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Which is greater - The extent of membrane polarization at threshold potential or that of the resting membrane potential?
A cell is more depolarized at it's threshold potential than it is at it's resting potential. This is important because a nervous system where a random excitatory post synaptic potential (epsp) would trigger the next neuron would lead to an overly excitable nervous system (btw, this is why caffeine makes you jittery).
What else can I help you with?
An action potential is triggered if?
the membrane potential of a neuron reaches a threshold level, typically around -55mV. At this point, voltage-gated sodium channels open, allowing an influx of sodium ions that depolarizes the cell and initiates an action potential.
Explain why the EPSP is larger if the membrane potential becomes more hyperpolarized than the resting membrane potential?
An excitatory postsynaptic potential (EPSP) is larger when the membrane potential is more hyperpolarized than resting potential because the driving force for sodium ions (Na⁺) influx increases. When the membrane is hyperpolarized, the difference between the resting potential and the sodium equilibrium potential is greater, leading to a stronger current flow when sodium channels open. This enhanced influx of sodium ions results in a more significant depolarization, producing a larger EPSP. Essentially, the larger potential difference allows for a greater excitatory response.
Can action potentials be summated?
Yes, action potentials can be summated when multiple sub-threshold stimuli are received in rapid succession, causing the neuron to reach threshold and fire an action potential. This process of summation can lead to greater depolarization and stronger signals being sent along the neuron.
What determines if an action potential is initiated in the postsynaptic neuron?
Every time neurotransmitter is released from the presynaptic neuron it generates an excitatory post synaptic potential(EPSP) in the postsynaptic neuron. When the EPSP is greater than the threshold for excitation an action potential is generated.
Why sncl4 more covalent than sncl2?
SnCl4 is more covalent than SnCl2 primarily due to the higher oxidation state of tin in SnCl4, which leads to a greater polarization of the chloride ions. The Sn4+ ion has a stronger positive charge, attracting the electron cloud of the Cl- ions more significantly, enhancing covalent character. In contrast, SnCl2, with Sn2+, exhibits less polarization and therefore has a greater ionic character. This difference in charge and polarization explains the greater covalent nature of SnCl4 compared to SnCl2.
An action potential is triggered if?
the membrane potential of a neuron reaches a threshold level, typically around -55mV. At this point, voltage-gated sodium channels open, allowing an influx of sodium ions that depolarizes the cell and initiates an action potential.
What is concentration polarization in membrane science?
Many electrochemical reactions produce or consume species in the solution. The rates of reactions involving dissolved species which participate as reactants in the rate-determining step(that stage in the reaction which controls its rate) will be dependent on the concentration of the dissolved species. As the dissolved species are consumed by the reaction, so a greater change in potential will be required to maintain the current, and this is known as concentration polarization. A reaction for which concentration polarization dominates is referred to as mass-transport or diffusion controlled.
Explain why the EPSP is larger if the membrane potential becomes more hyperpolarized than the resting membrane potential?
An excitatory postsynaptic potential (EPSP) is larger when the membrane potential is more hyperpolarized than resting potential because the driving force for sodium ions (Na⁺) influx increases. When the membrane is hyperpolarized, the difference between the resting potential and the sodium equilibrium potential is greater, leading to a stronger current flow when sodium channels open. This enhanced influx of sodium ions results in a more significant depolarization, producing a larger EPSP. Essentially, the larger potential difference allows for a greater excitatory response.
The greater influx of sodium ions results in what of the membrane?
The greater influx of sodium ions results in membrane depolarization. This is because sodium ions carry a positive charge, which leads to a decrease in the membrane potential towards zero or a positive value.
Can action potentials be summated?
Yes, action potentials can be summated when multiple sub-threshold stimuli are received in rapid succession, causing the neuron to reach threshold and fire an action potential. This process of summation can lead to greater depolarization and stronger signals being sent along the neuron.
What are graded potentials?
Voltage impulses in neuronal dendrites which vary in strength. (and btw, the following previous DETAILED answer is WONDERFUL!!)Upon being stimulated (by another neuron or as a special receptor) the dendrites of a neuron produce a graded potential. Stimulation can occur in many ways, including chemical stimulation (neurotransmitters, etc.), mechanical stimulation (certain pain receptors, hair receptor, etc.), light stimulation (photoreceptors) and a few other methods. Regardless of the method of stimulation the same general result is effected. Certain receptor protein ion channels on the dendrites are activated, and opened. This causes an influx (or efflux) of whatever ion the receptor channel was geared for. Thus it can cause either a depolarization (an excitatory response that may lead to an action potential) or hyperpolarization (an inhibitory response which makes it harder for an action potential to occur) depending on the ion let in (or out). The more receptor protein ion channels that are stimulated the stronger, or more intense the signal. A slight stimulation of a receptor protein ion channel will often open the channel and let in ions. However in order for a depolarization of threshold strength to reach the axon hillock, it generally requires multiple depolarizing receptor protein ion channels to open. Because of this, graded potentials are said to summate. In effect the total polarizing effect of the ion channels adds together. This is important in that one channel cannot stimulate an action potential, it takes multiple channels working in concert to depolarize a membrane enough to cause and action potential. Graded potentials (or receptor potentials when they occur in receptor cells) are short lived depolarizations or hyperpolarizations of an area of membrane. These changes cause local flows of current (current reflects the movement of ions) that decrease with distance. The magnitude of a graded potential is a direct reflection of the intensity or strength of the stimulus. The more intense the stimulus, the more ion channels that are opened, and the greater the voltage change (hyper or de- polarization) and the farther the current flows. Once stimulated polarization occurs as ions rush in. These ions accumulate very close to the stimulated area. From there the surplus of ions radiates out in all directions, polarizing adjoining membranes. As this polarization spreads like a wave it leaves behind it a wake of formerly polarized membrane that very quickly returns to resting membrane potential. As the wave of polarization ripples across the membrane it either summates (adds or subtracts) with other polarization waves or quickly looses intensity. This is in part due to the ever present leakage channels . Because the current dissapates quickly and is short lived graded, potentials can only act as signals over short distances. However their purpose is only to drive the axon hillock to threshold membrane potential, at which point an action potential will be generated.changes in the transmembrane potential that cannot far from the site of stimulationamplitude of various sizes
What is the difference between a compound action potential and a single action potential?
Single action potentials follow the "all or none" rule. That is, if a stimulus is strong enough to depolarize the membrane of the neuron to threshold (~55mV), then an action potential will be fired. Each stimulus that reaches threshold will produce an action potential that is equal in magnitude to every other action potential for the neuron. Compound action potentials do not exhibit this property since they are a bundle of neurons and have different magnitudes of AP's. Thus compound action potentials are graded. That is, the greater the stimulus, the greater the action potential.
What determines if an action potential is initiated in the postsynaptic neuron?
Every time neurotransmitter is released from the presynaptic neuron it generates an excitatory post synaptic potential(EPSP) in the postsynaptic neuron. When the EPSP is greater than the threshold for excitation an action potential is generated.
Why is the amplitude of the compound action potential recorded from the frog sciatic nerve increased when the voltage of the stimulus was increased above the threshold value?
Increasing the stimulus voltage above the threshold value results in recruiting more nerve fibers to generate action potentials. This leads to a greater number of action potentials being generated simultaneously along the nerve, resulting in a larger compound action potential amplitude being recorded.
Two layered serous membrane attached to the greater curvature of the stomach?
The greater omentum
Is threshold toxicity value greater or less than LC50?
Less.
What is elite polarization?
Elite polarization refers to the increasing divergence of political attitudes and beliefs among political leaders, parties, and influential figures, which often contrasts with the views of the general public. This phenomenon can lead to heightened partisanship and a lack of compromise, as elites become more extreme in their positions. The result is a political landscape characterized by greater conflict and division, as well as a potential disconnect between elite and voter priorities. Ultimately, elite polarization can exacerbate societal divisions and hinder effective governance.
