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Period during which potassium ions diffuse out of the neuron due to a change in membrane permeability?
Wiki User
∙ 14y ago
Membrane potential - a nerve cell set and ready to fire;
"The wave of reverse polarity" i.e. sodium versus potassium trans-cell-membrane ion passaging - a nerve cell firing; and
Recharge period - the regeneration time.
Wiki User
∙ 13y ago
Wiki User
∙ 15y agothe beginning of repolarization of the neuron
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∙ 8y agoThe neuron repolarizes when potassium ions diffuse out of a neuron.
Wiki User
∙ 14y agoAction potential
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∙ 12y agosodium-potassium pump
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∙ 12y agoRepolarization phase
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∙ 12y agoRepolarization
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How many potassium ions does the sodium-potassium pump move into a cell if it moves six sodium ions out of the cell?
I think you're looking for three ... over the long run. But the trick is that K+ doesn't need to be pumped in. Membrane proteins act as variable sized pore in the membrane (channels) and the potassium flows in under electrostatic forces ... all the work is done pumping the Na+ out.
What will happen to dye crystals initially in the bottom of a beaker of water over a long period of time?
They will diffuse equally throughout the beaker
During the absolute refractory period along an axon membrane of a neuron?
the neuron is unable to respond to a stimulus of any intensity
How do neurons conduct impulses?
axonsAction Potential and Axon Conduction- Resting membrane potential provides and immediate source of power (it can cause a rapid change)- Hyperpolarize - makes membrane potential more negative- Depolarize - makes membrane potential less negativeo Depolarization reaches a threshold, at this threshold you cause a massive electrical change (Action Potential aka Impulse aka Spike)- Threshold - generally 15mV above resting membrane potentialo Threshold for a neuron is around -70 less 15 = -55mV- All-or-none lawo Size of action potential for a given neuron is always the same regardless of the size of the stimulus that initiated it- Information about Magnitudeo Conveyed by frequency of action potentials (#/sec [Hz])- Alternative to Action Potential:o Graded Potential - passive change occurso Signal gets smaller and smaller as it moves on - such as some neurons found in the eyesMolecular Basis of Action Potential- Depolarizationo Results in sodium membrane "channels" or "gates" begin to open- At threshold, the number of open channels overcomes the sodium-potassium pumpo The channels have a time-limit and once open will automatically close after ½ msec.- Sodium current makes membrane potential positive, and at peak, sodium channels close and potassium channels open- Now, potassium channels open and potassium ions rush out (triggered by threshold, but have a delay to open so open after the sodium channels)- Brief hyperpolarization (voltage surpasses -70mV) while sodium potassium pump restores ion distribution- These voltage-dependant (activated) channels define the action potential- Sustained activity leads to an increase in extra-cellular potassium (typically picked up by astrocytes)- Glial cell (astrocytes) transports excess potassium to nearby arteries causing a dilation of the artery wallo More active areas need more oxygen and glucose, so the movement of the potassium to the arteries, cause them to dilate and thus allow more volume of blood (and nutrients) to the area- Refractory period - period when the cell is resistant to the generation of further action potentialso Restricts the firing rate of the cell- Two phases of the refractory period:o Absolute - no firing regardless of the size of the stimuluso Relative - threshold is higher than normalConduction of the Nerve Impulse- Action potential is regenerated at each adjacent patch of the membrane (because of diffusing sodium from generation of action potential)- Cannot move backwards - seen as a wave rather than distinct action potentials because the patches are so small, and it moves so fast- Called the propagation of the action potential- Slower than conduction of electricity down a copper wire (1-10m/sec vs. 300million m/sec)- Axons with myelin sheaths are faster (120m/sec)o Myelin sheath insulates the axon, so that sodium ions cannot pass into or out of the cello Sodium can cross at Nodes of Ranvier to generate a new action potentialo From one Node to the next, a graded potential regenerates a new action potential at the next nodeo Called "salutatory conduction"
Why do synapse transmissions go in one direction only?
It's true that the structure of the neurone and its synapses mean that transmission will only be in one direction. However, the fibre itself is capable of transmitting in both directions: if you artificially stimulated the axon in the middle, impulses would go out in both directions from the point of stimulation. However, in a working neurone, there has to be some mechanism preventing the impulse from echoing back on itself all the time. This is prevented by the refractory period. When any one part of the neurone has an action potential, local electrical currents stimulate the next part - hence transmission. But the part which has just had an action potential is in the refractory period - it is temporarily hyperpolarised, so the local currents have no effect. This hyperpolarisation only lasts for about half a millisecond, so another action potential can come along very soon afterwards. Hyperpolarisation is due to potassium gates in the membrane being open, so positively charged K+ ions diffuse in.
Period during which potassium ions diffuse out of the neuron's membrane?
sodium-potassium pump
What is the chief positive intracellular ion in a resting neuron?
The chief positive intracellular ion in a resting neuron is a potassium ion. Just inside the cell of a resting neuron, the membrane is negative.
How many potassium ions does the sodium-potassium pump move into a cell if it moves six sodium ions out of the cell?
I think you're looking for three ... over the long run. But the trick is that K+ doesn't need to be pumped in. Membrane proteins act as variable sized pore in the membrane (channels) and the potassium flows in under electrostatic forces ... all the work is done pumping the Na+ out.
What is the correct sequence of events that follows a threshold potential?
§Labor and management§Productivity§Wage levels§Training needs§Local infrastructureMeasuring site potential in step 3 involves determining whether a site can supply adequate resources needed to carry out the proposed business activity. Key issues include:•For many companies the most important resources will be labor and management.•The productivity and wage levels of local labor and managers.•The cost of training local managers, which can mean substantial investments of time and money.•And the efficiency of local infrastructures, including roads, bridges, airports, seaports, and telecommunications systems.
Is potassium and magnesium in the same period?
No. Magnesium is in the second period and potassium is in the third.
What is the first element in the fourth period?
potassium :D
What period is potassium k located?
Potassium (K) is a metal in Group I of the Periodic Table of the Elements. K has an atomic number of 19 and a molecular weight of 39.10 grams per mole.
What element is the first element in the fourth period?
The first element in the fourth period of the periodic table is potassium (K).
What events occur in the relaxation period?
The Na/K pump kicks out three sodium from the cell for every two potassium they take in thereby reestablishing the membrane potential.
The first element in the fourth period?
Potassium
What is the period and group number of potassium?
Potassium belongs to group-1. It has one valence electron.
Why does regeneration of action potential occurs in one direction?
As the action potential passes an area on the axon, sodium channels are closed, preventing influx of more sodium ions. At the same time, voltage-sensitive potassium channels open, allowing the membrane potential to fall quickly. After this repolarization phase, membrane permeability to potassium remains high, allowing for the "afterhyperpolarization" phase. During this entire period, while the sodium ion channels are forced closed, another action potential cannot be generated except by a much larger input signal. This helps to prevent the action potential from moving backwards along the axon.
