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9.9 Option – Space science: 3. Effects on the body of reduced gravity
| Syllabus
reference (October 2002 version) |
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| 3. Reduced gravity in space
can have short and long term effects on body functions |
Students learn to: |
Students: |
Extract from Senior Science Stage 6
Syllabus (Amended October 2002) © Board of Studies, NSW.
[Edit: 16 Sept 08]
Prior learning: Science Stages 4-5 Syllabus. Outcome 4.8 (content 4.8.5, subsection a and 4.8.5 subsection b).
Background: As stated in 9.9.2. gravity becomes less the further away you go from the object that is causing that gravity, in this case the Earth. Our bodies have evolved with Earth gravity so in negligible gravity the body responds in a different way.
define ‘ingestion’ and explain how ingestion occurs without the assistance of gravity
- Ingestion simply means the taking of food and or drink into the body. In humans this occurs via the mouth.
- When we eat and drink, gravity helps our food and liquid go down the oesophagus into our stomach.
- This movement is also assisted by peristalsis; a muscular contraction that squeezes the oesophagus at the top then follows down like a ripple to the stomach.
discuss the problems associated with drinking fluids while in an environment of negligible gravity
- We usually hold a glass up to our lips and pour the fluid into our mouth. However in negligible gravity you can’t pour so liquids are put in tubes and squeezed to expel liquid into the mouth. The other way liquids are ingested is by using a polythene straw. This works well as the spaceship is pressurised so air pressure, not gravity is involved. You could also squeeze the container to force the fluid out the straw.
- Fluids don’t usually need peristalsis as they normally just flow down the oesophagus with gravity. In negligible gravity fluid moves down the oesophagus with peristalsis.
describe possible containers through which food may be accessed so as to reduce spillage.
- Food containers and food preparation will be different in space. Find out
from NASA
what containers were used to store food
. Space Food History to find out
about early food containers and how they changed later, providing more appetising
food. You'll have to scroll down to find the relevant parts.Almost Like Eating
at Home mentions containers and utensils.
describe the forms in which food and drinks could be transported and stored for use by space personnel over their time in space.
- Refer to the information gained in the point above.
- Find out about transporting
and storing food in the space shuttle .Space Food History, NASA
- Pantry
- Shuttle Extended Duration Missions
- Thermostabalized Food
to find some information on transporting and storing food.
Look in
gather information from first-hand and secondary sources and use available evidence to devise a series of exercises for all major muscle groups of the body that could be performed within the confines of a spacecraft
- Use the internet and books, including encyclopedias to find out the size of the area in spacecrafts where astronauts will exercise. Some spacecrafts you check out could be the shuttle and the International Space Station.
- Talk to the PE staff or biology teachers or consult books in the library to find the major muscle groups.
- Go to a local gymnasium and find out what exercises they have their clients do and the purpose of the exercises.
- Using this information gathered, work in a group to work out the most appropriate exercises for the muscle groups. Don’t forget that you may have to consider working in a small space but the International Space Station has more room than previous space vessels.
- Consider also the fact that the exercises will be done in negligible gravity conditions.
- Test these exercises in the gym at school if possible.
account for the role of gravity in the maintenance of bone health
- Studies done by NASA have shown that bone density remains less than normal in flights up to 84 days and the most significant bone loss occurs in the lower bones that would normally bear more weight.
- Astronauts do impact-loading, weight bearing exercises while in space to reduce their bone loss.
- One site that may be useful for the role of gravity in space. Exercise
and bone health in space by Peter R Cavanagh, the Cleveland Clinic Foundation,
Department of Biomedical Engineering and the Center for Space Medicine, Cleveland,
Ohio. USA.
Another good site is the ABC web site, The Lab, News in Science, Health and Medical, Friday 28 September 2001. The health hazards of life in space.
account for the role of gravity in the maintenance of muscle tone
- Muscle tone is the condition where muscle fibres are slightly contracted to keep the body in good shape and not flabby.
- The muscles of the body that keep the torso upright have to be in partial contraction all the time. As well the muscles of the lower body have to support the weight of the upper body.
- When astronauts are in micro-gravity these muscles don’t need to support the weight of the body so atrophy (shrinking) occurs. This muscle wasting is similar to that which occurs to people on earth when they do not get exercise, such as when they are bed ridden.
identify some human circadian rhythms and discuss effects of disruption to biorhythms
- Circadian rhythms are cycles of the body that are inbuilt but synchronise with environmental cues such as day and night and the seasons.
- Some examples of circadian rhythms are sleeping and waking, rest and activity, formation of urine, production of hormones and body temperature.
- These rhythms are upset by shift work and by rapid travel into different time zones.
- After long journeys it takes several days for the inbuilt rhythm generator to become synchronised to the local time (jetlag).
- In space there is no regular night and day (the shuttle, Columbia, in 1996 experienced six sun rises and sun sets in 24 hours.
- The astronauts sleep at regular times as though it was night but they may sleep upside down, horizontal or vertical with the head to the ‘top’.
- In 1996 the astronauts were experimental animals and many tests were done on them to discover the effect of micro-gravity on the body, including circadian rhythms.
gather
from secondary sources information to identify activities that disrupt circadian
rhythms
- Look in a variety of sources such as scientific journals
and CD-ROMS as well as the internet for information
on disruption of circadian rhythms , PsycheNet-UK. Scroll down to ‘Specify’
to find some activities that disrupt sleep patterns. Then scroll down to ‘Cause’
to read some more about insomnia and sleeping when you don’t want to.
describe ways in which normal circadian rhythms can be maintained during space travel
- Normal circadian rhythms are attempted by the astronauts living their own 24 hour cycle by having a normal working day, followed by some leisure and then a time when they sleep, arising after about a seven hour period.
- Having this regular day would not only assist the waking and sleeping circadian rhythms but also the urinating and body temperature rhythm. (Your body temperature is slightly lower when you are asleep)
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