IB Biology Topic B2.1.14 Gated Ion Channels in Neurons Revision Notes (HL)

IB Biology Topic B2.1.14 Gated Ion Channels in Neurons Revision Notes (HL) | RevisionDojo

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Voltage-Gated Sodium and Potassium Channels Drive Neural Activity

Ion channels are specialized proteins embedded in cell membranes that let specific ions cross.
They allow ions to diffuse down the concentration gradient, from high to low concentration, without using energy.
Voltage-gated sodium and potassium channels are critical in neurons, where fast ion movement carries nerve impulses.

How Voltage Controls the Channels

Nerve impulses and ion movement
1. Sodium and potassium ions move rapidly across the neuron membrane by facilitated diffusion.
2. They pass through voltage-gated channels that open or close in response to changes in membrane voltage.
Voltage dependency
1. At rest, the inside of the neuron sits at about -70 mV, which keeps the channels closed.
2. When the voltage rises to the threshold of about -50 mV, sodium channels open and Na⁺ diffuses into the neuron.
3. This influx pushes the voltage higher, and near the peak of about +40 mV potassium channels open and K⁺ diffuses out.

Note

Voltage-gated channels generate and propagate the action potential.
This is what lets neurons communicate.

How Voltage-Gated Channels Work

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Voltage-Gated Sodium and Potassium Channels Drive Neural Activity

Ion channels are specialized proteins embedded in cell membranes that let specific ions cross.
They allow ions to diffuse down the concentration gradient, from high to low concentration, without using energy.
Voltage-gated sodium and potassium channels are critical in neurons, where fast ion movement carries nerve impulses.

How Voltage Controls the Channels

Nerve impulses and ion movement
1. Sodium and potassium ions move rapidly across the neuron membrane by facilitated diffusion.
2. They pass through voltage-gated channels that open or close in response to changes in membrane voltage.
Voltage dependency
1. At rest, the inside of the neuron sits at about -70 mV, which keeps the channels closed.
2. When the voltage rises to the threshold of about -50 mV, sodium channels open and Na⁺ diffuses into the neuron.
3. This influx pushes the voltage higher, and near the peak of about +40 mV potassium channels open and K⁺ diffuses out.

Note

Voltage-gated channels generate and propagate the action potential.
This is what lets neurons communicate.

How Voltage-Gated Channels Work

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Note

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Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

IB Biology Topic B2.1.14: Gated Ion Channels in Neurons Notes

Voltage-Gated Sodium and Potassium Channels Drive Neural Activity

How Voltage Controls the Channels

How Voltage-Gated Channels Work

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Voltage-Gated Sodium and Potassium Channels Drive Neural Activity

How Voltage Controls the Channels

How Voltage-Gated Channels Work

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A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics