Biology · Rung 6 of 9

Hormones and nerves

The body has two messaging systems and they split the work by deadline. A nerve takes thousandths of a second and goes to one place: that is why pulling your hand off a hot pan is nervous. A hormone travels in the blood, takes seconds or minutes and reaches the whole body, but only whoever has its receptor obeys; it is a message posted on the city wall, seen by everyone and heeded only by those who can read it. That is why feeling hungry is hormonal. Each hormone comes from a gland and does one thing: insulin from the pancreas puts sugar into cells, adrenaline from the adrenals gets you ready to run, melatonin announces that night has fallen, thyroxine sets the general pace. And nearly all are regulated by negative feedback, the thermostat's trick: the effect switches off the signal that asked for it.

Where this sits

This is where the ladder starts: nothing is needed before it.

Exercises from this rung

Generated by the app, from easiest to hardest

  1. What does melatonin do?

    • sets the pace at which the whole body works
    • tells the body that night has fallen
    • makes cells take sugar out of the blood
    • speeds the heart and gets you ready to run or fight

    Why Melatonin comes from the pineal gland and tells the body that night has fallen. A hormone travels in the blood, so it reaches the whole body and only whoever has the receptor for it obeys. It is a message posted on the city wall: everyone sees it and only those who can read it act.

    easier

  2. What makes insulin?

    • the pancreas
    • the pineal gland
    • the adrenal glands
    • the thyroid

    Why Insulin comes from the pancreas and makes cells take sugar out of the blood. A hormone travels in the blood, so it reaches the whole body and only whoever has the receptor for it obeys. It is a message posted on the city wall: everyone sees it and only those who can read it act.

    in between

  3. What makes melatonin?

    • the thyroid
    • the pineal gland
    • the pancreas
    • the adrenal glands

    Why Melatonin comes from the pineal gland and tells the body that night has fallen. A hormone travels in the blood, so it reaches the whole body and only whoever has the receptor for it obeys. It is a message posted on the city wall: everyone sees it and only those who can read it act.

    harder