Exam 4 (Gastric Secretion) Flashcards
1
Q
5 components of gastric juice in the simple stomach
A
- HCl
- water
- pepsin
- intrinsic factor
- mucus
2
Q
HCl in gastric juice of simple stomach is (hypertonic/hypotonic/isotonic).
A
isotonic
3
Q
Pepsin, a component of gastric juice, is ______ (breaks down _____).
A
proteolytic
proteins
4
Q
Function of intrinsic factor (gastric juice component)
A
B12 absorption in ileum (in pancreas in dog/cat)
5
Q
Surface epithelium of gastric mucosa is lined with _______ and has numerous ______.
A
simple columnar epithelium
gastric pits
6
Q
How many gastric glands do one gastric pit serve in surface epithelium of gastric mucosa?
A
1-3
7
Q
What 2 epithelial cell types are in the Cardiac Gland Region?
A
mucous cell
enteroendocrine cell
8
Q
Mucous cells secretory products
A
mucus + pepsinogen
9
Q
Enteroendocrine cell secretory product in cardiac gland region
A
variable
10
Q
Oxyntic Gland Region epithelial cell types
A
parietal cell
chief cell
mucous cell
enteroendocrine cell
11
Q
Parietal cell secretory products
A
HCl + intrinsic factor
12
Q
Chief cell secretory product
A
pepsinogen
13
Q
Enteroendocrine cell types in the Oxyntic Gland Region
A
ECL (enterochromaffin-like cell)
D cells
14
Q
What do ECL cells produce?
A
histamine (paracrine)
15
Q
D cells secretory product in Oxyntic Gland Region
A
somatostatin (paracrine)
16
Q
Function of somatostatin
A
inhibit release of histamine + gastric acid
17
Q
Which cell type is NOT in the Pyloric Gland Region?
A
parietal cells
18
Q
Epithelial cell types in the Pyloric Gland Region
A
mucous cell
enteroendocrine cell
19
Q
What 2 enteroendocrine cells are in the Pyloric Gland Region?
A
G cell
D cell
20
Q
Secretory product of G cells
A
gastrin (endocrine)
21
Q
Function of Somatostatin in Pyloric Gland Region
A
inhibits gastrin release
22
Q
Function of Somatostatin in Pyloric Gland Region
A
inhibits gastrin release when pH too low
23
Q
What is the “universal inhibitor of gastric acid”?
A
somatostatin
24
Q
5 functions of Gastric HCl
A
- activate pepsinogen
- provide optimal pH for pepsin action
- denature/hydrolyze protein –> AAs
- bacteriocidal
- demineralizes ingested bone
25
How does Gastric HCl activate pepsinogen?
acid cleavage to activate & autocleave --> pepsin
26
What is the optimal pH for pepsin action which Gastric HCl provides?
2-4
27
What is the purpose of denaturing/hydrolysis of native protein --> amino acids by Gastric HCl?
gastrin stimulus (for release)
28
What about Gastric HCl is lost with certain meds? Why?
bacteriocidal function lost
PPT (proton pump inhibitor) blocks HCl secretion
29
It's usually not a problem when an animal swallows a bone because gastric HCl demineralizes ingested bone by dissolving ____.
CaPO4
30
HCl is secreted via _______ and is (primary/secondary/tertiary) active transport.
H+ / K+ ATPase (H+ pump)
primary (uses ATP)
31
For HCl secretion, ____ and ___ diffuse into the parietal cell.
H2O + CO2
32
_____ is on the apical membrane and exchanged for ___, so ___ is pumped into the lumen during HCl secretion mechanism.
H+ pump
K+
H+
33
On the basolateral membrane, ______ exchanger brings ___ in and ___ out during HCl secretion mechanism.
Cl/HCO3
Cl
HCO3
34
What two things combine to form HCl in the lumen which passes to the blood?
H+ + Cl- = HCl
35
What is created when HCO3 enters blood as H+ into the lumen?
alkaline tide
36
Alkaline tide (increases/decreases) blood pH when HCO3 enters blood as H+ enters lumen during HCl secretion mechanism (before/during/after) a meal.
increases
during + after
37
What 3 substances are "secretagogues" (promoters) in terms of affecting parietal cell HCl secretion?
1. histamine
2. acetylcholine
3. gastrin
38
Histamine is (endocrine/exocrine/paracrine/neural) and binds to the ___ receptor which increases _____.
paracrine
H2
cAMP
39
The increase in cAMP by histamine directly stimulates _____ which potentiates Ach/gastrin stimulation of ______.
H-K ATPase
40
What is the main source of histamine? Minor sources (2)?
ECL cells
mast cells + histaminergic nerves
41
Stimuli of ECL cell for histamine release (2)
gastrin
acetylcholine
42
Gastrin stimulates ECL cells to release histamine by binding to ____ receptor on ____ cells.
CCK-B
ECL
43
Acetylcholine as a stimulus of ECL cell has ____ and ___ reflex activity during appetite + when meal is in stomach.
local + central
44
What is the inhibitor of ECL cell (and therefore histamine release)?
somatostatin
45
Somatostatin is released when pH is (high/low).
low
46
Histamine can block ___% HCl secretion with ______.
80%
H2 inhibitor
47
Acetylcholine is (endocrine/exocrine/paracrine/neural) and binds to _____ receptor to increase intracellular ___.
neural
muscarinic
Ca2+
48
Increased intracellular Ca2+ by Acetylcholine stimulates _____.
H/K ATPase
49
What is the indirect action of Acetylcholine?
stimulates:
gastrin release from G cells
histamine from ECL cells
50
What is the source of Acetylcholine?
cholinergic effector neurons
51
2 stimuli of acetylcholine
PSNS outflow
local enteric nervous sytem
52
2 stimuli of acetylcholine
PSNS outflow
local enteric nervous system
53
Gastrin is (endocrine/exocrine/paracrine/neural) and binds _____ receptor on parietal cell which increases intracellular ____ and stimulates _______.
CCKB
Ca2+
H/K ATPase
54
Gastrin indirectly stimulates ____ release from ____ cells.
histamine
ECL
55
Source of Gastrin
antral G cells
56
2 neural stimuli of Gastrin
1. Acetylcholine at muscarinic receptor on G cell
2. GRP neurons (release GRP in response to antral filling)
57
2 luminal stimuli of Gastrin
1. amino acids
2. decreased H+ in lumen (up pH)
58
What is the one inhibitor of HCl secretion?
somatostatin
59
Somatostatin works locally (paracrine) in what 2 parts of the stomach?
oxyntic stomach
antral stomach
60
In the Antral Stomach, Somatostatin inhibits _____ release.
gastrin
61
In the Oxyntic Stomach, Somatostatin inhibits _____ and _____ release.
H/K ATPase
histamine
62
Source of Somatostatin is from D cells in ____ and ___ stomach.
oxyntic + antral
63
Stimulus of Somatostatin
up H+ in lumen (down pH)
64
When parietal cells have a small (apical/basolateral) membrane they are (active/inactive) and when they are large, they are (active/inactive) b/c ______.
apical
inactive
active
active pumps
65
If cells become too acidic or damaged, it releases _____ and causes inhibition of _____.
prostaglandins (PGE3)
parietal cells
66
3 phases of gastric secretion (meal stimulus)
1. cephalic phase
2. gastric phase
3. intestinal phase
67
The cephalic phase of gastric secretion is ___% of total gastric secretion and is a (conditioned/unconditioned) reflex of appetite.
15
conditioned
68
In the cephalic phase of gastric secretion, your appetite is via CNS --> ____ --> ____ effectors.
vagus (PS)
cholinergic
69
Function of cephalic phase
prepares stomach for upcoming meal
70
3 outcomes of cephalic phase
1. gastrin release
2. histamine release
3. direct parietal cell stim.
71
The Gastric Phase of gastric secretion is ___% of total gastric secretion.
70-80
72
What is the primary stimulus for gastric phase of gastric secretion?
presence of food in stomach
73
What are the 2 neural stimuli of the gastric phase of gastric secretion?
1. mechano/chemoreceptors activate
2. antrum stretch --> GRP neurons
74
Mechano + chemoreceptors of the gastric phase of gastric secretion are activated by local + (PSNS/SNS) reflexes which activate ____ neurons.
PSNS
cholinergic
75
3 outcomes of local + PSNS reflexes which activate cholinergic neurons in the gastric phase of gastric secretion
1. direct activation of parietal cell
2. gastrin release
3. histamine release
76
4 hormonal stimuli for gastrin release (during gastric phase of gastric secretion)
1. acetylcholine
2. GRP
3. AA's in lumen
4. "food buffering" effect (pH > 4)
77
Food buffering effect = decreased _____ concentration by neutralization with ____ constituents.
gastric proton
food
78
2 outcomes of food buffering effect
1. remove inhibition of gastrin release
2. decrease somatostatin release
79
Intestinal Phase of gastric secretion if ___% of total gastric secretion.
5
80
At the Intestinal Phase of gastric secretion, ____ is a(n) ____ agonist at the ____ receptor.
CCK
partial
gastrin
81
2 stimuli of CCK
lipid + amino acids
82
In the intestinal phase of gastric secretion, CCK keeps HCl (up/down) via binding to the ____ receptor.
up
CCKB
83
[CCK] reaches its peak (before/after) [gastrin] (increases/decreases).
after
decreases
84
Acid secretion is physiologically inhibited by ____ and ____ feedback.
local
duodenum
85
Local feedback control of acid secretion occurs when pH in the lumen is _____, and this releases _____ from ___ cells.
low
somatostatin
D cells
86
_____ reflex, along with ____ and ___ hormones are a part of the feedback control of acid secretion in the duodenum.
enterogastric
CCK + GLP-1
87
A ______ gastric ulcer is where the blood vessels are exposed.
crater
88
5 drug types to treat gastroduodenal ulcers
1. antibacterial
2. H/K ATPase inhibitors
3. H2 receptor antagonists
4. muscarinic antagonists
5. antacids/sucralfate
89
2 surgical treatments for gastroduodenal ulcers
antrectomy
vagotomy
90
What bacteria strain causes gastric ulcers?
helicobacter pylori
91
Give a drug example of H/K ATPase inhibitor. Also, what are they also known as?
omeprazole
PPI (proton pump inhibitor)
92
Example of drug that is H2 receptor antagonist
ranitidine
93
H2 receptor antagonists decrease ___% of acid release.
80
94
Example drug of muscarinic antagonist
pirenzipine
95
How does Sucralfate work?
binds/protects "craters" like scab to cover while healing
96
Pepsinogen is (inactive/active) and made in ____ and ____ cells.
inactive
chief + mucous
97
Pepsinogen release is mediated by ____ reflexes responding to ____ acid.
neural
luminal
98
Pepsin is activated by _____ and acts as a ______.
HCl
protease
99
How does pepsin act as a protease?
cleaves amino acids from proteins at hydrophobic AA's
100
Intrinsic factor has a main source in ________ in dogs/cats.
pancreatic acini
101
Intrinsic factor is a ______ made + secreted by _____ cell.
glycoprotein
parietal
102
Vitamin B12 binds to _______, containing cobalt, which is ingested in food and binds to _______.
cobalamin
intrinsic factor
103
Vitamin B12 binds to intrinsic factor in the _____ and ____ (2 locations).
stomach
duodenum
104
In the ______, the intrinsic factor complex dissociates and _____ is actively transported to the blood.
ileum
B12
105
Vitamin B12 is needed for _____ formation in ____ production.
hemoglobin
RBC
106
A decrease in parietal cells is called _____.
achlorhydria
107
A decrease in intrinsic factor leading to B12 deficiency leads to what disease?
pernicious anemia
108
Term for autoimmunity against parietal cell that destroys them and treated long-term with PPIs.
atrophic gastritis
109
What is the milk clotting enzyme of neonatal ruminants?
rennin
110
In species other than ruminants, ____ causes milk to clot.
pepsin
111
Rennin is produced in the ____ cells and hydrolyzes ____ (main milk protein).
casein
112
When rennin hydrolyzes casein, this generated a precipitate called _____ which gives some "bulk" solid content to neonate's diet.
curd
113
What is a soluble protein that results when rennin hydrolyzes casein and is watery + used in cheese?
whey
