Sec 32.2: Digestive System

Question 1

What is digestion?

Answer 1

It is the process by which the large complex molecules in food are broken down into smaller molecules used by the body.

Question 2

What is the digestive system?

Answer 2

It is a collection of organs that break down food into energy.

Question 3

What are the major organs of the digestive system? Which ones are not a part of the digestive tract?

Answer 3

Mouth, esophagus, stomach, gallbladder, large & small intestines, rectum, and anus. the pancreas and liver are not part of the digestive tract but contribute to the digestive system

Question 4

What are sphincters?

Answer 4

They are rings of muscle that separate one section from another, opening and closing to keep food moving in one direction.

Question 5

What is peristalsis?

Answer 5

It is the rhythmic, involuntary contraction of the smooth muscles in organ walls, and it takes place mainly in the esophagus

Question 6

What is the esophagus?

Answer 6

It is a tube that connects the mouth to the stomach.

Question 7

What mechanical digestion occurs in the mouth?

Answer 7

It begins the moment you eat with teeth chewing and mixing food.

Question 8

What chemical digestion occurs in the mouth?

Answer 8

Salivary glands release saliva, which moistens food and contains the enzyme “amylase”

Question 9

What is salivary amylase?

Answer 9

It is the enzyme found in the saliva that begins the breakdown of complex starch molecules (or carbs) into sugar. (starches to simple sugars)

Question 10

What happens after mechanical and chemical digestion in the mouth?

Answer 10

Food is pushed by the tongue to the esophagus, where it moves down by peristalsis.

Question 11

What is the stomach?

Answer 11

It is a muscular sac that can stretch to nearly twice its original size and holds up to 2 liters of food.

Question 12

What mechanical digestion occurs in the stomach?

Answer 12

The stomach walls contain three layers of smooth muscles that contract every 20 seconds. This “churning” breaks food into smaller pieces and mixes it with the stomach’s digestive juices.

Question 13

What chemical digestion occurs in the stomach?

Answer 13

The stomach lining secrets gastric juice. which contains hydrochloric acid (HCl) and pepsin.

Question 14

What is pepsin?

Answer 14

It is an enzyme that digests proteins, active only when food is present to prevent chewing the stomach itself

Question 15

How many hours does it take to empty your stomach after a meal?

Answer 15

2-6 hours

Question 16

What is chyme?

Answer 16

It is a semi-liquid mixture that digestive juices and enzymes turn food into. Peristaltic actions push chyme against sphincter between stomach and small intestine.

Question 17

What is the small intestine?

Answer 17

It is a long, narrow tube in which most digestion takes place.

Question 18

How is food digested in the small intestine?

Answer 18

Smooth muscle contractions churn the food and chemical digestion breaks down the complex molecules

Question 19

What is the duodenum?

Answer 19

It is the section of the small intestine closest to the stomach where remaining carbs, proteins, and fats are digested.

Question 20

What is the pancreas?

Answer 20

It is a small gland located behind the stomach, and it releases an alkaline fluid when chyme enters to help neutralize the acid and stop pepsin action.

Question 21

What is the liver?

Answer 21

It is a digestive organ that produces bile and also filters blood

Question 22

What is bile?

Answer 22

It is a chemical substance that helps digest fats and is stored in the gallbladder.

Question 23

What enzymes are produced in the small intestine to continue digestion?

Answer 23

Maltase, Lactase, & Sucrase -> break down sugars into simpler molecules
Peptidase -> break down proteins into amino acids

Question 24

What type of sugar does lactase break down?

Answer 24

Lactose, a sugar found in milk

Question 25

What enzymes are released by the pancreas into the small intestine to resume digestion?

Answer 25

Trypsin -> continues break down of proteins
Amylase -> continues break down of starches
Lipase -> aids in breaking down fats

Question 26

Why and how is bile released?

Answer 26

Bile is released from being stored in the gallbladder through ducts that empty into the duodenum when needed to digest fats

Question 27

Where is the process of digesting proteins finished?

Answer 27

In the duodenum, through enzymes that break chains of amino acids into individual amino acids.

Question 28

To summarize, where does protein digestion happen?

Answer 28

In the stomach (pepsin) and small intestine (peptidase + trypsin from pancreas)

Question 29

Where does carbohydrate digestion happen?

Answer 29

In the mouth (salivary amylase) and small intestine (maltase, lactase, sucrase + amylase from pancreas)

Question 30

Where does lipid digestion happen?

Answer 30

In the small intestine (lipase from pancreas + bile from liver/stored in gallbladder)

Question 31

Overall, how does digestion take place?

Answer 31

Through the interaction of enzymes, stomach acid, hormones, bile, and a network of nerves and muscles.