UNIT 12: The Digestive System

Question 1

What are the two main functions of the digestive system?

Answer 1

digestion and absorption

Question 1

Which organs make up the digestive tract?

Answer 1

mouth, pharynx, esophagus, stomach, small intestine, and large intestine (and layers of smooth muscle to contract)

Question 2

What are these organs lined with

Answer 2

mucosa

Question 3

How many layers are in the GI tract?

Answer 3

4

Question 4

What are the 4 layers?

Answer 4

mucosa, submucosa, muscolaris, and serosa

Question 5

What is mucosa?

Answer 5

absorptive and secretory layer

Question 6

What is the submucosa?

Answer 6

highly vascular layer of connective tissue

Question 7

What is the muscolaris?

Answer 7

responsible for contractions and perstaltic movement

Question 8

What is the serosa?

Answer 8

connective tissue continuous with the mesentery and visceral peritoneum

Question 9

What are the three accessory digestive organs?

Answer 9

salivary glands, liver, and the pancreas

Question 10

What do these accessory organs do?

Answer 10

they produce digestive juices that reach the digestive system through small ducts

Question 11

What does the gallbladder do?

Answer 11

Stores the liver’s digestive juices until they are needed in the intestine.

Question 12

What is digestion?

Answer 12

the breaking down of food substances so the body can take them up and use them to build/repair tissues, nourish cells and to provide energy

Question 13

What is it called when food moves from one organ to the next?

Answer 13

peristalsis (looks like a wave in when travelling through the muscle)

Question 14

What is the first major muscle movement in the digestive system?

Answer 14

swallowing (involuntary)

Question 15

What is the ring-like muscle called at the junction of the stomach and esophagus?

Answer 15

lower esophageal sphincter (closes passage between two organs)

Question 16

What happens when the sphincter relaxes?

Answer 16

food passes through to the stomach

Question 17

How many functions does the stomach have?

Answer 17

3

Question 18

What is one function?

Answer 18

storage of swallowed foods and liquids (muscles in upper part of the stomach relax in order to accept larger volumes of swallowed material)

Question 19

What is another function?

Answer 19

mixing up the food, liquid, and digestive juice produce by the stomach

Question 20

What is the last function of the stomach?

Answer 20

empties contents (now chyme) into the small intestine

Question 21

What nutrient spends the least amount of time in the stomach?

Answer 21

carbs (protein stays longer but fats stays the longest)

Question 21

What enzyme digests proteins

Answer 21

pepsin

Question 21

What is the first digestive juice used in the digestive system?

Answer 21

saliva. Contains an a-amylase that breaks the starches down into sugars

Question 22

What does the pancreas produce?

Answer 22

enzymes that breakdown carbs, protein and fats

Question 23

Where are enzymes such as lactase, sucrase, and maltase found?

Answer 23

in the glands in the intestinal wall. they digest disaccharides and small glucose polymers into monosaccharides, while peptidases cleave polypeptides into individual amino acids

Question 24

What digestive juice does the liver produce?

Answer 24

bile

Question 25

What does bile acids do?

Answer 25

they dissolve fat into watery contents

Question 26

Where are most food molecules, water and minerals absorbed?

Answer 26

the small intestine

Question 27

What does the mucosa contain?

Answer 27

covered in villi (allows for foods to be absorbed)

Question 28

What is villi covered in?

Answer 28

microvilli (allows for foods to be absorbed)

Question 29

how are fatty acids, cholesterol and phospholipids taken up?

Answer 29

lipid micelles that are formed with bile salts by the cells of the small intestines

Question 30

How many steps are carbs digested in?

Answer 30

2

Question 31

What are the two steps?

Answer 31

salivary amylase and pancreatic juice

Question 32

What happens to proteins in the small intestine?

Answer 32

trypsin, chymotripsin, carboxypeptidase, proelastase form the pancreatic juices and peptidases from the lining of the intestine complete the breakdown of proteins into amino acids

Question 33

What breaks down fat molecules?

Answer 33

pancreatic and intestinal lipases

Question 34

How is digestion controlled?

Answer 34

hormonal and nervous control mechanisms

Question 35

What are the main hormones that control digestion?

Answer 35

gastrin, secretin and cholecytokinin (CCK), and gastric inhibitory peptide (GIP)

Question 36

What does gastrin do?

Answer 36

causes the stomach to produce the acid that is necessary for pepsin to work (stimulates pepsin release)

Question 37

What does secretin do?

Answer 37

causes the pancreas to send out a digestive juice that is rich in bicarbonate

Question 38

What does the bicarbonate do?

Answer 38

neutralize the acidic stomach contents as they enter the small intestine

Question 39

What does CCK do?

Answer 39

causes the pancreas to produce enzymes of pancreatic juice and stimulates contraction of the gallbladder

Question 40

What hormones regulate appetite?

Answer 40

ghrelin and leptin

Question 41

What does ghrelin do?

Answer 41

stimulates appetite

Question 42

What does leptin do?

Answer 42

inhibits appetite

Question 43

What doe extrinsic neural receptors do?

Answer 43

release acetylcholine and adrenaline

Question 44

What do intrinsic neural receptors do?

Answer 44

speed up or delay movement of food

Question 45

What are ruminants?

Answer 45

have a 4-chambered stomach that has the capicity to breakdown cellulose (think about cow)

Question 46

What are hind-gut fermenters?

Answer 46

large intestines are larger than ruminant fermenters and a richer diet is requires (harder time breaking down cellulose)