Topic: Digestive SystemAim: Describe the parts and functions of the

digestive system.

Do Now: Take out your digestive system reading notes

HW: Food Label Lab due tomorrow!Science Fair Materials, Procedures and Parts of a

Controlled Experiment due Monday!

Did you know....• Americans eat about 700 million

pounds of peanut butter. • Americans eat over 2 billion pounds of

chocolate a year. • In your lifetime, your digestive system

may handle about 50 tons of food!! • What you ate for breakfast that was

not digested will come out in about 48 hours-normally.

• From intake to outlet, the digestive tract is about thirty feet long.

1. Describe the function of the digestive system.

•Breakdown of food into small molecules so that they can be absorbed into the blood and enter your cells

2. Identify the two parts of the digestive system.

•Digestive tract•Accessory organs

3. Identify the 6 accessory organs.

•Tongue•Teeth•Salivary glands•Liver•Gall bladder•Pancreas

Does food pass through these organs???

Organs where food DOES NOT pass through

4. List the major organs of the digestive tract.

•Mouth•Esophagus•Stomach•Small intestine•Large intestine•Rectum•Anus

Does food pass through these organs???

Organs where food passes through and is digested.

5. Identify the structure where digestion begins.

• Mouth

(Oral cavity)TEETH

Incisors

Canine

Premolars

Molars

“Wisdom”tooth

Tongue

Salivaryglands

Opening of asalivary gland duct

5. Identify the type of digestion that occurs in the mouth..

• Mechanical and Chemical Digestion

TEETH

Incisors

Canine

Premolars

Molars

“Wisdom”tooth

Tongue

Salivaryglands

Opening of asalivary gland duct

7. Identify the accessory organ that aids with chemical digestion in the mouth.

• Salivary glands

These glands may become swollen and painful if you develop certain conditions, such as mumps

8. What does saliva contain?

• Water

• Mucus

• Enzyme that aids in the breakdown of starch

Did you know....• We make 1 to 3 pints of saliva a day• Your teeth started growing 3 months before

you were even born. • The hardest substance in your body is the

enamel on your teeth. • As you are sitting there listening, more

than 100 million germs are swimming, feeding, reproducing, and making waste in the area behind your lips. In your mouth there are more living things than there are people in Australia and Canada combined.

9. Describe the role of teeth in your mouth.

• Chews food

• Mechanical digestion

10. Identify the structure food passes after the mouth.

• Pharynx

Uvula

Through history, scientists have had many theories about the uvula. Among them:

•That it once helped guide the flow of food and water, and, in humans, was a mere remnant from previous mammals who had to lean down to eat and drink.

•That it induces the gag reflex. And therefore isn’t the best place to get a piercing.

•That it contributed to “chronic cough.” A problem that 19th-century doctors treated with a “simple” “clipping” procedure.

•That it contributes disorders such as sudden infant death syndrome (SIDS) and sleep apnea.

Uvula

Several such studies have concluded that the uvula is really good at excreting saliva. A lot of saliva, in a really short amount of time.

Because the uvula is basically unique to humans, scientists basically agree that it primarily serves as an accessory to speech. You know what it’s like to have your throat go dry before talking to a large group? The uvula is there to provide the proper lubrication for complicated human speech.

11. Describe the function of the epiglottis.

• It automatically covers the opening to the windpipe to prevent food from entering.

• Prevents choking• http://www.youtube.com/watch?v=rJS-Kh5wCQU

12. Describe how food is pushed down the esophagus and throughout your whole digestive tract.

• Peristalsis: smooth muscles push food downwards with a squeezing action

Did you know....•An adult esophagus ranges from 10 to 14 inches in length, and 1 inch in diameter

Opening to stomach from the esophagus

13. How is food mechanically digested in the stomach?

• Peristalsis

• Contraction of stomach muscle

• http://www.youtube.com/watch?v=o18UycWRsaA

14. How is food chemically digested in the stomach?

• Enzymes

• Hydrochloric acid

15. Identify the substance that makes your stomach acidic.

• Hydrochloric acid

16. Identify the enzyme made by your stomach that digests proteins.

• Pepsin

17. Describe the function of mucus in the stomach.

• Makes stomach slippery

• Protects stomach lining from HCl

http://www.youtube.com/watch?v=SWMWsOXlBwE

Did you know....•An adult’s stomach can hold

approximately 1.5 liters of material.

•Food sloshing in the stomach can last 3-4 hours.

•The stomach's wall is lined with three layers of powerful muscles.

18. Identify the end result of digestion in the stomach.

• Chyme (thin, watery material)

19. Where does most digestion in the small intestine take place?

• Duodenum – first part of the SI

Length = 4-7 meters

Why is it called the SMALL intestine?

20. Identify the 2 accessory organs that help with chemical digestion in the small intestine.

• Liver

• Pancreas

21. Describe the substances that help chemically digest food in the SI.

• Bile: released from liver–Breaks down large fat

particles

• Enzymes from pancreas: chemically digest carbohydrates, proteins, fats

22. Identify the structure that stores bile.

• Gall bladder

Liver

Gall bladder

Small Intestine

Pancreas

Stomach

23. What happens in the small intestine once digestion is completed?

• Absorption of NUTRIENTS into the blood

24. Identify the fingerlike projections on the walls of the small intestine.

• Villi

25. Identify what is found in each villus.

• Blood vessels

26. Describe the importance of villi in the small intestine.

• They increase the surface area so nutrients have more places to be absorbed.

If you stretched out an adult's small intestine, it would be about 22 feet long.

http://www.youtube.com/watch?v=JCA9HQ795i8

27. Describe the function of the large intestine.

• Absorbs water

28. Identify the name of the waste in the large intestine after excess water is absorbed.

• Feces

29. Identify the last part of the large intestine.

• Rectum

30. Identify the structure that releases wastes from the body.

• Anus• http://www.youtube.com/watch?v=cdijh32NiLs

31. Describe how the bacteria in the large intestine are beneficial to humans.

• Bacteria feed on undigested material (cellulose)

• Produce vitamins

If you squeezed out all of the bacteria that lives in your

intestines, you could almost fill up a coffee mug. Anyone want a

sip?

•Did you know....•Within the colon, a typical person harbors more than 400 distinct species of bacteria.

The function of the appendix is unknown. One theory is that the appendix acts as a storehouse for good bacteria, “rebooting” the digestive system after diarrheal illnesses. Other experts believe the appendix is just a useless remnant from our evolutionary past. Surgical removal of the appendix causes no observable health problems.

Gallstones occur when Bile forms solid particles (stones) in the gallbladder Stones form when the amount of cholesterol or bilirubin in the bile is high.

Risk factors for the formation of cholesterol gallstones include the following: female gender being overweight, losing a lot of weight quickly on a "crash" or starvation diettaking certain medications such as birth control pills or cholesterol lowering drugs

As the stones mix with liquid bilethey can block the outflow of bile from the gallbladdercan block the outflow of digestive enzymes from the pancreas. If blockage persists, these organs can become inflamed. Inflammation of the gallbladder is called cholecystitis. Inflammation of the pancreas is called pancreatitis.

http://www.youtube.com/watch?v=_QYwscALNng

Let’s summarize: Identify the digestive organ described.

1. Where the digestion of protein begins.2. Where mechanical digestion begins.3. Site of water absorption.4. All chemical digestion is completed here.5. Where the breakdown of starch begins.6. Where bile is stored.7. Releases many enzymes into the SI.8. Where feces is formed.9. Pushes food into the stomach.10. Where the absorption of nutrients occurs.11. Lining is protected by a mucus layer.12. Lined with villi.

Salivary glands

Esophagus

Stomach

Pancreas

Large intestine

Liver

Gall baldder

Small intestine

Appendix

http://www.youtube.com/watch?v=bo2Ape8JHqA

http://www.youtube.com/watch?v=ttQtDfv6dCo

Oral cavity

Stomach

Pancreas

Small intestine

Rectum

Gall bladder

Large intestinne

Which substances in the small intestine of humans serve to increase the surface area for absorption?

(a.) intestinal glands

(b.) villi

(c.) pseudopodia

(d.) cilia

Food is ingested through the

(a.) salivary glands

(b.) small intestine

(c.) mouth

(d.) rectum

In humans, chemical digestion is accomplished by enzyme action that begins in the mouth and ends in the

(a.) liver

(b.) small intestine

(c.) gall bladder

(d.) stomach

In which organ of the human digestive system does most digestion occur?

(a.) mouth

(b.) stomach

(c.) small intestine

(d.) large intestine

Which substances are released into the small intestine of a human and aid in the digestion of the intestinal contents?

a. bile, pancreatic juice, and intestinal juice

b. hydrochloric acid, pancreatic juice, and intestinal juice

c. salivary amylase, intestinal juice, and pancreatic juice

d. bile, hydrochloric acid, and salivary amylase

The main function of the human digestive system is to

a. rid the body of cellular waste materials

b. process organic molecules so they can enter cells

c. break down glucose in order to release energy

d. change amino acids into proteins and carbohydrates