p.69
Graded Potentials and Their Characteristics
What is the effect of distance on graded potentials?
Graded potentials decrease in amplitude as they spread away from the point of origin.
p.62
Action Potential Generation and Phases
What happens to voltage-gated channels if a cell membrane is maintained above threshold voltage?
They become inactivated and cannot generate action potentials.
p.63
Graded Potentials and Their Characteristics
What is a generator potential?
A change in membrane potential that occurs in response to a stimulus at a sensory receptor.
p.12
Resting Membrane Potential
What happens to membrane potential as the amount of separated charges increases?
The membrane potential increases.
p.9
Resting Membrane Potential
What occurs when opposite charges are separated across a membrane?
Membrane potential exists.
p.77
Graded Potentials and Their Characteristics
What types of receptors respond to stimuli that generate receptor potentials?
Mechanoreceptors, thermoreceptors, nociceptors, chemoreceptors, and electromagnetic receptors.
p.7
Ion Permeability and Membrane Potential
What does the lipid bilayer separate?
Two very conductive (salty) solutions.
p.73
Graded Potentials and Their Characteristics
What happens to charge in graded potentials due to 'leaky' channels?
Charge is lost across the membrane, causing the magnitude of the potential to decrease with distance from the site of origin.
p.15
Ion Permeability and Membrane Potential
What is the role of the chemical gradient in membrane potentials?
It drives the movement of ions based on their concentration differences.
p.75
Graded Potentials and Their Characteristics
What role do graded potentials play in neurons?
They are important for the initiation and integration of long-distance signals.
p.59
Action Potential Generation and Phases
What initiates an action potential?
A sufficient depolarization of the neuron's membrane.
p.46
Action Potential Generation and Phases
What is constant along a nerve fiber during action potentials?
The size and shape of the action potential.
p.50
Action Potential Generation and Phases
Is the duration of an action potential the same for specific tissues?
Yes, it is always the same for a specific tissue.
p.50
Action Potential Generation and Phases
What influences the time frame of action potentials?
Specific transport protein cycle times.
p.66
Graded Potentials and Their Characteristics
What is a subthreshold response in graded potentials?
A local response that does not reach the threshold for action potential generation.
p.48
Action Potential Generation and Phases
What happens during the depolarization phase of an action potential?
Sodium channels open, allowing Na+ ions to flow into the cell.
p.22
Nernst Equation and Goldman Equation
What does the equilibrium potential represent?
The charge that the membrane would have if only that ion could cross the membrane.
p.7
Ion Permeability and Membrane Potential
What is the electrical resistance of the lipid bilayer?
It has a high electrical resistance, meaning charged particles do not move easily across it.
p.69
Graded Potentials and Their Characteristics
What are graded potentials?
Changes in membrane potential that vary in size and are not all-or-nothing.
p.83
Resting Membrane Potential
What is potential in the context of voltage?
The voltage difference between two points.
p.7
Ion Permeability and Membrane Potential
What happens with small differences in the electrical balance of charges inside the cell?
They easily attract opposite charges to the outside of the cell.
p.68
Graded Potentials and Their Characteristics
What are graded potentials?
Changes in membrane potential that vary in size and are not all-or-nothing.
p.59
Role of Ion Channels in Action Potentials
What is the role of ion channels in action potentials?
Ion channels open and close to allow the flow of ions, which changes the membrane potential and propagates the action potential.
p.69
Action Potential Generation and Phases
What is the role of graded potentials in neurons?
They can lead to action potentials if the threshold is reached.
p.31
Action Potential Generation and Phases
What is an action potential?
A rapid change in membrane potential that propagates along the axon of a neuron.
p.45
Role of Ion Channels in Action Potentials
What role do sodium (Na+) ions play in action potentials?
They rush into the neuron during depolarization, causing the membrane potential to become more positive.
p.82
Differences Between Graded and Action Potentials
What mechanisms do action potentials depend on?
Action potentials depend on voltage-gated channels.
p.48
Action Potential Generation and Phases
What is the significance of the all-or-nothing principle in action potentials?
Once the threshold is reached, an action potential will occur fully or not at all.
p.48
Action Potential Generation and Phases
What occurs during the hyperpolarization phase?
The membrane potential becomes more negative than the resting potential.
p.49
Action Potential Generation and Phases
What does 'all or none' mean in the context of action potentials?
When the membrane reaches threshold, an action potential is generated; it is not graded.
p.10
Resting Membrane Potential
What is responsible for the potential across a membrane?
Unbalanced charges that accumulate in a thin layer along opposite surfaces of the membrane.
p.60
Refractory Periods in Action Potentials
What are refractory periods in relation to action potentials?
Times when it is either impossible or more difficult than normal to generate a second action potential.
p.84
Graded Potentials and Their Characteristics
What is the difference between EPSP and IPSP?
EPSP is a depolarizing synaptic potential, while IPSP is a hyperpolarizing synaptic potential.
p.46
Action Potential Generation and Phases
What happens to membrane polarity during an action potential?
It reverses, resulting in complete depolarization.
p.83
Nernst Equation and Goldman Equation
What is equilibrium potential?
The voltage difference across a membrane that produces a flux of a given ion species equal but opposite to the flux due to the concentration gradient of that same ion species.
p.68
Differences Between Graded and Action Potentials
How do graded potentials differ from action potentials?
Graded potentials can vary in magnitude, while action potentials are uniform and all-or-nothing.
p.82
Differences Between Graded and Action Potentials
What types of changes can graded potentials cause?
Graded potentials can be either a depolarization or a hyperpolarization.
p.37
Role of Ion Channels in Action Potentials
What ions are primarily involved in the conductance during an action potential?
Potassium (K) and Sodium (Na).
p.3
Bioelectricity and Functional Anatomy of Neurons
What is bioelectricity in the context of neurons?
Bioelectricity refers to the electrical properties and activities of neurons that enable communication within the nervous system.
p.94
Ion Permeability and Membrane Potential
What are the three factors that affect diffusion potential when the membrane is permeable to several different ions?
1) Polarity of the electrical charge of each ion, 2) Permeability of the membrane to each ion, 3) Concentrations of the respective ions inside and outside the membrane.
p.31
Action Potential Generation and Phases
What occurs during the depolarization phase of an action potential?
Sodium channels open, allowing Na+ to flow into the neuron, making the inside more positive.
p.8
Resting Membrane Potential
What happens when positive and negative charges are distributed equally across the membrane?
No membrane potential exists.
p.84
Action Potential Generation and Phases
What characterizes an action potential?
A brief all-or-none depolarization of the membrane, reversing polarity in neurons; it has a threshold and refractory period and is conducted without decrement.
p.59
Action Potential Generation and Phases
What is an action potential?
A rapid change in membrane potential that propagates along the membrane of a neuron.
p.69
Ion Permeability and Membrane Potential
What causes graded potentials?
They are caused by the opening of ion channels in response to stimuli.
p.78
Graded Potentials and Their Characteristics
What specialized cells are involved in the pacemaker potential?
Specialized cells in the cardiac pacemaker region (SA node).
p.2
Resting Membrane Potential
Why does the resting membrane potential of most cells approximate the Nernst potential for potassium (K)?
Because potassium ions (K+) are the most permeable ions at rest, influencing the membrane potential significantly.
p.45
Action Potential Generation and Phases
What is an action potential?
A rapid, temporary change in the membrane potential of a neuron.
p.45
Action Potential Generation and Phases
What triggers the generation of an action potential?
A depolarization that reaches a threshold level.
p.45
Action Potential Generation and Phases
What are the phases of an action potential?
Depolarization, repolarization, and hyperpolarization.
p.82
Differences Between Graded and Action Potentials
What mechanisms do graded potentials depend on?
Graded potentials depend on ligand-sensitive channels or other chemical or physical changes.
p.76
Graded Potentials and Their Characteristics
How do graded potentials differ?
They have different names depending on the type of stimulus and location where they occur.
p.49
Action Potential Generation and Phases
Where do action potentials occur?
Only on regions of cell membranes that are electrically excitable.
p.89
Differences Between Graded and Action Potentials
Are graded potentials always hyperpolarizing?
A. Graded potentials are always hyperpolarizing, whereas action potentials are always depolarizing.
p.65
Graded Potentials and Their Characteristics
What are the two types of physiochemical disturbances produced by stimuli?
1. Local, graded, non-propagated potentials (receptor or generator potentials, synaptic potentials, or electrotonic potentials) 2. Action potentials (nerve impulses) which are propagated down the axon.
p.22
Nernst Equation and Goldman Equation
What does the Nernst Equation calculate?
The equilibrium potential for a specific ion.
p.72
Graded Potentials and Their Characteristics
What are graded potentials?
Changes in membrane potential that vary in size and are conducted with decrement.
p.85
Graded Potentials and Their Characteristics
What is a receptor potential?
A graded potential produced at the peripheral endings of afferent neurons in response to a stimulus.
p.91
Bioelectricity and Functional Anatomy of Neurons
Which option describes the effect of hyperkalemia on nerve threshold potential?
Nerve becomes more excitable.
p.27
Active Transport Mechanisms: Na+/K+ Pump
What is the electrogenic nature of the Na+/K+ ATPase pump?
It contributes to inside-negativity by moving 3 Na+ out for every 2 K+ in.
p.61
Refractory Periods in Action Potentials
Why is it more difficult to generate a second action potential during the relative refractory period?
Due to the hyperpolarization of the cell.
p.70
Graded Potentials and Their Characteristics
What happens during hypopolarizing graded potentials?
There is a decrease in potential difference.
p.83
Resting Membrane Potential
What is resting membrane potential?
The steady transmembrane potential of a cell that is not producing an electric signal.
p.48
Action Potential Generation and Phases
What initiates the action potential in a neuron?
A depolarization that reaches the threshold potential.
p.66
Graded Potentials and Their Characteristics
What does it mean that graded potentials are local?
Changes in membrane potential are confined to relatively small regions of the plasma membrane.
p.48
Action Potential Generation and Phases
What is the role of potassium channels during the action potential?
They open during repolarization, allowing K+ ions to exit the cell.
p.32
Action Potential Generation and Phases
What is an action potential?
A transient change in the membrane potential that conveys information within the nervous system.
p.15
Ion Permeability and Membrane Potential
What are the two gradients responsible for the movement of ions across the membrane?
Electrical gradients and chemical (concentration) gradients.
p.79
Action Potential Generation and Phases
What happens if graded potentials reach the threshold?
An action potential develops.
p.27
Active Transport Mechanisms: Na+/K+ Pump
How can the Na+/K+ ATPase pump be neutral regarding membrane charge?
By moving equal numbers of K+ in and Na+ out.
p.61
Refractory Periods in Action Potentials
What does the relative refractory period correspond to in action potentials?
The positive after potential period.
p.62
Action Potential Generation and Phases
What is voltage inactivation?
It is the state where voltage-gated channels are not reset and remain inactivated, preventing action potential generation.
p.68
Graded Potentials and Their Characteristics
Where do graded potentials typically occur?
In the dendrites and cell body of neurons.
p.82
Differences Between Graded and Action Potentials
What initiates graded potentials?
Graded potentials are initiated by environmental stimuli (receptors), neurotransmitters (synapses), or spontaneously.
p.76
Graded Potentials and Their Characteristics
What are receptor potentials?
Graded potentials that occur in sensory receptors.
p.87
Differences Between Graded and Action Potentials
What could be a consequence of increased action potential amplitude?
It could lead to stronger signals but does not explain the lack of response after ion concentration equilibration.
p.6
Resting Membrane Potential
What equipment is typically used to record membrane potentials?
Microelectrodes and an oscilloscope or a voltmeter.
p.89
Differences Between Graded and Action Potentials
What is true about graded potentials?
D. Graded potentials are always decremental, whereas action potentials are always non-decremental.
p.51
Action Potential Generation and Phases
What type of stimuli causes the generation of an action potential?
Threshold stimuli (Graded Potential).
p.72
Graded Potentials and Their Characteristics
How is the conduction of graded potentials characterized?
By decrement, meaning the conduction magnitude falls off the further you get from the point of origin.
p.21
Nernst Equation and Goldman Equation
What does the Nernst potential relate to?
The concentration difference of a particular ion.
p.46
Action Potential Generation and Phases
What generates action potentials?
Graded potentials that reach threshold.
p.7
Ion Permeability and Membrane Potential
What property of the lipid bilayer allows it to store a large amount of charge?
Its thinness allows for high capacitance.
p.78
Graded Potentials and Their Characteristics
What is the role of graded potentials in the heart?
Graded potentials can potentially induce a true cardiac action potential.
p.50
Action Potential Generation and Phases
Do action potentials have a specific size and shape?
Yes, they have a specific size and shape.
p.63
Role of Ion Channels in Action Potentials
How does transduction occur in sensory receptors?
Transduction converts a stimulus into an electrical signal, typically a generator potential.
p.37
Action Potential Generation and Phases
What happens to sodium conductance during the depolarization phase of an action potential?
Sodium conductance increases rapidly.
p.31
Ion Permeability and Membrane Potential
What ions are primarily involved in generating an action potential?
Sodium (Na+) and potassium (K+).
p.45
Action Potential Generation and Phases
What happens during repolarization?
Potassium (K+) ions exit the neuron, restoring the negative membrane potential.
p.6
Resting Membrane Potential
What is the first step in setting up for recording membrane potentials?
Insert a microelectrode into the cell.
p.49
Action Potential Generation and Phases
How do action potentials vary among different cell types?
They generally have a standard size and shape for a specific cell type.
p.31
Propagation of Nerve Impulse
What is the role of myelin in nerve impulse propagation?
Myelin insulates the axon, allowing for faster transmission of action potentials via saltatory conduction.
p.51
Action Potential Generation and Phases
What are some functions that action potentials are important for?
Nerve traffic, muscle contraction, hormone release, G.I. secretions, and cognitive thought.
p.77
Graded Potentials and Their Characteristics
What are receptor (generator) potentials?
Graded potentials in response to stimuli from sensory receptors.
p.80
Graded Potentials and Their Characteristics
What is the End Plate Potential (EPP)?
A post synaptic potential at the neuromuscular junction that is always stimulatory.
p.84
Graded Potentials and Their Characteristics
What is a synaptic potential?
A graded potential change produced in the postsynaptic neuron in response to the release of a neurotransmitter by a presynaptic terminal; it may be depolarizing (EPSP) or hyperpolarizing (IPSP).
p.2
Resting Membrane Potential
What does it mean for a cell to have a resting membrane potential difference?
It refers to the voltage difference across the cell membrane when the cell is not actively transmitting signals.
p.85
Action Potential Generation and Phases
What is threshold potential?
The membrane potential at which an action potential is initiated.
p.87
Action Potential Generation and Phases
What happens when the ionic composition of the medium is equilibrated with the intracellular concentration in the giant squid axon?
No more action potentials are seen upon stimulation.
p.62
Action Potential Generation and Phases
What occurs during accommodation to slow depolarization?
Voltage-gated channels do not respond, and no action potential occurs.
p.63
Action Potential Generation and Phases
What happens when a generator potential reaches a certain threshold?
It can trigger an action potential in the sensory neuron.
p.63
Graded Potentials and Their Characteristics
What is the relationship between stimulus intensity and generator potential?
Higher stimulus intensity results in a larger generator potential.
p.6
Resting Membrane Potential
What is the primary purpose of recording membrane potentials?
To measure the electrical activity across a cell membrane.
p.49
Action Potential Generation and Phases
What causes action potentials?
Rapid changes in ion conductance.
p.64
Bioelectricity and Functional Anatomy of Neurons
What is a receptor in the context of sensory modalities?
A specialized cell or distal portion of a neuron that responds to specific sensory modalities like touch, pressure, cold, light, or sound, and converts it to an electrical signal.
p.25
Nernst Equation and Goldman Equation
What is the Goldman equation also known as?
The Goldman - Hodgkin - Katz equation.
p.51
Action Potential Generation and Phases
Which senses depend on action potentials for information transmission to the brain?
Sight, hearing, and touch.
p.88
Action Potential Generation and Phases
What causes repolarization of the neuronal cell membrane when a nerve is stimulated?
Increase in outward permeability of K+ ion.
p.32
Role of Ion Channels in Action Potentials
Which types of cells generate action potentials?
Electrically excitable cells, such as nerve and muscle cells.
p.32
Action Potential Generation and Phases
What stimulates the generation of an action potential?
A change in membrane potential due to the flow of current in and out of the cell.
p.77
Action Potential Generation and Phases
What happens if a graded potential reaches the threshold?
An action potential is generated, sending sensory information to the spinal cord and brain.
p.84
Graded Potentials and Their Characteristics
What is a graded potential?
A potential change of variable amplitude and duration that is conducted decrementally; it has no threshold or refractory period.
p.91
Bioelectricity and Functional Anatomy of Neurons
What is hyperkalemia?
An electrolyte disorder characterized by elevated potassium levels in the blood.
p.15
Ion Permeability and Membrane Potential
What does the electrical gradient influence in membrane potentials?
The movement of charged ions across the membrane.
p.79
Graded Potentials and Their Characteristics
What types of stimuli can graded potentials be during synaptic transmission?
They can be stimulatory (EPSP) or inhibitory (IPSP).
p.75
Graded Potentials and Their Characteristics
What is one characteristic of graded potentials?
They are the only type of communication by some neurons.
p.80
Graded Potentials and Their Characteristics
Is the End Plate Potential (EPP) excitatory or inhibitory?
It is always stimulatory.
p.73
Graded Potentials and Their Characteristics
How do graded potentials function in terms of distance?
They can function as signals over very short distances.
p.70
Graded Potentials and Their Characteristics
What does it mean that graded potentials are 'graded'?
Their magnitude can vary with the magnitude of the stimulus.
p.69
Differences Between Graded and Action Potentials
How do graded potentials differ from action potentials?
Graded potentials can vary in magnitude, while action potentials are uniform and all-or-nothing.
p.59
Differences Between Graded and Action Potentials
What are the types of action potentials?
There are different types based on the stimulus and the resulting response, such as graded potentials leading to action potentials.
p.85
Graded Potentials and Their Characteristics
What is a pacemaker potential?
A spontaneously occurring graded potential change that occurs in certain specialized cells.
p.83
Resting Membrane Potential
What does membrane potential refer to?
The voltage difference between the inside and outside of a cell.
p.70
Graded Potentials and Their Characteristics
What are the two types of graded events?
Hypopolarizing (depolarizing) and hyperpolarizing.
p.73
Graded Potentials and Their Characteristics
How far do graded potentials typically die out from their origin?
In 1 - 2 mm of the origin.
p.2
Ion Permeability and Membrane Potential
How do changes in ion permeability affect membrane potential?
Changes in ion permeability can lead to depolarization or hyperpolarization of the membrane potential, depending on which ions are more permeable.
p.27
Active Transport Mechanisms: Na+/K+ Pump
What does the Na+/K+ ATPase pump maintain?
The concentration gradients for the two most important ions that determine the membrane potential.
p.20
Ion Permeability and Membrane Potential
What happens to the membrane potential when it becomes permeable to sodium ions?
It generates a diffusion potential due to sodium ion movement.
p.82
Differences Between Graded and Action Potentials
How does the duration of graded potentials compare to action potentials?
Graded potential duration varies with initiating conditions, while action potential duration is constant for a given cell type under constant conditions.
p.63
Graded Potentials and Their Characteristics
What are the properties of generator potentials?
They are graded, meaning their amplitude varies with the strength of the stimulus.
p.87
Refractory Periods in Action Potentials
What does the term 'absolute refractory period' refer to?
A phase during which no new action potentials can be generated, regardless of stimulus strength.
p.24
Resting Membrane Potential
What does RMP stand for in neurophysiology?
Resting Membrane Potential.
p.37
Action Potential Generation and Phases
What role does potassium conductance play during the repolarization phase of an action potential?
Potassium conductance increases, allowing K+ to exit the cell.
p.94
Ion Permeability and Membrane Potential
How does the polarity of the electrical charge of each ion affect diffusion potential?
It influences the movement of ions across the membrane based on their charge.
p.31
Action Potential Generation and Phases
What happens during the repolarization phase of an action potential?
Potassium channels open, allowing K+ to flow out of the neuron, restoring the negative membrane potential.
p.45
Action Potential Generation and Phases
What is the significance of the threshold potential?
It is the critical level that must be reached for an action potential to occur.
p.36
Action Potential Generation and Phases
What happens during the repolarization phase?
Potassium channels open, allowing K+ ions to exit the neuron.
p.36
Action Potential Generation and Phases
What occurs during hyperpolarization?
The membrane potential becomes more negative than the resting potential.
p.65
Graded Potentials and Their Characteristics
What are receptor or generator potentials?
Local, graded, non-propagated potentials produced by stimuli.
p.26
Active Transport Mechanisms: Na+/K+ Pump
What energy source does the Na+/K+ pump use to function?
ATP (adenosine triphosphate).
p.81
Differences Between Graded and Action Potentials
Is there a threshold for graded potentials?
No, there is no threshold.
p.68
Graded Potentials and Their Characteristics
What factors influence the size of a graded potential?
The strength of the stimulus and the type of ion channels activated.
p.82
Differences Between Graded and Action Potentials
What type of change does an action potential cause?
An action potential is only a depolarization.
p.62
Action Potential Generation and Phases
What is the effect of slow depolarization on action potential generation?
It prevents the generation of action potentials due to unresponsive voltage-gated channels.
p.82
Differences Between Graded and Action Potentials
What initiates action potentials?
Action potentials are initiated by a graded potential.
p.76
Graded Potentials and Their Characteristics
What are generator potentials?
Graded potentials that occur in sensory neurons.
p.87
Action Potential Generation and Phases
How does the speed of conduction of action potentials relate to ion concentration?
The speed of conduction can be affected by ion concentration, but in this case, the lack of response is due to ion equilibration.
p.52
Action Potential Generation and Phases
What occurs during the repolarization stage of the action potential?
K+ outflow through voltage-gated K+ channels, moving the membrane potential back toward RMP.
p.24
Resting Membrane Potential
What role do ion channels play in maintaining RMP?
They allow selective permeability to ions, influencing the membrane potential.
p.31
Refractory Periods in Action Potentials
What is the refractory period?
A period during which a neuron cannot fire another action potential, ensuring unidirectional propagation.
p.26
Active Transport Mechanisms: Na+/K+ Pump
What is the primary function of the Na+/K+ pump?
To actively transport sodium out of and potassium into the cell.
p.58
Action Potential Generation and Phases
What happens during the depolarization phase of an action potential?
Sodium channels open, allowing Na+ ions to flow into the cell.
p.4
Bioelectricity and Functional Anatomy of Neurons
What is the significance of the axon terminal?
It releases neurotransmitters into the synapse.
p.87
Ion Permeability and Membrane Potential
What is the likely cause of no response after equilibrating ion concentrations in the axon?
Increased permeability for Na+ is not achieved, leading to no action potential generation.
p.76
Graded Potentials and Their Characteristics
What is a postsynaptic potential?
A graded potential that occurs in the dendrites or cell body of a neuron in response to a neurotransmitter.
p.52
Action Potential Generation and Phases
What happens during the depolarization stage of the action potential?
Threshold for voltage-gated Na+ channels is exceeded, leading to Na+ influx.
p.24
Resting Membrane Potential
What primarily determines the resting membrane potential?
The distribution of ions across the cell membrane, particularly sodium (Na+) and potassium (K+).
p.94
Ion Permeability and Membrane Potential
What role does membrane permeability (P) play in diffusion potential?
It determines how easily ions can pass through the membrane.
p.3
Nernst Equation and Goldman Equation
How does the Nernst equation relate to ion permeability?
The Nernst equation shows how the concentration gradient of an ion affects its equilibrium potential, which influences the overall membrane potential based on permeability.
p.47
Action Potential Generation and Phases
What characterizes an action potential?
A rapid but transient change in membrane potential.
p.4
Bioelectricity and Functional Anatomy of Neurons
What are synapses?
Junctions where neurons communicate with other neurons or cells.
p.81
Differences Between Graded and Action Potentials
How are graded potentials conducted?
Decrementally; amplitude decreases with distance.
p.76
Graded Potentials and Their Characteristics
What is a graded potential?
A change in membrane potential that varies in size depending on the strength of the stimulus.
p.68
Graded Potentials and Their Characteristics
What happens to graded potentials as they move away from the stimulus site?
They decrease in amplitude due to passive current flow.
p.87
Refractory Periods in Action Potentials
What is the difference between absolute and relative refractory periods?
During the absolute refractory period, no action potentials can occur; during the relative refractory period, a stronger-than-normal stimulus can trigger an action potential.
p.66
Graded Potentials and Their Characteristics
What does it mean that graded potentials are graded?
It refers to the magnitude of the potential change, indicating that the signal can be reinforced.
p.48
Refractory Periods in Action Potentials
What is the refractory period?
The time during which a neuron cannot fire another action potential.
p.89
Differences Between Graded and Action Potentials
Which statement correctly describes graded potentials and action potentials?
B. Graded potentials are proportional to the magnitude of the stimulus, whereas action potentials are 'all-or-none.'
p.3
Nernst Equation and Goldman Equation
What does the Nernst equation calculate?
The Nernst equation calculates the equilibrium potential for a specific ion based on its concentration gradient across the membrane.
p.3
Resting Membrane Potential
What factors influence the resting membrane potential?
Ion concentrations inside and outside the cell, permeability of the membrane to different ions, and the activity of ion pumps.
p.47
Action Potential Generation and Phases
What does a change in local membrane polarity indicate?
It indicates the transition from polarized to depolarized states.
p.4
Bioelectricity and Functional Anatomy of Neurons
What is the role of neurotransmitters?
Chemical messengers that transmit signals across synapses.
p.49
Action Potential Generation and Phases
What is required for the generation of an action potential?
Specific voltage-gated ion channels.
p.36
Action Potential Generation and Phases
What occurs during the depolarization phase?
Sodium channels open, allowing Na+ ions to enter the neuron.
p.31
Propagation of Nerve Impulse
How is an action potential propagated along a nerve?
By the sequential opening and closing of ion channels along the axon.
p.89
Refractory Periods in Action Potentials
Can suprathreshold stimuli depolarize a neuron during absolute refractory periods?
C. Suprathreshold stimuli are able to depolarize a neuron in absolute refractory periods.
p.36
Action Potential Generation and Phases
What restores the resting membrane potential after an action potential?
The Na+/K+ pump and the closing of potassium channels.
p.4
Bioelectricity and Functional Anatomy of Neurons
What are the main components of a neuron?
Dendrites, cell body (soma), and axon.
p.58
Active Transport Mechanisms: Na+/K+ Pump
What is the role of the sodium-potassium pump during action potential generation?
It helps restore the resting membrane potential after the action potential.
p.81
Differences Between Graded and Action Potentials
What is the threshold for action potentials?
Usually about 15 mV depolarized relative to the resting potential.
p.37
Ion Permeability and Membrane Potential
How does the change in sodium and potassium conductance affect the membrane potential?
Increased Na+ conductance depolarizes the membrane, while increased K+ conductance repolarizes it.
p.37
Differences Between Graded and Action Potentials
What is the effect of sodium channel inactivation during an action potential?
It prevents further influx of Na+, contributing to repolarization.
p.94
Ion Permeability and Membrane Potential
Why are the concentrations (C) of ions important for diffusion potential?
They dictate the gradient that drives the movement of ions across the membrane.
p.47
Action Potential Generation and Phases
What is the 'All or None Response' in action potential generation?
The size and shape of the action potential are not influenced by the size of the stimulus.
p.4
Bioelectricity and Functional Anatomy of Neurons
What is myelin and its function in neurons?
A fatty substance that insulates axons, increasing signal transmission speed.
p.81
Differences Between Graded and Action Potentials
Do graded potentials have a refractory period?
No, they have no refractory period.
p.45
Refractory Periods in Action Potentials
What is the refractory period?
The time during which a neuron cannot fire another action potential.
p.6
Resting Membrane Potential
What is the significance of the reference electrode in membrane potential recording?
It provides a stable reference point for measuring the potential difference.
p.45
Action Potential Generation and Phases
How does the action potential propagate along the axon?
Through a wave of depolarization and repolarization, often facilitated by myelin sheaths.
p.64
Bioelectricity and Functional Anatomy of Neurons
What is a specific molecule or cluster of molecules in the context of receptors?
A receptor that recognizes and binds a particular ligand.
p.58
Action Potential Generation and Phases
What occurs during the repolarization phase?
Potassium channels open, allowing K+ ions to flow out of the cell.
p.64
Bioelectricity and Functional Anatomy of Neurons
What types of sensory modalities can receptors respond to?
Touch, pressure, cold, light, or sound.
p.89
Differences Between Graded and Action Potentials
What happens to the magnitude of action potential as it travels away from the point of generation?
E. Magnitude of action potential is in a gradual decreasing order as it travels away from the point of generation.
p.24
Nernst Equation and Goldman Equation
What is the Nernst equation used for?
To calculate the equilibrium potential for individual ions.
p.65
Graded Potentials and Their Characteristics
What are graded potentials?
Subthreshold electrical stimuli that do not produce a true action potential but generate electrical signals.
p.65
Action Potential Generation and Phases
What happens during an action potential?
Complete depolarization occurs and is propagated down the axon to cause the release of neurotransmitters.
p.58
Action Potential Generation and Phases
What is the all-or-nothing principle in action potentials?
Once the threshold is reached, an action potential will occur fully or not at all.
p.81
Differences Between Graded and Action Potentials
Do action potentials have a refractory period?
Yes, they have a refractory period.
p.64
Bioelectricity and Functional Anatomy of Neurons
What is the electrical signal generated by receptors called?
Generator or receptor potential.
p.6
Resting Membrane Potential
What factors can affect the accuracy of membrane potential recordings?
Electrode placement, cell health, and external electrical noise.
p.65
Graded Potentials and Their Characteristics
What types of stimuli can produce graded potentials?
Electrical, chemical, or mechanical stimuli.
p.4
Bioelectricity and Functional Anatomy of Neurons
What is the function of dendrites in a neuron?
To receive signals from other neurons.
p.58
Refractory Periods in Action Potentials
What is the refractory period?
The time during which a neuron cannot fire another action potential.
p.81
Differences Between Graded and Action Potentials
How are action potentials conducted?
Without decrement; the depolarization is amplified to a constant value at each point along the membrane.
p.24
Nernst Equation and Goldman Equation
What is the Goldman equation used for?
To calculate the resting membrane potential considering multiple ions.
p.47
Action Potential Generation and Phases
What are the three states of membrane potential during action potential?
Polarized, depolarized, and then polarized again.
p.26
Active Transport Mechanisms: Na+/K+ Pump
What is the significance of the Na+/K+ pump in maintaining cellular function?
It helps maintain the resting membrane potential and cell volume.
p.81
Differences Between Graded and Action Potentials
What is the nature of action potentials in terms of amplitude?
All-or-none; once the membrane is depolarized to threshold, amplitude is independent of the initiating event.
p.31
Action Potential Generation and Phases
What is the threshold potential?
The critical level of depolarization that must be reached for an action potential to occur.
p.58
Action Potential Generation and Phases
What initiates the action potential in a neuron?
A depolarization that reaches the threshold potential.
p.4
Bioelectricity and Functional Anatomy of Neurons
What is the purpose of the axon in a neuron?
To transmit electrical impulses away from the cell body.
p.81
Differences Between Graded and Action Potentials
Can action potentials be summed?
No, they cannot be summed.
p.4
Bioelectricity and Functional Anatomy of Neurons
What role does the cell body (soma) play in a neuron?
It contains the nucleus and organelles, integrating signals.
p.81
Differences Between Graded and Action Potentials
How does the amplitude of graded potentials vary?
Amplitude varies with conditions of initiating events.
