Grossology is the study of really gross

things!

Duh!!!

What kinds of gross things do humans

do?

How do we break down the foods that we eat?

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Try to “digest” or break down a cracker as much as you can without putting it in

your body.

Any luck?• A saltine cracker is made up mostly starch

molecules or carbohydrates.• These carbohydrates can be broken down

into smaller units called sugars that our bodies are able to absorb and use for energy.

• How can we tell this is happening?– Iodine (normally dark yellow brown) makes a complex

with starch called starch-iodide (dark blue black). It doesn’t make that same complex with simple sugars, so it doesn’t change color.

How do we break down the foods that we eat?

There are two ways:

Digestion• Mechanical

–Chewing–Peristalsis

• Chemical–Enzymes are

used to break chemical bonds

Not shown actual size.

What is an enzyme?

PepsinAmylase

Where are these enzymes found?

An enzyme is a protein that catalyzes (accelerates) a chemical reaction.

Try to identify the organs used in digestion and place them in the

approximate location you think they are found in the human body.

THE DIGESTIVE TRACT

MouthStomach

Pancreas

Liver

Small Intestine

Large Intestine

Different foods begin to digest in different places.We are going to find out where some different foods start to digest today.

What is the pH of the digestive tract?

pH 1-3pH 6-7

Digestion starts in the mouth!

Acid Base

7

Neutral

1 14

pH 6-7

Are enyzmes specific?

• Are enzymes specialized for different organs?

• Are enzymes specialized for what kind of reaction they perform (or food type they break down)?

As the Stomach Churns…Activity

Think of a way to see whether the starch in our crackers was digested into

sugars.

You have 5 minutes to look at your experiment from yesterday

and compile results.

1. Did water mechanically digest the foods?

A ) Yes

B ) No

C ) Sometimes

2. Did water chemically digest the foods?

A ) Yes

B ) No

C ) Sometimes

3. Did hydrochloric acid (pH 1) digest foods?

A ) Yes

B ) No

4. Did pepsin in water digest the foods?

A ) Yes

B ) No

5. Did pepsin in acid (HCl) chemically digest the foods?

A ) Yes

B ) No

6. Did saliva chemically digest the foods?

A ) Yes

B ) No

7. Are enzymes specific for their environments?

A ) Yes

B ) No

C ) Sometimes

8. Are enzymes specific for a particular type of food?

A ) Yes

B ) No

C ) Sometimes

pH 1-3pH 6-7

Acid Base

7

Neutral

1 14

pH 6-8

Mouth pH 6-7

Stomach pH 1-3

Small Intestine pH 6-8

Amylase starch

Pepsin proteins

Trypsin Pancreasproteins

Lysozyme kills bacteria

Chymotrypsin Pancreas

proteins

Amylase Pancreasstarch

Nucleases PancreasDNA

Lactasemilk sugar lactose

Lipase fats

9. Do organs work together to digest food?

A ) Yes

B ) No

C ) Sometimes

D ) Only when they want to

Not shown actual size.

PepsinAmylase

What is in saliva?

• 99.5% water• Antibacterial agents• Salts

• Gases• Antacids• Mucus• Enzymes- molecules

that break down foodIs it acidic?

Am I drooling?

Where is the dirtiest (most

unsanitary) place in your body?

Who might need to use an antacid?

• Sometimes, when bodies are under more stress than normal, an bacterial infection in the stomach can breakdown the protective mucus lining of the stomach. Ouch!

• Heartburn or acid reflux is caused by an overproduction of stomach acid. Ouch!

What is feces made of?

Undigested foodWaterSaltsSkin cellsBacteriaBacterial wastesPigment from bile

Don’t be embarrassed by your bodily functions…

It’s what w

e do!!!

Flarp if you’re happy!