Digestive Physiology

Question 1

Chemical and physical breakdown of food is referred to as what?

Answer 1

Digestion

Question 2

What happens during absorption?

Answer 2

Nutrients are taken into the blood

Question 3

What contributes to the high rate of surface area for absorption in the small intestine?

Answer 3

Convoluted surface area of the lumen

Question 4

What is the difference between endocrine and exocrine?

Answer 4

Endocrine is secretions into the blood and exocrine is secretions into the digestive tract

Question 5

What is the main point of the regulation of GI processes?

Answer 5

Regulated by stomach volume and contents, not the nutritional state of the body

Question 6

What are the 4 ways that the GI processes are regulated?

Answer 6

Distension of stomach walls, osmolarity of chyme, chyme acidity and the concentration of digestive enzymes in the chyme

Question 7

How do emotional states and hunger influence the GI system?

Answer 7

Emotional states trigger the CNS which innervates the smooth muscles, response in the gastrointestinal lumen

Question 8

Sublingual, submandibular and parotid are 3 types of what?

Answer 8

Salivary glands

Question 9

What are the contents of saliva?

Answer 9

Mucus, water, HCO3- and enzymes

Question 10

Which enzymes are in saliva?

Answer 10

Lysozyme, salivary lipase and salivary amylase

Question 11

What does salivary amylase do?

Answer 11

Breaks down carbs

Question 12

What does salivary lipase do?

Answer 12

Breaks down fat

Question 13

What is the purpose of saliva?

Answer 13

Lubricate food, buffer acidity

Question 14

Increased salivary gland activity by increased blood flow to the salivary glands is under control of what?

Answer 14

Parasympathetic activity

Question 15

Decreased salivary gland activity is under the control of what?

Answer 15

Sympathetic activity

Question 16

What causes heartburn?

Answer 16

Acid reflux into the cardiac sphincter

Question 17

What are the two sphincters in the esophagus?

Answer 17

Upper esophageal sphincter and lower esophageal sphincter

Question 18

How does regurgitation of chyme into the esophagus happen?

Answer 18

Esophageal sphincters don’t always close properly during and following swallowing, allows chyme into esophagus

Question 19

The wave of contractions to bring food downward is referred to as what?

Answer 19

Peristalsis

Question 20

What are the 3 types of cells in the stomach?

Answer 20

Parietal cells, chief cells and G cells

Question 21

Which cells secrete pepsinogen in the stomach?

Answer 21

Chief cells

Question 22

Which cells secret HCl and intrinsic factor in the stomach?

Answer 22

Parietal cells

Question 23

Where does the HCl in the stomach come from?

Answer 23

The bicarbonate buffer system, secreted by parietal cells

Question 24

Which cells in the stomach secrete gastrin?

Answer 24

G cells

Question 25

Where does gastrin go after secretion?

Answer 25

Into the blood

Question 26

Out of carbs, fats and proteins, which macromolecule gets partially digested in the stomach?

Answer 26

Proteins

Question 27

The increase of proteins in the stomach lumen stimulates what?

Answer 27

Gastrin release and the insertion of H/K Atpase pumps, ultimately means increased acidity

Question 28

How is stomach acidity increased in the stomach?

Answer 28

Insertion of H/K ATPase pumps into the parietal cells

Question 29

What shuts off gastrin?

Answer 29

Too much acidity - example of negative feedback

Question 30

How much protein digestion occurs in the stomach?

Answer 30

About 20%

Question 31

Why is pepsinogen inactive in the small intestine?

Answer 31

Requires a low pH

Question 32

Where is the pyloric sphincter located?

Answer 32

At the junction of the stomach and the small intestine

Question 33

What does the pyloric sphincter do?

Answer 33

It only allows a small amount of chyme into the small intestine at a time

Question 34

How does increased fat presence affect gastric emptying?

Answer 34

It inhibits/slows it down

Question 35

What is the whole volume of the stomach?

Answer 35

0.5-4L

Question 36

Where is the brush border?

Answer 36

Fancy apical membranes of the small intestine

Question 37

What are the 3 parts of the small intestine?

Answer 37

Duodenum, jejunum, ileum

Question 38

What is secreted by the pancreas?

Answer 38

Bicarbonate, zymogens (ex: trypsinogen)

Question 39

Which cells secrete trypsinogen?

Answer 39

Acinar cells in the pancreas

Question 40

What converts trypsinogen to trypsin?

Answer 40

Enterokinase

Question 41

Why is HCO3- secreted by the pancreas?

Answer 41

Needs to buffer acidity of the chyme, too much acidity would inactive the zymogens

Question 42

Increased acid from stomach increases the secretion of what from the small intestine?

Answer 42

Secretin

Question 43

What does secretin do?

Answer 43

Stimulates HCO3- secretion, increases plasma secretin

Question 44

What is CCK production stimulated by?

Answer 44

Increased fatty acids and amino acids in the small intestine

Question 45

What does CCK do?

Answer 45

Increases enzyme secretion from the Acinar cells of the pancreas

Question 46

What is bile composed of?

Answer 46

HCO3-, cholesterol, phospholipids, bile pigments and bile salts

Question 47

What does bile do?

Answer 47

Solubilizes dietary fats (mechanical digestion)

Question 48

How is bile brought into the small intestine?

Answer 48

It gets taken up by transporters in the ileum

Question 49

What does CCK do?

Answer 49

Signals gallbladder and pancreas to contract, results in release of bile

Question 50

Glucose and galactose take what transporter into the epithelial cell?

Answer 50

sGLUT

Question 51

Fructose takes what transporter into the epithelial cell?

Answer 51

GLUT

Question 52

Do glucose, fructose and galactose take the same transporter out of the epithelial cells or travel separately?

Answer 52

They take the same GLUT transporter out

Question 53

Which gradient is amino acid transport into the epithelial cell associated with?

Answer 53

Na+

Question 54

Which ion gradient is small peptide transport into the epithelial cell paired with?

Answer 54

Hydrogen

Question 55

What converts small peptides into amino acids in the lumen?

Answer 55

Brush border enzymes

Question 56

What converts small peptides into amino acids in the epithelial cell?

Answer 56

Peptidase

Question 57

What breaks triglycerides into monoglycerides and fatty acids?

Answer 57

Pancreatic lipase

Question 58

How do dietary fats get into the intestinal epithelial cell?

Answer 58

Diffusion

Question 59

What happens to dietary fats in the intestinal epithelial cells?

Answer 59

They're converted into triglycerides by the smooth ER, then transported into lymphatic circulation as chylomicron

Question 60

Which vitamins are fat soluble?

Answer 60

Vitamins A, D, E, and K

Question 61

How do water soluble vitamins get absorbed?

Answer 61

Diffusion and mediated transport

Question 62

What is the name of the sphincter between the small and large intestines?

Answer 62

ileocecal

Question 63

How is the defecation reflex triggered?

Answer 63

Distension of the walls of the rectum

Question 64

What are some functions of the gut microbiota?

Answer 64

Vitamin K synthesis, metabolic aid, and education of the immune system

Question 65

What does gluten do in Celiac's disease?

Answer 65

Damages the epithelial cells and decreases surface area for absorption of nutrients

Question 66

What bacteria causes ulcers?

Answer 66

Heliobacter pylori

Question 67

What are two drugs that help ulcers?

Answer 67

Histamine receptor blockers (cimetidine) and H/K pump inhibitors (omeoprazol)

Question 68

What does histamine do?

Answer 68

Increases acid production