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Block 3 Week 1 Meg > Valencik: Intro to the Endocrinology of Digestion > Flashcards

Valencik: Intro to the Endocrinology of Digestion Flashcards

1
Q

Polysaccharides are digested to yield (blank)

A

di and monosaccharides

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2
Q

Proteins yield (blank)

A

component amino acids and di or tripeptides

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3
Q

Fat is ingested mostly as (blank), the esters of glycerol and fatty acids

A

triacylglycerides

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4
Q

During digestion, a stepwise removal of fatty acid molecules takes place yielding what?

A

Free fatty acids and 2 monoacylglycerols

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5
Q

Three main phases of digestion

A
  1. Mechanical phase
  2. Hydrolysis
  3. Transport
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6
Q

The mechanical phase begins in the mouth with (blank). It continues to the stomach with (blank).

A

Mastication; peristalsis

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7
Q

The second phase of digestion is (blank). It begins in the mouth and continues in the stomach. Where are the major players in hydrolysis found?

A

hydrolysis; small intestine

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8
Q

After hydrolysis is complete, at the surface of the small intestine, we have (blank) of small molecules across the intestinal wall where they can enter the bloodstream.

A

transport

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9
Q

2 locations of mechanical phase
3 locations of hydrolysis phase
1 location of transport phase

A
  • mouth, stomach
  • mouth, stomach, sm intestine
  • sm. intestine
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10
Q

3 functions of gastric acid

A
  1. kill microbes
  2. denature protein
  3. makes the pH optimum for activation and enzymatic activity of pepsin
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11
Q

What is the goal of peristalsis?

A

To homogenize the nutrients

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12
Q

In the mouth, (blank) hydrolyzes beta 1,4 glycosidic bonds in bacterial cell wall peptidoglycans. This helps to kill off any bacteria that was ingested.

A

lysozyme

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13
Q

Where is protein digestion initiated?

A

Stomach

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14
Q

Alpha-amylase begins to digest (blank) in the mouth. It works best at what pH?

A

carbohydrates; pH of 6.5-7

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15
Q

What does lingual lipase do?

A

Binds to the surface of fat globules and liberates free fatty acids

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16
Q

(blank) denatures proteins in the stomach at an optimal pH of (blank). This allows pepsinogen to be cleaved to (blank)

A

HCl; pH of 2.0; pepsin

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17
Q

5 important enzymes in the small intestine for hydrolysis

A
  1. alpha amylase (isoenzyme)
  2. glycosidases
  3. proteases
  4. lipases
  5. bacteria
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18
Q

What metabolites can be absorbed in the small intestine?

A

From carbohydrates we can transport monosaccharides
from proteins we transport di-or tri-peptides and from fat we transport free fatty acids, 2-monoacylglycerides and glycerol.

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19
Q

4 important hormones

A

Cholecystokinin
Gastrin
Histamine
Secretin

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20
Q

Describe what happens when food enters the stomach.

A

Food entering stomach stimulates gastrin secretion, histamine and HCl are secreted, decreases pH, increases somatostatin, and then thru negative feedback, decreases gastrin.

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21
Q

The chyme (carbs, protein, lipids and acid) from the stomach enters the duodenum and stimulates the ENDOCRINE secretion of what?

A

cholecystokinin (CCK) and secretin.

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22
Q

(blank) stimulates the watery/bicarbonate (HCO3-) phase of pancreatic excretions.

A

Secretin

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23
Q

What three things does CCK do?

A
  1. stimulates the secretion of zymogens from the pancreas
  2. increases bile production in the liver
  3. stimulates contraction of the gallbladder (bile secretion).
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24
Q

How does the pancreas protect itself from the digestive enzymes it produces?

A

There is an inactive form of enzymes

25
Q

Describe enzyme secretion

A

The cytoplasm of exocrine cells is completely filled with rough ER, the site of synthesis of the zymogens of many digestive enzymes.
The zymogens are concentrated in membrane-enclosed transport particles called zymogen granules.
In the pancreas, when an exocrine cell is stimulated, its plasma membrane fuses with the zymogen granule membrane and zymogens are released into the lumen of the collecting duct by exocytosis.
The collecting ducts ultimately lead to the pancreatic duct and then to the small intestine.

26
Q

Inactive gastric and pancreatic peptidases (or lipases) stored in secretory granules

A

Zymogens

27
Q

The pancreatic acinar cells secrete (blank) and the intestinal mucosal epithelial cells secrete (blank)

A

trypsinogen; enteropeptidase

28
Q

The enteropeptidase cleaves trypsinogen thereby activating (blank).

A

trypsin

29
Q

The trypsin in turn can cleave trypsinogen to generate more active (blank). The pancreas also synthesizes a trypsin (blank)

A

trypsin; inhibitor

30
Q

How many kcals do carbs generate? Fat? Protein? Alcohol?

A

4kcal/g
9.3kcal/g
4-4.5kcal/g
7kcal/g

31
Q

What is sucrose?

A

It is a glucose molecule linked by a beta 1 2 glycosidic bond to fructose

32
Q

What are the two dietary carbs?

A

Sucrose and starch

33
Q

Two starches

A

Amylose; amylopectin

34
Q

Amylose has (blank) bonds, while amylopectin has (blank) bonds.

A

alpha 1-4 glycosidic bonds; alpha1-4 and alpha 1-6 glycosidic bonds

35
Q

What are the most common disaccharides?

A

Sucrose and lactose

36
Q

What are the most common monosaccharides?

A

Fructose and glucose

37
Q

What is lactose?

A

A disaccharide consisting of galactose linked to glucose via a beta1-4 glycosidic bond

38
Q

Which starch is more linear?

A

amylose

39
Q

Alpha amylase cleaves which bonds? Which bonds can it not digest?

A

Cleaves alpha 1-4

Cannot cleave alpha 1-6

40
Q

Because none of the products of its cleaving can be absorbed in the small intestine, alpha amylase is known as a (blank)

A

endoglycosidase

41
Q

Where does final hydrolysis occur?

A

At the mucosal surface

42
Q

Common symptoms of lactose intolerance? Causes?

A

flatulence and diarrhea; caused by the osmotic activity of lactose and the gas and acids produced by bacteria hydrolyzing lactose

43
Q

Patients lacking functional (blank) have severe gastrointestinal symptoms due to malabsorption of glucose and galactose

A

SGLT1

44
Q

To get glucose into the epithelial cell, is it active or passive transport?

A

Active; requires an ATPase

45
Q

When glucose moves to the basal surface of the cell, it passes into the blood via (blank), a passive glucose uniporter

A

GLUT2

46
Q

What is the Rate Limiting Step in carbohydrate metabolism?

A

Absorption/transport of monosaccharides

47
Q

The preliminary stage for protein digestion is (blank) which takes place in the stomach.
Nonspecific hydrolysis occurs and (blank) is secreted by chief cells.

A

denaturation; pepsinogen

48
Q

4 steps in protein digestion

A
  1. Low pH of stomach denatures proteins.
  2. Nonspecific hydrolysis occurs and pepsinogens are secreted.
  3. The resultant peptone (polypeptides + free amino acids) enter the duodenum.
  4. The low pH of this chyme stimulates secretin and CCK secretion leading to pancreatic bicarbonate and zymogen secretion.
49
Q

What makes up a triacylglycerol?

A

Glycerol + 3 FA

50
Q

5 steps in emulsifying TAGs in the stomach

A

Melt
Peristaltic movements help form a lipid emulsion.
Acid-stable salivary and gastric lipases produce small amounts of fatty acids.
Di/monoglycerides act as emulsifiers.
Dietary phospholipids, fatty acids also aid emulsification and promote lipase binding

51
Q

Once in the duodenum (blank) and (blank) are added to aid in emulsification and digestion

A

lipases; bile

52
Q

Bile salts have a (blank) and (blank) surface

A

hydrophilic and hydrophobic

53
Q

Bile acid is synthesized in the (blank) and conjugated with (blank) or taurine

A

liver; glycine

54
Q

What is the most abundant bile salt in humans?

A

Glycocholate

55
Q

Sequence of fat digestion

A

Lingual lipase starts fat digestion in the stomach. Large fat droplets break down into smaller ones.
Pancreatic lipase binds to smaller fat droplets and releases free FA and monoacylglycerol. These products diffuse to micelles where they are taken to the brush border of enterocytes and diffuse across

56
Q

Where are the bullk of nutrients absorbed?

A

In the ileum

57
Q

What is the Na+ independent transporter that takes fructose into the enterocyte?

A

GLUT5

58
Q

What is the Na+ dependent transporter that takes glucose and galactose into the enterocyte?

A

SGLT1

59
Q

The protonated form of bile salts are called (blank)

A

bile acids

Block 3 Week 1 Meg (17 decks)

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