that wields enormous power over your body.

It's called the thyroid.

Like the operations manager in a company,

its role is to make sure that the cells in your body are working properly.

It does that by using hormones to deliver messages to every single one of them.

This high-ranking organ is made up of lobules

that each contains smaller cells called follicles,

which store the hormones the thyroid sends out into your blood.

Two of the most important hormones it produces

are thyroxine and triiodothyronine, or T3 and T4.

As messengers, the hormone's job

is to instruct every cell in the body when to consume oxygen and nutrients.

That maintains the body's metabolism,

the series of reactions our cells perform to provide us with energy.

This hormonal notification from the thyroid

gets the heart pumping more efficiently,

and makes our cells break down nutrients faster.

When you need more energy,

the thyroid helps by sending out hormones to increase metabolism.

Ultimately, the thyroid allows our cells to use energy, grow and reproduce.

The thyroid is controlled by the pituitary gland,

a hormonal gland deep in the brain that oversees the thyroid's tasks,

making sure it knows when to send out its messengers.

The pituitary's role is to sense if hormone levels in the blood

are too low or too high,

in which case it sends out instructions

in the form of the thyroid- stimulating hormone.

Even in this tightly controlled system, however,

management sometimes slips up.

Certain diseases,

growths in the thryoid

or chemical imbalances in the body can confuse the organ

and make it deaf to the pituitary's guiding commands.

The first problem this causes is hyperthyroidism,

which happens when the organ sends out too many hormones.

That means the cells are overloaded with instructions

to consume nutrients and oxygen.

They become overactive as a result,

meaning a person with hyperthyroidism experiences a higher metabolism

signaled by a faster heartbeat, constant hunger, and rapid weight loss.

They also feel hot, sweaty, anxious, and find it difficult to sleep.

The opposite problem is hypothyroidism,

which happens when the thyroid sends out too few hormones,

meaning the body's cells don't have as many messengers to guide them.

In response, cells grow listless and metabolism slows.

People with hypothyroidism see symptoms in weight gain,

sluggishness, sensitivity to cold, swollen joints and feeling low.

Luckily, there are medical treatments

that can help trigger the thyroid's activities again,

and bring the body back to a steady metabolic rate.

For such a little organ, the thyroid wields an awful lot of power.

But a healthy thyroid manages our cells so effectively

that it can keep us running smoothly without us even noticing it's there.