Lecture # 4 Digestive Organs and the Endocrine System

Question 1

Organs of the gastrointestinal tract are made of four distinct layers; the mucosa, the submucosa, the muscularis, and the serosa. (T/F)

Answer 1

T

Question 2

The mucosa is the layer in contact with the ingested food. (T/F)

Answer 2

T

Question 3

Oral cavity

Answer 3

no absorption, but mastication.

Question 4

Where does digestion begin?

Answer 4

If carbohydrates, begins in the mouth by salivary amylase

Question 5

Large intestine

Answer 5

Region where fermentation occurs.

Question 6

Liver

Answer 6

produces biles, an important secretion needed for lipid digestion

Question 7

Pancreas

Answer 7

releases pancreatic juice that neutralizes chyme and contains enzymes needed for carbohydrate, protein, and lipid digestion.

Question 8

What are the four sites for the secretion of digestive enzymes?

Answer 8

Mouth, stomach, pancreas, and the small intestine.

Question 9

Retinyl ester hydrolases

Answer 9

secreted by the pancreas, responsible for the digestion of vitamin A.

Question 10

Proteases

Answer 10

breaks down protein

Question 11

Trypsinogen

Answer 11

Zymogen. active form is trypsin, secreted by the pancreas. protein digestion

Question 12

Pepsinogen

Answer 12

zymogen. active form pepsin, secreted by the stomach. protein digestion.

Question 13

Alpha dextrinase or isomaltase

Answer 13

breaks down a1,6 bonds in dextrins and oligosaccharides, starch.

Question 14

What are the three types of salivary glands in the mouth?

Answer 14

parotid, sublingual, submandibular

Question 15

Environment of the oral cavity

Answer 15

pH7, water, electrolytes (K+, and HCO3-), Mucus (mucins), enzymes (lipase, amylase), and antibacterial compounds.

Question 16

ptyalin

Answer 16

a-amylase in the oral cavity

Question 17

Antibacterial/Antimicrobial substance of the mouth

Answer 17

Lysozyme, breaks down cell walls of microbes.

Question 18

What is the saliva secretion rate?

Answer 18

0.5-1.5L/day; influenced by CNS activation by smell, taste, mastication etc. also stimulated by norepinephrine and acetylcholine

Question 19

Salivary Amylase

Answer 19

breaks down alpha 1-4 bonds

Question 20

Lower esophogeal or gastroesophogeal sphincter

Answer 20

regulates the flow of food from the esophagus into the stomach. Important in the development of Acid reflux, GIRD, and other reflux diseases

Question 21

Pyloric sphincter

Answer 21

regulates the flow of chyme from the stomach into the upper or proximal small intestine (duodenum)

Question 22

What are the 3 layers of muscle in the stomach? Why are they important?

Answer 22

Longitudinal, circular, and diagonal. Contractions of these muscles enable food to mix with gastric juice to form chyme.

Question 23

Where does lipid and protein digestion start?

Answer 23

In the stomach. By pepsin. Carbohydrate digestion slows.

Question 24

Is this recommendation regarding patients with gastroesophagial reflux disease (GERD) true? “You should consume substances that increase gastroesophagial sphincter pressure” (T/F)

Answer 24

True, you should consume substances that increase GS sphincter pressure. If you make the sphincter tighter, less reflux. Proteins make sphincter tighter.

Question 25

What substances increase probability of GERD?

Answer 25

Alcohol, chocolate, and fatty foods.

Question 26

What cells produce pepsinogen and gastric lipase?

Answer 26

Chief Cells.

Question 27

What cells produce HCL

Answer 27

Parietal cells. HCl converts pepsin from pepsinogen They also produce intrinsic factor which is important for the absorption of vitamin B12

Question 28

What cells produce Gastrin? What is its function?

Answer 28

Enteroendocrine G-Cells. Stimulates parietal and chief cells.

Question 29

Vagus nerve

Answer 29

a part of the autonomous nervous system that plays a stimulating role on the stomach.

Question 30

Small intestine

Answer 30

9 feet long. Regions; Duodenum, jejunum, and ileum.

Question 31

What is the role of the duodenum?

Answer 31

Initial point of contact from the stomach…

Question 32

Brunner’s glands

Answer 32

Found in the submucousa, and secretes bicarbonate, which helps neutralize acid contents of stomach.

Question 33

Sphincter of Oddi

Answer 33

region where secretions from the pancreas and gallbladder empty into the small intestine, located in the lower duodenum.

Question 34

Why is the duodenum free of microbes?

Answer 34

Because of the acidity of the chyme from the stomach. If stomach acids fail, microbes grow, obstruct the sphincter of oddi, and cause the inability of pancreatic and gallbladder secretions from entering the small intestine.

Question 35

Crypts of Lieberkuhn

Answer 35

Regions where new enterocytes are produced. Oldest cells are near the top of the villi.

Question 36

Turnover of enterocytes

Answer 36

3-5 days.

Question 37

Role of the liver in digestion

Answer 37

Production of bile acids from cholesterol.

Question 38

Gallbladder

Answer 38

Role is to store bile generated from the liver.

Question 39

Exocrine pancreas

Answer 39

Contain duct cells and Acinar cells ( secrete NaHCO3 and digestive enzymes respectively)

Question 40

Endocrine Pancreas

Answer 40

Ductless; islets of langerhans are found here. responsible for secreting glucagon and insulin.

Question 41

What is the purpose of producing a protein as a zymogen?

Answer 41

To protect the producing cell.

Question 42

What vein connects the G.I tract to the liver?

Answer 42

The portal vein.