First-Place Winner: TMA Excellence in Science Teaching
Awards
Jean Durrett
Maedgen Elementary
Lubbock,Texas
Health Issues Related to Space Experiments
Sample Lesson
Overview
Sixth grade students participate in a science lesson that
integrates connections between health issues on Earth and how those
issues are related to studies conducted on the International Space
Station. The two-week lesson helps students connect concepts
related to advances in space science-health issues with
biological-medical advances on Earth.
During the first week of the lesson, students experience an
online resource at
www.science.nasa.gov
to study health issues in the environment of the International
Space Station. Along with studies of water recycling, air
recycling, and other environmental issues, students refer to the
Web site to acquire information about health of astronauts and
problems that astronauts experience in microgravity environments.
The major health issues involve bone density and the need for
exercise to keep bones and muscles in good shape. The article for
information is titled, "Space Bones." Other research articles
included in the study are "Wide Awake in Outer Space," "Mixed
Up in Space," "The Phantom Torso," and "Leafy Green
Astronauts." The articles address health issues of physical
affects of microgravity, radiation issues, orientation and
dizziness issues and growing plants for healthy food intake.
As students study the articles, they compare and contrast the
differences in space environmental effects and Earth environmental
effects.
This is an example of one of the NASA sites the students
studied:
Space Bones:
Weightlessness sure looks like a lot of fun, but prolonged exposure
to zero-G in space can have some negative side
effects - like the weakening of human bones!
Listen to this story via
streaming audio
, a
downloadable file
, or
get help
.
October 1, 2001:
Everybody knows space is dangerous.
Some of the perils are obvious: hard vacuum, extreme cold, and
unpredictable blasts of radiation from the Sun.
Other perils are less conspicuous. The effects of prolonged
weightlessness on the human body, for example, can be slow and
subtle - yet no less dangerous if astronauts fail to take
proper precautions.
Right:
The loss of bone mass that many people experience in space could
eventually weaken the bone and so present problems when the person
returns to a weight-bearing environment, such as the Earth or Mars.
Image courtesy
NASA's Johnson Space Center
.
Weakening of the bones due to the progressive loss of bone mass
is a potentially serious side-effect of extended spaceflight.
Studies of cosmonauts and astronauts who spent many months on space
station Mir revealed that space travelers can lose (on average) 1
to 2 percent of bone mass each month. Sign up for
Express Science news
delivery.
"The magnitude of this [effect] has led NASA to consider bone
loss an inherent risk of extended space flights," says Dr. Jay
Shapiro, team leader for bone studies at the National Space
Biomedical Research Institute.
Space travelers aren't the only ones who worry about bone loss.
At least 10 million people suffer from bone loss in the U.S. and
untold numbers worldwide - it's called
osteoporosis
. Postmenopausal women are especially prone to osteoporosis, but
they're not alone. Most of us contract the disease as we age,
including men. Researchers hope that solving the riddle of bone
loss in space will reveal important clues about what causes
osteoporosis (and other bone disorders) right here on Earth.
Spacefarers typically experience bone loss in the lower halves of
their bodies, particularly in the lumbar vertebrae and the leg
bones. Diminishing bone mass also triggers a rise in calcium levels
in the blood, which increases the risk of kidney stones.
Researchers suspect the root cause of bone loss in space is
weightlessness.
The pull of gravity 350 km above our planet's
surface - where the space station and the shuttle
orbit - is 90 percent as strong as it is on the ground.
That hardly sounds weightless! But orbiting astronauts nevertheless
feel
weightless because they and their spacecraft are freely falling
together toward the planet below. Just as gravity seems briefly
suspended in a downward-accelerating elevator, so does the crew in
the freely-falling space station experience "zero-G." In fact, it's
not exactly zero - but near enough. The acceleration they
feel is as little as 0.001% of the gravitational acceleration on
Earth's surface.
Above:
Living in space might appear to be nothing but fun, but some of the
effects of weightlessness on the body can spoil the party.
Astronauts feel some of them - such as back pains and
vertigo - while others like bone loss would go undetected
without medical equipment. This image was taken in NASA's Skylab.
Image courtesy NASA JSC.
In this mutual free-fall, bones no longer have to fight against
Earth's gravity during locomotion. As a result, less mechanical
strain is applied to the skeletal system Scientists think reduced
stress on bones may be responsible for the progressive bone loss
seen in long-term residents of space. (Lack of stress on bones
among sedentary Earthlings, such as those confined to beds due to
illness or old age, also contributes to bone loss.)
People often think of bones as rigid, unchanging calcium
pillars. But bones are actually dynamic living tissues that
constantly reshape themselves in response to the stresses placed on
them. (This is how archaeologists can tell whether skeletal remains
belonged to a laborer or an aristocrat, for example. The incessant
pull of a laborer's muscles causes the bones to reshape themselves
slightly where the muscles were attached.)
This reshaping is performed by two types of bone cell that are
constantly building new bone or destroying old bone. The actions of
these two cell types - called "osteoblasts" and
"osteoclasts" - usually balance each other out. But when
stresses on bones are reduced (or during the onset of
osteoporosis), removal outpaces replacement, leading to too little
bone which can more easily break.
Left:
The main weight-bearing bones of the body - indicated
with light-purple shading in this drawing - are also the
ones most affected by space-induced bone loss. Picture from
Human Physiology in Space
, a curriculum supplement for secondary schools. (Lujan and White)
In prolonged weightlessness, bone mass appears to decrease because
the lack of stress on the bones slows the formation of osteoblast
cells. Fewer bone-building cells, along with a constant level of
bone-destroying activity, translates into a net loss of bo
Why weightlessness should inhibit the development of osteoblasts
is the subject of a
current study at Vanderbilt University
. A key chemical in the development of osteoblast cells from
precursor cells is an enzyme called "creatine kinase-B."
Investigators are trying to figure out which molecules in the body
regulate the activity of this enzyme and how those chemicals are
affected by low gravity, in the hope that this knowledge will point
to a way to boost osteoblast formation in space.
Another study at the Medical College of Georgia is investigating
a possible connection between eating and bone destruction.
Ingestion of food causes levels of a certain
hormone - called "glucose-dependent insulinotropic
peptide" - to increase in the bloodstream. The main
function of this hormone is to stimulate the production of insulin
after a meal, which in turn triggers cells to absorb
energy-providing glucose from the blood.
Bone cells are sensitive to this hormone, too. Researchers have
found that when this hormone attaches to "receptor" molecules on
bone cells, osteoclast (bone destroying) activity goes down and
osteoblast (bone creating) activity goes up.
Could hormones like this one be given to space travelers as a
supplement to prevent bone degradation? Scientists don't yet know.
Genetic make-up might also play a role, as suggested by the
variation of bone loss observed between individual astronauts and
cosmonauts.
"The 1 to 2 percent per month loss is an estimate of bone
loss - an average value," Shapiro says. "Certain
individuals on six month flights have lost as much as 20 percent of
bone mass throughout their lower extremities." Others were less
affected, losing bone only in
some
areas of the lower extremities.
Above:
NASA research has already led to the development of a fast and
inexpensive tool to measure the extent of osteoporosis by analyzing
the stiffness of bones. It takes measurements without exposing the
patient to radiation. [
more information
]
"Bone loss of this magnitude leads to a significant increase in
fracture risk, which may be as much as fivefold that expected with
normal bone mass on Earth," he added. "A limb fracture involving,
say, one of a six-person space crew could seriously compromise a
mission's objectives."
Indeed, adds Shapiro, "the problem of bone loss must be overcome
before people are placed in the position of performing physically
challenging tasks after a long space-voyage in zero-G."
|
Credits and Contacts
|
| Author |
Doug Hullander, Patrick L. Barry |
| Responsible NASA official |
Ron Koczor |
| Production Editor |
Dr. Tony Phillips |
| Curator |
Bryan Walls |
| Media Relations |
Steve Roy |
The Science Directorate at NASA's Marshall Space Flight Center
sponsors the Science@NASA Web sites. The mission of Science@NASA is
to help the public understand how exciting NASA research is and to
help NASA scientists fulfill their outreach responsibilities.
The second week involves a hands-on realistic experiment that
has taken place on the International Space Station. Students grow
protein crystals in the Earth environment and compare their results
with the results of protein crystal growth on the International
Space Station. The hope is that studying protein crystal growth
will help determine the structure of these proteins, to understand
how a protein's structure affects its function and ultimately
design drugs that intercede in protein activities. The drug,
penicillin, is an example of a drug that works by blocking a
protein's function. Determining protein structure is the key
to the design and development of effective drugs.
Learning Objectives
The objectives of the lesson are twofold. First, students
must experience learning concepts that will affect their
lives. The space program is involved in educational
opportunities involving students in real-life applications of the
goals of the space program. The second objective is to give
opportunities to students that enhance the conceptual framework of
understanding health issues in space. The lesson includes
technological resources and a hands-on inquiry lesson that is
performed on the International Space Station. The objective
of the inquiry lesson is to perform a screening experiment to
determine the optimum salinity concentration for producing quality
lysozyme crystals in sodium acetate buffer solution with a pH of
4.3.
Materials Used
The first week involves the use of Internet resources and a
projection system. During the second week, students use
materials from a kit that is put together by NASA for teachers
involved in a program called, "Liftoff." The price of the kit
is funded in part by NASA and in part by the teacher. The kit
includes beakers, flasks, a rack, pipets, culture tubes, parafilm,
scissors, a gelatin capsule of lysozyme and a tube of sodium
chloride.
Methods of Implementation
Students observe the NASA Web site on the projection system in
the classroom, take notes and discuss comparisons of microgravity
effects on humans and Earth effects of gravity on humans.
Students write compare/contrast papers and create graphs and charts
to compare data and information.
The experiment involves knowledge of vocabulary common to the
experiment and knowledge of the use of scientific equipment in a
safe environment. The students must understand the importance
of the study and how if affects them. Then they will take
ownership of the medical experiment and understand the objectives
set up in the procedure. Students study the theory of the
experiment so that they understand the importance of lysozyme to
the chick embryo and its protection against attack from bacterial
invasion. They must also understand pH and the difference
between bases and acids.
Students are members of a lab team and work together in a
cooperative group setting. Members of each team are selected
to perform steps in the experiment process.
Evaluation Tool
Evaluation involves more than one measurement tool. First,
students are evaluated on cooperative group activity. Each
student in the group must be treated equally to ensure the success
of the experiment. If all students participate equally and
cooperatively, this goal has been met. Students evaluate
themselves on active participation and equality among the team
members. They actually determine if the group worked
successfully.
Another measurement tool involves the correct identification of
variables by the group. If groups have varying results, the
students must be able to determine the variables that affected the
different outcomes. A rubric can be filled out for grade
determination.
Teams are evaluated on their knowledge of the objectives of the
experiment, knowledge of the procedure, use of safety precautions,
and ability to relate their results verbally and in written
form - and be able to identify variables affecting
results. Again, a rubric is used to grade results
and knowledge of the experiment processes. The most important
evaluation includes a demonstration of understanding and relating
the results of the experiment to health issues. The
demonstration can include a presentation, written log, or
prediction for future experiments. Students are given a
chance to expand on their knowledge by predicting the effects of
the results of their experiment. I like to give students
evaluation options to meet their learning styles.
New drugs may be developed based on the protein crystal growth
experiment and students need to be able to relate the importance of
how these drugs may affect their future. Hopefully, students
will develop an appreciation for scientific experimentation that
produces world-changing results.
I know that sixth grade students do not fully comprehend such a
complicated process, but my goal is for them to use scientific
procedures and processes to investigate a problem, develop a
hypothesis, perform an experiment and correlate their results with
actual scientific results performed by NASA scientists. I
want students to be able to synthesize information and develop
reasonable conclusions. Perhaps a spark will ignite that will
produce a scientist who will become involved in scientific medical
research in the future.
Description of What Makes the Lesson Effective
Sixth grade students are eager to learn and like to accept a
challenge relating to science. Their interest in the space
program is evident to me as we discuss daily NASA site information
and students bring more news to me or develop an experiment at home
to expand on their learning. I like to challenge my students
and I have high goals for them.
This lesson is effective because of the technology aspect and
the fact that all information is current and applicable to their
lives. Students are especially proud that they are given the
opportunity to perform an experiment that astronauts performed in
space. The fact that the knowledge they obtain goes beyond
the curriculum resources available in sixth grade classrooms gives
my students a sense of pride in their abilities and
performance. The idea that the experiment results may have an
impact on drug development in the future makes them aware of how
important science and medicine are. Who knows? Someday
one of these students may develop a drug that will ease pain and
suffering for all of us.
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