Download WHY DO WE EAT? - San Juan Unified School District

WHY DO WE EAT?
The physiology of the Digestive System
Friendly Talk

Shelley and Debbie are talking about ways to lose weight
before the Homecoming dance.

Shelley says to Debbie: “I am only going to each Hot
Tamales from now to Homecoming because they only
have sugar and no fat.”
Debbie counters with: “I think you can still gain fat by
eating sugar.”


Who do you agree with and why? (State the claim that
you agree with and the reasoning)
Day 1: Observations of Food and Food
Labels

Complete the following chart for each of the following
food items shown.
Observations and Descriptions
Food Item 1:
Food Item 2:
Food Item 3:
Food Item 4:
Similarities and
Differences
Food Item 1
Food Item 2
Food Item 3
Food Item 4
Share Out

What are the similarities between these foods?
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What are the differences between these foods?
Nutrition Label Patterns

Open your bag of food labels and sort
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You pick the categories but you want to divide the labels into 3
piles
Label your handout with the three categories you chose
Make a list of the defining characteristics you chose to
decide which pile each label went into
Class shareout
Nutrient Labels

1.
2.
3.
Exit Question: What did we learn about labels today?
Day 2: Observations about Biomolecules

Complete the following chart for each of the following
food items shown.
Molecule 1 – A Fat
Glycerol
3 Fatty Acid molecules
Molecule 2 – Fatty Acids
Molecule 3 – A Carbohydrate
Molecule 4 - Protein
Share Out

All four molecules are similar because:

All four molecules are different because:
Model Sheet
Biomolecules are unified because they all have the same
ingredients: Carbon (C), Hydrogen (H), and Oxygen (O)
Biomolecules are all different because they have different proportions of
C, H, and O (sometimes extra elements like Nitrogen, N) and how they
are arranged
Something else for Day 2

Crash Course Biology: Biological Molecules


https://www.youtube.com/watch?v=H8WJ2KENlK0
Macromolecules Song

https://www.youtube.com/watch?v=cYLUZuzifuw
Day 3 & 4 – Constructing Organic Molecules



Each table will be given a set of paper “atoms”.
The following will show you how to use them correctly.
Then complete the Constructing Organic Molecules
handout.
Using Atom Models
Day 3 & 4
Carbon Atoms

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Find your carbon atom
that looks like this 
Notice it has four lines.
That is because Carbon
can make four bonds.
Building a molecule


Now find one of your
hydrogens and attach it
to your carbon.
Does it look like this?


Now continue to add
three more hydrogens
to your carbon atom.
You have just made a
molecule of methane!
Check for Errors


Make sure each bond
(line) on the carbon is
attached to a bond line
on the hydrogens.
Your molecule is
incorrect if any bonds
(lines) are not attached
to another bond (line).
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The bond (lines) are to represent
electrons being shared between
the atoms.
Each line on the carbon represents
one electron from carbon.
Each line on the hydrogens
represents one electron.
Now carbon is stable since it
thinks it has 8 electrons in its
outermost electron orbital.
Variations

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You can add other
atoms onto this to
create other compounds
Here is butane 
Notice how the carbons
form a chain?
Variations (cont’d)
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
Or we can add an
oxygen in between a
carbon and hydrogen.
Here is methanol 
Notice the oxygen has
to go between the
hydrogen and carbon so
that it has all of its lines
attached to another line
Variations (cont’d)

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We can also make the
carbon have double
bonds (these look like =
sign)
Here is an example 
Notice we had to use a
different carbon and
oxygen paper model.
Now complete your handout….
Day 5 - Intro



Examine the structural formulas of each of the following
sugars…..
What similarities and differences can you note about each
one?
Discuss with your partners and Record in a T- chart
Molecule
Sucrose
Glucose
Maltose
Galactose
Lactose
Fructose
Similarities
Differences
Day 5 - Intro
Day 5 - Intro

Now we are going to taste each sugar to see if the
differences you noted affects the physical properties of
each sugar.
Day 5 – Molecules Webquest
Day 6

Complete the following handout/questions using the next
few slides (slide #35-52):
Plant Fat - Source


Examples: Olive Oil, Peanut Oil, Canola Oil
Liquid at room temperature
Plant Fat – polymer formula

The polymer is composed of one glycerol molecule
connected to 3 unsaturated fatty acids
Plant Fat – monomer formula



Broken down in stomach and intestine using bile secreted
from the liver and lipase from the pancreas
Separates into a glycerol which is turned into glucose
3 fatty acids (still a very large molecule)
Plant Fat – use in body

The fatty acids are used
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to provide padding and insulation to organs in the body
to create the myelin sheath around each of your neurons
(helps conduct the nerve impulses faster)
to create our cell membranes
to aid in the absorption of vitamin A, D, E and K
Excess fat in the diet leads to fatty acid conversion into
cholesterol. This molecule can accumulate and build up in
the arteries of the body

This can lead to blockages of the arteries (heart disease) and
heart attacks
Animal Fat - Source


Examples: lard, bacon grease, butter
Solid at room temperature
Animal Fat – Polymer

Still a glycerol attached to 3 fatty acids….not there is no
double bond between the carbons in the fatty acids
Animal Fat - Monomer



Also broken down in stomach and intestine using bile
secreted from the liver and lipase from the pancreas
Separates into a glycerol which is turned into glucose
3 fatty acids (still a very large molecule)
Animal Fat – Use in Body

The fatty acids are used





to provide padding and insulation to organs in the body
to create the myelin sheath around each of your neurons
(helps conduct the nerve impulses faster)
to create our cell membranes
to aid in the absorption of vitamin A, D, E and K
Excess fat in the diet leads to fatty acid conversion into
cholesterol. This molecule can accumulate and build up in
the arteries of the body

This can lead to blockages of the arteries (heart disease) and
heart attacks
Protein - Source

Found in plants and animals
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Meat
Beans (tofu, kidney beans)
Milk and cheeses
Protein - Polymer

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Made up of many amino acids hooked together in a long
chain.
This chain then folds on itself and joins with other chains
to create large macromolecules.
Protein - Monomer
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Proteins are broken down in the stomach by enzymes
known as “peptases”. They become individual amino
acids.
The amino acids travel through the blood stream to cells
and are used to create new proteins in the body
Protein - Monomer

All amino acids have the same “foundation” and differ in
their “branches”
Protein – Uses in Body

Protein makes up your
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Hair
Nails
Pigments (hair, eye, and skin color)
All your muscles and organs
Enzymes (used to regulate homeostasis and
help the stomach digest food)
Without proteins, you would be
reduced to this:
Carbohydrate - Source

starchs.
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Sugars
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Pasta
Rice
Glucose
Fructose
Lactose
Cellulose
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Paper
Tough part of plants
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Chitin
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Shell on bugs and
crustaceans
Carbohydrate - Polymer
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Composed of repeating glucose molecules
The way the glucoses are bonding together affects the
physical properties of the resulting polymer (cellulose vs
chitin)
Carbohydrate - Monomer
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The polymer is digested in the stomach with the aid of
enzymes such as amylase and lactase.
The individual glucoses then travel through the blood
stream to individual cells throughout the body
Carbohydrate – Uses in Body

Glucose is used to fuel the making of ATP in cells.

Cellular respiration
Carbohydrates – Uses in Body

If too much glucose is consumed and not needed for ATP
(energy), the excess glucose turns into glycogen..which
the liver then converts into fat and stored for future use
Model Sheet
Biomolecules are unified because they all have the same
ingredients: Carbon (C), Hydrogen (H), and Oxygen (O)
Biomolecules are all different because they have different proportions of
C, H, and O (sometimes extra elements like Nitrogen, N) and how they
are arranged
Biomolecules can be broken down and put back together
When biomolecules are broken down/created, energy can
be released and/or stored
Day 7 – Fats taste test

Does the type of fat (saturated or unsaturated) affect
how a food tastes?
Day 7 – Digestion notes


Take notes on the following.
Label and color the diagram on the back of the handout
Digestive System
Doesn’t just break down food so you can eat!
Digestive System

The digestive system is made up of the digestive tract—a
series of hollow organs joined in a long, twisting tube
from the mouth to the anus—and other organs that help
the body break down and absorb food
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Organs that make up the digestive tract are the mouth,
esophagus, stomach, small intestine, large intestine—also
called the colon—rectum, and anus.
Inside these hollow organs is a lining called the mucosa. In
the mouth, stomach, and small intestine, the mucosa
contains tiny glands that produce juices to begin the
process of digestion.
The digestive tract also contains a layer of smooth muscle
that helps break down food and move it along the tract.
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Two “solid” digestive organs, the liver and the pancreas,
produce digestive juices that reach the intestine through
small tubes called ducts.
The gallbladder stores the liver’s digestive juices until they
are needed in the intestine.
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The small intestine allows the broken down food (in the
form of glucose and other molecules of life) to be
absorbed by the bloodstream and transported to all parts
of the body.
The large intestine allows water to be reabsorbed by the
body. All leftover wastes are left over to be excreted out
of the body.
Parts of the nervous and circulatory systems also play
major roles in the digestive system.
Digestive System

Liver – Controls blood sugar level with the following
feedback loop:
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If too low, converts stored glycogen (glucose) into sugar
If too high, removes sugar from the blood and stores as
glycogen
Diseases/afflictions of the digestive
system
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Diabetes
Ulcers
Acid reflux/heartburn
Stomach or liver cancer
Cavities/gum disease/root canal
Tonsillitis
Gall stones/gall bladder removal
Flatulence
Constipation
Diarrhea
Day 8 - Opener

Place your piece of cracker in your mouth.
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Don’t chew
Just let the cracker sit there
Write down your observations about the cracker
Where does digestion begin? Defend your answer with
evidence from your opener.
Day 8 – Link to Feedback Loops


Read the Insulin Feedback Loops article
Fill in the reading sheet and feedback loop handout based
on the article.
Day 9 – Friendly Talk revisited

Shelley and Debbie are talking about ways to lose weight
before the Homecoming dance.

Shelley says to Debbie: “I am only going to each Hot
Tamales from now to Homecoming because they only
have sugar and do not have fat.”
Debbie counters with: “I think you can still gain fat by
eating sugar.”


Who do you agree with and why? (State the claim that
you agree with and use specific examples from this unit)