Stomach Flashcards
(40 cards)
1
Q
Functional Dyspepsia (FD)
A
- dyspepsia: discomfort centered in upper abdomen usually related to eating
- FD is when there is dyspepsia and no organic etiologies
- 45% of pts have delayed gastric emptying
2
Q
Gastroparesis
A
-means “stomach paralysis”
-mechanical obstruction of the gastric outlet excluded
-sx: NV, early satiet, postprandial abdominal distention/pain
-causes: idiopathic, post-surgical, diabetic, opiates,
dx: gastric emptying study
=tx: small meals, low fat diet, prokinetic agents
3
Q
Stomach Basic Electrical Rhythm (BER)
A
- 3 cycles per minute
- duodenum is faster bc distal end needs to be fast than proximal end for correct digstion
4
Q
Phases of Digestion and Type of Control
A
- interdigestive (basal) phase- between meals following circadian rhythm (highest in evening)
- cephalic phase- neural control
- gastric phase- neural (early) and hormonal (endocrine)
- intestinal- mostly hormonal (endocrine) but some neural
5
Q
Pyloric Sphincter
A
- serves as sieve
- prevents passage of >1-2mm particles
6
Q
Oxyntic Gland Area
A
-where secretion occurs in the stomach
7
Q
Rate of Food Emptying
A
- carbs leave stomach in few hours
- protein rich foods leave more slowly
- fat is slowest
8
Q
Emesis
A
- centrally regulated
- salivations (HCO3) and sensation of nausea
- reverse peristalsis from upper small intestine to stomach
- abdominal muscles contract and UES and LES relax
- gastric contents ejected
9
Q
Migrating Motor Complex (MMC)
A
- occurs during fasting
- every 90-100 min
- 3 phases
- phase 1- quiescnce occurs for 40-60% of the 90 min duration
- phase 2- motility inc, contractions irregular, fials to propel luminal contect, last 20-30% MMC duration
- 5-10 min of intense contractions, pylorus fully opens
- hormone motilin appears to initiate
10
Q
Bezoar
A
-ball of hair
11
Q
Acid Secretion
A
- HCl
- kills bacteria
- begins protein digestion
- acid producing parietal cells also secret intrinsic factor (for vitamin B12 absorption)
- energy consuming process (H+/K+/ATPase pumps across luminal surface against a significant gradient)
12
Q
Defenses in Stomach
A
- mucus layer and alkaline HCO3 layer at the cell surface protects stomach lining
- PGs can inc. mucus production
- tight junctions between cells prevent acid from infiltrating layers of the wall
- rapid cell turnover maintains surface integrity
13
Q
Vitamine B12
A
- important for RBC production
- B12 binds salivary R protein in stomach
- pancreatic proteases remove R protein in duodenum
- IF from stomach then binds B12 in duodenum
- IF/B12 complex binds to receptor in terminal ilieum for absorption
14
Q
Regulation of Acid Production and Secretion
A
- amplification of the apical surface area is accompanied by inc. density of H+/K+ APTase molecules
- ACh and gastrin signal via Ca++, whereas histamine signals via cAMP
15
Q
Acid Secretion- Parietal Cell
A
- protons are generated in the cytosol via action of carbonic anhydrase
- bicarb ions are exported from the basolateral pole of the cell either by vesicular fusion or via a Cl/HCO3 exchanger
- “alkaline tide”
16
Q
Peptic Ulcer Disease Risk Factors
A
- NSAID use (COX inhibitors -| PGs -> dec. mucus -> inc. gastric acid damage)
- tumors (zollinger ellison syndrome) (gastroma -> inc. gastrin-> dec. mucus -> inc. damage)
- heicobacter pylori (binds mucus -> inc. H. pylori -> inc. immune activation -> inc. ulcers)
17
Q
Protein Digestion
A
-pepsin breaks down about 15% of the proteins to small peptides
18
Q
Enterogastric Reflexes
A
- gastric emptying is slowed in response to:
- dec. in pH
- fatty acids and caloric density
- inc. in osmolality
19
Q
Autoimmune Gastritis
A
- autoimmune attack against parietal cells, IF
- achlorhydria
- pernicious anemia (B12 low)
- biopsy: atrophy, loss of parietal cells, intestinal metaplasia
- gastric carcinoid tumor risk
- gastric cancer risk higher
- loss of normal folds in stomach
- more common in body and fundus
20
Q
Gastropathies
A
-non-inflammatory epithelial cell injury
21
Q
Infectious Gastritis
A
- bacterial: H pylori, syphilis, TB
- fungal: candida, aspergillosis, histoplasmosis, mucormycosis
- parasidic: giardia, cryptospyridiosis, anisakiasis, strongyloidasis
- viral: CMV
22
Q
H. Pylori
A
- most common human bacterial infection
- infection is life long
- neutralizes H+ with urea ammonia
- corkscrews into mucus
- makes CagA- pathogenicity island/effector protein
- makes VacA exotoxin, inhibits T cells
- dec. cell adhesion, associated with ulcers
- most people are asymptomatic
- intestinal metaplasia presents as white plaques
- more common in developing countries
- acid secretion inversely correlates with severity of gastric body gastritis
- inc risk: PUD, inflammatory/hyperplastic polyps, MALT lymphoma, gastric adenocarcinoma
23
Q
Chronic Gastritis
A
- presence of mononuclear inflammatory cells (lymphocytes and plasma cells) within lamina propria
- blue is bad
24
Q
H. Pylori Diagnosis
A
- endoscopy
- mucosal biopsy
- rapid urease test (sensitive and specific)
- blood antibody test
- stool antigen test (sensitive and specific)
- urea breath test (sensitive and specific)
25
H Pylori Tx
- triple therapy: PPI + clarithromycin + amoxicillin 10-14 days
- rescue quadruple therapy
26
Menetrier Disease
- very rare
- inc. mucus secretion, dec. acid
- abd pain, weight loss, bleeding, hypoalbuminemia
27
Ethanol Gastropathy
- similar to early NSAID type injury
- disrups mucosa
- inc. acid secretion
- PUD with high concentration amounts of use
28
NSAID Gastrophathy
- inhibits PG, which protect gastric mucosa
- can inc. GI bleeding
- sx: heartburn, nausea, vomiting, abd pain
29
Peptic Ulcer Disease
- lifetime prevalence is 5-10%
- male=female GU
- male>female DU
- inc. in people with COPD, cirrhosis, chronic renal failure, post-transplant, smokers
- associated with H pylori
30
Stress Ulcers
- common in ICU patients
- fundus and body
- impaired mucosal protection
- inc. acid secretion
- features: abd. pain, anemia, bleeding, perforation, obstruction
- tx: IV volume, acid suppression, PPI drip, endoscopy, surgery, tx H pylori, risk factor avoidance
31
Gastric Polyps
- hyperplastic
- ademona: premalignant, FAP
- fundic gland polyps: chronic PPI use (benign), unrelated to H. pylori
32
Gastric Adenocarcinoma
- incidence dec. in developed countries
| - inc. Wnt pathway signaling (ex. APC loss) or CDH1 loss
33
GIST
- GI stromal tumor
- most common mesenchymal tumor of stomach
- prognosis is worse than other stromal tumors
- tx: gleevac (imatinib), surgery
- cell of origin: interstitial cell of cajal (pacemaker)
- + for C kit (CD117) mutation in transmembrane RTK
- 10-30% malignant
34
Gastric Carcinoid Tumor
- neuroendocrine tumor
| - found in fundus/body
35
Mucosa Associated Lymphoid Tumor (MALT) Lymphoma
- low grade B cells lymphomas arise in gastric MALT stimulated by H pylori
- tx of H pylori can sometimes induce regression of lymphoma
36
Chief Cells
- cell in the stomach that releases pepsinogen
| - located in stomach
37
Pepsin
- secreted by chief cells in stomach
- involved in protein digestion
- pepsinogen is converted to pepsin in presence of H+
- inc. by vagal stimulation and local acid
38
G Cell
- located in atrum of stomach and duodenum
| - secretes gastrin
39
Gastrin
- secreted by G cells in antrum of stomach and duodenum
- actions: inc. gastric H+ secretion, inc. growth of gastric mucosa, inc gastric motility
- inc. in H. pylori
- very inc. in Zollinger Ellison
- inc. in chronic PPI use
40
Neck Mucous Cell
- mucous producing cells that cover the inside of the stomach
- found in the necks of gastric pits
