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DEMS Unit 1 > Stomach > Flashcards

Stomach Flashcards

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
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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

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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

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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
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5
Q

Pyloric Sphincter

A
  • serves as sieve

- prevents passage of >1-2mm particles

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6
Q

Oxyntic Gland Area

A

-where secretion occurs in the stomach

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7
Q

Rate of Food Emptying

A
  • carbs leave stomach in few hours
  • protein rich foods leave more slowly
  • fat is slowest
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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
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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
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10
Q

Bezoar

A

-ball of hair

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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)
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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
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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
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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
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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”
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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)
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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
Q

H Pylori Tx

A
  • triple therapy: PPI + clarithromycin + amoxicillin 10-14 days
  • rescue quadruple therapy
26
Q

Menetrier Disease

A
  • very rare
  • inc. mucus secretion, dec. acid
  • abd pain, weight loss, bleeding, hypoalbuminemia
27
Q

Ethanol Gastropathy

A
  • similar to early NSAID type injury
  • disrups mucosa
  • inc. acid secretion
  • PUD with high concentration amounts of use
28
Q

NSAID Gastrophathy

A
  • inhibits PG, which protect gastric mucosa
  • can inc. GI bleeding
  • sx: heartburn, nausea, vomiting, abd pain
29
Q

Peptic Ulcer Disease

A
  • 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
Q

Stress Ulcers

A
  • 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
Q

Gastric Polyps

A
  • hyperplastic
  • ademona: premalignant, FAP
  • fundic gland polyps: chronic PPI use (benign), unrelated to H. pylori
32
Q

Gastric Adenocarcinoma

A
  • incidence dec. in developed countries

- inc. Wnt pathway signaling (ex. APC loss) or CDH1 loss

33
Q

GIST

A
  • 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
Q

Gastric Carcinoid Tumor

A
  • neuroendocrine tumor

- found in fundus/body

35
Q

Mucosa Associated Lymphoid Tumor (MALT) Lymphoma

A
  • low grade B cells lymphomas arise in gastric MALT stimulated by H pylori
  • tx of H pylori can sometimes induce regression of lymphoma
36
Q

Chief Cells

A
  • cell in the stomach that releases pepsinogen

- located in stomach

37
Q

Pepsin

A
  • 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
Q

G Cell

A
  • located in atrum of stomach and duodenum

- secretes gastrin

39
Q

Gastrin

A
  • 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
Q

Neck Mucous Cell

A
  • mucous producing cells that cover the inside of the stomach
  • found in the necks of gastric pits

DEMS Unit 1 (8 decks)

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