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The energy cells spend while you stay still

One quiet expense is maintaining the difference between the sodium and potassium concentrations inside and outside a cell, using a pump powered by ATP.

3–5 min

Questions you could explore

  • What would happen to this difference if the pump stopped but ions could still leak across the membrane?
  • Why do cells need to maintain ion gradients even when the whole body is at rest?

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Health and the body

Daylight and the body's clock

Internal daily rhythms respond to outside cues, with light helping coordinate the body's sense of time.

3–5 min

Daylight and the body's clock

Health and the body3–5 minInternal daily rhythms respond to outside cues, with light helping coordinate the body's sense of time.

Health and the body

How vaccines build immune memory

Vaccines make use of recognition and memory, though different vaccine types introduce the relevant information in different ways.

4–5 min

How vaccines build immune memory

Health and the body4–5 minVaccines make use of recognition and memory, though different vaccine types introduce the relevant information in different ways.

Antibiotics and the viruses they cannot treat

Health and the body2–3 minAn antibiotic that helps against certain bacteria has no matching target in the viruses that cause a cold.

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