Podcast
Questions and Answers
What primarily triggers the influx of Na+ during the rising phase of an action potential?
What primarily triggers the influx of Na+ during the rising phase of an action potential?
- Gated K+ channels opening
- Large driving force causing Na+ to rush into the cell (correct)
- Inactivation of Ca2+ channels
- Hyperpolarization of the cell
What occurs during the falling phase of an action potential?
What occurs during the falling phase of an action potential?
- The intercellular voltage becomes more positive
- K+ channels open, allowing K+ to flow out of the cell (correct)
- Na+ continues to rush into the cell
- The cell remains depolarized
What is the effect of Na+ rushing into the cell on its membrane potential during the rising phase?
What is the effect of Na+ rushing into the cell on its membrane potential during the rising phase?
- It causes hyperpolarization of the cell
- It has no effect on membrane potential
- It makes the inside of the cell more positive (correct)
- It stabilizes the resting membrane potential
What value does the membrane potential approach during the peak of depolarization?
What value does the membrane potential approach during the peak of depolarization?
What initiates the inactivation of Na+ channels during the action potential?
What initiates the inactivation of Na+ channels during the action potential?
What causes the depolarization of a neuron to reach the threshold?
What causes the depolarization of a neuron to reach the threshold?
Which statement describes the role of sodium channels in the action potential?
Which statement describes the role of sodium channels in the action potential?
What event occurs after sodium channels open and sodium rushes into the cell?
What event occurs after sodium channels open and sodium rushes into the cell?
Why is a threshold voltage important in the generation of an action potential?
Why is a threshold voltage important in the generation of an action potential?
What is the primary effect of increased sodium permeability during a neuron’s depolarization phase?
What is the primary effect of increased sodium permeability during a neuron’s depolarization phase?
What happens to the neuron's membrane potential during repolarization?
What happens to the neuron's membrane potential during repolarization?
What triggers the opening of potassium channels during the action potential process?
What triggers the opening of potassium channels during the action potential process?
What is the consequence of a cell becoming depolarized?
What is the consequence of a cell becoming depolarized?
What is the primary characteristic of Gray's Type I synapses?
What is the primary characteristic of Gray's Type I synapses?
Which type of receptors are primarily associated with EPSPs?
Which type of receptors are primarily associated with EPSPs?
What occurs immediately after the presynaptic membrane depolarizes and reaches threshold?
What occurs immediately after the presynaptic membrane depolarizes and reaches threshold?
What are the two major functions of receptors?
What are the two major functions of receptors?
Which statement is true regarding ionotropic receptors?
Which statement is true regarding ionotropic receptors?
What is an example of an inhibitory neurotransmitter that may lead to an IPSP?
What is an example of an inhibitory neurotransmitter that may lead to an IPSP?
Which feature distinguishes Gray's Type II synapses?
Which feature distinguishes Gray's Type II synapses?
Which type of potential is primarily generated by ligand-gated ionotropic receptors?
Which type of potential is primarily generated by ligand-gated ionotropic receptors?
What is the primary function of microglia in the central nervous system?
What is the primary function of microglia in the central nervous system?
Which glial cell type is responsible for forming the blood-brain barrier?
Which glial cell type is responsible for forming the blood-brain barrier?
What ion primarily contributes to repolarization during an action potential?
What ion primarily contributes to repolarization during an action potential?
Which equation relates the concentration of ions outside and inside the cell to the membrane potential?
Which equation relates the concentration of ions outside and inside the cell to the membrane potential?
What does a membrane potential of -70 mV indicate?
What does a membrane potential of -70 mV indicate?
What is the main role of oligodendrocytes in the central nervous system?
What is the main role of oligodendrocytes in the central nervous system?
What drives the ion flow until equilibrium is reached according to the Nernst Equation?
What drives the ion flow until equilibrium is reached according to the Nernst Equation?
What characteristic of a membrane does the Goldman Equation take into account?
What characteristic of a membrane does the Goldman Equation take into account?
What is hyperpolarization in the context of membrane potential?
What is hyperpolarization in the context of membrane potential?
What force opposes the concentration gradient for ions during membrane potential changes?
What force opposes the concentration gradient for ions during membrane potential changes?
Which type of cell in the peripheral nervous system myelinates neurons?
Which type of cell in the peripheral nervous system myelinates neurons?
What does Ohm's Law relate to in the context of neuronal function?
What does Ohm's Law relate to in the context of neuronal function?
What potential difference exists across the resting membrane of most neurons?
What potential difference exists across the resting membrane of most neurons?
What ion is more concentrated outside of a resting neuron compared to inside?
What ion is more concentrated outside of a resting neuron compared to inside?
What effect does depolarization have on a neuron's membrane potential?
What effect does depolarization have on a neuron's membrane potential?
What role do voltage-gated channels play in neuronal function?
What role do voltage-gated channels play in neuronal function?
What is the primary function of the Sodium-Potassium pump?
What is the primary function of the Sodium-Potassium pump?
What does hyperpolarization refer to in neuronal activity?
What does hyperpolarization refer to in neuronal activity?
What type of ion is primarily involved in depolarization?
What type of ion is primarily involved in depolarization?
What effect does TTX have on neuronal activity?
What effect does TTX have on neuronal activity?
Which ionic condition describes the term 'cation'?
Which ionic condition describes the term 'cation'?
What does permeability refer to in the context of ion channels?
What does permeability refer to in the context of ion channels?
What is the effect of TEA on neuronal currents?
What is the effect of TEA on neuronal currents?
How does the concept of 'current' relate to ion movement in neurons?
How does the concept of 'current' relate to ion movement in neurons?
What happens to membrane potential during the influx of sodium ions?
What happens to membrane potential during the influx of sodium ions?
Which of the following statements about ion gradients is true?
Which of the following statements about ion gradients is true?
What occurs during the depolarization phase of an action potential?
What occurs during the depolarization phase of an action potential?
What role does ATP play in the function of the Sodium-Potassium pump?
What role does ATP play in the function of the Sodium-Potassium pump?
Study Notes
Glial Cells
- Microglia are immune cells that phagocytize (engulf and digest) foreign invaders and cellular debris in the central nervous system (CNS).
- Ependymal cells line the ventricles of the brain and the central canal of the spinal cord.
- Oligodendrocytes are responsible for creating the myelin sheath, which insulates axons in the CNS and aids in signal transmission.
- Astrocytes are star-shaped cells that provide structural support and maintain the blood-brain barrier, limiting potassium (K+) movement. They fill most of the space between neurons in the brain.
- Schwann cells myelinate axons in the peripheral nervous system (PNS).
Membrane Potential
- The membrane potential (Vm) is the difference in electrical potential across the cell membrane.
- Vm depends on ion concentration gradients and the selective permeability of the membrane.
- At rest, neurons typically have a Vm of around -65 to -70 mV, which is considered hyperpolarized.
- This resting potential exists due to the differences in ion concentrations across the membrane – sodium ions (Na+) have a higher concentration outside the cell, while potassium ions (K+) have a higher concentration inside the cell.
- Forces driving ion movement include:
- Chemical diffusion: Ions move down their concentration gradients, from areas of high concentration to low concentration.
- Electrical opposition: Ions move to areas with opposite charges.
- Conductance (g) represents how easily ions can move across the membrane. Ohm's Law (V = IR) relates membrane potential (V), current (I), and resistance (R), which is the inverse of conductance.
- Driving force refers to the difference between the membrane potential (Um) and the ion's equilibrium potential (Eion), which is the potential at which there is no net ion movement.
- Nernst Equation calculates the equilibrium potential (Eion) for a specific ion. It considers the charge of the ion, the concentrations of the ion inside and outside the cell, and the ideal gas constant.
- Goldman Equation calculates the membrane potential (Um) considering the permeability of the membrane to multiple ions, including potassium (K+), sodium (Na+), and chloride (Cl-).
- Depolarization: The membrane potential becomes less negative, moving towards zero.
- Hyperpolarization: The membrane potential becomes more negative, moving further away from zero.
- Current: The flow of ions across the membrane. Inward current causes depolarization, while outward current causes hyperpolarization.
- Permeability: How easily ions can cross the membrane.
- Voltage-gated channels: Open and close in response to changes in membrane potential.
Sodium-Potassium Pump
- The sodium-potassium pump uses ATP to actively transport 3 Na+ ions out of the cell and 2 K+ ions into the cell.
- This exchange works against the concentration gradients of both ions, maintaining the resting membrane potential.
- The pump contributes to the neuron's ability to depolarize and repolarize.
Action Potential
- An action potential (AP) is a rapid change in membrane potential that travels down the axon of a neuron.
- Threshold potential: The membrane potential at which enough voltage-gated Na+ channels open to trigger a positive feedback cycle, leading to a rapid depolarization.
- Rising phase: The depolarization of the membrane due to the influx of Na+ ions through open voltage-gated Na+ channels.
- Peak: The point at which the membrane potential reaches its most positive value, typically around +40 mV.
- Falling phase: The repolarization of the membrane as voltage-gated Na+ channels inactivate and voltage-gated K+ channels open, allowing K+ ions to flow out of the cell.
- Undershoot: The membrane potential briefly becomes more negative than the resting potential due to the continued efflux of K+ ions.
- This all-or-none event is essential for neural communication, enabling the transmission of information over long distances in the nervous system.
Important Considerations
- Tetrodotoxin (TTX) blocks Na+ currents, while Tetraethyl ammonium (TEA) blocks K+ currents.
- These toxins are useful tools for studying the roles of specific ions in neural function.
- Understanding these fundamental processes allows for a deeper understanding of neural signaling and its connection to brain function and behavior.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Explore key concepts in neuroscience focusing on glial cells and membrane potential. This quiz covers the roles of different glial cells in the central and peripheral nervous systems, as well as the fundamentals of membrane potential in neurons. Test your understanding of these vital topics in neurobiology.
