6. How are messages sent around the body?

Knowledge

Electrical Impulses

One way messages are sent around your body is by the nervous system and electrical impulses.

If you touch something hot, nerves in you hand send an electrical message to your spinal cord along cells called neurons. The spinal cord processes the message and almost instantly sends a message back to your arm muscles to contract, which pulls your hand away from the hot object.

Hormones

Another way messages are sent around the body is by hormones.

Hormones are chemicals that are made by glands (like the pancreas or pituitary) and released into the blood when they are needed. The blood carries hormones all around they body to where they are needed.

Hormones make things happen in the body.

Adrenalin is released when you get a fright or are in a stressful situation. It makes your pupils dilate, blood be sent to your muscles and your energy production to speed up. This is all so you are ready to “fight” or “flight” (run away).

Melatonin is produced by your body when it is dark. Higher levels of melatonin make you feel sleepy, lower levels make you wake up. In teenagers melatonin is made a few hours later than in adults - this makes teenagers want to go to bed later and walk up later than adults.

Gut Hormones

The gut is the body’s largest hormone-producing organ, releasing more than 20 different peptide hormones. Some of these and their sites of production are shown.

gastric hormones.mp4

Video transcript

Vocabulary

Electrical impulse: Charged signals that flow through the spinal cord and nerves.

Spinal cord: Thick bundle of nerves in the spine that connect the brain to nerves in the rest of the body.

Hormone: Chemical signals in the body.

Gland: Organ that makes and releases hormones.

Adrenalin: Hormone responsible for the fight or flight response.

Melatonin: Hormone responsible for when we sleep and wake up.

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