Biochemistry Exam 1, Ch. 2

Front 1

Which enzymes begin to digest in the mouth?

Back 1

Carbohydrates & lipids

Front 2

What is bolus and where is it found?

Back 2

• Food + Saliva

• Mouth and the esophagus

Front 3

1. What regulates swallowing?

2. How?

Back 3

1. Medulla

2. Esophageal sphincter relaxes, epiglottis shifts to cover trachea, once bolus is in the esophagus the epiglottis reopens

Front 4

What is Peristalsis?

Back 4

• A wavelike motion moving bolus from mouth to stomach

• Voluntary and involuntary muscles are stimulated by parasympathetic nerves to carry out this function

Front 5

What is the gastroesophageal sphincter?

Back 5

• Located between the esophagus and the stomach

• Prevents reflux of stomach contents into the esophagus

• Loss of this function causes GERD (Gastroesophageal reflux disorder)

Front 6

Describe the physicality of the stomach.

Back 6

1. J-shaped organ between the esophagus and small intestine

2. Empty = 1/4 cup

3. Can stretch to about 6 cups

Front 7

What are the four main regions of the stomach?

Back 7

1. Cardia - receives bolus from esophagus

2. Fundus - gas trapping compartment

3. Body - gastric juice production

4. Antrum (distal pyloric region) - grinds and mixes food with gastric juice (peristalsis)

Front 8

What is chyme?

Back 8

Partially digested food

Front 9

What are the 4 types of cells found in the stomach?

Back 9

1. Neck cells - secrete mucus and bicarbonate (w/out would have ulcers)

2. Parietal Cells - secrete HCl and intrinsic factor (IF, absorbs vit. B12)

3. Chief cells - secrete enzymes (pepsinogen and gastric lipase)

4. Enteroendocrine cells - secrete hormones (G cells)

Front 10

Which cells secrete enzymes in the stomach?

Back 10

Chief cells

Front 11

Which enzymes secrete mucus and bicarbonate in the stomach?

Back 11

Neck cells

Front 12

Which enzymes secret hormones in the stomach?

Back 12

Enteroendocrine cells

Front 13

Which enzymes secret HCl and intrinsic factor in the stomach?

Back 13

Parietal Cells

Front 14

Gastric Juice contains:

Back 14

1. water
2. electrolytes
3. intrinsic factor
4. hydrochloric acid
5. enzymes
6. mucus

Front 15

What is needed to absorb Vit. B12?

Back 15

Intrinsic factor

Front 16

What denatures proteins, is a basteriodicde, converts pepsinogen to pepsin, and releases nutrients from organic complexes?

Back 16

HCl

Front 17

What enzymes are present in the stomach?

Back 17

Pepsin and Gastric lipase

Front 18

What is stomach mucus composed of?

Back 18

Glycoproteins, glycolipids, water and bicarbonate

Front 19

1. What activates the inactive enzyme pepsinogen?

2. What active enzyme does it become?

Back 19

1. HCl or pepsin

2. Pepsin

Front 20

Which enzymes are found in the stomach?

Back 20

Lipids and Proteins

Front 21

Which peptide hormones affect the stomach? (5)

Back 21

1. Gastrin
2. Secretin
3. Cholecystokinin (CCK)
4. Gastric Inhibitory Peptide (GIP)
5. Motilin

Front 22

What affect does Gastrin have on the stomach?

Back 22

• lowers pH
• stimulates HCl secretion and mucosal growth

Front 23

What affect does Secretin have on the stomach?

Back 23

• it opposes Gastrin
• increases pH
• stimulates pepsinogen secretion, decreases gastric motility

Front 24

What affect does Cholecystokinin have on the stomach?

Back 24

• decreases gastric emptying
• stay fuller longer

Front 25

What affect does Gastric Inhibitory Peptide (GIP) have on the stomach?

Back 25

Decreases gastric motility

Front 26

What affect does motilin have on the stomach?

Back 26

Increases motility

Front 27

Which Peptide hormone(s) affect secretion AND motility?

Back 27

All (gastrin, secretin, cck, gip, and motilin)

Front 28

Which Peptide hormone(s) affect motility only?

Back 28

Motilin

Front 29

How is chyme released?

Back 29

• Released to small intestine through pyloric sphincter at a rate of 2 tsp/min

Front 30

How long does gastric emptying take?

Back 30

• 1 to 6 hours following a meal

• 1 - 2 hours for liquid meal

• 2 - 6 hours for a solid meal

Front 31

List in order of fastest to slowest:

a. protein
b. fat = soluble fiber
c. starchy or processed carbohydrates

Back 31

1. Starchy or processed carbohydrates

2. Protein

3. Fat = Soluble fiber

Front 32

Are large meals or small meals emptied faster?

Back 32

Large meals because they increase stomach distention

(Distention causes gastrin secretion, gastrin increases gastric motility = faster emyptying)

e.g rice --> steak --> fruits and veg

Front 33

In gastric emptying, macronutrients are dependent on:

Back 33

Volume (fast -> slow)

Front 34

What are the 3 portions of the small intestine?

Back 34

1. Duodenum (chyme enters from pyloric sphincter, 10 inches long)
2. Jejunum (middle section)
3. Ileum (jejunum and ileum together are 18 ft long)

Front 35

Which part of the small intestine is the primary site for digestion?

Back 35

duodenum

Front 36

In the small intestine, where is the site for primary absorption?

Back 36

Jejunum

Front 37

Which part of the small intestine connects to the large intestine?

Back 37

Ileum (through the Ileocecal Sphincter)

Front 38

What are the four layers of the small intestine?

Back 38

1. Mucosa
2. Submucosa
3. Muscularis Externa
4. Serosa

Front 39

Which layer of the small intestine produces and releases enzymes, hormones, and digestive juices?

Back 39

Mucosa (innermost mucous membrane)

Front 40

Which layer of the small intestine regulates secretions from mucosal glands, mucosal movement and blood flow?

Back 40

Submucosa (connective tissue)

Front 41

Which layer of the small intestine is involved in peristalsis?

Back 41

Submucosa? and muscularis externa

Front 42

Which layers of the stomach make up the Villi and Microvilli?

Back 42

Mucosa and Submucosa

Front 43

What makes up the brush border?

Back 43

Enzymes

Front 44

Which layer of the small intestine is made up of two layers of smooth muscle that are necessary for peristalsis?

Back 44

Muscularis Externa

Front 45

Which layer of the small intestine is a membrane (protective coating)?

Back 45

Serosa

Front 46

Why are the Villi and Microvilli important?

Back 46

Increase surface area for enhanced nutrient absorption

Front 47

How fast do intestinal contents move through the SI?

Back 47

Rate of 1 cm per minute (chyme is in the SI for 3-8 hours)

Front 48

What makes up the Villi?

Back 48

Microvilli/Enterocytes

Front 49

Microvilli are part of:

Back 49

The brushborder

Front 50

What is different about the anatomy of the microvilli from other cells?

Back 50

The brushborder

Front 51

What is the life span of an enterocyte?

Back 51

• 3-5 days

• inactive enterocytes migrate from Crypts of Lieberkuhn to villi

• Functional on villi for 2-3 days only

• Recycled into lumen, digested, and reabsorbed

Front 52

Where do enterocytes get their energy?

Back 52

45% comes from nutrients passing through the diet

Front 53

What happens to the GI tract after a few days of starvation?

Back 53

Atrophies

(an optimal GI function needs a constant supply of food, rather than fasts and binging)

Front 54

Describe the Master Cleanse Diet:
1) What and how long?
2) How many kcal/day?

Back 54

1. 14 days of water, maple syrup (carbs), lemon juice, cayene pepper

2. 300 kcal/day with 0 grams of protein

Front 55

What enzymes are found in the small intestine:
1) brush border
2) pancreas

Back 55

1) Brushborder: Carbohydrates and proteins

2) Pancreas: Carbohydrates, lipids, and proteins

Front 56

What are the sources of the enzymes in the small intestine?

Back 56

The brush border and the pancreas

Front 57

Which peptide hormones affect the small intestine and how does it affect it?

Back 57

Motilin: increases motility

Front 58

How do the pancreatic enzymes reach the small intestine?

Back 58

The pancreatic juice secreted from pancreas through pancreatic duct to duodenum.

Front 59

In the pancreas, what do the:

1) Endocrine cells secrete?

2) Exocrine cells secrete?

Back 59

1) Insulin and glycagon (peptides)

2) Pancreatic juice (Bicarbonate [neutralizes acidic chyme], elecrolytes, digestive enymes)

Front 60

The majority of macronutrient digestion occurs in the small intestine due to the:

1) pancreatic enzymes
-or-
2) brushborder enzymes

Back 60

1) pancreatic enzymes

Front 61

Which hormones affect the pancreas?

Back 61

Secretin, cholecystokinin (CCK), and Gastric Inhibitory Peptide (GIP)

Front 62

How does secretin affect the pancreas?

Back 62

Stimulates bicarbonate secretion (increases pH)

Front 63

How does Cholecystokinin affect the pancreas?

Back 63

Stimulates secretion of enzymes and bicarbonate

Front 64

How does Gastric Inhibitory Peptide affect the pancreas?

Back 64

Stimulates insulin synthesis and secretion

Front 65

What does the liver do?

Back 65

Produces bile for lipid digestion

Front 66

What is bile composed of?

Back 66

bile acids & bile salts, cholesterol, phospholipids, bile pigments, water, electrolytes, and bicarbonate)

Front 67

What does the gallbladder do?

Back 67

concentrates and store bile (if it is too concentrated, cholesterol will precipitate out causing gallstones)

Front 68

Which hormone affects the gallbladder and how?

Back 68

Cholecystokinin (CCK): Contracts gallbladder releasing its contents

Front 69

Gastrin:
1. Site of release
2. Stimulant for release
3. affect on pH

Back 69

1. G cells of the antrum, duodenum & jejunum

2. antrum distention; vagus nerve impulses triggered by site/smell of food; proteins

3. decreases pH

Front 70

Secretin:
1. Site of release
2. Stimulant for release
3. Affect on pH

Back 70

1. S cells of the duodenum, jejunum & ileum

2. Acidic chyme in duodenum

3. Increases pH

Front 71

Cholecystokinin (CCK):
1. Site of release
2. Stimulant for release

Back 71

1. I cells of the duodenum, jejunum & ileum

2. fat or protein rich chyme in duodenum

Front 72

Gastric inhibitory peptide (GIP):
1. Site of release
2. Stimulant for release

Back 72

1. K cells of the duodenum and jejunum

2. Fatty acids, amino acids & some carbs

Front 73

Motilin:
1. Site of release
2. Stimulant for release

Back 73

1. M cells of the stomach, duodenum & jejunum

2. Fasted state

Front 74

1) What are bile acids and bile salts?

2) What are they made from?

Back 74

1) Like a detergent that emulsifies lipids and breaks down large fat globules into smaller droplets (increases surface area to enhance digestion)

2) Cholesterol

Front 75

Where are bile acids made?

Back 75

In the liver

Front 76

What signifies a bile acid or a bile salt (in a word)?

Back 76

cholate

Front 77

Name the conjugated bile acids:

1. bile acid + glycine

2. bile acid + taurine

Back 77

1. Glycocholate

2. Taurocholate

Front 78

What is the benefit of having bile acids when breaking down a lipid?

Back 78

Enzymes can only break the outer layer of a lipid. The bile acid (from the gallbladder) can break the lipid down more.

Front 79

What should you eat Vitamins A, D, E, & K with?

Back 79

Fat!

Front 80

1. What percent of secreted bile acids and bile salts are reabsorbed in the small intestine?

2. What happens to the remaining bile acids and bile salts?

Back 80

1. 95%

2. lost in feces which is the main mechanism for cholesterol excretion

Front 81

Where do reabsorbed bile acids go?

Back 81

1. They are transported via the portal vein to the liver for reconjugation

2. New bile and old bile are transported to the gallbladder for storage and concentration

Front 82

What does unabsorbed material from the small intestine enter the large intestine through?

Back 82

The ileocecal valve

Front 83

What are the 5 sections of the large intestine (colon)?

Back 83

1. Cecum
2. Ascending
3. Transverse
4. Descending
5. Sigmoid

Front 84

Does digestion occur in the large intestine?

Back 84

No, but fermentation does!

Front 85

1) How long does it take to pass material through the large intestine?

2) What happens to the chyme during this time?

Back 85

1) 12 to 70 hours

2) 1 L of chyme is reduced to about 200 g of feces (water is absorbed!)

Front 86

The large intestine contains more than 400 types of bacteria, what are they?

Back 86

Mostly anaerobes (ferment unabsorbed carbohydrates & proteins into shor-chain fatty acids and gas [colonic salvage])

Front 87

Feces exits via the:

Back 87

anal canal

Front 88

Most water is absorbed in the:

Back 88

Large intestine

Front 89

1) How long does it take to pass material through the large intestine?

2) What happens to the chyme during this time?

Back 89

1) 12 to 70 hours

2) 1 L of chyme is reduced to about 200 g of feces (water is absorbed!)

Front 90

The large intestine contains more than 400 types of bacteria, what are they?

Back 90

Mostly anaerobes (ferment unabsorbed carbohydrates & proteins into shor-chain fatty acids and gas [colonic salvage])

Front 91

Feces exits via the:

Back 91

anal canal

Front 92

Most water is absorbed in the:

Back 92

Large intestine

Front 93

Macronutrient digestion summary:
1. mouth
2. stomach
3. small intestine (brush border)
4. small intestine (pancreas)
5. large intestine

Back 93

1. carbs & lipids
2. lipids & proteins
3. carbs & proteins
4. carbs, lipids, & proteins
5. none

Front 94

What are the four types of absorption?

Back 94

1. passive diffusion
2. facilitated diffusion
3. active transport
4. pinocytosis

Front 95

Passive Diffusion

Back 95

Crosses membrane freely, moving from higher concentration to lower concentration

e.g. water, small fatty acids, sugar alcohols, free fatty acids, monoglycerides, cholesterol, fat-soluble vitamins (ADEK), Vit B6

Front 96

Facilitated Diffusion

Back 96

Able to cross cell membrane using a carrier (transport protein), moving from higher concentration to lower concentration

e.g. fructose, Vit C, niacin, bile acids

Front 97

What are the two steps of faciliated diffusion?

Back 97

1. Carrier protein binds compound.

2. Carrier protein releases compound inside enterocyte.

Front 98

Active Transport

Back 98

Requires carrier and energy expenditure (from ATP); lower to higher concentration (Na+/K+ pumps)

e.g. glucose, galactose, sodium, potassium, magnesium, phosphate, iodide, calcium, iron, amino acids, dipeptides, tripeptides, thiamin, folate

Front 99

What are the four steps to active transport?

Back 99

1. sodium binds carrier protein
2. compound binds carrier protein
3. carrier protein releases sodium & compound inside enterocyte
4. sodium is pumped out of enterocyte and potassium is pumped in using ATP

Front 100

Pinocytosis

Back 100

Cell membrane engulfs large molecule to move into cell (endocytosis)

e.g. whole proteins (causes allergic reactions), immunoglobulins from breast milk, Vitamin B12

Front 101

Following absorption:
1) water-soluble nutrients:
2) Fat-soluble nutrients:

Back 101

1) pass through portal vein to liver for uptake

2) travel through the lymphatic system

Front 102

Give some examples of water-soluble nutrients

Back 102

carbs, protein, minerals, B & C vitamins, short-chain FA, bile acids

Front 103

Give some examples of fat-soluble nutrients

Back 103

medium & long chaing FA, Vitamins ADEK, cholesterol, phospholipids)