Download lpch anatomy lab: teacher`s guide

Anatomy Lab: The Gastro & Urinary System in 3D
Teacher Version
This part of the Anatomy Lab is designed to give students a sense of the 3-dimensional
positioning of organs in the Gastro-intestinal and urinary tract, as analogously viewed in
the MRI image the students explored.
Key Concepts:
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The organs are positioned relative to each other in the gastro-intestinal and
urinary tract through dense and efficient packing of organs within our abdominal
cavity.
The many differnt organs in our body vary in size, scaling with water, diameter,
and length.
Materials:
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2 packs of water- balloons (a pack of small and large ones)
2 Graduated 250 ml water balloon filling bottles
Plastic tub to model the Abdominal Cavity
Models for the small intestine, large intestine and oesophagus
Felt images of the lungs, heart, stomach, liver, intestines (both small and large)
and the kidneys
Procedure: The body model will be laid down in two stages. Divide students into two
groups of half: group A can work on the MRI parts of the lab, while group B can work on
the 3D model.
1st Stage: This stage comprises of sticking the felt images onto the felt background that
represent the body at the bottom of the tub. The students can do so by following the
organization of the organs on a projected image of the GI and urinary tract.
Order of the Organs on the felt background (top down):
1. First come the lungs. (There are velcro pieces attached to the back of the felt organs
and on the corresponding parts on the felt background as well.)
2. Right in between the two lungs will be the heart.
3. Below the lungs will be the stomach on the right, and then the liver over the stomach
on the left.
4. Right below the liver and the stomach will the intestinal system.
5. On top of the intestinal system will go the kidneys.
2nd Stage: This stage will require student to make up the water/ air balloon models of
the different organs. The balloons will be filled using graduated fillers measuring out the
appropriate amount of water. For the lungs dimensionality is maintained by blowing out
the balloon to the appropriate diameter.
Instructions on how to set up the organ models and arrange them in the tub:
1. At least 2 students should be assigned to take two of the bigger balloons and blow
them up till the diameter corresponds to the 11cm long stick we have provided.
2. They should then tie the balloons and set them aside to model lungs. Students should
be made aware that they lungs are not spherical but more flat-like. The 11cm value
for its diameter was arrived at by modeling the lungs as spheres with the average
maximum volume of 6000cm3 and using the formula for the volume of a sphere:
4/3*pi*(radius)3.
3. At least two students should take one of the bigger balloons and fill it up with 750ml
of water (equivalent to three fillers full of water) to model the stomach. (All water
balloon filling should be carried out on top of the tub) The students should begin with
one of them blowing up the balloon, and then holding the mouth over the nozzle of
the filled bottle, while the other student squeezed water into the balloon.
4. Between each squeeze, the student holding the balloon should cinch the balloon tight
as the other student refills, or squeezes the bottle again.
5. Once they have filled the balloon up with three equivalents of the bottle, the balloon
should be tied shut and put aside. It is important for the students to realize that the
real stomach actually has the potential to hold twice as much food as the volume of
water the students filled the balloon with. For the convenience of the project, the
volume of the stomach was scaled by one-half.
6. At least two students should take two of the smaller balloons and fill each of the
balloons up with 75ml of water to model kidneys, using the same techniques
described above. The balloons should then be tied shut and put aside. Students should
be aware that the kidney volume was also scaled by one-half.
7. At least two students should take one of the small balloons and fill it up with 175ml
of water to model as a heart. They should do so using the same techniques used for
filling the stomach and kidney models. Students should be aware that the kidney
volume was also scaled by one-half.
Following is a table summarizing the scaling and the actual dimensions of the organs the
students modeled:
Analog Dimensions
(water balloon
models altered by a
factor of 0.5)*
Organ
Construction
Material
Real-World
Dimensions
Esophagus
Rope (pre-sized)
2cm < diameter
2cm < diameter
<5cm; 25cm < length <5cm; 25cm < length
< 30cm
< 30cm
Heart
Small balloon filled
with water
300g < mass < 350g 175 ml
Lungs (x2)
Large balloons filled
6000 ml
with air
Balloon diameter of
approximately 11cm
Stomach
Large balloon filled
with water
1500g when full
750 ml
Large Intestine
Rope (pre-sized)
6cm in diameter;
1500cm in length
6cm in diameter;
1500cm in length
Small Intestine
Rope (pre-sized)
2.5cm in diameter;
6m in length
2.5cm in diameter;
6m in length
Liver
Felt (pre-cut)
1400g < mass
<1600g
approximated as a
felt diagram
Small balloons filled
125g < mass <175g 75 ml
with water
*We have altered the balloon dimensions by a factor of 0.5 because these dimensions
were optimal for the water balloons.
Kidneys (x2)
Instructions on how to fit the organ models inside the abdominal cavity modelled by the
tub:
1. Students should lay down the map of the GI and urinary tract made on the felt
background with the felt organ images. Students should begin by first laying down
their two air balloon lungs on top of the lung image they had velcroed earlier.
2. They should then place the water balloon heart in between the two lungs.
3. Next step would be to place the rope oesophagus model on top of the lungs, pointing
towards the stomach.
4. Students should then take the water balloon stomach and place it below the lungs on
to the right (of the viewer) of the lungs.
5. Students should then place the felt liver model below the lungs, to the left of the
lungs, overlaying the stomach. [Advanced]: Figure out how stomach and liver should
be placed.
6. Students should then place the two water balloon kidney model on either side of the
tub right below the stomach and liver. [Advanced]: Figure out where kidneys should
be.
7. The next step would be to pack the 6m long rope model of the small intestine within
the space left between the stomach and the lower edge of the tub (including over the
kidneys).
8. They will have to figure out how they should fold the intestine to fit it all within that
cramped space.
9. Finally, students should lay down the red rope large intestine model bordering the
left, top and right edge of the small intestine.
Students should then proceed to answer the following questions in their worksheets:
How much do you know about the Gastro-Intestinal and Urinary tracts?
In the table above we have approximated the organ masses as volumes of water. Why can
we make this approximation? (The density of water = 1g/cm^3 and 1cm^3 = 1ml)
The majority of our body is composed of water, so it is reasonable to use the density of
water in our approximations.
[Advanced]:We approximate the shape of the lung as a sphere, and are given the
following: (4500/π)^(1/3) = 11.27, V= (4/3)*π*r^3. Perform the appropriate calculation
to find the real-world diameter approximation. [Basic]: Only make an estimate, no
calculations.
22.54cm is the real world diameter.
Your esophagus is quite small in diameter. How do you think that it is possible for food to
fit in the esophagus?
You chew food to break it into smaller pieces, and your esophagus has smooth muscles
that allows it to stretch (is elastic).
What did you have to do with your 6m long small intestine in order to pack it within the
small space inside the body cavity? What do you think is the advantage of packing the
small intestine this way inside the body?
They should have repeatedly folded the long model to fit it within the small space. The
folds help increase surface area for digestion and absorption of food to occur efficiently.
There is a structure that separates the pulmonary space from the abdominal space in
your body that was not modeled in this activity. What is this muscular structure called?
The diaphragm