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Which is greater - The extent of membrane polarization at threshold potential or that of the resting membrane potential?
Wiki User
∙ 15y ago
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).
Wiki User
∙ 15y ago
The extent of membrane polarization at threshold potential is greater than that of the resting membrane potential. At threshold potential, the cell membrane undergoes a significant depolarization, leading to the initiation of an action potential. In contrast, the resting membrane potential represents the stable charge difference across the membrane when the cell is not actively conducting impulses.
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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.
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.
If the frequency of light is greater than the threshold frequency will photoelectric effect starts?
Yes - that's how it works.
What describes the potential energy diagram of an exothermic reaction?
The potential energy of the reactants is greater than the potential energy of the products.
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?
Concentration polarization in membrane science refers to the buildup of solutes near the membrane surface during filtration, leading to a reduction in permeate flux and efficiency. This can occur when the driving force for filtration is not strong enough to overcome the resistance caused by the accumulated solutes, ultimately impacting the performance of the membrane. Strategies to mitigate concentration polarization include optimizing operating conditions, using anti-fouling coatings, and periodic cleaning of the membrane.
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 is the difference between a compound action potential and a single action potential?
A compound action potential is the summation of multiple individual action potentials from different neurons, resulting in a larger, composite response. A single action potential is the brief electrical impulse that travels down an individual neuron in response to a stimulus.
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 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.
How does an object affect the height of the object?
Directly. The greater the potential fall, the greater the potential energy.
What is silt density index?
The silt density index (SDI) is a measurement used to assess the amount of suspended solids in water. It is a way to evaluate the fouling potential of water on reverse osmosis membranes. The higher the SDI value, the greater the potential for membrane fouling.
