Digestive System

Question 1

alternate terms for the alimentary canal are:

Answer 1

the digestive tract and the gastrointestinal tract (GI tract).

Question 2

name some traits of the digestive sac.

Answer 2

• only one opening (food and waste exits from the same hole)
• in less complex animals
• less effective than the digestive canal.

Question 3

name some traits of the digestive canal.

Answer 3

• two openings (a mouth and an anus).

- more effective than the digestive sac because it has specialized regions.

Question 4

humans have a digestive…

Answer 4

digestive canal.

Question 5

the four stages of food processing are:

Answer 5

ingestion, digestion, absorption, and elimination.

Question 6

ingestion:

Answer 6

the act of eating or drinking.

Question 7

digestion:

Answer 7

the act of breaking down food into molecules that are small enough for the body to absorb.

Question 8

the two types of digestion are:

Answer 8

mechanical and chemical digestion.

Question 9

mechanical digestion:

Answer 9

chewing, grinding, etc. (increases food surface area).

Question 10

chemical digestion:

Answer 10

breaks chemical bonds in the large molecules (carbohydrates, fats, and proteins) and makes them smaller by hydrolysis.

Question 11

hydrolysis is:

Answer 11

the process of breaking down food bonds in molecules by adding water in the presence of specific enzymes. `

Question 12

absorption:

Answer 12

the act of absorbing small molecules by cells (amino acids, sugars, etc.) in the small intestine, where it’s transported to the circulatory system. the molecules are then transported to the body cells from the blood cells where they’re joined to make bigger molecules or broken down for energy.

Question 13

where do unneeded molecules go?

Answer 13

they’re converted to fat for storage.

Question 14

elimination:

Answer 14

the act of removing undigested materials from the digestive tract through the large intestine.

Question 15

in absorption, nutrients are used for:

Answer 15

• energy

- as building blocks for molecules in cells.

Question 16

who found out the liquids in our stomach would dissolve meat after they made their test subjects swallow a piece of sponge attached to a string in the 1700’s?

Answer 16

Lazzaro Spallanzani.

Question 17

alimentary canal length facts:

Answer 17

• length is often correlated with diet
• herbivories + omnivores usually have longer alimentary tracts than carnivores because vegetation has cell walls where meat does not.
• the alimentary canal is much longer than the path from mouth to anus because of the various folds and loops.

Question 18

the six main organs of the alimentary canal are:

Answer 18

the mouth, pharynx, esophagus, stomach, small intestine, and large intestine.

Question 19

the accessory glands/organs are:

Answer 19

the salivary glands, liver, pancreas, and gallbladder.

Question 20

the accessory glands/organs:

Answer 20

secrete digestive juices into the alimentary canal.

Question 21

where does digestion start?

Answer 21

the mouth.

Question 22

mechanical digestion:

Answer 22

• starts in the mouth

- tongue moves food so it comes into contact with teeth

Question 23

we chew food because:

Answer 23

• crushes food into a paste that’s easier to swallow.

- exposes more surface area so chemical digestion occurs more easily.

Question 24

saliva is:

Answer 24

a watery liquid that contains digestive enzymes, mucus, and other chemicals that help digest food.

Question 25

in general, saliva:

Answer 25

• moistens foods, making them easier to chew.

- breaks chemical bonds in starches to form sugars.

Question 26

salivary glands make x liters of saliva a day.

Answer 26

more than one liter.

Question 27

mucus in saliva is:

Answer 27

a sticky substance that coats food so that it can slide down the tube without harming the tissues. lubricant.

Question 28

bolus:

Answer 28

a chewed clump of food.

Question 29

the pharynx is:

Answer 29

the upper portion of the throat; a tube that’s shared by the digestive and respiratory systems.

Question 30

epilottis:

Answer 30

a cartilage flap that temporarily seals off the airway, preventing food from moving into the air passageway / windpipe (also called trachea).

Question 31

the esophagus:

Answer 31

is a tube that connects the pharynx to the stomach.

Question 32

peristalsis is:

Answer 32

a series of muscle contractions that push the bolus down the esophagus. these contractions are strong enough that we can eat upside down.

Question 33

the esophageal sphincter is:

Answer 33

a muscular valve that closes the esophagus after food passes into the stomach. this prevents its contents from flowing back up the esophagus.

Question 34

heartburn happens when:

Answer 34

the esophageal sphincter opens at an inappropriate time, allowing acid from the stomach to flow backward into the esophagus. (inappropriate times: overeating, etc).

Question 35

the stomach is:

Answer 35

an elastic, muscular sac that contains continues the chemical and mechanical digestion of food.

Question 36

rugae are:

Answer 36

the folds in the stomach.

Question 37

chemical digestion in the stomach:

Answer 37

• the bolus is bathed in gastric juice
• hydrochloric acid breaks apart the cells in food; also kills bacteria
• pepsin (one of the gastric enzymes) helps to break down protein molecules.

Question 38

mucus in the stomach:

Answer 38

protects the walls of the stomach from hydrochloric acid, ensuring it doesn’t digest itself.

Question 39

ulcers occur when:

Answer 39

there isn’t enough mucus in the stomach and it starts to digest itself.

Question 40

gastric juice is:

Answer 40

a liquid mixture of hydrochloric acid, enzymes, and mucus secreted by glands in the stomach lining.

Question 41

in general, gastric juice:

Answer 41

• is only secreted in the presence of food.

- gastric glands can make up to 3L of juice a day.

Question 42

mechanical digestion in the stomach:

Answer 42

the contents of the stomach are mixed by the muscles every twenty-ish seconds. this process turns the bolus into chyme.

Question 43

chyme is:

Answer 43

a nutrient-filled, acidic liquid.

Question 44

chyme exits the stomach through the:

Answer 44

pyloric sphincter.

Question 45

the five enzymes are:

Answer 45

salivary amylase, pepsin, trypsin, lipase, and pancreatic amylase.

Question 46

salivary amylase:

Answer 46

in saliva; chemical breaks down food.

Question 47

pepsin:

Answer 47

in the stomach; breaks down proteins.

Question 48

trypsin:

Answer 48

the small intestine; breaks proteins into amino acids.

Question 49

lipase:

Answer 49

the stomach; breaks fats into glycerol and fatty acids.

Question 50

pancreatic amylase:

Answer 50

the small intestine; breaks carbs into simple sugars.