Messages in the blood
Before a race, the heart beats faster, even before the whistle.
- The pituitary makes growth hormone.
- The thyroid makes thyroxin. It needs iodine.
- The adrenal glands make adrenaline, in danger.
- The pancreas makes insulin. It controls blood sugar.
- Testes and ovaries are glands too.
Read each clue. Tap the gland that makes the hormone.
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A hormone is a chemical messenger. A gland is a body part that makes hormones. It releases them into the blood. The blood carries each hormone round the body. Only its target cells, the cells it affects, respond to it.
The pituitary sits at the base of the brain. It makes growth hormone. Too little growth hormone in childhood leads to dwarfism. Dwarfism means staying very short as an adult.
The thyroid makes thyroxin, a hormone that needs iodine. Too little iodine can cause goitre, a swollen neck. Iodised salt gives the iodine.
The pancreas makes insulin. Insulin controls blood sugar.
The adrenal glands make adrenaline. Adrenaline prepares the body for danger. It makes the heart beat faster. Excitement before a race also releases adrenaline.
The rule
A hormone is a chemical messenger. A gland releases it into the blood. The blood carries it round the body. It acts only on its target cells.
For example, a scare makes the adrenal glands release adrenaline. The blood carries it to the heart. The heart beats faster.