UNIT 12- DIGESTIVE SYSTEM

Question 1

What are the 4 layers of the GI tract?

Answer 1

1. mucosa- absorptive secretory layer
2. submucosa- vascular layer of connective tissue
3. muscolaris- contractions and peristaltic movement
4. serosa- connective tissue continuous with mesentery and visceral peritoneum

Question 2

What are the 3 accessory digestive organs responsible for producing digestive juices?

Answer 2

salivary glands
liver
pancreas

Question 3

What is peristalsis?

Answer 3

muscle organ involuntarily contracts to create a narrowing and propels narrowed portion slowly down the organ like a wave. Waves push food and fluid in front of them through each hollow organ

Question 4

What is located at the junction of esophagus and stomach?

Answer 4

Lower esophageal sphincter- as food is introduced sphincter relaxes and allows passage into stomach

Question 5

What are the 3 main functions of the stomach?

Answer 5

1. storage of swallowed food and liquid
2. mixes food, liquid and digestive juices produced by stomach
3. empties its contents (chyme) slowly into small intestine

Question 6

Order the following from the least amount of time in the stomach to the most amount of time in the stomach: fat, carbohydrates, proteins

Answer 6

1. carbohydrates
2. proteins
3. fats (longest)

Question 7

Salivary glands contain ____________ which digests starch into sugars

Answer 7

Salivary glands contain ptyalin (alpha amylase) which digests starch into sugars

Question 8

Stomach lining produces _________ and ________

Answer 8

Stomach lining produces stomach acid and enzyme-pepsin

Question 9

Pancreas produces ____________ to break down carbohydrates, _____________ to break down fats, ________, ____________, and ____________ to breakdown proteins

Answer 9

Pancreas produces PANCREATIC AMYLASE to break down carbohydrates, PANCREATIC LIPASE to break down fats, TRYPSIN, CHYMOTRYPSIN, and CARBOXYPEPTIDASE to breakdown proteins

Question 10

The ____________ of intestine secretes enzymes that digest disaccharides into monosaccharides

Answer 10

The BRUSH BORDER of intestine secretes enzymes that digest disaccharides into monosaccharides

Question 11

Liver produces bile that is stored in ____________ between meals. What does bile do and when is it released?

Answer 11

Liver produces bile that is stored in GALL BLADDER between meals
- bile is squeezed out of gallbladder and into intestine to mix with fat in food, dissolves fat into watery substance so It can be digested

Question 12

__________ and _________ of mucosa of small intestine create surface area through which _________ can be absorbed

Answer 12

VILLI and MICROVILLI of mucosa of small intestine create surface area through which NUTRIENTS can be absorbed

Question 13

Starch is digested in 2 steps… and are further hydrolyzed into monosaccharides by ____________ enzymes in __________

Answer 13

1. salivary amylase from saliva
2. pancreatic juice (breaks down starch into maltose, maltriose and oligosaccharides)
   are further hydrolyzed into monosaccharides by BRUSH BORDER enzymes in MICROVILLI

Question 14

How are these monosaccharides (maltose and maltriose) absorbed in the blood stream and how does this differ from fructose?

Answer 14

These monosaccharides are transported across the mucosal membrane with sodium co-transporters which are then carried through the blood stream to liver to be stored for energy
Fructose is absorbed directly

Question 15

Breakdown of proteins is assisted by….

Answer 15

• PEPSIN from stomach juice
• TRYPSIN, CHYMOTRYPSIN, and CARBOXYPEPTIDASE from pancreatic juice
• PEPTIDASE from lining of intestines

Question 16

Describe the process of breaking down fat…

Answer 16

• bile acids in liver dissolve fat into droplets
• pancreatic and intestinal lipase break larger fat molecules into smaller ones
• bile acids combine fatty acids and cholesterol into micelles and help these molecules move into cells of mucosa which are passed to lymphatic vessels

Question 17

Water soluble vitamins include _______ which are __________ and removed through excess in urine

Answer 17

Water soluble vitamins include B and C which are NOT EASILY STORED and removed through excess in urine

Question 18

Fat soluble vitamins include __________ which are stored in __________ and _________

Answer 18

Fat soluble vitamins include A, D, E, K which are stored in LIVER and FATTY TISSUES

Question 19

Gastrin function in controlling digestion

Answer 19

stomach produces acid necessary for pepsin to work

Question 20

Secretin function in controlling digestion

Answer 20

pancreas sends out digestive juice rich in bicarbonate and enzymes that complete digestion of fats, carbohydrates and proteins

Question 21

CCK function in controlling digestion

Answer 21

produce enzymes of pancreatic juice, stimulates contraction of gall bladder- empties contents into duodenum

Question 22

GIP function in controlling digestion

Answer 22

inhibits gastric secretion + motility, stimulates insulin

Question 23

Ghrelin function in regulating appetite

Answer 23

hunger hormone produced in stomach and upper intestine

Question 24

Peptide YY and CCK function in regulating appetite

Answer 24

inhibit appetite, produced in response to meal

Question 25

Insulin function in regulating appetite

Answer 25

responds to rising glucose levels- inhibits appetite

Question 26

Leptin function in regulating appetite

Answer 26

produced by fat cells, inhibits appetite

Question 27

Extrinsic nerves release 2 chemicals. What are they and what function do they serve?

Answer 27

1. acetylcholine- increased push of food and juice through contraction
2. adrenaline- relaxes muscle of stomach and intestine- stops digestion

Question 28

Intrinsic nerves make up _____________________ and are part of the ________ NS

Answer 28

Intrinsic nerves make up DENSE NETWORK IN WALLS OF ESOPHAGUS, STOMACH, SMALL INTESTINE, COLON and are part of the ENTERIC NS ( speed up or delay movement of food)

Question 29

Ruminants vs hind gut fermenters

Answer 29

Ruminants are dominant herbivores who gave a 4 chambered stomach, the first chamber “rumen” components are capable fo fermenting cellulose- after fermentation, solid material (cud) is regulated via second chamber and chewed again before passing to omasum and abomasum
Hind gut fermenters- digestive tracts like non-herbivores, but large intestine is much larger and is filled with bacteria that can digest cellulose
processes between the 2 are the same but hind gut rats are LESS efficient than ruminants, therefore, hind gut rats require a richer diet