Hormones and Growing Up

Messages in your blood

Your body is made of trillions of cells, and somehow they all have to work together — growing, using energy, sleeping and waking at the right times. How does one part of your body tell another part what to do? One important way is through hormones, the body's chemical messengers.

Hormones are tiny chemicals released into your blood. They travel around your body and deliver instructions, a bit like text messages sent to exactly the right phones. They work alongside the fast electric signals of the brain and nervous system, but hormones act more slowly and can affect your whole body at once.

The endocrine system

Hormones are made by special organs called glands. Together, all these glands make up the endocrine system. Here are some of the most important ones:

• The pituitary gland, a pea-sized gland in your brain, is the "control centre". It releases growth hormone, which tells your body to grow, and it bosses the other glands.
• The thyroid, in your neck, controls how fast your body burns energy.
• The pancreas makes insulin, which controls the amount of sugar in your blood.
• The adrenal glands, on top of your kidneys, make adrenaline, the "action" hormone.
• The ovaries and testes make the sex hormones that guide growing up.

What hormones do every day

You probably feel your hormones working without realising it. They control much more than growth:

• Energy from food. After a meal, insulin helps your cells take in sugar to use as fuel, working hand in hand with the digestive system.
• Fight or flight. If something startles you, your adrenal glands flood your blood with adrenaline. Your heart races, your breathing speeds up and you feel a burst of energy, ready to run or react. That pounding-heart feeling before a race or test is adrenaline at work.
• Sleep. As it gets dark, a gland in your brain releases melatonin, which makes you feel sleepy and helps you rest at night.
• Mood. Hormones also affect how you feel, which is one reason your emotions can change.

Hormones and growing up

The biggest hormone job of your school years is puberty — the natural process of your body changing from a child's body into an adult's. During puberty, the pituitary gland signals the ovaries or testes to make more sex hormones, and these cause a series of changes over several years.

Some common changes include:

• A growth spurt, where you suddenly get taller.
• Body shape changing and body hair growing.
• Skin becoming oilier (which is why spots are common at this age).
• Stronger and sometimes up-and-down emotions, because hormones affect your brain too.

The most important things to understand are that these changes are completely normal, that they happen to everyone, and that they happen at different ages and speeds for different people. There is no "right" time. If a friend grows faster or slower than you, that is just their body's own timetable. Hormones are simply doing their job of turning you into a healthy adult.

Keeping your hormones balanced

You cannot control hormones by thinking, but your daily habits help keep them balanced:

• Sleep well. Lots of growth hormone is released while you sleep, which is one reason children and teenagers need plenty of rest. You can read more in why we sleep.
• Eat a balanced diet. Good food gives your glands the raw materials they need.
• Exercise. Being active helps balance the hormones that control energy and mood.
• Talk about feelings. Because hormones affect emotions, sharing worries with a trusted adult really helps.

Try it: spot adrenaline in action

This safe activity lets you notice one of your most powerful hormones working in real time.

1. Sit quietly for a minute. Place two fingers on your wrist or neck and count your heartbeats for 15 seconds. Multiply by four to get your beats per minute. Write it down — this is your resting rate.
2. Now do something that gives you a small, safe thrill: do 30 fast star jumps, or have a friend surprise you (kindly!) with a sudden, harmless "Boo!"
3. Straightaway, count your heartbeats again for 15 seconds and multiply by four.
4. Compare the two numbers. Notice how much faster your heart is beating, and whether your breathing has sped up too.

Why it works: Exercise and surprise both trigger your adrenal glands to release adrenaline into your blood. Within seconds, this hormone tells your heart to beat faster and your lungs to breathe quicker, getting more oxygen to your muscles so you are ready for action. You have just watched a chemical messenger change your whole body — proof that hormones, though invisible, are powerfully real.