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A breath-hold diver carries oxygen in more places than the lungs

A breath-hold diver starts with oxygen in the lungs, blood hemoglobin, and muscle myoglobin. During the dive, changes in heart rate and blood flow affect how these finite stores are used. Explore how the body's responses redistribute resources without creating a fresh oxygen supply.

3–5 min

Questions you could explore

  • How is storing more oxygen different from using it more slowly?
  • How can the diving response change where oxygen is used during a breath hold?

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Health and the body

Daylight and the body's clock

Even in a room with no clocks, your body follows an internal roughly 24-hour schedule of sleepiness, hunger, and alertness. Those internal daily rhythms respond to outside cues, with morning and evening light helping reset and coordinate the body's master clock.

3–5 min

Daylight and the body's clock

Health and the body3–5 minEven in a room with no clocks, your body follows an internal roughly 24-hour schedule of sleepiness, hunger, and alertness. Those internal daily rhythms respond to outside cues, with morning and evening light helping reset and coordinate the body's master clock.

Health and the body

How vaccines build immune memory

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4–5 min

How vaccines build immune memory

Health and the body4–5 minThe first time the immune system encounters an unfamiliar antigen, building a response takes time. Vaccines help develop recognition and memory before a later encounter with a pathogen. Different types introduce antigens or instructions for making them in different ways, offering a starting point for exploring how immune memory works.

Health and the body

Antibiotics and the viruses they cannot treat

Antibiotics can treat certain bacterial infections, but they do not treat the viruses that cause a common cold. Because bacteria are living cells with their own metabolic machinery and viruses are tiny genetic packages that hijack your cells, an antibiotic that disables bacteria has no matching target in the viruses that cause a cold.

2–3 min

Antibiotics and the viruses they cannot treat

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A breath-hold diver carries oxygen in more places than the lungs | Speech Topic | speaking.app