Intro to BCH and Endo Valencik Flashcards
1
Q
Fat gets broken down into what three things?
A
FFA, MAG and DAG
2
Q
What does MAG get further broken down into?
A
glycerol
3
Q
(blank) are digested to yield di and monosaccharides
A
polysaccharides
4
Q
(blank) yield the component AA and di or tripeptides
A
proteins
5
Q
Fat is ingested mostly as (blank) (triglycerides, TAG), the esters of glycerol and fatty acids.
A
triacylglycerols
6
Q
During digestion a stepwise removal of fatty acid molecules takes place yielding (blank) and (blank)
A
free fatty acids
2-monoacylglycerols.
7
Q
What are the three main phases of digestion?
A
mechanical phase
hydrolysis
tranposrt
8
Q
The mechanical phase begins in the mouth with (blank( and continues into the stomach with (blank)
A
mastication, peristalsis
9
Q
Hydrolysis begins in the (blank), continues in the (blank) and the major players in hydrolysis are in the (blank)
A
mouth
stomach
small intestine
10
Q
After the completion of hydrolysis, at the surface of the (blank), we have transport of small molecules across the (blank) where they can enter the blood stream
A
small intestine
intestinal wall
11
Q
What does the mechanical phase consist of?
A
mastication and peristalsis
12
Q
What is the goal of the mechanical phase?
A
to homogenize nutrients
13
Q
What are the 3 functions of gastric acid?
A
1: kill microbes
2: denature proteins
3: makes the pH optimum for activation and enzymatic activity of pepsin
14
Q
What enzymes aid with hydrolysis in the mouth?
A
α-amylase (pH 6.5-7)
Lingual lipase
Lysozyme (β 1,4 bonds
15
Q
What kind of bonds do lysozymes hydrolyze?
A
beta 1,4 bonds
16
Q
What pH is α-amylase optimal at?
A
pH of 6.5-7
17
Q
What enzymes aid with hydrolysis in the stomach?
A
HCl pH 2.0
pepsin
18
Q
What is the optimal pH of HCl?
A
2.0
19
Q
What enzymes aid with hydrolysis in the small intestine?
A
α-amylase (isoenzyme) Glycosidases Proteases Lipases Bacteria `
20
Q
The (blank) is where protein digestion is initiatied.
A
stomac
21
Q
(blank) kills microorganisms, denatures protein, creates the pH necessary (<5.0) to first cleave pepsinogen and than the pH necessary for pepsin activity (≈ 2.0).
A
HCl
22
Q
What allows for the cleavage of pepsinogen and the activity of pepsin?
A
optimal pH created by HCl
23
Q
When acid hits the duodenum, the (blank) secretes bicarbonate to neutralize the chyme
A
pancrease
24
Q
Hydrolysis begins at the mouth where (blank) starts to digest carbohydrates.
A
alpha amylase
25
(blank) binds to the surface of fat globules in the mouth and begins liberating free fatty acids.
lingual lipase
26
the (blank) secrete lysozome
salivary glands
27
(blank) primarily digests beta 1,4 glycosidic bonds found in the peptidoglycans that make up the bacterial cell walls. This helps to kill off the bacteria that you just happen to ingest.
lysozyme
28
In the stomach (blank) begins to denature proteins and drops the pH of the food creating an environment where pepsinogen is cleaved to pepsin.
HCl
29
Pepsin is an (blank) that cleaves proteins.
endopeptidase
30
Once chyme is released into the duodenum, (blank) are released and activated to continue the hydrolysis.
pancreatic zymogens
31
α-amylase (isoenzyme), Glycosidases, Proteases and Lipases (blank) the hydrolysis carbohydrates, proteins and fats
complete
32
There is also hydrolysis by (blank) that reside in the intestinal tract.
bacteria
33
What is an an isoenzyme of salivary alpha amylase?
pancreatic alpha amylase
34
The enzymes in the salivary glands are mostly there for (blank)
cleaning teeth
35
Once you have all the food digested to the appropriate metabolites, the metabolites will be absorbed into the (blank)
intestinal epithelial cells
36
What metabolites can be absorbed/transported from carbs? proteins? fat?
monosaccharides
AAs, di- or tri- peptides
free fatty acids, 2 monoacylglycerides, glycerol
37
What four hormones are secreted as endocrine hormones in the GI tract?
cholecystokinin
gastrin
histamine
secretin
38
The chyme (carbs, protein, lipids and acid) from the stomach enters the duodenum and stimulates the ENDOCRINE secretion of (blank) and (blank)
cholecystokinin (CCK) and secretin.
39
Food entering the stomach stimulates an increase in (blank) secretion which stimulates histamine which stimulates HCL. HCl will then decrease pH which will increase (blank) and decrease gastrin.
gastrin
| somastatin
40
(blank) (neurotransmitter) is the major neurotransmitter that stimulates electrolyte secretion in the intestinal mucosa.
acetylcholine
41
(blank) is a peptide that regulates fluid secretion at the brush border (acts on guanylyl cyclases)
guanylin
42
Decreasing pH down-regulates gastrin secretion via (blank).
somatostatin
43
(blank) stimulates the watery/bicarbonate (HCO3-) phase of pancreatic excretions.
Secretin
44
(blank) stimulates the secretion of zymogens from the pancreas, increases bile production in the liver and stimulates contraction of the gallbladder (bile secretion).
CCK (pancreozymin)
45
How does the pancreas protect itself from the digestive enzymes it produces?
proenzymes (aka zymogens)
46
is enzyme secretion and endocrine or exocrine process?
exocrine
47
The cytoplasm of exocrine cells is completely filled with (blank), the site of synthesis of the zymogens of many digestive enzymes
Rough endoplasmic reticulum
48
The zymogens are concentrated in membrane-enclosed transport particles called (blank)
zymogen granules.
49
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 (blank). The collecting ducts ultimately lead to the (blank) and then to the small intestine.
About 30g of digestive enzymes/day are secreted.
exocytosis
| pancreatic duct
50
(blank) are Inactive gastric and pancreatic peptidases (or lipases) stored in secretory granules.
zymogens
51
Pepsinogen is made by the chief cells in the (blank) and the 44 amino acid N-terminus is not cleaved until it is at pH
stomach
| ≈ 2.0.
52
The pancreas, in turn, secretes what 5 pro-enzymes?
trypsinogen, chymotrypsin, proelastase, procarboxypeptidases, prolipases and prophospholipases.
53
When chyme enters into the duodenum, it stimulates the intestinal endocrine cells to secrete (blank).
hormones
54
hormones secretion stimulated by chyme in the duodenum then stimulate (blank) and (blank) to secrete peptidase.
pancreatic acinar cells and intestinal mucosal epithelial cells
55
The pancreatic acinar cells secrete (blank) and the intestinal mucosal epithelial cells secrete (blank)
trypsinogen
| enteropeptidase
56
The enteropeptidase cleaves (blank) thereby activating trypsin. The trypsin in turn can cleave trypsinogen to generate more active trypsin.
trypsinogen
57
The (blank) also synthesizes a trypsin inhibitor. This provides additional protection to the pancreas if trypsin is activated prior to release from the pancreas. (blank) then cleaves a number of pro-enzyme into their active form.
pancreas
| Trypsin
58
85% of patients with cystic fibrosis suffer from (blank). In this disorder what are blocked? what type of vitamins are not efficiently absorbed
pancreatic insufficiency
pancreatic ducts (no enzymes can get to small intestine)
fat-soluble vitamins
59
what are the two typical dietary carbs?
sucrose and starch
60
Starch has 2 structural forms, what are they?
| How can you tell them apart?
amylose and amylopectin
amylose is in a linear chain with alpha 1,4 glycosidic bonds, amylopectin is a plant form of glycogen with alpha 1,4 and 1,6 glycosidic bonds
61
amylose has what type of bonds?
| amylopectin has what type of bonds?
alpha 1,4
| alpha 1,4 and 1,6
62
What are the two most common disaccharides?
| most common monosaccharids?
sucrose and lactose
| fructose and glucose
63
(blank)is a disaccharide that consists of a galactose linked to glucose via a beta 1,4 glycosidic bond.
lactose
64
a-amylase is a (blank)
endoglycosidase.
65
alpha-Amylase Substrate cleaves what but not what?
cleaves alpha 1,4 glycosidic bonds
| but not alpha 1,6 bonds.
66
following hydrolytic cleavage with alpha amylase what are the products? Can these products be directly abosorbed by the small intestine?
maltose, maltotriose, and alpha-limit dextrins
| NO
67
What causes the gas and bloating from lactose intolerance?
bacteria breaking down lactose
68
All disaccharidases, except (blank), are inducible (the more you eat – the more enzyme you make).
lactase
69
The final step in carbohydrate hydrolysis occurs at the (blank) surface. Once maltose, maltotriose and limit dextrins reach the mucosal surface there are a number of enzymes that are bound to the membrane.These glycosidases (blank) the small polysaccharides into monosaccharides that can be absorbed.
mucosal
| cleave
70
(blank) are anchored to the surface of microvilli in the intestinal brush border.
disaccharidases (ectoenzymes)
71
Patients lacking functional SGLT1 have severe gastrointestinal symptoms due to malabsorption of (blank) and (blank)
glucose and galactose
72
Na and Glucose are actively transported across the apical portion into the epithelial cell. Once there, glucose moves the the basal surface it passes passively into the blood via (blank)
GLUT 2 (a uniporter)
73
At least two carrier-mediated transport mechanisms exist for monosaccharides at the enterocyte luminal surface, what are they and what sugar uses them?
1: Na-cotransport (SGLT1) (glucose and galactose)
2: Na-independent transporter (Glut-5) facilitated diffusion (FRUCTOSE)
74
Name what sugar uses this, where it goes, and if it is active or passive:
GLUT 5
SGLT 1
GLUT 2
GLUT 5: faciliated/passive, fructose into epithelial cell
SGLT1: glucose and galactose into epithelial cell
GLUT 2: all sugars into blood stream
75
The transport of monosaccharides into the cell is the (blank) in carb metabolism
rate limiting step in carbohydrate metabolism
76
Is it possible for glucose or galactose to passively diffuse into epithelium?
yes it is just really really slow
77
The preliminary stage for protein digestion is (blank) which takes place in the stomach. Nonspecific hydrolysis then occurs and (blank) is secreted by chief cells.
denaturation
| pepsinogen
78
Is acid and pepsin essential for protein digestion?
no
79
polypeptides and free amino acids (now called peptones) enter the gut lumen. The low pH of the chyme stimulates (blank) and (blank) which in turn stimulates bicarb and zymogen secretion.
secretion and Cholecystokinin (CCK) secretion
80
What stimulates bicarb production?
secretin
81
summarize the digestions of protein:
1. Low pH of stomach denatures proteins.
2. Nonspecific hydrolysis occurs and pepsinogens are secreted.
(Note: Neither acid or pepsin in the stomach is essential for protein digestion.)
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.
82
pepsin is both a (blank) peptidase and a (blank) peptidase
endopeptidase and exopeptidase
83
Zymogens in stomach are (blank) and (blank)
pepsinogen A and B.
84
The exopeptidases, carboxypeptidase A and B are considered (blank) because their enzymatic activity is dependent upon zinc.
metalloproteinases
85
What are the four common endopeptidases?
pepsin, trypsin, chymotrypsin, elastase
86
What is a carboxyl protease with a specificity for the NH side of hydrophobic amino acids?
pepsin
87
What is a serine protease with a specificity for CO side of basic amino acids?
trypsin
88
What is a serine protease with a specificity for CO side of hydrophobic amino acids?
chymotrypsin
89
What is a serine protease with a specificity for CO side of small amino acids?
elastase
90
What is a metalloprotease (Zn2+) with a specifity for a hydrophobic amino acids at C terminus
carboxypeptidase A
91
What is a metalloprotease (Zn2+) with a specificity for a basic amino acid at the C- terminus?
carboxypeptidase B
92
The final digestion of proteins occurs at the (blank) surface. Here the peptide bonds between AA are hydrolyzed by endo- and exopeptidases. Because of this, there are numerous (blank) on the surface of the small intestine. This transport is energy dependent and is thus active transport via symport with (blank).
luminal
AA transporters
sodium
93
90% of fats are (blank)
triglycerides
94
what is phosphatidylcholine important for?
making up membranes (liver makes this)
95
How can you digest fats since they are hydrophobic?
you emulsify them
96
What makes up a triglyceride?
3 FA and a glycerol
97
Summarize the emulsification of triglycerides in the stomach?
1: melt TAGS via core body temp
2: peristaltic movements help form a lipid emulsion
3: acid-stable salivary and gastric lipases produce small amounts of fatty acids
4: Di/monoglycerides act as emulsifiers
5: Dietary phospholipids, fatty acids also aid emulsification and promote lipase binding
98
What is the main goal of emulsification?
to increase surface area
99
Once fats leave the stomach and enter the duodenum, what happens?
bile and lipases are added
100
(blank) triggers bile synthesis in the liver and its release from the gallbladder.
CCK
101
(blank) acts as a detergent and aids in the emulsification of lipids.
Bile
102
(blank) also triggers release of pancreatic lipase and colipase to hydrolyze TAGs
CCK
103
(blank) triggers release of bicarbonate to neutralize stomach acids
secretin
104
Once in the duodenum (blank) and (blank) are added to aid in emulsification and digestion. As chime enters the duodenum the acinar endocrine cells secrete (blank) and (blank).
lipases and bile
| cholecystokinin and secretin
105
(blank) are planar fat emulsifiers
bile salts
106
(blank) has a hydrophilic and hydrophobic surface. It is synthesized in the liver and conjugated with glycine and taurine.
bile salts
107
(blank) is the most abundant bile salt in humans
glycocholate
108
Do bile acids or bile salts reversibly from stable aggregates (micelles)
bile acid
109
The conjugation of bile acids changes he pKA of the molecules, and create (blank)
micelles
110
What is the overall sequence of fat digestion?
1: mouth-> fat begins to be hydrolyzed by lingual lipase
2: stomach-> melting, peristalsis
3: duodenum-> pancreatic lipase and colipase bind to fat globule and create FA and 2 monoacylglycerol
4: -> formation of micelles
5: micelles ferry lippids through intestinal mucosa
6: micelles taken up into intestinal epithelial cells
111
(blank) is generally anaerobically fermented and digested by the bacterial flora beginning in the lower ileum.
Fiber
112
(blank) is generally plant polymers such as cellulose, inulin, pectin, lingnin, suberin
Fiber
113
Bacterial digestion of fibers produce (blank) and (blank). What kind of these?
Gases: Hydrogen, Methane, CO2
| Organic acids: Acetate, Propionate, Byrutate, Lactate
114
Where does digestion of fiber take place?
lower illeum
115
What are the types of fibers?
cellulose, inulin, pectin, lignin, suberin
116
The bulk of nutrients are absorbed in the (blank)
ileum
117
The (blank) is involved in the absorption of water and electrolytes, and participates in the recirculation of the bile acids to the liver.
large intestine
