Text reads: The Mysteries of Life with Tim & Moby

Tim holds up a letter. Tim reads from the typed letter.

TIM: Dear Tim & Moby, What are hormones and what body system do they belong to? From Q T pie.

The signature on the letter indicates that the author resides in Highland Village. We get a wider view and see that Moby is standing next to Tim. Moby is covering his eyes with his hands.

MOBY: Beep!

TIM: No, Moby, this isn't the puberty movie all over again. Puberty is just one of the things controlled by hormones from the endocrine system. Ever wonder how your body stays around the same temperature, or why you fall asleep and wake up automatically?

A drawing shows two pictures of Moby’s head. In one, Moby has a thermometer in his mouth. In the other, Moby has his eyes closed and is sleeping, as represented by "ZZZ" on the drawing. The screen returns to Tim and Moby standing side-by-side.

MOBY: Beep.

TIM: The endocrine system is in charge of making sure that your body's many functions are coordinated. It's made up groupings of cells called glands.

The outlines of a man and a woman are shown. Each figure shows a number of drawings of internal glands. The diagrams are very similar, with the main difference being that the woman shows ovaries, while the man shows testes.

TIM: There are eight major endocrine glands: the pituitary gland, the thyroid gland, the adrenal glands, the pineal gland, the pancreas, the thymus, the parathyroids, the ovaries in women, and the testes in men.

As Tim mentions each type of gland, a white circle indicates the corresponding gland. The pituitary gland is located in the head. The thyroid gland is located in the neck. The adrenal glands are located below the lungs. The pineal gland is located in the head above the pituitary gland. The pancreas is located below the adrenal glands. The thymus is located in the center of the chest between the lungs. The parathyroids are also located in the neck. In women, the ovaries are located below the pancreas. The testes for men are located in the crotch area.

TIM: These glands make more than 30 types of hormones, each with their own special job.

The names of various hormones float around the screen. They include prolactin, glucagon, thyrotropin, adrenaline, vasopressin, oxytocin, and vasopressin.

TIM: Hormones are responsible for regulating your metabolism, mood, growth, and organ function.

Diagrams corresponding to each of these four items are shown. Metabolism is represented by a figure showing the stomach and intestines. Mood is represented by a pair of cartoon faces—one smiling, one frowning. Growth is represented by three outlines of a person at various stages of growth: child, teenager, adult. Organ function is represented by a drawing of the heart.

TIM: A part of your brain called the hypothalamus is critical to your endocrine system.

A close-up drawing of the brain is shown. The hypothalamus is shown in green and is located near the brain stem.

TIM: It monitors your body and sends the information to your pituitary gland.

The pituitary gland is shown just below the hypothalamus.

TIM: The pituitary gland is attached to the hypothalamus, and it’s like the king of the endocrine system.

A blow-up of the pituitary gland is shown. It has connectors leading to other parts of the body.

TIM: It sends out its own chemical messages and rules the actions of most of the other major endocrine glands.

The view switches back to Tim and Moby.

MOBY: Beep.

TIM: Well, each gland has a different job. The thyroid releases hormones that control how fast your body’s cells burn energy.

The outline of a person is shown with the thyroid circled.

TIM: That’s important, because it affects how other parts of you grow and develop. The parathyroid glands keep the level of calcium in your blood at a certain level.

The parathyroid glands are shown as four glands inside the circle marking the location of the thyroid.

TIM: If, say, your blood has too much or too little calcium, your nerves and muscles don’t work right.

An animation of two nerves appears. They are connected by a string of three ovals. A signal can be seen coming in from the left, entering one nerve bundle, and then passing though the ovals to the other nerve bundle.

TIM: The adrenal glands regulate your response to stress.

The outline of a person is shown with the adrenal glands circled.

MOBY: Beep.

TIM: Right, they release the hormone adrenaline in dangerous or exciting situations.

An animation shows a man lying on a blanket, leaning up against a tree and reading a newspaper. A bee enters the picture and begins flying around. The man looks up and sees the bee heading towards a large nest of bees.

TIM: It gives you a quick burst of strength and speed.

Moments later, we see the man fleeing from the scene. Following behind him is a swarm of bees.

TIM: The adrenal glands are also involved with your body’s regulation of salt, and its sexual development during puberty.

The view switches back to a close-up of Tim.

TIM: The function of the pineal gland isn’t fully understood yet.

The outline of a person is shown with the pineal gland circled.

TIM: All we know is it secretes a hormone called melatonin that’s thought to influence our sleep cycle, metabolism, and sexual development.

Diagrams of these three items are shown. Our sleep cycle is represented by a cartoon balloon reading “UpperWord Z Z Z.” Metabolism is represented by a drawing of the stomach and intestines. Sexual development is represented by the gender symbols for males (a circle with an arrow pointing up and to the right) and females (a circle with a plus sign underneath).

TIM: The pancreas secretes the hormone insulin, which regulates your blood sugar.

The outline of a person is shown with the pancreas gland circled.

TIM: You’ve probably heard of type 1 diabetes—that happens when the pancreas can’t produce enough insulin to control your blood sugar.

An image appears, showing a finger that has been pricked. A drop of blood falls onto a test strip about to be inserted into a glucometer, a device for measure the amount of glucose in the blood.

TIM: The thymus helps your body fight off infections.

The outline of a person is shown with the thymus gland circled.

TIM: It’s a key player in the production of T cells, which identify and kill germs in your blood.

An animation shows a germ with green triangles extruding from its body. It is approaching a barbed-wire fence. From behind the fence, four Upper T cells rise up from a trench. They are wearing hard hats. One of the Upper T cells throws an antibody at the germ and the germ disintegrates in a cloud of smoke. The sound of an explosion can be heard.

The view returns to Tim and Moby. Moby is frowning.

MOBY: Beep.

TIM: Almost done, buddy, hang in there. Finally, there are the ovaries in women, and the testes in men.

The outlines of a man and a woman are shown with the testes and ovaries labeled.

TIM: These glands produce hormones that help us reach maturity, fight infections, stay energetic, and more!

Diagrams for these three activities are shown. Maturity is represented by the outline of a grown adult. Infection fighting is represented by a set of crosshairs pinpointing a cartoon depiction of a germ. Staying energetic is represented by the drawing of a woman jogging.

TIM: They also produce the sex cells for reproduction.

An animation shows a large number of sperm heading toward an egg. One of them gets to the egg and punctures it to get inside. The sound of an explosion is heard. A tiny baby springs into existence.

MOBY: Beep?

TIM: Well, no matter what gland produces them, hormones all work in the same basic way.

On one side we've got the glands and cells that produce hormones.

A drawing shows a red circle, labeled “cell,” and a blue rectangle, labeled “gland,” on the left side of the screen.

TIM: And on the other side we've got cells and tissues that respond to the hormones.

On the right side of the screen, a red circle labeled “cell” appears. Below it is an orange rectangle labeled “tissues.” An arrow labeled “hormones” points from the objects on the left side of the screen to those on the right side.

TIM: When glands secrete hormones into the bloodstream, the hormones travel to a target cell or target tissue.

An animation shows red blood cells, shaped like small rafts, floating down a stream. White circles representing hormones are also traveling down the stream.

TIM: When the target's receptors get their chemical message, they go to work carrying out their function.

A close-up shows a hormone encountering a cell. The cell starts to replicate, first dividing into a set of two cells, then a set of four, then eight, then many until it is a larger group of cells in a globular cluster.

TIM: Every cell in your body has receptors for particular hormones.

A close-up view of the cells is shown. Receptors are depicted in each cell.

MOBY: Beep.

TIM: Well, the endocrine system works in cycles.

An outline of a man is shown with the various glands drawn in.

TIM: It produces hormones, and the hormones do their job, causing many different things to happen in many different types of cells.

Various parts of the image begin to flash.

TIM: Think about how you suddenly start growing in your teen years. When it’s time for a growth spurt, the pituitary gland sends out a growth hormone that tells your cells, "It's time to grow up! Start dividing!”

An outline of a person appears with the pituitary gland circled. The circle grows larger and smaller. The word “grow” flashes on and off. A signal is seen entering a cell. The outline of the person gets larger as the cell is seen dividing into two, then four, then eight, and so on.

TIM: Your adrenal glands and sexual glands also contribute. When your body is finished growing, your cells will produce chemicals that stop those growth hormones from being released.

An animation shows growth hormones entering cells. After a bit, they slow down and eventually stop. The hormone is then released from the image.

TIM: That’s why you stop growing. This is called negative feedback, and it’s how most hormone production is regulated. When a job’s done, negative feedback occurs and the hormone production stops until it's time for the whole process to start over again.

MOBY: Beep.

Moby hands Tim a sheet of paper. The paper reads: Start growing.

TIM: Don’t be so literal.

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