GI Secretions Flashcards
1
Q
what secretion is in saliva
A
HCO3- K+ hypotonic α amylase lingual lipase
2
Q
what increase salivary secretion
A
parasympathetic & sympathetic
3
Q
what decrease salivary secretion
A
sleep, dehydration, atropine
4
Q
what secretion in gastric secretion
A
HCl
mucin
pepsinogen
intrinsic factor
5
Q
what increase secretion of HCl
A
gastrin
Ach
histaine
6
Q
what increase secretion of pepsinogen
A
PNS
7
Q
what decrease gastric secretion
A
H+ in stomach chyme in duodenum somatostatin atropine cimetidine omeprazole (prilosec)
8
Q
what are the three major salivary glands
A
parotid
submandibular
sublingual
9
Q
what does parotid gland secrete
A
secretes salt, water and enzymes that moisten food to enhance taste and digestion, provide some antibacterial action, and keep a more alkaline pH to protect teeth and mouth from gastric and food acids
10
Q
what do submandibular and sublingual glands secrete
A
mostly mucus
11
Q
what kinds of cells in parotid gland
A
serous cells
12
Q
what do serous cells secrete
A
watery fluid with ions and enzymes, not mucousy
13
Q
what kinds of cells in submandibular and sublingual glands
A
mixed mucous
serous cells
14
Q
what do mucous cells secrete
A
mucin glycoprotein
15
Q
what is xerostomia
A
deficient salivation
16
Q
pts with xerostomia have greater risk for
A
dental cavities
17
Q
describe serous acinar cells
A
zymogen granules that contain amylase
18
Q
describe mucus acinar cells
A
secrete glycoprotein mucins
19
Q
describe ductal cells
A
alter electrolyte concentrations in saliva
20
Q
describe myoepithelial cells
A
eject saliva into mouth when stimulated by neuronal input
21
Q
what is the functional unit of the salivary gland
A
salivon
22
Q
the salivon consists of
A
acinus, the intercalated duct, the striated duct, and the excretory (collecting duct).
23
Q
what is function of kallikrein
A
enzyme that acts on kininogen to release bradykinin – vasodilator which accounts for high salivary blood flow during increased salivary activity
24
Q
draw out salivon
A
pg 9
25
what cells make initial saliva
acinar cells
26
what cells modify initial saliva
ductal cells
27
describe the fluid produced by acicnar cells that makes initial saliva
isotonic fluid w/ same electrolyte composition as plasma
28
striated duct epithelium is impermeable to
water
29
striated duct epithelium transports
salts
30
describe absorption and secretion of striated duct
abosrbs sodium and Cl-
| secretes K+ and HCO3-
31
the striated duct epithelium does what to final secretion
makes it hypotonic but alkaline
32
saliva is always _____ to plasma
hypotonic
33
describe flow rates and what they do regarding saliva and ductal cells
low flow rate: the ductal cell has time to exchange ions. the result is that the saliva is much different from plasma, it has low concentrations of Na+ and Cl- and high concentation of K+
high flow rate: the ductal cell has less time to exhange ions. result is that saliva is not as much different from plasma.
34
kallikrein acts on
kininogen
35
kininogen releases what when akllikrein acts on it
lysyl-bradykinin
36
what does lysyl-bradykinin do
causes dilation of blood vessels supplying salivary glands
37
what does vasoactive intestinal peptide do
increases blood flow to salivary glandq
38
what does VIP stand for
vasoactive intestinal peptide
39
draw out the salivary ductal cell and the ion exchange in it
pg 11
40
blood flow in salivary glands is controlled by what system
PNS
41
draw out the PNS and SNS regulation of saliva
pg 14
42
what are the four major components of gastric juice
HCl
pepsinogen
intrinsic factor
mucus
43
what is function of HCl
acidic
| initiates process of digestion
44
what is function of pepsinogen
initiates process of protein digestion
45
what is function of intrinsic factor
needed for absorption of vitamin B12
46
what part of stomach secretes HCl, intrinsic factor, and pepsinogen
body and fundus
47
what part of stomach secrete gastrin & somatostatin
antrum
48
all regions of stomach secrete
mucus
49
oxyntic also means
acid secreting
50
describe oxynitic gland of stomach
in body
| empties secretory products, containsmucus cells, parietal cells, chief cells
51
what do mucous neck cells secrete
clear mucus
52
what do parietal cells secrete
HCl
| intrinsic factor
53
what do chief cells secrete
pepsinogen
54
what kind of glands are in antrum of stomach
pyloric glands
55
what kinds of cells in pyloric glands
G cell
| mucous cell
56
what do g cells secrete
gastrin
57
what do mucous neck cells in antrum secrete
mucus
HCO3-
pepsinogen
58
parietal cells are also called
oxyntic cells
59
chief cells are also aclled
peptic cells
60
the reason we need such a low pH in stomach is for
pepsinogen to become active → pepsin, to begin protein digestion
61
how do hydrogen ions enter stomach
H K ATPase pump
62
what cell are protons secreted from
apical membrane of parietal cells
63
what drug inhibits H, K ATPase
omeprazole
64
omeprazole is used in treatment of
ulcers, reduces H+ secretion
65
overal, what is the net secretion and abosrption of parietal cell
net secretion HCl and net absorption HCO3-
66
draw out the secretion and absorption of parietal cell
pg 23
67
what three subtances stimulate H+ secretion by parietal cells
ACh
histamine
gastrin
68
sympathetic acts mainly on what salivary glands
sublingual
69
three ways to stimulate acid secretion
gastrin
Ach
Histamine (they all potentiate each other)
70
what does potentiate mean
enhances the response of the other stimulus
71
how much secretions are produced each day
9L/day
72
parotid gland is mainly what cells
serous
73
what side of ductal cell is the sodium potassium exchanger
basolateral (side of blood)
74
why do you need bicarbonate in saliva
enzymes work at more alkaline pH
75
where is Ach released from
vagus nerves
76
ACh binds to what receptors
M3
77
second messengers for ACh are
IP3/Ca2+
78
what blocks muscarinic receptors on parietal cells
atropine
79
what cell secretes gastrin
g cell
80
where is gastrin secreted into
stomach antrum
81
what is gastrin's target cell
parietal cells
82
how does gastrin reach parietal cells
secreted from stomach into systemic circulation and then delivered back to stomach via circulation.
83
what kind of receptor does gastrin bind to on parietal cells
CCK receptors
84
what is second messenger for gastrin
IP3/Ca2+
85
what stimulate secretion of gastrin from stomach
distension of stomach
presence of small peptides and AA
vagus nerve stimulation
86
what kind of receptors does Histamine bind to
H2 receptors
87
how does histamine reach its target cell
paracrine mechanism
88
what is the second messenger for histamine
cAMP
89
what blocks H2 receptors
cimetidine
90
when is little gastrin secreted
in response to a meal
91
when is big gastrin secreted
b/w meals (fasting)
92
what is gastrin's response to a stimulus
Promotes H+ secretion by gastric parietal cells
Promotes growth of gastric mucosa
Inhibits gastric emptying
93
what stimulates gastrin release
A meal – Small peptides and AAs
Distention of the stomach
Vagal Stimulation (GRP)
94
what is potentiation
the ability of two stimuli to produce a combined response that is greater than the sum of the individual responses.
95
rate of H+ secretion is regulated by what
Ach
histamine
gastrin
working alone and together
96
what does cimetidine do
blocks H2
97
what does atropine do
blocks muscarine (muscarine antagonist)
98
how does potentiation relate to drug use for H+ release
if you block one pathway you could have bigger consequences than expected b/c you're not just blocking that pathway you're blocking the interaction b/w them
99
what are the three phases of gastric HCl secretion
cephalic, gastric, and intestinal
100
what nerve accounts for cephalic phase
vagus
101
cephalic phase accounts for how much of total HCl secretion
30%
102
what is stimulation for HCl secretion in cephalic phase
smelling and tasting, chewing, swallowing, and conditioned reflexes in anticipation of food
103
what are the two mechanisms that promote HCl secretion in cephalic phase
1. direct stimulation of parietal cell by vagus nerve
| 2. indirect stimulation of parietal cell by gastrin
104
gastric phase accounts for how much of total HCl secretion
60%
105
what is stimuli for HCl secretion in gastric phase
distension of stomach
| presence of proteins, AA, small peptides
106
what are the four mechanisms that promote HCl secretion in gastric phase
1. direct stimulation of parietal cell by vagus nerve
2. indirect stimulation of parietal cell by gastrin
3. distension of stomach antrum → local reflexes → gastrin release
4. AA and peptides stimulate G cells to release gastrin
107
what do alcohol and caffeine do regarding secretions
they stimulate gastric HCl secretion
108
intestinal phase accounts for how much of total HCl secretion
10%
109
when is HCl secretion inhibited
when it is no longer needed for activation of pepsinogen to pepsin
110
what happens with HCl when gastric contents PH is decreased
inhibits HCl secretion
111
what does somtostatin do to HCl
inhibits it, directly and indirectly
112
how does somatostatin directly inhibit HCl
binds to Gi which will inhibit adenylyl cyclase and reduce cAMP levels
113
how does somatostatin indirectly inhibit HCl
inhibits histamine release and gastrin release
114
what do prostaglandins do to HCl
lower HCl secretion
115
how do prostaglandins lower HCl secretion
activate Gi and inhibit adenylyl cyclase
116
what is pepsinogen
inactive enzyme precurosr
117
what pH is pepsinogen activated to pepsin
below 5
118
what do the salivary glands produce that has higher affinity for vitamin B12 than intrinsic factor has
R protein
119
what happens in duodenum with vitamin B12
R protein can no longer bind it b/c of pancreatic proteases, so intrinsic factor takes over
120
once B12 is absorbed into enterocytes what happens
it is transferred from IF to transcobalamin II where it will go to blood
121
what is pernicious anemia
your body can't absorb enough vitamin B12 to make healthy RBC
122
what usually causes pernicious anemia
autoimmune disorder
123
describe the autoimmune disorder taht usually causes pernicious anemia
degeneration of parietal cell → loss of IF
124
what is another name for R protein
Haptocorrin
125
stimulation of mucus cells causes
exocytosis of mucin into lumen of stomach
126
what does prostaglandins do to mucous
stimulates the secretion of mucin
127
name the ways the body helps protect stomach from the acid
```
bicarb
mucous
tight epithelium
blood flow
HCl regulated
```
128
how does bicarb protect stomach from acid
helps to neutralize it
129
how does mucous protect stomach from acid
very thick and covers the epithelium. it also traps bicarb, so it keeps the cell surface to stay at pH 7
130
how does blood flow help protect sotmach from acid
removes toxic bi products from acid secretion
131
what things can harm the protective stomach barrier
NSAID (asprin)
stress
smoking
alcohol
132
what is zollinger ellison syndrome
gastrin secreted by pancreatic tumor
| H+ secretion and gastrin levels increase
133
draw out the parietal cell and its HCl secretions
pg 23
134
omeprazole targets
target decreasing acid secretion
| it will lower or eliminate acid secretion
135
what receptor does gastrin act on
CCK2
136
draw out the control of HCl secretion
pg 25
137
for little gastrin what is the minimum you can have to have it work
the last 4 AA
138
for CCK what is minimum you can have to have it work
last 5 AA
139
describe gastrin compared to CCK
the last 4 AA are the same
140
GRP stands for
gastrin releasing peptide
141
what is trophic
relating to feeding and nutrition
142
draw out control of HCl secretion
pg 28
143
somatostatin will stimulate Gi and inhibit
AC (Adenylyl cyclase)
144
what does ECL stand for
enterochromaffin-like
145
how is secretion of HCl turned off once chyme goes to duodenum
Somatostatin.
| pH will go down and the decrease in pH will shut off parietal cells.
146
why does pH go down when food leaves stomach
food acts as buffer
147
where is haptocorrin released from
salivary gland
148
H. pylori causes 90% of
ulcers
149
NSAID stands for
non steroidal anti-inflammatory drugs
150
H pylori increases
gastrin levels
151
what does gastrin normally do?
HCl secretion
152
zollinger-ellison syndrome causes issue b/c
gastrin levels high because of tumor then it will act on stomach and secrete more acid
