0:00:02 > 0:00:03BELL RINGS
0:00:03 > 0:00:04Feel the burn, Colin. That's it.
0:00:04 > 0:00:09Oh, crumpets, McCork, I don't know if I can keep this up!
0:00:09 > 0:00:11Huh, you call THAT a challenge?
0:00:11 > 0:00:13Aargh!
0:00:13 > 0:00:15So then, Doctor Know-It-All,
0:00:15 > 0:00:20seeing as you find everything so easy, riddle me this.
0:00:20 > 0:00:24Rich people want me, poor people have me
0:00:24 > 0:00:27and if you eat me, you will die.
0:00:27 > 0:00:29- What am I?- Hmm.
0:00:29 > 0:00:32Time starts now.
0:00:32 > 0:00:35Rich people want me, poor people have me...
0:00:35 > 0:00:37BELL RINGS
0:00:37 > 0:00:39Aargh!
0:00:39 > 0:00:40Positions, everyone!
0:00:40 > 0:00:43This is Brain Freeze
0:00:43 > 0:00:46with Dr Knowles,
0:00:46 > 0:00:48Professor McCork...
0:00:49 > 0:00:52..Colin, the floor manager
0:00:52 > 0:00:54and Ms Hucklebuck.
0:00:54 > 0:00:56Stand by!
0:00:56 > 0:00:59Come on, everybody.
0:01:01 > 0:01:03It's time for...
0:01:05 > 0:01:09Today we're asking how does my heart keep beating?
0:01:09 > 0:01:12The heart is a powerful muscle that pumps blood around our bodies.
0:01:12 > 0:01:16Arteries carry oxygen-rich blood away from the heart to all
0:01:16 > 0:01:17parts of the body.
0:01:17 > 0:01:21Smaller capillaries deliver this oxygen and nutrients into our
0:01:21 > 0:01:23organs and tissues, and veins return the blood,
0:01:23 > 0:01:27which now has most of its oxygen removed, back to the heart
0:01:27 > 0:01:29where the whole process starts again.
0:01:29 > 0:01:32And did you know that if you laid all your blood vessels end-to-end
0:01:32 > 0:01:34they'd be long enough to go around the Earth
0:01:34 > 0:01:37almost two and a half times?
0:01:37 > 0:01:42Rich people need me, poor people have me...
0:01:42 > 0:01:44Er, Dr Knowles?
0:01:44 > 0:01:47..and if you eat me you will die.
0:01:47 > 0:01:49Right, come with me. I know exactly what you need.
0:01:49 > 0:01:53- Aargh!- Cut cameras. Cut.
0:01:53 > 0:01:55And we're clear!
0:01:55 > 0:01:58Whoa, this actually feels quite good.
0:01:58 > 0:02:01That's it, Dr Knowles. Pump those legs.
0:02:01 > 0:02:05The key I find, Dr Knowles, is to keep it slow and steady.
0:02:05 > 0:02:08Hmm, maybe I'll just try it a bit faster.
0:02:08 > 0:02:12Careful. Colin's tiny legs can't keep up.
0:02:12 > 0:02:14But it's so much fun.
0:02:14 > 0:02:16My head feels clearer already.
0:02:16 > 0:02:18I can't keep up!
0:02:18 > 0:02:20Do something, McCork!
0:02:20 > 0:02:22BELL RINGS
0:02:24 > 0:02:25Positio-o-o-o-o-ons!
0:02:25 > 0:02:27Ow!
0:02:32 > 0:02:36So, Dr Knowles, how does my heart keep beating?
0:02:36 > 0:02:39Your heart beats around 100,000 times per day.
0:02:39 > 0:02:42That's about 35 million times a year.
0:02:42 > 0:02:44No holidays or anything?
0:02:44 > 0:02:45What a thankless job!
0:02:45 > 0:02:49These heartbeats are controlled by groups of cells called pacemakers
0:02:49 > 0:02:52which produce small electric currents that stimulate the muscles
0:02:52 > 0:02:56of the heart to contract and then relax, creating a heartbeat.
0:02:56 > 0:02:59When you exercise, your heart beats faster to deliver more oxygen
0:02:59 > 0:03:01to your muscles,
0:03:01 > 0:03:04but it also increases blood flow to the brain, making you feel
0:03:04 > 0:03:07more alert and awake during exercise and more focused afterwards.
0:03:07 > 0:03:10Healthy body, healthy mind.
0:03:10 > 0:03:11See you next time.
0:03:13 > 0:03:17Well, Dr Brainy-Boots, solved my riddle yet?
0:03:17 > 0:03:19Time's nearly up.
0:03:19 > 0:03:21No time. Exercising my brain.
0:03:21 > 0:03:25Oh, McCork, I don't think I can take another session.
0:03:25 > 0:03:30Ah, come on, Colin, it's better than just sitting around doing nothing.
0:03:30 > 0:03:32Ah, that's it!
0:03:32 > 0:03:33Nothing!
0:03:33 > 0:03:36Rich people need nothing. Poor people have nothing.
0:03:36 > 0:03:40And if you eat nothing, you'll die.
0:03:40 > 0:03:42Yes, riddle solved!
0:03:42 > 0:03:46Congratulations, McCork, you've solved the riddle.
0:03:46 > 0:03:48Did I? What's a riddle?
0:03:48 > 0:03:50Hard luck, Dr Knowles.
0:03:50 > 0:03:54You'll just have to try harder next time.
0:03:54 > 0:03:56Oh, come on, really?!
0:03:56 > 0:03:58He gets the credit?
0:03:58 > 0:04:01Urgh, sometimes I wonder why I bother! Aargh!