Digestive System

Digestion Lab

We are going to use household items to model the digestive system.

 

Digestion Lab

• Substances in food that provide raw materials and energy the body needs to live

• Our digestive system turns the chemical energy in these nutrients into energy we can use

Digestion Lab

Procedure

1. Label four plastic sealable bags with

the following:protein (lunchmeat)

vegetable (lettuce) 

starch (crushed cracker)

dairy (cheese)

Digestion Lab

Procedure

2. Use a cotton swab to lightly coat the

inside of the bag with vaseline.

3. Measure out 60 mL of vinegar in a

graduated cylinder and pour into the bag

Digestion Lab

Procedure4. Add 1 drop of food coloring to one side of the bag so the drop slides down the vaseline.

5. Using the balance, mass 10 g of your groups food item.

6. Add the 10 g of food to the correct bag and seal.

Digestion Lab

Procedure7. Shake the sealed bag from side to side 50 times.

8. Compare each bag and make an inference about how fast each is “digesting”

9. At the end of the period, make sure the bags go in the trash.

Digestion Lab

Questions. Write these answers in your spiral:

1. Which food type was digested the

fastest? ______________________

2. Which food type needed more digesting time? _________________

Digestion Lab

Questions. Write these answers in your spiral:

3. What did the plastic bag represent in this model?______________________

4. What did the vaseline represent in this model?__________________________

Digestion Lab

Questions. Write these answers in your spiral:

5. What did the vinegar represent in this model?______________________

6. What is at least one limitation of this model? _________________________

Stomach and Intestine Slides

Now using the microscopes. Look at the slides labeled stomach and small intestine.

In your spiral, diagram what you see.

Organs of the Digestive System

• Mouth Rectum• Esophagus Anus• Stomach Pancreas• Small intestine Gall

Bladder• Large intestine Liver

Functions of the Digestive System

• Digests food into molecules the body can use (physical or chemical change)

• Absorbs nutrient molecules and carries them around the body (physical change)

• Eliminates waste material from unused nutrients

Digestion

• body breaks down food into small nutrient molecules– mechanical– chemical

Mechanical Digestion

• Food is physically broken down into smaller pieces

• Begins in the mouth– Teeth chewing/tearing– Movement of

smooth muscles

Chemical Digestion

• Chemicals produced by the body break foods into their smaller nutrients– mouth– stomach

Absorption

• Process by which nutrient molecules pass through the wall of your digestive system into your blood– The lining of the small intestine is covered

in villi that aid in absorption

Elimination

• Materials that are not absorbed leave the body as waste

• The waste material left over after food is digested must leave the body to prevent illness

Which is not a function of the digestive system?

a) Breaking down food into molecules the body can use

b) Absorbing food molecules into the blood to deliver to the body

c) Changing waste into molecules the body can use

d) Eliminating undigested waste from the body

Mouth

• Digestion begins in the mouth– Mechanical – teeth– Chemical - saliva

Esophagus• Muscular tube that connects your

mouth to your stomach– moves food down into your stomach

using involuntary muscle

contractions (peristalsis)– Lined with mucus that

allows food to slide down

The Stomach

• J-shaped muscular pouch• Most mechanical digestion takes place

in the stomach• Chemical digestions also takes place

– Stomach secretes digestive juice (enzymes) that break down food

• Average adult stomach holds 2 liters• Mucus keeps the acids from burning a

hole in your stomach

Stomach

Modeling• Place the marble in the end of the tube

and squeeze it down into the balloon.

Modeling• What do you think this could be a model

of?

– What is the tube?– What is the balloon?– What is the marble?– What is the soap?

esophagusstomachfood

saliva and mucus

Which is not an example of mechanical digestion?

a) Teeth chewing food

b) Tongue breaking up food

c) Smooth muscles in stomach churning food

d) Hydrochloric acid breaking down proteins

Small Intestine• Where most of the chemical digestion

takes place • Where most of the absorption takes

place• Covered in villi which

enlarge the surface area

a) Most digestion happens here.b) Intestinal juice (full of enzymes)

breaks down food.c) Digestive Helpers

• Liver, Gall bladder, Pancreasd) Digested food is absorbed

through the villi into a network of blood vessels that carry the nutrients to all parts of the body.

e) By the time food leaves the small intestine, it is empty of all nutrients except water.

Small Intestine

Small Intestine

The villi increase the surface area that can absorb nutrients

Where does most digestion take place?

a) Mouth

b) Stomach

c) Small intestine

d) Liver

Liver• Breaks down medicines and other

chemicals• Produces bile that breaks up fat

particles• The gall bladder

stores bile

Pancreas• Produces enzymes that flow into the

small intestine• Secretes insulin• Causes diabetes when it does not make

insulin

Large Intestine

• Last section of the digestive tract• Food spends 18-24 hours here• Where water is absorbed• Vitamins B & K are made by bacteria in

the large intestine

Rectum and Anus

• Rectum – end of the large intestine, forms the solid waste– elimination

• Anus – muscular opening at the end of the rectum– elimination

Which cell parts are like the digestive system?

Which one makes energy?

Which one helps get rid of waste?

mitochondria

lysosomes

Which one allows materials to pass in and out?

cell membrane

The Digestive System Interacts with:

• muscular system (smooth muscle) to move and digest food• respiratory system to provide oxygen• circulatory system to move nutrients