1 00:00:04,333 --> 00:00:05,667 - WE ALL KNOW THAT NASA ASTRONAUTS 2 00:00:05,667 --> 00:00:06,967 GO THROUGH A LOT OF TRAINING, 3 00:00:06,967 --> 00:00:09,800 BOTH PHYSICAL AND MENTAL, BEFORE GOING INTO SPACE. 4 00:00:09,800 --> 00:00:11,533 THAT'S BECAUSE LIVING IN SPACE 5 00:00:11,533 --> 00:00:13,266 IS A COMPLETELY DIFFERENT EXPERIENCE 6 00:00:13,266 --> 00:00:14,734 THAN LIVING HERE ON EARTH, 7 00:00:14,734 --> 00:00:16,567 AND IT HAS SOME INTERESTING EFFECTS 8 00:00:16,567 --> 00:00:18,133 ON THE ASTRONAUTS' BODIES. 9 00:00:18,133 --> 00:00:20,333 FIND OUT MORE ABOUT THEIR HEART-PUMPING ADVENTURES, 10 00:00:20,333 --> 00:00:21,767 NEXT ON "REAL WORLD." 11 00:00:28,500 --> 00:00:30,433 YOU PROBABLY ALREADY KNOW THAT WHEN IN ORBIT, 12 00:00:30,433 --> 00:00:32,000 ASTRONAUTS' BODIES STRETCH, 13 00:00:32,000 --> 00:00:34,266 AND THEY LOSE BONE AND MUSCLE MASS. 14 00:00:34,266 --> 00:00:36,000 BUT THOSE AREN'T THE ONLY PHYSICAL EFFECTS 15 00:00:36,000 --> 00:00:37,834 THE ASTRONAUTS HAVE TO PREPARE FOR. 16 00:00:37,834 --> 00:00:40,233 LET'S HEAR ABOUT SOME OTHER KINDS OF PHYSIOLOGICAL CHANGES 17 00:00:40,233 --> 00:00:43,533 FROM CANADIAN SPACE AGENCY ASTRONAUT BOB THIRSK, 18 00:00:43,533 --> 00:00:46,000 ON BOARD THE INTERNATIONAL SPACE STATION. 19 00:00:46,000 --> 00:00:49,000 - DURING SPACEFLIGHT, OUR HUMAN BODIES 20 00:00:49,000 --> 00:00:51,467 HAVE TO ADAPT TO THIS NEW, UNUSUAL 21 00:00:51,467 --> 00:00:54,567 LIVING AND WORKING ENVIRONMENT OF SPACEFLIGHT. 22 00:00:54,567 --> 00:00:57,600 WEIGHTLESSNESS AFFECTS EACH OF OUR PHYSIOLOGICAL SYSTEMS, 23 00:00:57,600 --> 00:01:00,200 INCLUDING OUR SENSORY-MOTOR SYSTEM. 24 00:01:00,200 --> 00:01:04,066 IN ADDITION, SPACEFLIGHT IS NOT EASY. 25 00:01:04,066 --> 00:01:06,333 IT PLACES SIGNIFICANT COGNITIVE DEMANDS 26 00:01:06,333 --> 00:01:08,433 UPON THE ASTRONAUT CREW. 27 00:01:08,433 --> 00:01:09,533 - COGNITIVE, 28 00:01:09,533 --> 00:01:11,400 OR BASICALLY THE PROCESS OF THOUGHT. 29 00:01:11,400 --> 00:01:12,700 COME ON, OUT THERE. 30 00:01:12,700 --> 00:01:14,633 IF SOMEONE HAS EVER TOLD YOU TO TURN ON YOUR BRAIN, 31 00:01:14,633 --> 00:01:16,834 THEY'RE TALKING ABOUT COGNITIVE PROCESSES. 32 00:01:16,834 --> 00:01:20,200 - ASTRONAUTS SPEAK OF A CERTAIN MUDDINESS 33 00:01:20,200 --> 00:01:22,533 OF COGNITIVE THINKING PROCESS 34 00:01:22,533 --> 00:01:24,500 DURING THE FIRST FEW DAYS OF SPACEFLIGHT. 35 00:01:24,500 --> 00:01:27,400 IT SEEMS THAT FOR THE FIRST FEW DAYS AFTER WE ARRIVE 36 00:01:27,400 --> 00:01:29,166 THAT WE'RE JUST NOT QUITE AS SHARP 37 00:01:29,166 --> 00:01:31,367 AS WE WERE ON THE GROUND. 38 00:01:31,367 --> 00:01:35,800 WELL, NEUROLOGICAL AND THINKING, OR COGNITIVE, PROCESSES 39 00:01:35,800 --> 00:01:39,300 CAN BE STUDIED BY MEASURING SIGNALS FROM THE BRAIN 40 00:01:39,300 --> 00:01:41,300 AND FROM THE PERIPHERAL NERVOUS SYSTEM. 41 00:01:41,300 --> 00:01:44,433 THAT'S THE REASON WHY WE WEAR THIS AMUSING HAT. 42 00:01:44,433 --> 00:01:47,367 WITHIN THE HAT, THERE ARE 54 ELECTRODES 43 00:01:47,367 --> 00:01:50,734 THAT MONITOR OUR BRAIN WAVES, OR EEG SIGNALS. 44 00:01:50,734 --> 00:01:54,333 IT ALSO CONTAINS ELECTRODES THAT MONITOR EYE MOVEMENTS. 45 00:01:54,333 --> 00:01:56,433 ELSEWHERE ON OUR BODY, WE WEAR SENSORS 46 00:01:56,433 --> 00:01:59,166 THAT MONITOR MUSCLE MOVEMENT IN OUR HANDS 47 00:01:59,166 --> 00:02:02,467 AND ALSO OUR CARDIAC RHYTHM AS WELL. 48 00:02:02,467 --> 00:02:05,233 - YOU EVER NOTICE HOW ASTRONAUTS LOOK ALL PUFFY IN THE FACE 49 00:02:05,233 --> 00:02:06,767 WHEN THEY FIRST GO INTO ORBIT? 50 00:02:06,767 --> 00:02:09,467 WELL, LET'S CHECK IN WITH BOB AGAIN TO FIND OUT WHY. 51 00:02:09,467 --> 00:02:12,834 - ON EARTH, OUR HEART PUMPS OXYGEN-RICH BLOOD 52 00:02:12,834 --> 00:02:14,400 UP TO THE BRAIN, 53 00:02:14,400 --> 00:02:16,567 AND THEN EARTH'S GRAVITY HELPS PULL THE BLOOD 54 00:02:16,567 --> 00:02:18,667 BACK DOWN TO THE LOWER PARTS OF THE BODY. 55 00:02:18,667 --> 00:02:22,300 SINCE THE BRAIN IS THE CAPSTONE OF OUR PROVERBIAL PYRAMID, 56 00:02:22,300 --> 00:02:24,100 OUR HEART HAS TO WORK ESPECIALLY HARD 57 00:02:24,100 --> 00:02:25,834 TO PUMP BLOOD UP TO IT. 58 00:02:25,834 --> 00:02:28,433 BUT IN WEIGHTLESSNESS, THERE IS A DIFFERENCE. 59 00:02:28,433 --> 00:02:32,867 THE BLOOD VOLUME IN OUR HEAD AND CHEST INCREASES. 60 00:02:32,867 --> 00:02:34,433 FOR THOSE OF YOU WHO KNOW ME, 61 00:02:34,433 --> 00:02:37,967 YOU RECOGNIZE THAT MY FACE IS NOW ROUNDER AND PUFFIER 62 00:02:37,967 --> 00:02:39,934 THAN TYPICAL ON EARTH. 63 00:02:39,934 --> 00:02:43,266 ANYWAYS, THIS INCREASED CENTRAL BLOOD VOLUME IN SPACE 64 00:02:43,266 --> 00:02:45,333 REDUCES THE WORKLOAD OF THE HEART. 65 00:02:45,333 --> 00:02:48,867 THIS DOESN'T POSE A CHALLENGE TO OUR HEALTH WHILE IN SPACE, 66 00:02:48,867 --> 00:02:51,700 BUT IT CAN HAVE NEGATIVE CONSEQUENCES 67 00:02:51,700 --> 00:02:53,800 ONCE WE'RE BACK ON THE GROUND. 68 00:02:53,800 --> 00:02:55,633 - [breathing heavily] 69 00:02:55,633 --> 00:02:58,033 BASICALLY, THE HEART DOESN'T HAVE TO DO AS MUCH WORK 70 00:02:58,033 --> 00:02:59,700 TO PUMP BLOOD WHEN ON ORBIT. 71 00:02:59,700 --> 00:03:03,567 YOU MIGHT SAY IT GETS LAZY. 72 00:03:03,567 --> 00:03:05,867 TO UNDERSTAND JUST HOW THAT HAPPENS, 73 00:03:05,867 --> 00:03:08,166 WE HAVE TO KNOW A LITTLE BIT ABOUT BLOOD FLOW. 74 00:03:08,166 --> 00:03:11,333 CARDIAC OUTPUT IS THE AMOUNT OF BLOOD IN MILLILITERS 75 00:03:11,333 --> 00:03:13,133 PUMPED BY THE HEART IN ONE MINUTE. 76 00:03:13,133 --> 00:03:14,700 ON EARTH AND IN SPACE, 77 00:03:14,700 --> 00:03:17,333 DIFFERENT CONDITIONS CAN CHANGE CARDIAC OUTPUT. 78 00:03:17,333 --> 00:03:20,700 TO FIND CARDIAC OUTPUT, WE USE MULTIPLICATION. 79 00:03:20,700 --> 00:03:23,867 CARDIAC OUTPUT, OR MILLILITERS OF BLOOD PER MINUTE, 80 00:03:23,867 --> 00:03:26,734 EQUALS STROKE VOLUME, IN MILLILITERS PER BEAT, 81 00:03:26,734 --> 00:03:29,133 TIMES HEART RATE, BEATS PER MINUTE. 82 00:03:29,133 --> 00:03:32,967 ON EARTH, STROKE VOLUME IS ABOUT 75 MILLILITERS PER BEAT. 83 00:03:32,967 --> 00:03:36,300 AN AVERAGE ADULT'S PULSE RATE IS ABOUT 70 BEATS PER MINUTE. 84 00:03:36,300 --> 00:03:38,934 IF WE MULTIPLY 75 MILLILITERS PER BEAT 85 00:03:38,934 --> 00:03:40,734 TIMES 70 BEATS PER MINUTE, 86 00:03:40,734 --> 00:03:42,867 WE FIND THAT AN AVERAGE CARDIAC OUTPUT 87 00:03:42,867 --> 00:03:46,800 WOULD BE AROUND 5,250 MILLILITERS PER MINUTE. 88 00:03:46,800 --> 00:03:50,433 WE KNOW THAT 1,000 MILLILITERS MAKE UP A LITER, 89 00:03:50,433 --> 00:03:53,266 SO ABOUT 5.25 LITERS OF BLOOD 90 00:03:53,266 --> 00:03:55,467 ARE PUSHED THROUGH THE HEART EACH MINUTE. 91 00:03:55,467 --> 00:03:56,934 WE ALSO KNOW THAT THE HUMAN BODY 92 00:03:56,934 --> 00:03:58,967 HOLDS ABOUT FIVE LITERS OF BLOOD. 93 00:03:58,967 --> 00:04:00,900 THAT MEANS THAT IN A MINUTE'S TIME, 94 00:04:00,900 --> 00:04:03,800 ALL OF THE BLOOD IN THE BODY IS PUMPED THROUGH THE HEART. 95 00:04:03,800 --> 00:04:06,600 BUT WHAT ABOUT CARDIAC OUTPUT IN SPACE? 96 00:04:06,600 --> 00:04:09,033 THE POOLING OF FLUID IN THE UPPER PART OF THE BODY-- 97 00:04:09,033 --> 00:04:12,400 THAT PUFFY HEAD STUFF BOB THIRSK WAS TALKING ABOUT-- 98 00:04:12,400 --> 00:04:13,967 SIGNALS THE HEART TO PUSH MORE BLOOD 99 00:04:13,967 --> 00:04:15,834 THROUGH THE HEART WITH EACH BEAT. 100 00:04:15,834 --> 00:04:17,934 AS A RESULT, THE ASTRONAUT'S STROKE VOLUME 101 00:04:17,934 --> 00:04:20,500 IS INCREASED TO ABOUT 90 MILLILITERS PER BEAT. 102 00:04:20,500 --> 00:04:22,333 BUT SOMETHING ELSE HAPPENS IN MICROGRAVITY 103 00:04:22,333 --> 00:04:23,967 WHEN THE BODY SENSES THE EXTRA BLOOD 104 00:04:23,967 --> 00:04:25,200 IN THE UPPER BODY. 105 00:04:25,200 --> 00:04:27,600 IT INTERPRETS THE POOLING BLOOD AS TOO MUCH FLUID, 106 00:04:27,600 --> 00:04:29,867 SOMETHING CALLED OVERHYDRATION. 107 00:04:29,867 --> 00:04:31,300 THIS SIGNALS THE KIDNEYS 108 00:04:31,300 --> 00:04:32,834 TO REMOVE THE WATER FROM THE BLOOD 109 00:04:32,834 --> 00:04:34,367 AND GET RID OF IT AS URINE. 110 00:04:34,367 --> 00:04:37,333 AFTER ONLY ONE DAY BEYOND EARTH'S GRAVITY, 111 00:04:37,333 --> 00:04:39,367 ASTRONAUTS HAVE A LOWER BLOOD VOLUME. 112 00:04:39,367 --> 00:04:42,367 THEY CAN LOSE AS MUCH AS 20% OF THEIR BLOOD VOLUME 113 00:04:42,367 --> 00:04:44,233 WHILE ON A SPACE MISSION. 114 00:04:44,233 --> 00:04:46,600 SINCE THE BODY HAS LESS BLOOD TO PUSH AROUND 115 00:04:46,600 --> 00:04:49,133 AND THE HEART IS PUSHING MORE BLOOD WITH EACH BEAT, 116 00:04:49,133 --> 00:04:52,300 AN ASTRONAUT'S HEART RATE ALSO SLOWS DOWN TO COMPENSATE. 117 00:04:52,300 --> 00:04:54,300 ASTRONAUTS JUST DON'T NEED AS MUCH BLOOD 118 00:04:54,300 --> 00:04:55,834 IN THE ENVIRONMENT OF SPACE, 119 00:04:55,834 --> 00:04:57,800 AND THE HEART JUST DOESN'T WORK AS HARD 120 00:04:57,800 --> 00:04:59,600 TO MOVE THE BLOOD THROUGH THE BODY, 121 00:04:59,600 --> 00:05:01,967 SO AN ASTRONAUT'S HEART RATE AND BLOOD PRESSURE 122 00:05:01,967 --> 00:05:05,967 ARE CAREFULLY MONITORED BEFORE, DURING, AND AFTER MISSIONS. 123 00:05:05,967 --> 00:05:08,133 AND ASTRONAUTS TAKE SPECIAL COUNTERMEASURES, 124 00:05:08,133 --> 00:05:10,967 LIKE EXERCISING AND DRINKING LOTS OF FLUIDS 125 00:05:10,967 --> 00:05:12,600 JUST BEFORE RETURNING TO EARTH, 126 00:05:12,600 --> 00:05:14,900 TO HELP THEIR BODIES RETURN TO NORMAL. 127 00:05:14,900 --> 00:05:17,133 SO THE NEXT TIME YOU TAKE YOUR PULSE, 128 00:05:17,133 --> 00:05:20,367 THINK ABOUT THE DOCTORS, NURSES, AND MEDICAL TECHNICIANS 129 00:05:20,367 --> 00:05:22,200 WHO ARE MONITORING THE ASTRONAUTS, 130 00:05:22,200 --> 00:05:24,066 KEEPING THEM HEALTHY IN SPACE. 131 00:05:24,066 --> 00:05:26,333 I'LL SEE YOU NEXT TIME ON "REAL WORLD."