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What is a Chemical gradient?
Concentration gradient for an ion across plasma membrane
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What is an electrical gradient?
Attraction between opposite charges or repulsion between like charges
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What is Equilibrium potential?
When electrical and chemical gradients are equal and opposite, resulting in no net movement across membrane
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Changes in membrane potential primarily occur due to _____ opening or closing in response to stimuli.
gated channels
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What are the three different gated channels?
- Chemicallygated channels
- Voltage-gated channels
- Mechanically gated channels
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Neuromuscular junction receptors that bind ACh, are and example of what type of gated channel?
Chemical
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What type of gated channel is most abundant on dendrites and cell body of neurons?
Chemical
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What type of gated channel is characteristic of excitable membranes?
Voltage-gated
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_____ open or close in response to changes in membrane potential.
Voltage-gated channels
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What are the three types of voltage gated channels that are most important to neurons?
- Voltage-gated
- potassium channels
- Voltage-gated
- calcium channels
- Voltage-gated
- sodium channels
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What two gates function independently inside voltage-gated sodium channels?
- Activation gates
- Inactivation gates
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What type of gate open in response to physical distortion of membrane?
Mechanically gated channels
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What type of gated channel is important in sensory receptors?
Mechanically gated channels
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When the membrane potential becomes less negative, the membrane is _____.
depolarized
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What is the approximate value of threshold of action potential?
-55mV
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Prior to action potential generation, sodium channels are _____ but capable of _____.
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Prior to action potential generation, potassium channels are _____ but capable of _____.
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Prior to action potential generation, the _____ gate is closed but capable of opening.
Activation
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Prior to action potential generation, the _____ is open in the sodium channels.
Inactivation gate
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What are the steps of action potential generation and propagation?
- Depolarization to threshold
- Activation of Na+ channels and rapid depolarization
- Inactivation of Na+ channels and activation of K+ channels
- Potassium channels close
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As membrane reaches resting potential (–70 mV)
K+ ions continue to leave cell until all channels are closed which produces brief _____.
hyperpolarization
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