B5-095 GI Physiology II Flashcards
(99 cards)
1
Q
describe pancreatic morphology
A
acinar + ductal cells = acinus
multiple acini =lobule
multiple lobules -> main pancreatic duct
2
Q
how does secretin affect the amount of HCO3-, Cl- and amylase
A
HCO3-: increase
Cl-: decrease
amylase: decrease
3
Q
the fall in amylase concentration after secretin reflects
A
dilution
volume increases
4
Q
stimulate acinar cell secretion of zymogen granules
5
A
- VIP
- secretin
- CCK
- ACh
- maybe gastrin?
5
Q
Ca++ oscillations are a hallmark of stimulation by
2
A
CCK and ACh
6
Q
potent stimulators of Cl- secretion
2
A
CCK and ACh
7
Q
the movement of […] into the lumen makes transepithelial voltage more negative, driving […} into the lumen via tight junctions
A
Cl-
Na+
8
Q
most powerful stimulus for HCO3- secretion
A
secretin
9
Q
activates cAMP, stimulates PKA, and phosphorylates CFTR
A
secretin
10
Q
activates Gq -> stimulates PLC to release DAG and IP3, releasing Ca++ from stores
A
ACh
11
Q
the lumen negative voltage pulls Na+ and water into the lumen via
A
tight junctions
12
Q
zymogens secreted by pancreas
5
A
- trypsinogen
- chymotrypsinogen
- proelastase
- Procarboxypeptidase A
- Procarboxypeptidase B
13
Q
activates trypsinogen to trypsin
A
enterokinase
and trypisin can too
14
Q
activates a majority of the zymogens in a sequential fashion
A
trypsin
15
Q
stimulant of cephalic pancreatic secretion
A
sight
smell taste
mastication
16
Q
regulatory pathway of the cephalic phase of pancreatic secretion
A
vagal pathways
17
Q
the cephalic phase of pancreatic secretion is responsible for […]% of secretions
A
25
18
Q
stimulant for the gastric phase of pancreatic secretion
A
distension
gastrin?
19
Q
regulatory pathway for the gastric phase of pancreatic secretion
A
vagal-cholinergic
20
Q
the gastric phase of pancreatic secretion is responsible for […]% of secretion
A
10-20
21
Q
stimulant of the intestinal phase of pancreatic secretion
A
amino acids
fatty acids
H+
22
Q
regulatory pathway of the intestinal phase of pancreatic secretion
A
CCK
secretin
enteropancreatic reflexes
23
Q
the intestinal phase of pancreatic secretion is responsible for […]% of secretions
A
50-80
24
Q
protein and lipid products simulate I cells to secrete
A
CCK
stimulates vagus nerve to release ACh
25
H+ stimulates S cells in duodenum to secrete
secretin
| stimulates HCO3- secretion
26
# how does this mechanism protect the pancreas from autodigestion?
packaging of many digestive proteins as zymogens
percursor proteins lack enzymatic activity
27
# how does this mechanism protect the pancreas from autodigestion?
selective sorting of secretory proteins and storage in zymogen granules
restricts the interaction of secretory proteins with other cellular compartments
28
# how does this mechanism protect the pancreas from autodigestion?
protease inhibitors in the zymogen granule
block the action of prematurely activated enzymes
29
# how does this mechanism protect the pancreas from autodigestion?
condensation of secretory proteins at low pH
limits the activity of active enzymes
30
# how does this mechanism protect the pancreas from autodigestion?
non digestive proteases
degrade active enzymes
31
morphology of salivary glands
acinar cells line acinus
intercalated cells line acinar duct
striated cells line striated duct
32
parasympathetic autonomic control of salivation is regulated by
ACh
33
sympathetic autonomic control of salivation is regulated by
norepinephrine
34
what two components of saliva contribute to lubrication and antimicrobial properties?
proline-rich proteins
mucin glycoproteins
35
enzymes present in saliva
| 4
* a amylase
* lipase
* ribonuclease
* kallikrein
36
how does the electrolyte composition of saliva change with stimulation?
Na:
K:
Cl:
Total CO2:
Na: increases
K: decreases
Cl: increases
bicarb: increases
| basically creates a more basic environment
37
does the large inestine have villi?
no
38
does the large intestine provide nutrient absorption?
no
39
does the small or large intestine have active K+ secretion?
large
40
does the small or large intestine have active Na+ absorption?
both small and large
41
* long lived
* antimicrobial
* secrete defensins, lysozyme, TNFa
paneth cells
42
anti-helminth cells
tuft cells
| use chemoreceptors
43
maintain mucosal barrier of intestinal epithelium
goblet cell
44
deliver luminal antigens to APCs
goblet cells
45
secrete cytokine and chemokines to stimulate TH2 response, promotes tissue restoration
goblet cells
46
overall, how much fluid is excreted in feces?
100 mL
47
describe the fluid balance in GI tract
in: 8.5 L/day
oral: 2 L
secreted: 6.5 L
reabsorbed: 8.4 L
| only about 100mL lost through feces/day
48
what bacterial endotoxins utilize the cAMP second messenger pathway?
| 2
cholera
E. coli
49
what bacterial endotoxins utilize the cGMP second messenger pathway?
| 2
E. coli
Yersinia
50
what bacterial endotoxins utilize the Ca++ second messenger pathway?
C. diff
51
what hormones/neurotransmitters utilize the cAMP second messenger pathway?
VIP
52
what hormones/neurotransmitters utilize the cGMP second messenger pathway?
| 1
guanylin
53
what hormones/neurotransmitters utilize the Ca++ second messenger pathway?
| 3
ACh
bradykinin
serotonin
54
what immune cell products utilize the cAMP second messenger pathway?
| 2
histamine
prostaglandins
55
what laxatives utilize the Ca++ second messenger pathway?
| 1
bile acids
56
primary mechanism for postprandial Na+ absorption
nutrient couple Na+ absorption in jejunum and ileum
57
electroneutral Na-H exchange at the apical membrane is stimulated by
high pH of HCO3- rich luminal contents
58
primary mechanism for interdigestive Na absorption
Na-H and Cl-HCO3 exchange coupled by intracellular pH
| results in electroneutral NaCl absorption
59
in electrogenic Na absorption, the apical step of Na movement occurs via
ENaC channels
60
Na/Glucose or Na/Amino acid cotransporters occurs where in GI tract?
high Na absorption at jejunum
low Na absorption at ileum
| primary mechanism of post prandial Na absorption
61
Na-H exchanger occurs where in GI tract?
moderate Na absorption at duodenum
high Na absorption at jejunum
62
parallel Na-H and Cl-HCO3 exchangers occur where in GI tract?
moderate absorption at ileum and proximal colon
| primary mechanism for interdigestive Na absorption
63
epithelial Na channels occur where in GI tract?
high Na absorption in distal colon
| ENaC channels
64
passive Cl- absorption occurs where in GI tract
high Cl- absorption in jejunum
low Cl- absorption in ileum
high Cl- absorption in distal colon
65
Cl-HCO3 exchanger occurs where in GI tract?
moderate Cl- absorption in ileum
high Cl-absorption in proximal colon
moderate Cl- absorption in distal colon
66
parallel Na-H and Cl-HCO3 exchangers occur where in digestive system?
moderate Cl- absorption in ileum and proximal colon
| through interdigestive period
67
passive K+ absorption occurs where in GI tract?
low K+ transport in jejunum and ileum
| via solvent drag
68
in the small intestine, K+ absorption occurs via
solvent drag
69
active K+ secretion occurs in what parts of the GI tract?
low K+ transport in proximal colon
high K+ transport in distal colon
70
throughout the colon, passive K+ secretion occurs via
tight junctions
| driven by negative transepithelial voltage
71
active K+ secretion occurs where in the GI tract?
moderate K+ transport in proximal colon
very low K+ transport in distal colon
72
throughout the colon, active K+ secretion is
transcellular
73
active K+ absorption occurs where in the GI tract?
low K+ transport in distal colon
74
in the distal colon, active K+ absorption is
transcellular
75
products macrophages produce that affect intestinal ion transport
| 2
prostaglandins
O2 radicals
76
products mast cells produce that affect intestinal ion transport
| 1
histamine
77
products neutrophils produce that affect intestinal ion transport
| 2
eicosanoids
platelet-activating factor
78
products fibroblasts produce that affect intestinal ion transport
| 2
eicosanoids
| bradykinin
79
mast cell activation causes histamine release to stimulate the release of [...] into the lumen
Cl-
80
activation of the immune response in the GI tract produces numerous and redundant pathways to increase [...] secretion
Cl-
81
anytime Cl- is moved into the lumen, we're moving [...] and [...] into the lumen
water and sodium
82
mast cells release histamine, which can activate the [...] to produce cramping with diarrhea
enteric neurons
83
directly activates epithelial secretion of Cl- by the ENS
ACh
84
indirectly increases Cl- secretion following release from Mast Cells via PGE2 release
IL-2
85
what toxin increases Ca++/CAMK activity?
C. diff
86
secrete CCK in response of dietary fat and protein
I cells
87
secretes somatostatin to inhibit gastic acid release
D cells
88
have specific chemoreceptors to
"taste" helmiths
tuft cells
89
what cells are important in the feedback to stop eating?
I cells and L cells
90
located in the duodenum and jejunum, allowing for quicker feedback to stop feeding
I cells
91
slow gastric empyting which may be perceived as a feeling of fullness
| macromolecules
protein and lipids
92
activates Cl- secretion in acinar cells, resulting in increased NaCl and water transport to lumen
gastrin
93
activates chloride secretion in salivary glands
ACh
94
activate Cl- secretion in pancreas
| 2
CCK and secretin
95
released out of basolateral surface of I cells following stimulation of fat entry into duodenum
CCK
96
sends signals via the vagus to the CNS and then to the pancreas to increase acinar secretions
CCK
97
causes slowing of gastric emptying
CCK
98
causes contraction of the gallbladder
CCK
99
produced by I cells
CCK
