Hormones (Heart and blood)

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					Heart            and        blood

A hormone is a chemical that changes
the way part of your body works.                                          The pea-sized
                                                                          pituitary gland is
Even tiny amounts of hormones are                                         just under your
powerful. Some work slowly over
                                                                          Main gland
years, but others have instant effects.                                   Hormones are made in parts of
                                                                          the body called glands. The most
                            Growth hormone                                important is the pituitary gland
                            Every day, your pituitary gland releases      in your brain. Its hormones
                                 about eight microscopic doses of         control many of the other glands.
                                    growth hormone, mostly when
                                        you’re asleep. This hormone
                                         makes your bones and
                                          muscles grow.

The amount of growth
hormone you make in
one year is less than
this tiny pinch of sugar.

                                                                       Growing up
                                                                       Toddlers and teenagers have
                                                                       very high levels of growth
                                                                       hormone, which is why they
                                                                       grow so quickly. Adults also
                                                                       make growth hormone, but
                                                                       the level falls with age.
                                      What carries hormones around the body?
Control chemicals                              The fright hormone
Hormones are important                         The hormone adrenaline makes you feel
– they control many                            scared or excited. It works in an instant,
body processes.                                preparing your whole
                                               body for sudden                          Your brain
                Oestrogen is the female
                sex hormone. It turns little   action in case you                       becomes alert so
                                                                                        you can think
                girls into adult women.        need to escape                           quickly.

                Testosterone is the male
                                               from danger.
                sex hormone. It turns little
                boys into adult men.
                                               Adrenaline makes your
                                               heart and lungs work
                Melatonin helps control        harder. Your heart
                the daily cycle of sleeping    starts to pound and
                and waking.                    you gasp as your lungs
                                               take in extra air.

                Glucagon raises the
                level of sugar in your
                blood, giving you energy.

                Parathyroid hormone
                tells your bones to release
                calcium into the blood.
                                                  an expert ...
Sugar control
The hormone insulin helps control                  on growing up,
the level of sugar in your blood.                  pages 102-103
Some people don’t make enough                         on sleep,
insulin and have to check their                    pages 108-109
blood sugar level regularly. They                                                                  above your kidneys
have a disease called diabetes.                                                                    release
People with diabetes
prick their skin to get a
drop of blood, so they
can check
how much sugar
it contains.                                        Your hairs stand
                                                    on end, making
                                                    your skin tingle.

                                                                        travels to your arms
                                                                        and legs
                                                                        and prepares the
                                                                        muscles for action.

                                                        The blood.                                         59

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Tags: Human, body