Review Flashcards
1
Q
The majority of epithelial components of the GI tract and accessory organs are derived from __________.
A
Endoderm
2
Q
Folding in the __________ plane yields the primitive gut tube?
A
Transverse
3
Q
Folding in the __________ plane yields the 3 subdivisions of the primitive gut tube.
A
Sagittal
4
Q
What do the ventral and dorsal mesenteries do?
A
Attach the stomach to the body wall
5
Q
Which way does the stomach rotate?
A
90˚ clockwise — LARP
6
Q
How does the midgut loop rotate?
A
Rotates 90˚ counterclockwise around SMA
Midgut retracts and rotates another180˚ counterclockwise
cranial first (left) then caudal (right) (10 weeks)
7
Q
The cloaca is partitioned by the ______________.
A
Urorectal septum - mesenchyme
8
Q
What do the liver and biliary system develop from?
A
Ventral foregut endoderm
9
Q
What does the pancreas develop from?
A
2 buds - dorsal and ventral foregut endoderm
10
Q
Which bud forms the majority of the mature pancreas?
A
Dorsal pancreatic bud - FGF2 (notocord) inhibits Sonic -> Pancreatic development
11
Q
Duodenal atresia/stenosis
A
Failure of duodenum to recanalize
Vomiting of stomach contents and bile
Leads to polyhydramnios
12
Q
Extrahepatic biliary atresia
A
Jaundice, clay colored stools - death w/o surgical correction
13
Q
Gastroschisis
A
Abdominal viscera extrude thru abdominal wall
Lateral to umbilicus on R
Eviceration
14
Q
Omphalocele
A
Herniation of abdominal contents into proximal umbilicus
Failure to retract
Assoc. w/ cardiac and urogenital abnormalities
15
Q
Non-rotation/malrotation
A
Abnormal intestine placement – volvulus
16
Q
Mekel diverticulum
A
Out-pocketing of ileum
May become inflamed, mimic appendicitis
17
Q
Hirschsprung disease
A
Aganglionosis of colon
Megacolon, dilated region = normal
18
Q
What are the 4 main layers of upper GI tract?
A
- Mucosa
- Submucosa
- Muscularis Externa
- Adventitia/Serosa
19
Q
What does the Submucosal (Meissner’s Plexus) control?
A
The muscularis mucosae - thin layer of smooth muscle
Movement, blood flow, gland secretion
20
Q
What does the Myenteric (Auerbach’s plexus) control?
A
The muscularis externa - inner circular and outer longitudinal
21
Q
Serosa
A
Simple squamous epithelium + CT in peritoneal cavity
22
Q
What kind of epithelium does the esophagus have?
A
Stratified squamous
23
Q
In what layers of the esophagus are glands located and what do they secrete?
A
- Mucosa: Cardiac glands - mucus
2. Submucosa: Mucus cells - basal nucleus & serous cells - central nucleus
24
Q
What type of epithelium does the stomach have?
A
Simple columnar
25
What are the 5 types of enteroendocrine cells and what do they secrete?
```
G Cells: Gastrin
EC cells: Serotonin
D cells: SST
A cells: Enteroglucagon
ECL cells: Histamine
```
26
What do parietal (oxyntic) cells secrete?
HCl and gastric intrinsic factor
27
What do chief sell secrete?
Digestive enzymes - stimulated by vagus nerve and secretin
28
What are the 3 phases of meal response?
1. Cephalic phase
2. Gastric phase
3. Intestinal phase
29
What happens in the cephalic phase?
Think about food - Vagus - G cells + Parietal cells - HCl (30%)
30
What happens in the Gastric phase?
Food enters stomach - distention - G cells - HCl(60%)
31
What happens in the intestinal phase?
Chyme released into duodenum, gastric emptying slows
Enterogastric reflex
CCK and secretin suppress gastric activity (10% HCl)
32
Enterogastric reflex
Intestinal distention sends gastric inhibitory impulses thru the ENS
33
The sequence of peristalsis is determined by the ______________.
Nucleus ambiguus - "central pattern generator"
34
The cricopharyngeus muscle makes up what?
UES
35
True or false: Vagal efferents synapse on both inhibitory and excitatory myenteric neurons?
True
Excitatory: 2nd mess, Substance P
Inhibitory: cGMP, block Ca, hyperpol
36
What are 3 common mechanical causes of dysphagia?
Peptic stricture, esophageal ring, cancer
37
What are 3 common neuromuscular causes of dysphagia?
Achalasia, esophageal spasm, dysmotility
38
Chronic heartburn can lead to _______________.
Peptic stricutre
39
Progressive dysphagia + heartburn and regurgitation to both solids and liquids is indicative of what?
Achalasia or Scleroderma
40
What 3 diagnostic tests allow to to visualize the upper GI tract?
1. Upper GI endoscopy - structure
2. Esophageal manometry - function - gold stnadard for motor disorders
3. Rad. Esophagram - structure and function
41
Achalasia
Impaired LES relaxation and loss of peristalsis - loss of inhibitory NO activity
42
How do you treat achalasia?
NO donors &/or anticholinergics, BOTOX, operative
43
What is the most important barrier to protect the esophagus from acid erosion?
Constant LES tone
44
What is the #1 and #2 treatment for GERD?
1. Lifestyle modification - weight loss, elevation of bed, avoid late/trigger meals
2. PPI
45
Eosinophilic Esophagitis
Epithelial infiltration by large #s of eosinophils superficially (15-20%)
T cell med hypersensitivity - Allergic rxn to inhaled/ingested allergens - MBP, IL5, IL13
46
How does eosinophilic esophagitis present differently in adults vs. children?
1. Adults: Dysphagia
| 2. Kids: Nausea, burning and food intolerance
47
What 3 things may clue you in to eosinophilic esophagitis?
1. Failure of acid suppressive meds
2. Hx/FHx of atopia - atopic dermatitis, rhinitis, or asthma
3. Corrugated esophagus, longitudinal furrows
48
How do you treat Eosinophilic Esophagitis?
1. Elimination diet
| 2. Steroids - topical
49
What are causes of chemical esophagitis?
Acid, alkali (lye), alcohol, excessively hot fluids, smoking
| Pills may lodge and dissolve - NSAIDs, Doxycycline
50
What are common causes of viral esophagitis?
HSV - punched out ulcers, nuclear inclusions
| CMV - shallow ulceration, cytoplasmic and nuclear inclusions
51
What are other causes of infectious esophagitis?
Candida, bacterial - can invade LP and cause necrosis
52
What are causes of iatrogenic esophagitis? (3)
Chemo, GVHD, radiation
53
What skin disorders also have esophagitis? (4)
Bullous pemphigoid and epidermolysis bullosa, lichen planus, and Crohn's disease
54
Barretts Esophagus
Normal squamous epithelium is replaced by metastatic columnar mucosa
55
What defines intestinal metaplasia in Barrett's Esophagus?
Goblet cells - distinct mucus vacuoles
56
What gene is likely involved in Barrett's?
Cdx
57
Who typically gets adenocarcinoma of the esophagus?
White, middle-aged male, western countries
58
What are characteristics of esophageal adenocarcinoma?
Distal 1/3 of esophagus
| Chromosomal changes and p53 mutations early
59
Who gets squamous cell carcinoma of the esophagus?
African American males, >45yo, Iran, China, Hong Kong, Brazil
60
What are risks for developing esophageal SCC?
EtOH, tobacco, poverty, Achalasia, Plummer-Vinson Syndrome, hot beverages
61
What are characteristics of esophageal SCC?
Middle 1/3
Small grey/white plaque like thickenings - may invade
Travels to LN
62
What are 6 ways saliva provides defense against bacteria?
1. Lysozyme: Kills Gram +
2. Peroxidase: Makes reactive Bromide and Iodine - kills bacteria
3. Lactoferrin: Bind Fe
4. IgA
5. Defensins: pore complexes
6. Mucins: modulate adhesion of bacteria
63
Baseline slow wave activity of the stomach is mediated by which cells?
Interstitial cells of Cajal
64
What is the goal for the small intestine to see calories?
1-4 kcal/min delivery
65
What is fasting motor activity?
Max strength, frequency, and coordination to clear large solids (enteric coated meds)
66
Contraction failure
Impaired triturition, retention of gastric contents, distention, pain and early satiety
67
Accommodation failure
Food, mostly liquid moves too rapidly thru small bowel
Fluid enters lumen - weight loss
Unabsorbed food to colon - bacterial fermentation
Hypoglycemia
Duodenal Ulcer
68
MMC failure
Failure to clear undigestible material
| Bezoar, poor drug delivery, sm. intestine bacterial overgrowth
69
Gastroparesis
Delayed emptying w/o mechanical obstruction
Early satiety, postprandial fullness, NV, bloating, pain
Must exclude other causes
70
What two things do you get with Vagal injury?
Poor accommodation - liquids empty fast
| Poor antral grinding - solids empty slow
71
What is the mechanism of disfunction in diabetics?
1. Extrinsic vagal dysfunction
2. Loss of enteric neurons
3. Loss of interstitial cells of Cajal
4. Hyperglycemia effects motor fx
5. Rapid or slow emptying
72
Causes of elevated H+ secretion
INC gastrin, vagal tone, histamine, parietal cell mass, paraneoplastic or
DEC acid to antrum (retained antrum)
73
By what mechanism does Zollinger Ellison Syndrome cause severe ulcer disease and where are they located?
```
Gastrin secreting NE tumor
Isolated gastrinoma (75%)
Multiple Endocrine Neoplasia 1 (25%)
Distal duodenum and jejunum
```
74
You suspect your patient has ZE, so you decide to do a secretin stimulation test. What must the Gastrin level be, to confirm the diagnosis?
Inc in Gastrin > 120
75
What are other causes of gastrin-mediated inc. H+ secretion (5)
```
H. pylori (dec. SST)
Antral G cell hyperplasia
Retained antrum
Gastric outlet obstruction
Renal failure
```
76
What things cause decreased acid secretion
1. Meds
2. Inflammatory destruction of parietal cells
3. Acute H. pyloric infection
4. Vagal injury
5. VIP producing tumors
77
What 4 main symptoms will you see in a person with dec. acid secretion?
1. Impaired protein digestion
2. Impaired Fe, Ca, B12 absorption
3. GI bacterial overgrowth
4. Impaired delivery of drugs
78
Decreased secretion of _________ and ________ is also affected by conditions that inhibit acid secretion.
1. Pepsin
| 2. Lipase
79
In the early stage of H. pylori infection, where is the infection commonly seen and what are the 3 main characteristics?
Antrum
Blocked D cell SST secretion
Inc. Gastrin/Acid
Duodenal ulcers
80
In the late stage of H. pylori infection, where is the infection commonly seen and what are the 3 main characteristics?
Corpus/fundus
Destruction of parietal cells: inc gastrin & dec acid
Gastric ulceration
81
Which 3 gastric neoplasias are associated with H. pylori infection?
Adenocarcinoma
MALToma
Carcinoid
82
When is H. pylori typically acquired, and where is it common?
Childhood
| Developing countries
83
Autoimmune gastritis
Lymphocytic inflammation - destruction of parietal cells (Associated w/ CD, T1DM, Thyroid)
Inherited - parietal cells and IF
Women x3
84
What is Atrophic Metastatic Gastritis and what can it lead to?
1. Destruction of normal mucosa and replacement by metastatic elements (Goblet cells)
2. Gastric cancer, gastric carcinoid
85
What are the direct effects of NSAIDs on gastric toxicity?
1. Trapped in epi cells
2. Uncoupling of ox phos
3. Dec. energy production
4. Inc. cell permeability and rapid cell death
86
What are the systemic effects of NSAIDs on gastric toxicity?
Blocks COX1:
Dec. mucosal BF and O2 delivery
Dec. mucin, bicarb and phospholipid
Epi proliferation and migration
87
What is the difference between and ulcer and an erosion?
Ulcer - thru muscularis mucosa
| Erosion - superficial to muscularis mucosa
88
What two risk factors increase the chance of developing peptic ulcer disease?
Increased age and smoking
89
90% of peptic ulcer disease is due to NSAIDs, __________, and unknown NSAID use.
H. pylori
90
What are the symptoms of peptic ulcer disease?
1. Chronic dyspeptic epigastric pain (2-3hrs - DU)
2. Nausea, anorexia, weight loss
3. Diarrhea = fistula
4. May be asymptomatic
91
In the setting of peptic ulcer disease, what does hematemesis indicate?
Loss of 25% of BV
92
In the setting of peptic ulcer disease, what does melana indicate?
Loss of 33% of BV
93
Who gets gastric adenocarcinoma?
Asian, hispanic, black, older men in developing countries
| smoking, salt, nitrates
94
What is the most common type of gastric adenoCA and what is it's main risk factor?
```
Intestinal type (50-70%)
H. pylori
```
95
What is diffuse type gastric adenoCA associated with, what does it look like, and who gets it?
1. Blood group A
2. Signet ring cell histology
3. Younger men or women
* More aggressive
96
What is the mutation associated w/ hereditary diffuse gastric adenocarcinoma and how is it inherited?
E-cadherin gene
AD
38 yo, inc. risk of breast cancer
97
Is diffuse type EBV associated gastric adenocarcinoma considered more or less aggressive on average?
Less
98
Who gets gastric lymphoma/MALToma and what is it associated with?
50-60 yo men
| H pylori, if no t(11;18) and doesn't extend below submucosa
99
What are gastric carcinoid tumors are caused by and who gets them?
ECL sells that prolif and transform in response to inc. gastrin - Achlorhydria, ectopic gastrin
Women 60s/70s
100
What is the typical course for gastric carcinoid?
```
< 10%
Sporadic type (20%) from normal circ. Gastrin - 65% present w/ hepatic/local mets
```
