The electrical potential difference across a cell membrane when not stimulated.

Signup and view all the flashcards

Action Potential

Rapid change in membrane potential, propagated along a neuron.

Signup and view all the flashcards

Graded Potential

Local, variable changes in membrane potential.

Signup and view all the flashcards

Membrane Potential Components

Factors contributing to resting membrane potential (RMP).

Signup and view all the flashcards

Resting Membrane Potential (RMP)

The electrical difference across a nerve cell's membrane when inactive.

Signup and view all the flashcards

Sensory Neuron

Carries signals from sensory receptors to the brain.

Signup and view all the flashcards

Motor Neuron

Carries signals from the brain/spinal cord to muscles.

Signup and view all the flashcards

Nerve Trunk

A bundle of nerve fibers.

Signup and view all the flashcards

Excitability

A nerve fiber's ability to respond to stimuli.

Signup and view all the flashcards

Conductivity

A nerve fiber's ability to transmit a signal.

Signup and view all the flashcards

Neuron

Structural and functional unit of the nervous system.

Signup and view all the flashcards

High Permeability to K+

Potassium ions (K+) cross the cell membrane significantly easier than sodium ions (Na+).

Signup and view all the flashcards

Electric Gradient (Inside is Negative)

The interior of a cell's membrane holds a negative charge compared to the exterior.

Signup and view all the flashcards

K+ ion and RMP

Potassium ions (K+) play a key role in establishing the resting membrane potential (RMP).

Signup and view all the flashcards

Passive Na Channels

Sodium ions (Na+) can passively pass through the cell membrane (but not as easily as K+).

Signup and view all the flashcards

Equilibrium Potential

The membrane potential where the diffusion force and electric force on an ion are balanced.

Signup and view all the flashcards

Diffusion Force

The force that moves an ion from a higher concentration area to a lower concentration.

Signup and view all the flashcards

Repulsion Force

The force that pushes ions away from other ions with the same charge.

Signup and view all the flashcards

RMP Calculation

The resting membrane potential is determined by the interplay of forces acting on ions, including the diffusion and repelling forces.

Signup and view all the flashcards

Resting Membrane Potential (RMP)

The electrical charge difference across a cell membrane when not active.

Signup and view all the flashcards

Ion Distribution (nerve cells)

Different ion concentrations (like sodium, potassium, chloride, and proteins) inside and outside nerve cells.

Signup and view all the flashcards

Selective Permeability

Cell membranes allow specific ions to pass through.

Signup and view all the flashcards

Leak Channels

Channels that allow ions to passively move across the membrane.

Signup and view all the flashcards

Concentration Gradients

Differences in ion concentrations between inside and outside the cell.

Signup and view all the flashcards

Microelectrodes

Tiny electrodes used to measure electrical differences in cells.

Signup and view all the flashcards

Sodium (Na+)

Ion that is more concentrated outside nerve cells.

Signup and view all the flashcards

Potassium (K+)

Ion that is more concentrated inside nerve cells.

Signup and view all the flashcards

Chloride (Cl-)

Ion that is more concentrated outside nerve cells.

Signup and view all the flashcards

Membrane Potential

The difference in electrical charge across a membrane (inside vs. outside).

Signup and view all the flashcards

RMP Value (excitable tissues)

Nerve: -70mV, Skeletal Muscle: -90mV, Cardiac Muscle: -90mV, Smooth Muscle: -60mV.

Signup and view all the flashcards

Nernst Equation

Calculates the equilibrium potential for an ion across a membrane based on ion concentrations and valence.

Signup and view all the flashcards

Equilibrium Potential

The membrane potential at which the net movement of an ion is zero; diffusion and electrical forces are balanced.

Signup and view all the flashcards

Sodium-Potassium Pump

Active transport protein that maintains ion gradients by pumping 3 sodium ions out and 2 potassium ions in.

Signup and view all the flashcards

Resting Membrane Potential (RMP)

The electrical potential difference across a cell membrane when the cell is not stimulated; a balance of passive ion diffusion and active transport.

Signup and view all the flashcards

Action Potential

Rapid, large changes in membrane potential that propagate along a nerve fiber, resulting in a response or action.

Signup and view all the flashcards

Graded Potential

Local, variable changes in membrane potential resulting from stimulation by sub-minimal stimuli; the strength and duration vary.

Signup and view all the flashcards

Ion Concentration (Nerve Cells)

Different ion concentrations (e.g., sodium, potassium, calcium, chloride) inside and outside nerve cells directly influence the membrane potential.

Signup and view all the flashcards

Membrane Potential Components

Factors that influence Resting Membrane Potential (RMP), including leak channels, the sodium-potassium pump, and ion concentrations.

Signup and view all the flashcards

Resting Membrane Potential (RMP)

The electrical difference across a nerve cell membrane when not active.

Signup and view all the flashcards

Neuron

The basic unit of the nervous system.

Signup and view all the flashcards

Sensory Neuron

Carries signals from receptors to the CNS.

Signup and view all the flashcards

Motor Neuron

Carries signals from the CNS to muscles or glands.

Signup and view all the flashcards

Nerve Trunk

A bundle of nerve fibers.

Signup and view all the flashcards

Excitability

Nerve fibers' ability to respond to stimuli.

Signup and view all the flashcards

Conductivity

Nerve fiber's ability to transmit signals.

Signup and view all the flashcards

RMP Value (Nerve)

Electrical charge difference is typically -70mV in nerve cells.

Signup and view all the flashcards

High Permeability to K+

Potassium ions (K+) cross the cell membrane much more easily (100 times) than sodium ions (Na+).

Signup and view all the flashcards

Electric Gradient (Inside is Negative)

The inside of the cell membrane has a negative charge compared to the outside.

Signup and view all the flashcards

K+ Ion and RMP

Potassium ions (K+) are the primary ions responsible for maintaining the resting membrane potential (RMP).

Signup and view all the flashcards

Passive Na Channels

Sodium ions (Na+) can pass through the cell membrane, but not as easily as Potassium.

Signup and view all the flashcards

Equilibrium Potential

The electrical potential that counteracts the concentration gradient of an ion, stopping its net movement across a membrane.

Signup and view all the flashcards

Diffusion Force

The force that pushes ions across a membrane from an area of high concentration to low concentration.

Signup and view all the flashcards

Repulsion Force

The force that pushes ions away from ions with the same charge.

Signup and view all the flashcards

RMP Calculation

The resting membrane potential is determined by the balance of diffusion and repulsion forces on ions.

Signup and view all the flashcards

Resting Membrane Potential (RMP) of Nerve

The electrical difference across a nerve cell membrane when inactive, typically -70mV.

Signup and view all the flashcards

Resting Membrane Potential (RMP) Values (Excitable Tissues)

The electrical charge difference across different excitable tissues at rest: nerve (-70mV), skeletal muscle (-90mV), cardiac muscle (-90mV), smooth muscle (-60mV).

Signup and view all the flashcards

Ion Concentration (Inside vs. Outside)

Different ions have varying concentrations inside and outside nerve cells; this creates a difference in electrical charge.

Signup and view all the flashcards

Selective Permeability of Membrane

Cell membranes allow certain ions to pass through more easily than others, influencing the RMP.

Signup and view all the flashcards

Leak Channels

Channels that allow ions to passively diffuse across the membrane.

Signup and view all the flashcards

Microelectrodes

Tiny electrodes used to measure electrical potential differences in cells.

Signup and view all the flashcards

Concentration Gradient (Ions)

Difference in ion concentrations between the inside and outside of a nerve cell.

Signup and view all the flashcards

High Permeability to Potassium (K+)

The cell membrane is more permeable to potassium ions.

Signup and view all the flashcards

RMP Causes

Unequal ion distributions, membrane selective permeability, and ion diffusion through leak channels create the Resting Membrane Potential.

Signup and view all the flashcards

Nernst Equation

Calculates the equilibrium potential for an ion, considering its concentration inside and outside the cell and its valence.

Signup and view all the flashcards

Equilibrium Potential

The membrane potential at which the net movement of an ion is zero; diffusion and electrical forces are balanced.

Signup and view all the flashcards

Sodium-Potassium Pump

Active transport protein that maintains ion gradients by pumping 3 sodium ions out and 2 potassium ions in.

Signup and view all the flashcards

Resting Membrane Potential (RMP)

The electrical potential difference across a cell membrane when the cell is at rest.

Signup and view all the flashcards

Action Potential

Rapid change in membrane potential that propagates along a nerve fiber, resulting in a response.

Signup and view all the flashcards

Graded Potential

Local, variable changes in membrane potential resulting from stimulation.

Signup and view all the flashcards

Ion Distribution

Different ion concentrations (like sodium, potassium, chloride) inside and outside nerve cells.

Signup and view all the flashcards

RMP Value (Nerve)

The electrical charge difference is typically -70mV in nerve cells.

Signup and view all the flashcards

Membrane Potential

Electrical charge difference between the inside and outside of a nerve cell membrane.

Signup and view all the flashcards

Resting Membrane Potential (RMP)

Electrical charge difference across a nerve cell membrane when not stimulated.

Signup and view all the flashcards

Sensory Neuron

Nerve cell that transmits signals from sensory receptors to the brain/spinal cord.

Signup and view all the flashcards

Motor Neuron

Nerve cell that transmits signals from the brain/spinal cord to muscles or glands.

Signup and view all the flashcards

Nerve Trunk

Bundle of nerve fibers (axons).

Signup and view all the flashcards

Excitability

Ability of nerve fibers to respond to stimuli.

Signup and view all the flashcards

Conductivity

Ability of nerve fibers to transmit signals along their length.

Signup and view all the flashcards

Neuron

Structural and functional unit of the nervous system.

Signup and view all the flashcards

RMP Value (Nerve)

Electrical charge difference of -70mV across a nerve cell membrane.

Signup and view all the flashcards

Resting Membrane Potential (RMP)

The electrical charge difference across a cell membrane when the cell is at rest, not transmitting a signal.

Signup and view all the flashcards

RMP value (Nerve)

The resting membrane potential in a nerve cell, typically -70mV.

Signup and view all the flashcards

RMP values (Excitable tissues)

Different excitable tissues have different RMP values: nerve (-70mV), skeletal muscle (-90mV), cardiac muscle (-90mV), smooth muscle (-60mV).

Signup and view all the flashcards

Ion Distribution (nerve cells)

Different ions (sodium, potassium, chloride, proteins) have varying concentrations inside and outside of nerve cells.

Signup and view all the flashcards

Selective Permeability

Cell membranes allow certain ions to pass through more easily than others.

Signup and view all the flashcards

Leak channels

Channels that allow ions to passively diffuse across the cell membrane.

Signup and view all the flashcards

Concentration Gradients

Differences in ion concentration between the inside and outside of a nerve cell.

Signup and view all the flashcards

Microelectrodes

Tiny electrodes used to measure electrical potential differences in cells.

Signup and view all the flashcards

High Permeability to K+

Potassium ions (K+) cross the cell membrane much more easily than sodium ions (Na+).

Signup and view all the flashcards

Electric Gradient (Inside is Negative)

The inside of the nerve cell membrane has a negative electrical charge compared to the outside.

Signup and view all the flashcards

High Permeability to K+

Potassium (K+) ions cross the cell membrane much more easily than sodium (Na+) ions.

Signup and view all the flashcards

Electric Gradient (Inside is Negative)

The inside of the cell membrane has a negative electrical charge compared to the outside.

Signup and view all the flashcards

K+ ion and RMP

Potassium (K+) ions are the primary ions responsible for the resting membrane potential (RMP).

Signup and view all the flashcards

Passive Na Channels

Sodium (Na+) ions can pass through the membrane, but it's harder than for potassium (K+).

Signup and view all the flashcards

Equilibrium Potential

The electrical potential that balances the concentration gradient of an ion, stopping its net movement.

Signup and view all the flashcards

Diffusion Force

The force that pushes ions from a high to a low concentration area.

Signup and view all the flashcards

Repulsion Force

The force pushing ions away from ions with the same charge.

Signup and view all the flashcards

RMP Calculation

The resting membrane potential results from the balance of diffusion and repulsion forces on the ions.

Signup and view all the flashcards

Nernst Equation

Calculates the equilibrium potential for an ion across a cell membrane.

Signup and view all the flashcards

Equilibrium Potential

The membrane potential at which the net movement of an ion is zero; diffusion and electric forces are balanced.

Signup and view all the flashcards

Resting Membrane Potential (RMP)

The electrical potential difference across a cell membrane when not stimulated; balance of passive ion diffusion and active transport.

Signup and view all the flashcards

Sodium-Potassium Pump

Active transport protein that maintains ion gradients by pumping 3 sodium ions out and 2 potassium ions in.

Signup and view all the flashcards

Action Potential

Rapid change in membrane potential that propagates along a nerve fiber, resulting in a response.

Signup and view all the flashcards

Graded Potential

Local, variable changes in membrane potential resulting from stimulation by subthreshold stimuli; the strength and duration vary.

Signup and view all the flashcards

Ion Distribution (Nerve Cells)

Different ion concentrations (e.g., sodium, potassium, calcium, chloride) inside and outside nerve cells affect membrane potential.

Signup and view all the flashcards

Membrane Potential Components

Factors contributing to the resting membrane potential (RMP), including leak channels, the sodium-potassium pump, and ion concentration differences.

Signup and view all the flashcards

RMP Value (Nerve)

The electrical potential difference is usually -70mV in nerve cells.

Signup and view all the flashcards

Study Notes

Neurons or Nerve Cells

  • Structural and functional unit of the nervous system
  • One trillion neurons
  • Classification:
    • Sensory neurons (afferent): Conduct impulses from receptors to CNS
    • Motor neurons (efferent): Conduct impulses from CNS to effector organs
    • Interneurons: Small, integrative neurons located in the CNS

Nerve Trunk and Nerve Fibers

  • Nerve trunk: Composed of many nerve fibers. Each nerve fiber is an axon covered by a myelin sheath and Schwann sheath
  • Nerve fibers:
    • Sensory nerve fibers conduct sensory information from receptors to the CNS
    • Motor nerve fibers conduct motor information from the CNS to effector organs
  • Properties:
    • Excitability: Ability to respond to stimuli and convert them into nerve impulses/action potentials
    • Conductivity: Ability to conduct nerve impulses/action potentials from one place to another

Resting Membrane Potential (RMP)

  • Definition: Potential difference between inside and outside of nerve during rest.
  • RMP is present in nerves, muscle fibers, and all cells in the body, with the inside being negative relative to the outside.
  • Value: Varies according to excitable tissues (Nerves = -70mV, Skeletal Muscle = -90mV, Cardiac Muscle = -90mV, Smooth Muscle = -60mV)
  • Measurement: Recorded using two microelectrodes and a voltmeter. One electrode is inserted into the nerve, the other on the surface.

Causes of RMP

  • Unequal distribution of ions inside and outside the nerve:

    • Extracellular Fluid (ECF): Na+ (140 mEq/L), K+ (4 mEq/L), Cl- (100 mEq/L)
    • Intracellular Fluid (ICF): Na+ (14 mEq/L), K+ (140 mEq/L), Cl- (4 mEq/L)
    • ECF:ICF ratio: 10:1 (Na+), 1:35(K+), 25:1(Cl-), 1:8 (protein)

  • Selective Permeability of Cell Membrane: Cell membranes allow specific ions to pass through, blocking others due to size, charge, or hydration.

  • Diffusion of ions through leak channels is the cause of RMP

  • Types of ion channels:

    • Leak/passive channels: Responsible for resting membrane potential (RMP)
    • Voltage-gated channels: Responsible for action potentials (AP)
    • Ligand-gated channels: Act as receptors

Diffusion

  • Movement of ions from an area of high concentration to an area of low concentration.
  • Helped by concentration gradients (inside > outside, 30-40 times for K+, outside>inside, 25 times for Cl-) and high permeability to K+ (100 times more than Na+)

Calculation of Resting Membrane Potential

  • When a selectively permeable membrane is permeable to one ion, that ion diffuses, creating an equilibrium potential where the concentration gradient is balanced

  • Ionic charges accumulate on one side of the membrane.

Equilibrium Potential

  • Electrical potential caused by charge separation due to diffusion of ions across a selectively permeable membrane.
  • Balance concentration gradient and electrical gradient.
  • In a cell where only one ion type crosses the membrane, RMP equals the equilibrium potential for that ion.

Sodium-Potassium Pump (Na-K Pump)

  • Electrogenic pump.
  • Pumps 3 Na+ ions out of the cell and 2 K+ ions into the cell.
  • Maintains high Na+ concentration outside and high K+ concentration inside the cell.
  • Conditions that lower metabolic activity (cooling) will lead to negative charges accumulating inside the cell and K+ ions being released.

Types of Membrane Potentials

  • Resting Membrane Potential (RMP): Stable electrical potential difference across a cell membrane maintained by the Na-K pump.
  • Action Potential: Rapid and large changes in membrane potential in response to stimulation.
  • Graded Potential: Local changes in membrane potential in response to effective or ineffective stimuli, their duration and magnitude vary.
    • Types of graded potentials include: receptor potential, synaptic potential, and local excitatory state.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

Physiology Lecture (13) PDF

Description

Test your knowledge on the structure and function of neurons and nerve cells. Understand the different types of neurons, their classifications, and properties related to nerve fibers. This quiz covers key concepts essential for grasping neuroscience fundamentals.

More Like This

Use Quizgecko on...
Browser
Open
Browser
Browser