Senior Science

9.9 Elective Option - Space science

Section 3

Effect of Space

on the Body

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Section 3 :: Effect on the Body

Reduced gravity in space impacts can have short-and long-term effects on body functions

9.9.3.a Define ‘ingestion’ and explain how ingestion occurs without the assistance of gravity

9.9.3.b Discuss the problems associated with drinking fluids while in an environment of negligible environment

9.9.3.c Describe possible containers through which food may be accessed so as to reduce spillage

9.9.3.d Describe the forms in which food and drinks could be transported and stored for use by space personnel over their time in space

9.9.3.e Account for the role of gravity in the maintenance of bone health

9.9.3.f Account for the role of gravity in maintenance of muscle tone

9.9.3.g Identify some human circadian rhythms and discuss effects of disruption of these

9.9.3.h Describe ways in which normal circadian rhythms can be maintained during space travel

9.9.3.i 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

9.9.3.ii Gather from secondary sources information to identify activities that disrupt circadian rhythms

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9.9.3.a Define ‘ingestion’ and explain how ingestion occurs without the assistance of gravity

INGESTION AND GRAVITY

Ingestion is the taking of food and drink into the body

Food does not fall into your stomach. You can eat and swallow food while standing on your head. This means that gravity is not assisting food reaching your stomach. Of course, people tend to eat when upright. In this situation ingestion is helped by gravity

In humans, ingestion can occur without the assistance of gravity because food is pushed into your stomach by a “wave of muscular contractions”. The process is called peristalsis. Circular muscles in the wall

of the oesophagus just behind the food contract. This squeezes the food towards the stomach. The muscles contract so that the region of contraction stays just behind the food. This constantly pushes the food towards the stomach.

Notes Questions

1. Activity Place a tennis ball just inside a long stocking. How can you get the ball to the other end of the stocking?

a. Explain why the tennis ball can be moved in terms of muscular contractions of the hand.

b. Describe how this is similar to the muscular contractions in the stomach.

Notes Questions (for next page)

2. Why is it possible to pour liquids on Earth?

3. Is it possible to pour liquids in space?

4. In space, what shape does a floating blob of liquid form?

5. Identify one problem associated with drinking in space.

6. Name two pieces of equipment needed to drink in space.

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9.9.3.b Discuss the problems associated with drinking fluids while in an environment of negligible environment

PROBLEMS WITH DRINKING

On earth, drinking involves holding a container to our lips and pouring the liquid into our mouths. The fluid passes down our oesophagus because of the muscular contractions (by peristalsis) and assisted by gravity. On earth, pouring a liquid is possible because gravity causes the liquid to fall down (away from the container).

Can you pour a liquid in a micro-gravity environment?Can a liquid be tipped out of a glass in a micro-gravity environment?Can you get the liquid out of a glass container in a micro-gravity environment?What happens if liquid is “spilt” while drinking?

Diagrama. Pouring on earth b ‘Pouring’ in micro-gravity

Note – You cannot pour in space. Why? – no gravity & you would not have an open container. The diagram is hypothetical.

In a micro-gravity environment, both the cup and liquid are falling together around the earth. When the liquid container is tipped ‘over’ the liquid does not fall out. It mostly stays where it is – in the container. Therefore, liquids cannot be poured in a micro-gravity environment. It would be impossible (or at least not easy to pour) to pour a liquid into your mouth while in space.

To get the liquid out of the cup you could quickly pull the cup away from the opening. This would leave the liquid floating. The floating blob of liquid would form a sphere because of the force of attraction between water molecules. [Remember from Lifestyle Chemistry – the surface tension produces the smallest surface area possible – a sphere] Obviously, a problem associated with drinking in space is liquid can just end up floating around inside the space capsule. This is a nuisance and potentially dangerous.

Therefore, there are THREE problems associated with drinking in space. These are: How to store the liquid How to get the liquid from the container to the mouth How to prevent the liquid escaping and then floating in a micro-gravity

environment.

How Do Astronauts Drink?

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To drink in space, astronauts use a method similar to drinking from a “Poppa”. A light, aluminium pouch is used to hold the liquid. A straw is used to sip the drink. Muscular action in the oesophagus squeezes the liquid into the stomach, without the assistance of gravity. The straw has a clamp to prevent the liquid from escaping when the astronaut is not drinking.

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9.9.3.c Describe possible containers through which food may be accessed so as to reduce spillage

PACKAGING OF FOOD FOR THE SPACE SHUTTLE

There are a number of factors that affect how food is packaged and eaten for a space mission.

Reducing weight - total weight of the spacecraft must be kept at a minimum for a successful launch. For a typical ten day mission, only 1.7 kg of food is taken on board for each astronaut.

Preserving stored food - bacteria and fungi grow very quickly in a micro-gravity environment. So food needs to be stored to ensure preservation of food. An important means of doing this is by dehydrating food.

Preventing spillage in weightless conditions- any food or drink that escapes from its container while being eaten in space may cause great danger to the space shuttle if it floats into the instrumentation etc. Short circuits could mean a major equipment failure and cause the crew to not be able to return from space. Problems can also occur if the escaped ‘floaters’ are inhaled. Consequently, all food and drink is prepared and stored in containers that will prevent spillage.

To prevent crumbs forming, tortillas are preferred to bread but sandwiches can be eaten early in the mission to ensure freshness and a tendency to not form crumbs.

To prevent food floating away, foods are generally made with a sauce or gravy to hold the food together. If any food does escape, the liquid will maintain the food as a large drop due to cohesion.

Where does the water comes from for drinking and rehydrating food?

The supply of fresh water on the space shuttle is never a problem because it is constantly being made as a bi-product of the fuel cells which produce electricity by the combination of hydrogen and oxygen (which forms water). The international space station, however, does not possess fuel cells for making electricity but takes advantage of solar arrays. Consequently, the continual supply of water on the space station must be ensured by:

recycling of the water in urine, exhaled air, etc. not requiring the addition of water to foods which are in a dehydrated form.

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KINDS OF PACKAGING

In the early days of space flight, Mercury astronauts squeezed processed food from aluminium toothpaste tubes. They also ate sandwich cubes coated in unflavoured gelatin that kept the bread crumbs from making a mess in the tiny spacecraft cabins. The food, though nutritious, was not very appetising. It lacked the look and feel that make eating pleasurable on Earth.

After many experiments with food types, packaging, and preparation, NASA reached an important conclusion. It was possible and safe to carry normal foods into space and eat them in an almost normal way. The big difference was how foods were packaged and prepared in orbit.

At first, a lot of food was packaged in rigid, square containers. These containers caused problems due to the large amount of rubbish created. Flexible, plastic packets replaced these rigid containers. They have a valve for inserting water to rehydrate the food inside. These are also much easier to be pack down in the rubbish compactor.

Foods for Space Shuttle astronauts come in many forms. Some are freeze-dried while others are thermally stabilized, dried, or eaten in natural form.

Natural form foods, such as peanuts or dried apricots, are packed in vacuum sealed plastic bags. The packages are cut open with scissors and the food is eaten as is.

Foods such as tuna or salmon come in metal cans with panel pull-back lids like those snack-food cans found at supermarkets.

Dinner entrees, such as beef stew or smoked turkey, are packed in foil and plastic pouches. They are heated in the Shuttle’s oven and eaten when ready.

Dried food is packed in special plastic containers with flexible lids. Hot or cold water must be added to make the food ready for eating.

The beverage packages are made from foil and a plastic laminate, in order to provide longer shelf life.

Notes Questions

7. Identify three factors that need to be considered for containers used in space.

8. How much food is provided per astronaut for a ten-day mission?

9. Name two reasons why it is necessary to prevent the spillage of food in space.

10.How was food packaged on the Mercury missions?

11.What conclusion did NASA reach about the food suppled for space missions?

12.Research What is meant by rehydrate?

13.Name three types of packages used for space missions.

14.What is the advantage of flexible, plastic packets compared to rigid, square containers?

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9.9.3.d Describe the forms in which food and drinks could be transported and stored for use by space personnel over their time in space

TYPES OF SPACE FOOD

Space food on the space shuttle may belong to one of the following categories:

Rehydratable food -- the water has been removed i.e. the food has been a dehydrated in a process known as freeze drying. eg beverages and hot cereal.

Thermostabilised food -- has been heat processed and canned to destroy bacteria and fungi allowing the food to be stored at room temperature. e.g. pudding, fruit and tuna fish in cans.

Intermediate moisture food -- some of the water has been taken out of the food to maintain the soft texture and reduce the potential for growth of bacteria and fungi. As a result, the food can be directly eaten without the need for preparation. eg. dried fruit

Natural form food -- stored in a flexible pouch and ready to eat e.g. nuts, biscuits and health bars

Irradiated food -- beef steak and smoked turkey are the only foods so far to be sterilised by ionising radiation which allows them to be kept at room temperature.

Frozen food -- a food may be quick frozen to maintain freshness and texture of the food. eg. casserole

Fresh food -- e.g. apples and bananas are not preserved or processed but are generally best eaten early in the mission.

Refrigerated food -- requires cool temperatures to prevent spoiling e.g. cream cheese

Most of food to be used on the international space station will be frozen, refrigerated or thermostabilised to reduce the use of valuable water.

Source http://liftoff.msfc.nasa.gov/academy/astronauts/food-menu.html

Notes Questions

15.Name one example of each of the followinga) rehydratable food b) natural form food c) thermo stabilised food.

16.How is food thermo stabilised?

17.When is it best to eat freah food?

18.Why is some food refrigerated?

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Selecting Food for a Space Mission

A good dinner is important for astronauts for both health and relaxation.

An astronaut's choice of food, which is checked by a dietician, must reflect: food liked by the astronaut. variety - rehydratable foods allow a greater variety of meal a balanced diet (five food groups; food pyramid; 1, 2, 3, 4, 5+ food plan) energy considerations (measured in kilojoules & about 3000 kJ daily) amount of food needed (a maximum weight of 1.7 kg).

Other factors include Preparation requirements Potential for spillage Wastage (food and packaging)

Typical menu for two days of an astronaut's mission

Meal A Meal B Meal CDried apricots (IM)Sausage patty (R)Scrambled eggs (R)Bran flakes (R)Strawberry juice (B)Cocoa(B)

Peanut butter (T)Jam (T)Bread (NF)Fruit cocktail (T)Fruitcake (T)Tea w/lemon and suger (B)

Frankfurters (T)Potato patty (R)Green beans/broccoli (R)Strawberries (R)Vanilla pudding (T)Tropical punch (B)

Abbreviations:T – thermostabilized; IM – intermediate moisture; B – beverage;R – rehydratable; FD – freeze dried; NF – natural form;

Meal A Meal B Meal CDried pears (IM)Beef patty (IM)Breakfast roll (NF)Pineapple (T)Cashews (NF)Orange-grapefruit drink (B)

Ham (T)Cheese spread (T)Bread (NF)Pineapple (T)Cashews (NF)Strawberry drink (B)

Meatballs w/BBQ sauce (T)Rice pilaf (R)Italian vegetables (R)Chocolate pudding (T)Apple drink (B)

Source: NASA Educational Briefs (EB-90-7(E)

Notes Questions

19.List all the foods in the table above that are natural form foods.

20.Name the foods that need water to be added before they are eaten.

21.List the foods that are possibly packaged in a metal can.

22.How are beverages stored?

23.How do astronauts drink beverages?

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9.9.3.e Account for the role of gravity in the maintenance of bone health

GRAVITY AND BONE HEALTH

Bone is living tissue. Bone tissue is constantly being renewed - broken down and built up. This process allows bones to grow and to mend (when bones are broken) In children more bone tissue is being built up than is being removed. This allows bone

growth. Normally, in adults the build up of bone tissue is about the same as the loss of bone

tissue. Adults stay about the same size. In old age, the build up of bone tissue is less that the break down of bone tissue. This

helps explain why older people seem to get smaller.

An important aspect of bone health is the uptake of calcium. Strong bones require calcium. Calcium needs to be deposited in bone tissue as part of the renewing process. If calcium levels are not maintained bones become brittle and break more easily. The maintenance of bone health means that the deposit of calcium in bone tissue is sufficient to maintain growth in children or at least balances the removal of calcium in adults.

Maintaining calcium levels in bone tissue depends on at least two factors. One factor is having enough calcium in the diet. The other is participating in weight bearing exercise (ie the role of gravity)Studies have shown that eating calcium rich foods is not enough. The uptake of calcium by the bones is greatly increased by exercise. This exercise needs to be “weight-bearing” exercise. Weight bearing activities involve the body working against the pull of gravity. On earth, walking and running are good examples of such activities. Every time a step is taken (and the heal ‘hits the ground) helps the heal bone and other leg bones to absorb calcium and maintain bone health. Swimming, where the body is supported by water, is not such a good activity for maintaining bone health.

The importance of gravity has been made obvious by studying bone mass losses by astronauts. It has been discovered that prolonged periods of “weightlessness” can cause serious calcium depletion in astronauts. This makes the bones become brittle, lose strength and increases the possibility of fractures. Cosmonauts on the Salyut 6 for 175 days, for example, lost eight percent of the calcium in their bones. To reduce calcium loss from bone tissue astronauts must maintain an exercise program. In space (a micro-gravity environment), there is no point walking for exercise since the body is not working against the pull of gravity. The exercises must be load bearing – that is, the muscles need to work against a resistance.

Notes Questions

24.Explain why people can get smaller as they get old?

25.Name the main factor that is important in maintaining calcium levels in bones.

26.Outline problems associated with the loss of calcium from bones.

27.How can bone health be maintained on space missions?

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9.9.3.f Account for the role of gravity in maintenance of muscle tone

GRAVITY AND MUSCLE TONE

Muscle tone relates to the condition where muscle fibres are slightly contracted to keep the body in good shape and not flabby.

Muscle tone, size and strength increase by exercising against a resistance (called resistance training). On earth, the resistance is provided mostly by the pull of gravity – ie weight. Muscle size and strength decrease when people stop exercising. A good example of this is when someone breaks their leg and gets a plaster cast. The lack of exercise can result in a significant decrease in the size of the leg muscles. Living on earth means you are always affected by the gravitational pull. This helps maintain muscle tone.

In the micro-gravity environment most activities require less effort. The heart, blood vessels, and muscles weaken because weightlessness involves less work for the body than working against the pull of gravity. As a result muscles lose tone and strength. Most of the loss is thought to occur in the leg bones and spine that are responsible for erect posture and locomotion. Soviet researchers found that cosmonauts who spent just one month in space lost between 10% to 20% of their muscle strength in their arms and legs.

Muscle and bone problems are insignificant in a short duration shuttle mission but it is of great concern for long stays in space on the space station and eventually for a trip to Mars. Sore muscles may be the end result of a space shuttle mission but there is a serious threat to an astronaut’s health from long duration space travel.

To reduce the loss of muscle tone and strength astronauts need to exercise, especially on long missions. The exercise must be regular and intense to maintain cardiovascular fitness, to maintain muscle strength and reduce calcium loss. This may be done on a treadmill or a bicycle ergometer as well as using bungee rubber bands for light resistance exercise. A well-conditioned cardiovascular system will minimise the potential for fainting on re-entry or landing. During the Skylab missions, which lasted up to 84 days, the astronauts exercised at least 30 minutes each day

Notes Questions

28.What is muscle tone?

29.Name two situations when a person might lose muscle tone?

30.What helps maintain muscle tone on Earth?

31.What important body organ is a muscle?

32.Suggest a reason why muscle problems are not significant on a space shuttle mission.

33.How can the loss of muscle strength and tone be reduced?

34.Name three devices used for exercise on a space mission.

35.Outline at least two reasons why swimming or table tennis would not be a suitable for astronauts while in space.

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9.9.3.i 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

EXERCISING IN SPACE

Aim To devise a series of exercises for all major muscle groups of the body that couldbe performed within the confines of a spacecraft

There are some basic principles of exercise programs.1. FITT principle: How many times?; How hard?; How long; What kind of exercise?2. Other features: Enjoyment; Specific; Variety

What to do

Consider the following ideas.

1. What are appropriate exercises? Identify useful exercises. Discuss which of the following would be useful: running on the spot; lifting weights;

using a rowing machine; playing pool / tennis; swimming; Chin ups; Riding a bike Load bearing exercises: Describe a load bearing exercise. How is a “load” or

“resistance” created in a weightless environment? Visit a gym to observe various types of equipment. Perform some of the suggested space exercises.

2. How much room is available?

3. What are the major muscle groups?What about the heart muscle? What about the diaphragm? Do these muscles need to be exercised? How is the heart exercised? How is the diaphragm exercised?

Results

Describe the exercises and equipment that would be appropriate.

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9.9.3.g Identify some human circadian rhythms and discuss effects of disruption of these

9.9.3.ii Gather from secondary sources information to identify activities that disrupt circadian rhythms

HUMAN CIRCADIAN RHYTHMS

NB The terms circadian rhythms and biorhythms are not the same. The word’ biorhythm’ is usually used when predicting a person's highs and lows for the month. However, the term ‘circadian rhythms’ can be replaced by ‘biological rhythms’.

Circadian rhythms Circadian rhythms are body functions that run on a 24-hour cycle. The nervous system, the urinary system, the endocrine system, the respiratory system and cardiovascular system are systems of the body coordinated by the circadian timing system. Thus it affects our physiology, biochemistry and behaviour.

Examples of these daily or circadian rhythms are: body temperature blood pressure the manufacture of urine sleep

If your daily clock is not functioning properly then you may experience headache, irritability, gastric discomfort, chills, light-headedness, difficulty in concentrating, degraded task performance and sleep problems. If you have travelled long distances on a plane, then I am sure that you have experienced some of these symptoms as a result of jet lag also caused by a disturbance of your body's daily clock.

Background Scientists believe that the master clock for circadian rhythms, which are often called

biological rhythms, is a part of the hypothalamus of the brain and are influenced by light cues.

As light fades, the cells in the retina pass messages directly to a cluster of cells called the suprachiasmatic nuclei inside the hypothalamus. This information is used to synchronise our circadian rhythms with the amount of sunlight.

With decreasing sunlight, the suprachiasmatic nuclei signal the pineal gland to produce the hormone melatonin that causes a drop in body temperature and sleepiness.

Source of italics - OTEN

Notes Questions

36.What is a circadian rhythm?

37.Name one circadian rhythm.

38.Name three effects of disruption to a person’s circadian rhythm.

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9.9.3.h Describe ways in which normal circadian rhythms can be maintained during space travel

SPACE TRAVEL AND CIRCADIAN RHYTHMS

The space shuttle orbits the Earth in only 90 minutes producing brilliant daylight every 45 minutes and extreme darkness every other 45 minutes. Since there is no normal day or night, normal circadian rhythms can be disrupted. This disruption of the sleep/wake cycle of an astronaut can affect alertness and performance. The astronaut may feel very exhausted and have poor reaction times. As a result, the astronaut may become sleepy and have poor responses at the wrong time such as during a space walk. Not being able to react instantly in times of danger may risk his life and possibly the life of the whole crew. Strategies for maintaining circadian rhythms in space

In the days leading up to the mission, astronauts will sleep in rooms that do not have windows. Throughout their sleep period, the lights in the room are switched on automatically every 90 minutes lasting for a period of 45 minutes. It is hoped that this kind of exercise will help acclimatize the astronauts for their time in space.

While in space:

the lights in the orbiter will be turned off during the astronauts sleep period.

All the astronauts will sleep at the same time.

A 24-hour period on board the space shuttle is organised, with regards to being awake and being asleep, in a similar way to being on Earth. Mission control wakes the astronauts 8 hours after bedtime.

shades are placed on all windows to reduce the entry of light.

the astronauts can wear eye masks to further prevent the rapidly changing ‘day’ and ‘night’ from disturbing their circadian rhythms and therefore their sleep pattern.

astronauts may also use their clothing to keep track of what day it would be on Earth and also organise their wake time.

Despite precautions taken, astronauts still suffer disruption to their circadian rhythms, which must be addressed if long distance space travel to Mars is to be undertaken.

Notes Questions

39.What can cause the circadian rhythms of an astronaut to be disrupted?

40.What problems can arise when the circadian rhythms of an astronaut are disrupted?

41. Identify one way an astronaut can be helped to maintain normal circadian rhythms before space travel

42. Identify two ways an astronaut can be helped to maintain normal circadian rhythms during space travel

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