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Questions and Answers
If a neuron is described as a 'banana in the sea,' which of the following best describes the relative concentrations of potassium (K+) and sodium (Na+) ions?
If a neuron is described as a 'banana in the sea,' which of the following best describes the relative concentrations of potassium (K+) and sodium (Na+) ions?
- High K+ inside the neuron, high Na+ outside the neuron. (correct)
- High Na+ inside the neuron, high K+ outside the neuron.
- Low K+ inside the neuron, low Na+ outside the neuron.
- Equal concentrations of Na+ and K+ inside and outside the neuron.
What is the primary role of ion channels in neuronal signaling?
What is the primary role of ion channels in neuronal signaling?
- To regulate the movement of ions across the cell membrane, enabling changes in electrical potential. (correct)
- To provide structural support to the neuron's membrane.
- To synthesize neurotransmitters for chemical signaling.
- To actively transport water molecules into and out of the cell.
Which of the following is NOT a major type of ion involved in neuron signaling?
Which of the following is NOT a major type of ion involved in neuron signaling?
- Chloride (Cl-)
- Potassium (K+)
- Sodium (Na+)
- Magnesium (Mg2+) (correct)
What is the 'concentration gradient' and why is it important for electrical signaling in neurons?
What is the 'concentration gradient' and why is it important for electrical signaling in neurons?
How do cellular membranes affect the movement of ions into and out of the cell?
How do cellular membranes affect the movement of ions into and out of the cell?
What distinguishes ligand-gated ion channels from other types of ion channels?
What distinguishes ligand-gated ion channels from other types of ion channels?
Which type of ion channel is most important for maintaining the neuron's resting membrane potential?
Which type of ion channel is most important for maintaining the neuron's resting membrane potential?
A certain experimental drug selectively blocks sodium leak channels in a neuron. What is the most likely effect of this drug on the neuron's resting membrane potential?
A certain experimental drug selectively blocks sodium leak channels in a neuron. What is the most likely effect of this drug on the neuron's resting membrane potential?
Why is it essential that a single EPSP is typically insufficient to trigger an action potential at the axon hillock?
Why is it essential that a single EPSP is typically insufficient to trigger an action potential at the axon hillock?
What is the primary difference between temporal and spatial summation of EPSPs?
What is the primary difference between temporal and spatial summation of EPSPs?
How does the location of excitatory synapses on dendrites contribute to the process of neuronal integration?
How does the location of excitatory synapses on dendrites contribute to the process of neuronal integration?
Why is the decay of an EPSP as it travels to the axon hillock an important characteristic of neuronal function?
Why is the decay of an EPSP as it travels to the axon hillock an important characteristic of neuronal function?
What is the critical area on the neuron for determining whether an action potential will occur?
What is the critical area on the neuron for determining whether an action potential will occur?
If two EPSPs arrive at the axon hillock, one immediately after the other, what is this an example of?
If two EPSPs arrive at the axon hillock, one immediately after the other, what is this an example of?
How do neurons integrate information from multiple active axons to determine whether to fire an action potential?
How do neurons integrate information from multiple active axons to determine whether to fire an action potential?
What would likely happen if the membrane potential returns to Em (resting membrane potential) too quickly between EPSPs during temporal summation?
What would likely happen if the membrane potential returns to Em (resting membrane potential) too quickly between EPSPs during temporal summation?
What is the primary effect of an EPSP on the dendrites of a neuron?
What is the primary effect of an EPSP on the dendrites of a neuron?
Why is it essential for neurons to summate multiple EPSPs rather than relying on a single EPSP to trigger an action potential?
Why is it essential for neurons to summate multiple EPSPs rather than relying on a single EPSP to trigger an action potential?
Temporal summation involves the integration of EPSPs that occur:
Temporal summation involves the integration of EPSPs that occur:
Why is the unequal distribution of ions inside and outside of a neuron crucial for its function?
Why is the unequal distribution of ions inside and outside of a neuron crucial for its function?
Spatial summation involves the integration of EPSPs that occur:
Spatial summation involves the integration of EPSPs that occur:
Using the analogy 'Neurons are like bananas in the sea,' what does the 'sea' primarily represent in terms of ion concentration?
Using the analogy 'Neurons are like bananas in the sea,' what does the 'sea' primarily represent in terms of ion concentration?
What is the primary role of ion channels in the context of neuronal function?
What is the primary role of ion channels in the context of neuronal function?
What happens if the time interval between two EPSPs in temporal summation is too long?
What happens if the time interval between two EPSPs in temporal summation is too long?
How do spatial and temporal summation work together to facilitate the firing of an action potential?
How do spatial and temporal summation work together to facilitate the firing of an action potential?
How does the structure of an ion channel contribute to its specific function?
How does the structure of an ion channel contribute to its specific function?
An action potential is most likely to be triggered when:
An action potential is most likely to be triggered when:
A researcher is studying a neuron and observes that a certain type of channel is always open, allowing ions to flow continuously. Which type of ion channel is the researcher most likely observing?
A researcher is studying a neuron and observes that a certain type of channel is always open, allowing ions to flow continuously. Which type of ion channel is the researcher most likely observing?
Excitatory axons typically form synapses on what part of the cell?
Excitatory axons typically form synapses on what part of the cell?
What is the primary mechanism by which ligand-gated ion channels open?
What is the primary mechanism by which ligand-gated ion channels open?
A scientist is studying the effects of a new drug on neuronal communication. The drug binds to a specific protein on the neuron's surface, causing an ion channel to open and allow ions to flow into the cell. What type of protein is the drug likely binding to?
A scientist is studying the effects of a new drug on neuronal communication. The drug binds to a specific protein on the neuron's surface, causing an ion channel to open and allow ions to flow into the cell. What type of protein is the drug likely binding to?
Why are ion channels highly specific for particular ions?
Why are ion channels highly specific for particular ions?
A certain neurotransmitter binds to a receptor on a neuron, causing an influx of chloride ions (Cl-). What effect would this have on the membrane potential of the neuron?
A certain neurotransmitter binds to a receptor on a neuron, causing an influx of chloride ions (Cl-). What effect would this have on the membrane potential of the neuron?
What is the primary difference between ligand-gated and voltage-gated channels?
What is the primary difference between ligand-gated and voltage-gated channels?
If a neuron's resting membrane potential is -70mV, what does this indicate about the charge distribution across the cell membrane?
If a neuron's resting membrane potential is -70mV, what does this indicate about the charge distribution across the cell membrane?
Which of the following best describes the movement of ions across a neuronal membrane through ion channels?
Which of the following best describes the movement of ions across a neuronal membrane through ion channels?
Which of the following events would most likely result in an Excitatory Postsynaptic Potential (EPSP)?
Which of the following events would most likely result in an Excitatory Postsynaptic Potential (EPSP)?
What is the Excitatory Postsynaptic Potential (EPSP)?
What is the Excitatory Postsynaptic Potential (EPSP)?
What causes a neuron to return to its resting membrane potential (Em) after being stimulated?
What causes a neuron to return to its resting membrane potential (Em) after being stimulated?
Which of the following is the most accurate description of hyperpolarization?
Which of the following is the most accurate description of hyperpolarization?
What is the main function of calcium ions (Ca2+) in neurons that differentiates it from the roles of sodium (Na+) and potassium (K+)?
What is the main function of calcium ions (Ca2+) in neurons that differentiates it from the roles of sodium (Na+) and potassium (K+)?
In a typical neuron, why does the efflux of potassium ions (K+) lead to hyperpolarization?
In a typical neuron, why does the efflux of potassium ions (K+) lead to hyperpolarization?
What would occur if a drug blocked the voltage sensor of voltage-gated channels?
What would occur if a drug blocked the voltage sensor of voltage-gated channels?
How would a mutation affecting the concentration gradient of potassium ions (K+)—making its intracellular and extracellular concentrations nearly equal—affect the neuron?
How would a mutation affecting the concentration gradient of potassium ions (K+)—making its intracellular and extracellular concentrations nearly equal—affect the neuron?
If a neurotoxin specifically targets and disables leak channels in a neuron, what would be the most likely immediate consequence?
If a neurotoxin specifically targets and disables leak channels in a neuron, what would be the most likely immediate consequence?
Consider a scenario where a new drug selectively blocks the movement of calcium ions (Ca2+) into the presynaptic neuron. Which neuronal function would be most immediately and directly affected?
Consider a scenario where a new drug selectively blocks the movement of calcium ions (Ca2+) into the presynaptic neuron. Which neuronal function would be most immediately and directly affected?
A researcher is studying a neuron and observes that when a specific ligand binds to its receptors, the membrane potential changes from -70mV to -80mV. What can the researcher conclude about the ion channel associated with this receptor?
A researcher is studying a neuron and observes that when a specific ligand binds to its receptors, the membrane potential changes from -70mV to -80mV. What can the researcher conclude about the ion channel associated with this receptor?
A certain neurotransmitter binds to a receptor on a neuron, causing an influx of chloride ions (Cl-). What effect will this have on the postsynaptic membrane potential?
A certain neurotransmitter binds to a receptor on a neuron, causing an influx of chloride ions (Cl-). What effect will this have on the postsynaptic membrane potential?
Which of the following best describes the primary function of leak channels in a neuron's membrane?
Which of the following best describes the primary function of leak channels in a neuron's membrane?
A researcher is studying a neuron and observes a sudden increase in the membrane potential from -70mV to -50mV. According to this change, which event is most likely occurring?
A researcher is studying a neuron and observes a sudden increase in the membrane potential from -70mV to -50mV. According to this change, which event is most likely occurring?
A certain toxin blocks voltage-gated potassium channels in a neuron. What effect would this toxin have on the neuron's ability to repolarize after an action potential?
A certain toxin blocks voltage-gated potassium channels in a neuron. What effect would this toxin have on the neuron's ability to repolarize after an action potential?
Which of the following scenarios would result in an inhibitory postsynaptic potential (IPSP)?
Which of the following scenarios would result in an inhibitory postsynaptic potential (IPSP)?
What is the primary role of calcium ions ($Ca^{2+}$) in neuronal function, despite their relatively small effect on membrane potential?
What is the primary role of calcium ions ($Ca^{2+}$) in neuronal function, despite their relatively small effect on membrane potential?
How do ligand-gated channels differ from voltage-gated channels in terms of their activation?
How do ligand-gated channels differ from voltage-gated channels in terms of their activation?
A neuron is at its resting membrane potential of -70mV. If the extracellular concentration of $Na^+$ is significantly increased, what immediate effect would this have on the neuron's response to the opening of $Na^+$ channels?
A neuron is at its resting membrane potential of -70mV. If the extracellular concentration of $Na^+$ is significantly increased, what immediate effect would this have on the neuron's response to the opening of $Na^+$ channels?
Considering both electrical and chemical gradients, which of the following ions is closest to its equilibrium potential at the typical neuronal resting membrane potential?
Considering both electrical and chemical gradients, which of the following ions is closest to its equilibrium potential at the typical neuronal resting membrane potential?
Which of the following explains why the effects of $Na^+$ and $K^+$ on membrane potential are opposite, despite both being positive ions?
Which of the following explains why the effects of $Na^+$ and $K^+$ on membrane potential are opposite, despite both being positive ions?
A new drug selectively blocks the reuptake of a neurotransmitter that opens chloride channels in the postsynaptic neuron. What is the most likely effect of this drug on the postsynaptic neuron?
A new drug selectively blocks the reuptake of a neurotransmitter that opens chloride channels in the postsynaptic neuron. What is the most likely effect of this drug on the postsynaptic neuron?
A researcher applies a drug that blocks all voltage-gated ion channels in a neuron. What immediate effect will this have on the neuron's basic function?
A researcher applies a drug that blocks all voltage-gated ion channels in a neuron. What immediate effect will this have on the neuron's basic function?
How does the concentration gradient affect the movement of ions across the neuronal membrane?
How does the concentration gradient affect the movement of ions across the neuronal membrane?
Why is calcium ($Ca^{2+}$) considered a more influential ion for neurons than sodium ($Na^+$) or potassium ($K^+$), despite having a weaker direct effect on membrane potential?
Why is calcium ($Ca^{2+}$) considered a more influential ion for neurons than sodium ($Na^+$) or potassium ($K^+$), despite having a weaker direct effect on membrane potential?
If a neuron is stimulated with a series of EPSPs that do not individually reach the threshold for an action potential, what process could allow these EPSPs to collectively trigger an action potential?
If a neuron is stimulated with a series of EPSPs that do not individually reach the threshold for an action potential, what process could allow these EPSPs to collectively trigger an action potential?
Flashcards
Excitatory Synapses
Excitatory Synapses
Excitatory axons create synapses on dendrites, causing them to depolarize (become more positive).
Action Potential Threshold
Action Potential Threshold
The amount of depolarization needed at the axon hillock to trigger an action potential.
EPSP Summation
EPSP Summation
Neurons depend on summating multiple EPSPs to fire an action potential (AP).
Temporal Summation
Temporal Summation
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Temporal Summation Limit
Temporal Summation Limit
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Spatial Summation
Spatial Summation
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Combined Summation
Combined Summation
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Summation Integration Role
Summation Integration Role
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Ions
Ions
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Major Ions in Neurons
Major Ions in Neurons
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Concentration Gradient
Concentration Gradient
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Membranes
Membranes
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Ion Channels
Ion Channels
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Leak Channels
Leak Channels
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Ligand-Gated Channels
Ligand-Gated Channels
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Ligand
Ligand
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Voltage-gated channel
Voltage-gated channel
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Membrane potential
Membrane potential
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Resting membrane potential (Em)
Resting membrane potential (Em)
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Depolarization
Depolarization
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Excitatory Postsynaptic Potential (EPSP)
Excitatory Postsynaptic Potential (EPSP)
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Time by voltage plot
Time by voltage plot
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Hyperpolarization
Hyperpolarization
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Inhibitory Postsynaptic Potential (IPSP)
Inhibitory Postsynaptic Potential (IPSP)
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Na+ effect on membrane potential
Na+ effect on membrane potential
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Chloride (Cl-) effect
Chloride (Cl-) effect
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Potassium (K+) effect
Potassium (K+) effect
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Na+ concentration gradient
Na+ concentration gradient
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K+ concentration gradient
K+ concentration gradient
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Calcium's (Ca2+) role
Calcium's (Ca2+) role
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Study Notes
- Neurons communicate using a combination of electrical and chemical signals.
- Ions are charged elements or molecules.
- Positive ions have a (+) charge.
- Negative ions have a (-) charge.
- Neuron electrical potential changes via ion movement.
Major Ions for Neuron Signaling
- Key ions include Sodium (Na+), Potassium (K+), Chloride (Cl-), and Calcium (Ca2+).
- Ion concentration is not equal inside and outside of cells.
- Concentration gradients are the primary driving force for electrical signaling.
- Neurons are containers of K+ in a solution of salt (Na+ and Cl-), also containing Ca2+.
Ion Channels & Membranes
- Cellular membranes restrict ion movement, requiring specialized proteins for ions to pass through.
- Ion channels are proteins folded into a spiral with a central pore.
- Electrical signaling in neurons is mainly controlled by the opening and closing of these channels.
- Channels are specific to certain ions; Na+ channels only allow Na+ to pass through, with rare exceptions.
- Main ion channel types include Leak, Ligand-Gated, and Voltage-Gated channels.
- Leak channels are always open and maintain the membrane potential, which keeps the electrical state stable during rest.
- Ligand-gated channels are usually closed.
- They contain a ligand binding site on the extracellular part of the protein.
- A ligand, like neurotransmitters or hormones, binds to open the channel.
- Each channel is specific to its ligand, with a few exceptions.
- These are important for synaptic signaling in dendrites.
- Similar to ligand-gated channels, voltage-gated channels are usually in the closed position
- Voltage-gated channels open when activated, not by external ligands, but through a voltage sensor located intracellularly.
- A sufficient positive change inside te cell triggers the voltage sensor, opening the channel.
Membrane Potentials
- All neurons are electrically charged due to an imbalance of positive and negative ions.
- This electrical charge is the membrane potential, also known as the cell's voltage, or Em
- Maintained by leak channels, neurons default voltage is always returned to over time, the resting membrane potential (Em).
- A neuron's Em is typically about -70 mV.
- As ions flow in and out the electrical potential will change, depending on the opening and closing of channels.
- Ions move down their gradient from high to low concentration.
- Ion movement changes the membrane potential because they are charged.
Na+ Movement
- There is a high extracellular concentration of Na+, and low intracellular concentration.
- Na+ flows into the cell when Na+ channels open, down its concentration gradient.
- Cell becomes more positive as Na+ enters, called Depolarization, or Excitatory Postsynaptic Potential (EPSP).
- Depolarization means the cell becomes more positive, as the membrane potential approaches 0mV, where "De" means undo and "Polar" means far away / opposite.
- Excitatory Postsynaptic Potential (EPSP) is when a cell becomes more positive, called "postsynaptic potential" due to potential changes that are typically recorded from a cell stimulated at a synapse.
- When Na+ channels open, the positive Na+ ions that enter the cell depolarize, causing an EPSP.
- Time vs voltage plots often display membrane potential
- X-axis is time (msec) and Y-axis is voltage (mV).
- EPSPs temporarily make the cell slightly less negative.
- Baseline is maintained by the consistent opening of leak channels, returning it to Em (~ -70mV) when not stimulated.
Cl- and K+ Movement
- Cl- influx makes the cell more negative because Cl- has a greater extracellular concentration than its intracellular concentration.
- It is known as Hyperpolarization or Inhibitory Postsynaptic Potential (IPSP).
- Hyperpolarization occurs when a cell becomes more negative ("Hyper" = exceed, go past; "Polar" = far away/opposite).
- Similar to EPSP, the membrane potential will always return to the Em (~ -70mV).
- When K+ channels open the cell also becomes more negative, even though K+ is a positive ion
- High intracellular and low extracellular environments causes K+ exits the cell due to a change in concentration gradient.
- Cell hyperpolarization is caused by the flux of positive ions exiting.
- The cell becomes more negative as positive charges exit .
- Despite being positive ions, Na+ and K+ have opposite effects on the membrane due to concentration gradients: Na+ depolarizes, while K+ hyperpolarizes.
Ca2+
- A unique ion, that flows down its concentration gradient but it is a weak gradient
- Minimal depolarization as only very little Ca2+ enters the cell (when compared to other ions)
- It is the most influential ion for neurons despite not significantly changing the membrane potential.
- Ca2+ activates proteins to perform neuron related functions like NT release, plasticity, muscle contraction, and gene expression.
EPSP Summation
- Typically, excitatory axons form synapses on the dendrites of cells and cause the dendrites to depolarize.
- The positive dendrite charge goes through the cell body to the axon hillock.
- An action potential (AP) will fire if the axon hillock becomes positive enough and it will reach the cells AP Threshold.
- Because a single EPSP causes a small change in the membrane potential and decays before reaching the axon hillock, multiple EPSPs must reach the axon hillock to cause an AP.
- Neurons need to summate multiple EPSPs to fire an AP, which prevents biological systems from being overly sensitive to spontaneous firing from random activity.
- There are two forms of EPSP summation: temporal (time) and spatial (space, area).
- Temporal Summation are two or more EPSPs on the same dendrite that happen in quick succession.
- The following EPSPs will add their positivity to first EPSP
- Temporal Summation can only happen when EPSPs are close in time, otherwise membrane potential returns to Em.
- Spatial Summation are two or more EPSPs that happen at the same time at multiple dendrites.
- The EPSPs from one dendrite will summate on the EPSP from another dendrite
- Both temporal and spatial summation are used in tandem.
- They work together make the neuron positive enough to cause an AP.
- Neurons use this method integrate information from very active axons or multiple axons.
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Description
Explore neuron communication through electrical and chemical signals, focusing on the roles of ions like Sodium, Potassium, Chloride, and Calcium. Understand how ion channels in cellular membranes facilitate ion movement, driving electrical signaling in neurons.
