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GI > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

What is a gross feature of the small intestine that is unique to the duodenum and jejunum, but not in the ileum?

A
  • Plicae circularis/ circular folds
  • folds of mucosa with submucosal core, responsible for increasing surface area for nutrient absorption
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2
Q

What’s the difference between plicae circularis and villi?

A

• plicae: large, reach out into the lumen. folds of mucosa with submucosal core

• villi: small, folds of epithelium with lamina propria core

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3
Q

What is the serosa of the small intestine?

A

CT covered by mesothelium (simple squamous epithelium derived from mesoderm)

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4
Q

Where are the crypts of the small intestine found?

A

In the valleys of the villi

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5
Q

What cells are unique to the crypt epithelium?

A

• Paneth cells
• stem cells

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6
Q

What is the name of the lymph vessel running through the villi?

A

Lacteal

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7
Q

Absorptive (enterocytes) columnar cells of the small intestine do what?

A

• secrete digestive enzymes, water and electrolytes
• absorbs salutes, water, and lipids

~ they are tall and have a basally positioned nucleus, microvilli, and tight junctions

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8
Q

What do goblet cells do in the small intestine?

A

Produce mucus. The increase in number from the duodenum—> ileum

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9
Q

What do the paneth cells do?

A

• they secrete antibacterial enzymes and lysozymes, and are responsible for phagocytosis of bacteria to regulate probiotic flora

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10
Q

What does a paneth cell of the small intestine look like?

A

• located at the base of the crypts/intestinal glands, they have a basophilic basal cytoplasm, and very eosinophilic large secretory granules in apical cytoplasm

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11
Q

What are unique histological features of the duodenum?

A

• Brunner’s glands
• many plicae circularis
• adventitia

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12
Q

What are Brunner’s glands?

A

• glands found in the duodenum that secrete alkaline mucus (~8.1-9.3 pH) into the lumen in order to neutralize acidic chyme arriving from the stomach

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13
Q

What are some unique histological features of the ileum of the small intestine?

A

* Peyer’s patches with M-cells in the micro fold, for endocytosis of antigen and transport to underlying lymphatic tissue (provide precursors of intestinal plasma cells that produce IgA)
* plicae circularis sparse/absent
* goblet cells are increasing a number

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14
Q

What are the functions and unique features of the large intestine?

A

• function: absorption of water, secretion of mucus to lubricate dehydrated feces
• unique features: no villi, no plicae circularis

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15
Q

Are there Paneth cells in the large intestine?

A

No

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16
Q

Which part of the large intestine has serosa, which part has adventitia?

A

Serosa = transverse colon

Adventitia = ascending and descending colon

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17
Q

Due to the high number of lymphocytes, what does the large intestine look like on H&E stain?

A

• very basophilic (blue)

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18
Q

Which part of the G.I. tract has the most goblet cells?

A

The large intestine

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19
Q

What does the appendix look like histologically?

A

Many lymphatic nodules, very blue mucosa

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20
Q

What does the rectum look like histologically?

A
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21
Q

What are the three zones of the anal canal?

A

• colorectal zone: simple columnar epithelium
• anal transitional zone: Where simple columnar cells become stratified squamous non-keratinizing epithelium
• squamous zone: stratified squamous keratinizing epithelium

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22
Q

What are the exocrine functions of the pancreas?

A

Pancreatic juice secretion (bicarbonate and digestive enzymes)

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23
Q

What type of ducts are found in the pancreatic system?

A

• excretory/interlobular: simple columnar with goblet cells
• intralobular: simple cuboidal
• intercalated: simple cuboidal

~ NO striated ducts

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24
Q

Are pancreas secretions serous or mucus?

A

Entirely serous

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25
Q

What are the acinar cells of the exocrine pancreas?

A

• simple columnar epithelial cells (pyramidal)
• serous secretory cells that produce digestive enzyme precursors (zymogens)
• basophilic basal cytoplasm with eosinophilic apical granules

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26
Q

What are the centroacinar cells of the exocrine pancreas?

A

• simple squamous epithelial cells
• duct cells located inside the acinus
• faintly stained

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27
Q

What are the differences between the pancreas and the Parotid gland?

A

Pancreas: also endocrine, thin capsule, thin CT, few fat cells, many ducts, centro-acinar cells, islets of langerhans

Parotid: only exocrine, thick capsule, abundant CT, many fat cells, few ducts, myoepithelial cells, striated ducts

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28
Q

What are the islets vs lobules of the pancreas?

A

Islets: endocrine function
Lobule: exocrine function (GI)

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29
Q

What is the effect of cholecystokinin on the gallbladder?

A

• stimulates contraction of smooth muscle in the gallbladder, and relaxes sphincter of Oddi
• also stimulates increased bile production by the liver hepatocytes

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30
Q

What is a unique histological feature of the gallbladder?

A

• Simple columnar epithelium that are very tall, microvilli on apical surface, mucosal folds filled with laminate propria
• Rokitansky-Aschoff sinuses
• adventitia near liver, serosa everywhere else

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31
Q

What are the primary plasma cations and anions?

A

Cation: sodium
Anion: chloride and bicarbonate

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32
Q

What are the primary intracellular cations and anions?

A

Cations: potassium
Anion: phosphate

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33
Q

What are the dietary sources of calcium?

A

Dairy, seafood, turnips, broccoli, kale, dietary supplements

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34
Q

What are the major functions of calcium?

A

• bone mineralization
• blood clotting
• muscle contraction
• metabolism regulator

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35
Q

What molecules increase calcium absorption?

A

• vitamin D
• sugar, sugar alcohols
• protein

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36
Q

What molecules decrease calcium absorption?

A

• fiber
• phytic, oxalic acids
• divalent cations (magnesium and zinc)
• unabsorbed fatty acids

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37
Q

What hormone increases uptake of calcium?

A

Parathyroid hormone via TRPV6 and calbindin

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38
Q

In the blood, how do you find calcium?

A

Primarily free ionized calcium, also bound to protein such as albumin

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39
Q

Intracellular signaling by calcium is mediated by what?

A

Calmodulin

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40
Q

Calcium blocks the uptake of what other dietary components?

A

• phosphorus
• iron (transiently)
• calcium trap fatty acids and bile salts that are non-digestible

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41
Q

A deficiency of calcium causes what? Who is at risk?

A

Deficiency symptoms: rickets, osteoporosis, tetany, colorectal cancer (maybe also hypertension, type two diabetes)

Patients at risk: fat malabsorption disorders, immobilized patients

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42
Q

Calcium toxicity (greater than 2500 mg per day) leads to what symptoms?

A

Acute: constipation, bloating

Chronic: calcification of soft tissue, hypercalciuria, kidney stones, cardiovascular disease

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43
Q

What are the dietary sources of phosphorus?

A

• meat, poultry, fish, eggs, dairy, cola (phosphoric acid)

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44
Q

Where is the majority of phosphorus found in the body?

A

85% is in the bones, also found in soft tissue/muscle (nucleic acid)

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45
Q

The active transport of phosphate is activated by what?

A

Calcitriol

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46
Q

What is phosphorus absorption inhibited by?

A

• magnesium
• aluminum
• calcium
• aka, antacids

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47
Q

What are the functions of phosphorus?

A

• bone mineralization
• molecules with high energy bonds (DNA, RNA, serine, threonine, tyrosine, TPP, PLP)
• acid base balance (buffer in the kidney)
• availability of oxygen (2,3 BPG)

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48
Q

Excretion of phosphorus renally is promoted by what?

A

• elevated dietary phosphorus
• parathyroid hormone
• acidosis
• phosphotonins (FGF-23)

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49
Q

Excretion of phosphorus renally is inhibited by what?

A

• low dietary phosphorus
• Calcitriol
• alkalosis
• estrogen
• thyroid hormone
• growth hormone

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50
Q

In what ways can phosphorus deficiency occur?

A

• extreme use of antacids
• refeeding syndrome
• inherited disorders (Dents, linked hypophosphatemic rickets, Autosomal dominant hypophosphatemic rickets)

~ symptoms: anorexia, reduced cardiac output, decreased diaphragmatic contractility, myopathy, death

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51
Q

What is FGF23?

A

Secreted from osteoclasts and osteoblasts and it decreases phosphate absorption and increases phosphate excretion in order to decrease serum phosphate level

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52
Q

What is familial tumoral calcinosis?

A
  • Inactivating mutation in the gene and coding FGF23
  • characterized by abnormal calcium and phosphate deposits in the body
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53
Q

What are the common dietary sources of magnesium?

A

Nuts, legumes, whole-grain, chlorophyll, chocolate, hard water

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54
Q

Where is magnesium found in the body?

A

In the bone in the soft tissues

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55
Q

How is magnesium transported in the small intestine?

A

• saturable transport across brush border, TRPM6
• basolateral transport (Na/Mg antiporter)
• non-saturable paras cellular diffusion

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56
Q

What are the functions of magnesium?

A
  • bone health
  • hydrolysis needed for DNA polymerase/kinesis used to make nucleotide triphosphates
  • synthesis of 25, hydroxychlorocalciferol in the liver (vit D)
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57
Q

What is the best way to measure magnesium in the body?

A

Erythrocyte magnesium

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58
Q

What are the therapeutic uses of magnesium?

A

Laxatives and to prevent seizures in pre-eclampsia

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59
Q

When can you see a magnesium deficiency?

A

Chronic Hypertension, type two diabetes, Gitelman syndrome (SLC12A3)

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60
Q

What are the symptoms of magnesium toxicity?

A

Diarrhea, dehydration, flushing, slurred speech, muscle weakness, loss of deep tendon reflexes —> cardiac arrest

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61
Q

What are the dietary sources of manganese?

A

Whole-grain cereals, fruits, leafy vegetables, legumes, nuts

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62
Q

Uptake and distribution of dietary manganese uses the same transporters as what?

A

Iron and zinc

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63
Q

What are the functions of manganese within the body?

A

• cofactor for galactosyltransferases needed to form cartilage, and important for protein and phospholipid glycosylation
• cofactor for pyruvate carboxylase and PEP carboxykinase in gluconeogenesis
• antioxidant defense (SOD 2)

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64
Q

Deficiency of the ZIP8 manganese transporter leads to what problems?

A

• cranial asymmetry, severe spasms/seizures, arrhythmia on EEG, disordered protein glycosylation

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65
Q

What are good dietary sources of selenium?

A

Seafood, meat, cereal grains (depending on the soil)

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66
Q

Selenium is present in our diet as what?

A

• inorganic: selenate or selenite
• amino acids: selenomethionine, selenocysteine

~ deficiency can lead to Keshan disease which progresses to fatal cardiomyopathy

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67
Q

Why does Keshan (chinese, cardiomyopathy) disease occur in selenium deficiency?

A

Decreased glutathione peroxides causing increase oxidative stress

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68
Q

What are the selenoproteins?

A
  1. Glutathione peroxidase
  2. Thioredoxin reductase
  3. Iodothryonine deiodinase
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69
Q

What is the purpose of thioredoxins (created with selenium)?

A

• oxidation of thiols in diverse substrates to maintain the pool of reduced thioredoxin
• can also maintain pool of reduced vitamin C

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70
Q

Why is selenium important for the thyroid?

A

It is a Deiodinator that creates T3 from T4

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71
Q

Molybdenum functions as a cofactor for what enzymes?

A
  1. Xanthine oxidase
  2. Sulfite oxidase
  3. Aldehyde oxidase
  4. Amidoxime reductase
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72
Q

What is Moco?

A

An organic cofactor created with molybdenum, without it results in seizures, encephalopathy, and death

~ neurotoxicity is due to sulphocysteine being structurally similar to glutamate (overexcitation)

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73
Q

Iodine is found where, and important for what?

A

• Found in salt, marine seafood, and dairy products
• important for thyroid hormone function and neurological well-being

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74
Q

What is a goiter?

A

Hypertrophy of the thyroid gland due to iodine deficiency

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75
Q

What are the dietary sources of chromium?

A

Egg yolk, meats, cheeses, brewers yeast

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76
Q

What does chromium do in the body?

A

Binds to chromomodulin, associated with the insulin receptor. This interaction enhances insulin receptor signaling

~ chromium supplementation may improve glucose tolerance

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77
Q

Functions of the duodenum, jejunum, ileum

A

Duodenum: chemical digestion with help from secretions of the pancreas and gallbladder

Jejunum: Absorption

Ileum: resorption of intrinsic digestive factors and sodium/water

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78
Q

Several toxins can increase small intestine water secretion by increasing adenylate cyclase activity, this moves more chloride into the lumen of the small intestine. What can occur when this happens?

A

This is seen with toxins such as cholera, this can lead to potentially fatal diarrhea

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79
Q

The small intestine has what type of capillaries?

A

Fenestrated with pores. The pores are only a glycoprotein layer with no endothelial cells allowing for passage of proteins and other small molecules (not blood cells)

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80
Q

What are the sources of enzymes/emulsifiers of the intestines?

A
  1. Intestinal on brush border (enterocytes)
  2. Pancreas
  3. Liver and gallbladder
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81
Q

What are the brush border enzymes that breakdown carbohydrates?

A

• lactase: lactose —> galactose + glucose (both SGLT1)
• sucrase: sucrose —> Fructose (GLUT5) + glucose
• Maltase: maltose —> glucose

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82
Q

How are monosaccharides absorbed?

A
  1. SGLT1/GLUT5 on apical membrane
  2. GLUT2 on basolateral membrane
    ~ in the duodenum/jejunum
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83
Q

What happens to starches that are not broken down in the small intestine?

A

They are fermented by bacteria in the large intestine leading to short chain fatty acids (SCFAs) that can be absorbed

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84
Q

What are brush border enzymes critical for protein digestion?

A

• peptidases and enterokinases (trypsin activated)

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85
Q

Enterokinase activates trypsin, which activates what?

A

Other zymogens

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86
Q

What is another way peptides/amino acids can be absorbed?

A

• Via secondary active transport (PEPT1 + hydrogen symporter or Na + amino acid)
• this is an important regulator of water absorption

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87
Q

Triglycerides are hydrolyzed by what?

A

Pancreatic lipase in order to release free fatty acids and 2-MG

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88
Q

Where does the majority of lipid digestion occur?

A

In the small intestine due to presence of bile salts and colipase and pancreatic lipase

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89
Q

What is orlistat?

A

• a lipase inhibitor, anti-obesity drug
• potent, slowly reversible inhibitor of pancreatic and gastric lipases and phospholipase A2
• SE: increased fatty/oily stool, flatulence, decrease absorption of fat soluble vitamins

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90
Q

Fatty acids and monoglycerides form what?

A

MICELLES, this is facilitated by bile salts —> then back into TGs to form chylomicrons and be exported in the lymph

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91
Q

How is lipid absorption facilitated?

A
  1. Diffusion (uncharged)
  2. Collision with and absorption into the membrane
  3. Carrier mediated transport (FAT/CD36)
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92
Q

What is ezetimibe?

A

Inhibits the Neiman pick C1 like 1 (NPC1L1) transporter resulting in decreased cholesterol absorption

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93
Q

Reabsorption of bile salts occurs where?

A

Distal ileum
• apical: sodium dependent bile salt transporter (ASBT) for uptake of conjugated vile acids
• basolateral: organic solute transporter (OST) to portal circulation

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94
Q

Summary of absorptive processes (picture/image)

A
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95
Q

What are the two ways the gut receives bicarbonate?

A
  1. Intracellular production via carbonic anhydrase
  2. Co-transporter of sodium/bicarbonate using the Na/K ATPase to drive gradient
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96
Q

What is pancrelipase?

A

• pancreatic enzyme supplement made of hog pancreas
• Given with acid suppression therapy, and meal/snacks to increase pancreatic enzymes
• should not be chewed —> oropharyngeal mucositis
• SE: diarrhea, abdominal pain, renal stones (hyperuricosuria)

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97
Q

Pancreatic secretion is controlled by what?

A

• cholecystikinin (CCK) from I cells acting on CCKa
• secretin

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98
Q

What causes the positive feedback loop for the release of CCK?

A
  1. Vagal stimulation—> motor protein from pancreas acinar cells—> increased CCK release
  2. FA, AA in duodenum —> CCK release

trypsin stops the positive feedback

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99
Q

How is gallbladder contraction/relaxation controlled?

A

CCK or vago-vagal release during intestinal phase —>

  1. ACh -> M3 receptor leads to contraction
  2. VIP/NO leads to relaxation
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100
Q

What is Ursodiol?

A

• secondary bile acid, ursodeoxycholic acid
• mech: reduces hepatic cholesterol secretion leading to decreased cholesterol content of bile AND continued maintenance of bile salts secretion
• used for dissolution of small cholesterol gallstones and prevention of gallstones in obese patients

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101
Q

What is the enterogastric reflex?

A

Regulation of gastric acid secretion during the intestinal phase (secretin, CCK, somatostatin)

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102
Q

How does CCK from I cells regulate the duodenal cluster unit?

A
  1. Stomach: reduces gastric emptying
  2. Pancreas: increased acinar secretion
  3. Gallbladder: contraction of gallbladder and relaxation of sphincter of Oddi
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103
Q

What substances increase motility?

A

• acetylcholine
• Gastrin
• insulin
• Motilin
• prostaglandin
• serotonin
• substance P

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104
Q

What substances decrease motility?

A

• epinephrine
• glucagon
• opioids
• secretin

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105
Q

What is the primary afferent neurotransmitter that initiates many enteric reflexes?

A

Serotonin (5HT) released by enterochromaffin cells

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106
Q

What causes an adynamic ileus?

A

Extensive distention or trauma to the abdomen leads to the intestinointestinal reflex, which causes a relaxation of the entire gut. This is dependent on intact extrinsic neural connections, and causes post-abdominal surgery constipation

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107
Q

What is Motilin?

A

Secreted by the M cells of the small intestine during the fastest state, this molecule contributes to the migrating motor complex (MMC)

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108
Q

How does the ileocecal valve work?

A

• tonically closed to prevent reflux
• Distention of the ileum leads to reduced tone, and emptying of the ileum. distention of the cecum leads to increased tone and decreased emptying of the ileum
• mediated by sympathetic input from the splanchnic nerves

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109
Q

What oxidizes ferrous iron to ferric iron?

A

Ceruloplasmin

(ferric iron to ferrous iron is done by low pH)

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110
Q

How is ferrous iron transported into the cytoplasm?

A

Divalent metal transporter-1 (DMT-1)

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111
Q

What transfers ferrous iron across the basolateral surface membrane?

A

Ferroportin

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112
Q

What is a copper dependent enzyme that oxidizes ferrous iron to ferric iron inside the gut epithelial cell?

A

Hephaestin

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113
Q

How is ferric iron transported in the blood?

A

Transferrin (Tf)

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114
Q

How is iron homeostasis regulated and maintained?

A

IRP1/2 and Hepcidin

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115
Q

When iron is low, translation of what is repressed?

A

Iron efflux from the cell, and heme synthesis (FTH, FTL, ferroportin, HIF2-alpha, ALAS2)

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116
Q

In low iron states, what becomes stabilized/activated?

A

Iron uptake from the diet (TFR1, DMT1)

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117
Q

What happens in a high iron state within the cell?

A

IRP1/2 are displaced allowing for gene transcription (iron flux from the cell is increased and iron uptake from the diet is decreased)

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118
Q

What accounts for most iron use in our bodies?

A

Erythropoiesis (heme)

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119
Q

Hepcidin expression is regulated by what?

A
  1. Transferin receptor (ERK1/2, SMAD)
  2. Inflammation, IL6 (STAT3)
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120
Q

When there is a lot of iron bound transferrin, is hepcidin produced or inhibited?

A

Produced— hepcidin encourages the degradation of ferroportin, so that uptake of iron does not occur

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121
Q

What are the functions of iron?

A
  1. Heme synthesis
  2. Iron sulfur clusters (electron transfer groups)
  3. Non-heme iron (dioxygenase)
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122
Q

What other vitamin/minerals does iron interact with?

A
  1. Vitamin C: enhances absorption and maintains iron in the reduced state
  2. Copper: required for export from enterocytes
  3. Iron inhibits zinc absorption
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123
Q

What are the symptoms of iron deficiency?

A

Microcytic hypochromic anemia, listlessness, fatigue

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124
Q

What happens in iron toxicity?

A

Typically seen in chronic hemachromatosis, can lead to excessive oxidative damage and organ failure

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125
Q

How is copper taken up by the gut epithelial cell (enterocyte)?

A

• brush border reductase creates cuprous copper (+1) from cupric (+2)
• transported into the cell by CTR1
• enters blood via ATP7A basolateral transporter, attaches to albumin to circulate

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126
Q

What are the functions of copper?

A
  1. Cofactor for hephaestin/ceruloplasmin
  2. Cytochrome C oxidase (has 3 Cu+)
  3. Cofactor for lysyl oxidase (collagen)
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127
Q

What is a cofactor for superoxide dismutase (SOD) 1 and 3?

A

Copper and zinc

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128
Q

What is a cofactor for dopamine beta-hydroxylase required for catecholamine and melanin synthesis?

A

Copper

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129
Q

What is Menkes (kinky hair) disease?

A

• A copper deficiency due to inherited mutation in the ATP7A transporter
• symptoms: anemia, leukopenia, hypopigmentation, brittle/sparse hair, altered cholesterol metabolism

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130
Q

What is Wilson disease?

A

• A disease of copper toxicity due to a mutation in the liver specific copper transporter ATP7B
• symptoms: G.I., hematuria, liver damage, kidney damage

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131
Q

What are the treatments for Wilson’s disease?

A

Chelation therapy and avoiding high copper foods. Potentially phlebotomy

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132
Q

What is a common physical exam finding of Wilson’s disease?

A

Kayser-Fleischer ring: ring of copper accumulated in the eye

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133
Q

What is osmotic diarrhea?

A

Increased luminal osmotic force by unabsorbed solutes. Abates during fasting

(Example: lactase deficiency)

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134
Q

What is secretory diarrhea?

A

Bowel epithelium secretes electrolytes into the lumen and water follows. Isotonic stool, persists during fasting

(example: cholera, Giardia, neuroendocrine carcinoma)

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135
Q

What is malabsorptive diarrhea?

A

Generalized failure of nutrient absorption, steatorrhea. abates with fasting

(example: pancreatic insufficiency, celiac disease, gastric bypass)

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136
Q

What is exudative (inflammatory) diarrhea?

A

Due to inflammatory disease, purulent bloody stools that persist during fasting

(example: IBD, ischemia, radiation, salmonella, campylobacter)

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137
Q

What does celiac disease look like on endoscopy/biopsy/blood test?

A

Endoscopy: flat, scalloped duodenal mucosa

Biopsy: villous atrophy with increased intra-epithelial lymphocytes

Blood: serum IgA tissue transglutaminase antibodies (highest sensitivity), serum IgA endomysial antibodies (absolute specificity)

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138
Q

What is the genetic predisposition for celiac disease?

A

HLA-DQ2, and HLA-DQ8

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139
Q

What is the part of gluten that has most of the disease containing components

A

Gliadin

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140
Q

What are common associated findings with celiac disease?

A

• IgA deficiency/ nephropathy
• dermatitis herpetiformis
• diabetes type one

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141
Q

What is the early histology of celiac disease compared to late?

A

Early: increased intraepithelial lymphocytes (CD8+)

Late: villous atrophy, elongated crypts

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142
Q

What is the scaling of celiac disease?

A

0-3c depending on lymphocytic activity and villous atrophy

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143
Q

What are two genetic disorders that you commonly see comorbid with celiac disease?

A
  1. Down syndrome
  2. Turner syndrome
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144
Q

What is tropical sprue?

A

Histologically identical to celiac, results in vitamin B12/folate deficiency. Associated with poor sanitation and warmer developing countries (E. coli, haemophilus)

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145
Q

How do you test for lactase deficiency?

A

Lactose hydrogen breath test

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146
Q

What is abetalipoproteinemia?

A

• mutation in the microsomal triglyceride transfer protein —> loss of apolipoprotein B
• cannot assemble lipoproteins (chylomicrons, VLDL, LDL)
• acanthocytes/burr cells are seen on blood smear due to lipoprotein deficiency

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147
Q

Cystic fibrosis (pancreatic insufficiency) can lead to what G.I. problems?

A
  1. Obstruction: meconium ileus of the newborn
  2. Malabsorption
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148
Q

What is Whipple disease?

A

• infection of tropheryma whippelii (PAS+, G+, intracellular bacilli) that compresses lacteals leading to impaired lymphatic transport
• may have cardiac, neurological, and arthralgic effects

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149
Q

What are the causes for a small bowel obstruction?

A

Mechanical: adhesions, hernia, tumor

Functional: decreased or absent peristalsis (ileus)

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150
Q

Small bowel obstruction causes graph/picture

A

• intrinsic
• extrinsic
• intraluminal

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151
Q

What is a hernia?

A

• weakness/defect in abdominal wall which can allow for protrusion of hernia with possible bowel segments
• common sites: inguinal and femoral canals, umbilicus, surgical incision/ventral hernia

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152
Q

What is the progression of a hernia?

A

1. Reducible: can return bowel/hernia sack back through the defect
2. Incarcerated: impaired venous drainage of entrapped intestine segment
3. Strangulated: arterial/venous compromise with strangulation/ischemia and infarction

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153
Q

What is a volvulus obstruction?

A

• twisting of loop of bowel at mesenteric attachment leading to ladd’s bands
• can cause obstruction and ischemia
• most common in the sigmoid colon

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154
Q

What is intussusception?

A

• telescoping of one segment of bowel into another causing peristalsis, obstruction, vascular compromise, and infarction
• most common in children under two and associated with rotavirus vaccine and peyers patch hyperplasia

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155
Q

What are adhesions in the G.I. tract?

A

• fiber bands that can cause obstruction and strangulation of the bowel
• development risks: surgery, Crohn’s colitis, endometriosis, infection/pelvic inflammatory disease

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156
Q

What is the difference between an omphalocele and gastroschisis?

A

• both are ventral wall herniation of organs in a newborn, however omphaloceles have a thin membrane around the protruding organs and gastroschisis does not

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157
Q

What radiographic sign is common in duodenal/intestinal atresia?

A

Double bubble (stomach and blind duodenal loop)

• seen in down syndrome, hx of polyhydramnios

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158
Q

What is Hirschprung disease?

A

• congenital aganglionic megacolon caused by failure of migration of ganglion cells (neural crest cells) during embryonic development from the cecum to the rectum/sigmoid colon
• lacks meissner and auerbachs plexus
• RET Loss of tyrosine kinase receptor, seen in familial cases

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159
Q

What is seeing histologically with Hirschprung disease?

A

• ganglion cells
• nerve hypertrophy

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160
Q

What is the cause of Meckel’s diverticulum?

A

• Vitelline duct remnant
• associated with intussusception and volvulus
• rule of 2’s

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161
Q

Where is the most common area to see ischemic bowel disease?

A

Watershed areas (regions were small vessels meet) including the splenic flexure, and the rectosigmoid colon

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162
Q

What are the two ways ischemic bowel disease cause injury?

A

Phase 1: hypoxic injury, cells fairly resistant
Phase 2: reperfusion injury, more serious, leakage of gut lumen bacteria into bloodstream, neutrophil infiltration, inflammatory mediator release

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163
Q

When and why does necrotizing enterocolitis occur?

A

• premature babies and low birthweight newborns
• ischemia/transmural necrosis of small and or large bowel
• considered a emergency due to perforation and short gut

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164
Q

What is angiodysplasia?

A

• submucosal and mucosal lesions with malformed vessels typically seen in the cecum and right colon of older patients
• major cause of lower G.I. bleeding
• could be acute (massive) or chronic (iron deficiency anemia)

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165
Q

What is inflammatory bowel disease (IBD)?

A

• chronic inflammatory bowel disease with protracted course and relapsing/remitting periods of activity. Resulting from an abnormal mucosal immune activation

  1. Crohn’s disease
  2. Ulcerative colitis
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166
Q

What is seen in acute colitis (days-weeks)?

A

• acute inflammation of neutrophils in the lamina propria and crypt epithelium, crypt abscesses
• often infectious
• no architectural changes

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167
Q

What is seen in chronic colitis (months-years)?

A

• gland architectural changes and distortion (splitting, shortening, dilatation, gland dropout)
• lymphocytes and macrophages

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168
Q

What are the symptoms of inflammatory bowel disease?

A

• diarrhea, bloody or mucoid
• urgency
• rectal bleeding
• fever
• abdominal pain/cramps
• fatigue/weight loss

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169
Q

What are the distribution patterns of Crohn’s disease versus ulcerative colitis?

A

Crohn’s disease: Skip lesions, transmural inflammation, ulceration, fissures

Ulcerative colitis: continuous colonic involvement, starting in the rectum, pseudo polyp/ulcers

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170
Q

What does Crohn’s disease look like grossly?

A

• linear ulcers
• cobblestone pattern
• segmental with skip areas
• stricture and perforation

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171
Q

What histology is unique to Crohn’s disease?

A
  • aphthous ulcers
  • Non-caseating granulomas
  • fistulas
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172
Q

How does ulcerative colitis present grossly?

A

• inflammatory pseudopolyps from regenerative mucosa
• diffuse continuous colitis with abrupt edges
• atrophic mucosa

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173
Q

What typically drives the initial onset of inflammatory bowel disease?

A

NSAIDs

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174
Q

Cigarette smoking increases the risk of ___1____, but decreases the risk of ___2___ in IBD.

A
  1. Crohn’s disease
  2. Ulcerative colitis
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175
Q

What is pouchitis?

A

Inflammation of the ileal pouch created as an artificial rectum following total cholectomy

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176
Q

What is acute self limited colitis?

A

• infectious colitis with neutrophil in the lamina propria and crypts (microabscesses) but normal gland architecture
• caused by: CMV, herpes, fungal organisms, Whipple organisms, C.diff

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177
Q

What does pseudomembranous colitis associated with C. Diff look like histologically?

A
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178
Q

What are the microscopic colitis causes?

A
  1. Lymphocytic colitis (intraepithelial lymphocytes)
  2. Collagenous colitis (thick collagen layer at base)

• presents with watery, non-bloody chronic diarrhea. Associated with age 50-70 and auto immune conditions
• not present on endoscopy

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179
Q

What are the causes of ischemic bowel disease?

A

• obstruction
• chronic mesenteric ischemia
• thrombosis/emboli of SMA
• hypoperfusion

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180
Q

What is seen on histology of ischemic colitis?

A
  1. Gland dropout
  2. Hyalinized lamina propria
  3. Scant inflammation
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181
Q

Where is the most common site for diverticulitis/diverticulosis?

A

Sigmoid: in people older than 60 (typically associated with low fiber diet)

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182
Q

What is acute pancreatitis?

A

Reversible autodigestion with acute inflammation typically caused by alcohol, trauma, obstruction of ducts, or infection.

Mech: trypsin release causes autodigestion with activation of prophospholipase, proelastase, Prekallikrein

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183
Q

What is interstitial acute pancreatitis?

A

• leakage of lipase and amylase leading to mild acute edematous interstitial pancreatitis
• edema, focal fat necrosis, saponification, and mild acute inflammation can be seen

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184
Q

What is necrotizing acute pancreatitis?

A

• severe necrosis of the pancreas parenchyma with hemorrhage, life-threatening medical emergency
• fat necrosis, calcium precipitation, and systemic lipase release all can be seen
• treatment is bowel rest and supportive medical treatment for shock

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185
Q

What is chronic pancreatitis?

A

• irreversible destruction of the pancreas parenchyma with fibrosis. Exocrine pancreas destroyed first, then islets.
• TGF-beta and PDGF can encourage chronic status
• can be complicated by pseudocysts and pancreatic insufficiency

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186
Q

What is a pancreatic pseudocyst?

A

• Peripancreatic pseudocyst of necrosis and hemorrhagic material rich in pancreatic enzymes. Fibrous cyst with no lining, fluid is high in amylase and lipase, low in CEA

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187
Q

What is autoimmune pancreatitis type one?

A

• IgG4 disease
• systemic multiorgan disease seen in older men
• periductal fibrosis, storiform fibrosis, lymphocytes and IgG4+ plasma cells

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188
Q

What is IgG4 related disease characterized by?

A

Lymphocytic sclerosing pancreatitis with increased IgG4 producing plasma cells

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189
Q

What is IgG4 related disease characterized by?

A

• lymphocytic sclerosing pancreatitis with increased IgG4 producing plasma cells

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190
Q

What is autoimmune pancreatitis type two?

A

• idiopathic duct-centric pancreatitis, limited to the pancreas
• seen concurrently with IBD
• characterized by periductal inflammation, ductile/lobular abscess, and duct ulceration with neutrophils

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191
Q

What is the only nonneoplastic pancreatic cyst?

A

Pseudocyst: seen an acute/chronic pancreatitis

Aspirate: brown fluid, high amylase/lipase, low CEA

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192
Q

Table/image of neoplastic pancreatic cysts

A
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193
Q

What is an intraductal papillary mucus neoplasia (IPMN)?

A

• neoplastic cyst lined by mucus epithelium, benign but precursor to adenocarcinoma especially in the main duct
• typically found in the pancreas head
• seen in individuals 80+

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194
Q

What is a mucinous cystic neoplasm (MCN)?

A

• multiloculated large cysts lined by columnar mucinous epithelium, ovarian like stroma around ducts
• seen in young and middle-aged women at the tail of the pancreas

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195
Q

What is a serous microcystic cystadenoma?

A
  • large mass with a central stellate scar and calcifications seen inthe pancreas of people 70+
  • usually benign, composed of glycogen rich cuboidal cells surrounding small cysts containing clear, thin fluid
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196
Q

Pancreatic adenocarcinoma

A

• ductal adenocarcinoma found in the head of the pancreas
• 80% occur after age 60
• risk factors: smoking, obesity, inactivity, diabetes, chronic pancreatitis, family history
• presentation: pain, jaundice, weight loss, migratory thrombophlebitis

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197
Q

What are the gene mutations typically seen with pancreatic adenocarcinoma?

A

• KRAS
• P16/CDK2A
• SMAD4
• TP53

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198
Q

What is the pancreatic interepithelial neoplasia/panIN scale?

A
  • scale determine the grade of the pancreatic adenocarcinoma (1= low-grade, 2-3= high-grade)
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199
Q

Photo/image of cells present in different stages of PanIN

A
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200
Q

Pancreatic adenocarcinoma typically presents with what types of invasion?

A
  1. Perineural
  2. Invasion into peripancreatic adipose tissue
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201
Q

What is a solid and cystic malignant tumor associated with WNT pathology seen in young women?

A

Solid and pseudopapillary neoplasm of the pancreas. Locally aggressive but cured with adequate surgery

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202
Q

What is acinar carcinoma?

A

A rare tumor seen in men/adults that makes pancreatic enzymes (zymogen granules with trypsin and lipase) causing subcutaneous fat necrosis, endocarditis, polyarthralgia

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203
Q

What is a pancreatoblastoma?

A

• Pediatric pancreatic tumor seen in ages 1-15, rare
• squamous islands mixed with acinar cells

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204
Q

What is an islet cell tumor?

A

A well differentiated pancreatic neuroendocrine neoplasm that makes and secrete islet cell hormones. Graded based off of mitotic activity and Ki67 staining

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205
Q

What is the most common anomaly of the gallbladder?

A

• phrygian cap of the gallbladder, with fundus folded inward
• benign, asymptomatic, may present as mass on ultrasound

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206
Q

What is cholelithiasis?

A

Gallstones: mixture of bile salt, bilirubin, calcium salt

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207
Q

What are the two types of gallstones?

A
  1. Cholesterol: yellow, radiolucent, due to diet
  2. Pigmented: brown/black, mixture of insoluble calcium salts and unconjugated bilirubin, radioopaque, due to infection typically
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208
Q

What are the five F’s of cholesterol stone risk factors?

A

Fair, female, forty, fertile, family

~ other risk factors include increasing age, rapid weight loss, bile stasis, hyperlipidemia, bile metabolism disorders

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209
Q

What is gallbladder cholesterolosis?

A

• cholesterol polyps made of cholesterol super saturated bile entering into the mucosa and is phagocytized into macrophages
• bright yellow flat/patchy or large polyps

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210
Q

What are the biggest risk factors for pigmented gallstones?

A
  • bacterial/parasitic biliary infection (E. coli, roundworm, liver fluke chonorchis)
  • chronic hemolytic syndrome like sickle cell, hereditary spherocytosis
  • illegal disease/dysfunction (Crohn’s, ileal resection, cystic fibrosis)
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211
Q

What are the complications of cholelithiasis?

A

• acute/chronic cholecystitis
• biliary colic (pain with ingested fatty food)
• empyema (Puss in lumen)
• pancreatitis
• gallstone ileus
• ascending cholangitis
• increase risk for adenocarcinoma

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212
Q

What causes 90% of cholecystitis?

A

Gallstones

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213
Q

What is the histology of acute cholecystitis?

A

• neutrophils in the epithelium and submucosa
• extensive hemorrhage in the wall and lumen
• fat necrosis

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214
Q

What is acute gangrenous cholecystitis?

A

• mural infection with high perversion rate
• associated with clostridium perfringens/coliforms

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215
Q

What is porcelain gallbladder?

A

A complication of chronic cholecystitis leading to dystrophic calcification of the gallbladder wall. —> increased gallbladder carcinoma risk

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216
Q

What is hydrops of the gallbladder?

A

• markedly distended gallbladder filled with mucoid or watery material
• atrophic, thin distended wall that is non-inflammatory
• due to chronic obstruction

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217
Q

What is the number one risk factor of gallbladder carcinoma?

A

Gallstones (more common in women and older people)

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218
Q

What are the different histology patterns of gallbladder adenocarcinoma

A

• infiltrative or exophytic gross pattern into the gallbladder lumen
• papillary, glandular, poorly differentiated/signet ring or even carcinosarcoma

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219
Q

The precursors to gallbladder adenocarcinoma are what?

A

• gallbladder dysplasia
• carcinoma in situ
• EGF (HER2) mutations
• RAS; P53 mutations

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220
Q

Bile duct carcinoma of the intrahepatic bile duct is called what?

A

Cholangiosarcoma

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221
Q

Bile duct carcinoma of the extrahepatic duct/common bile duct is called what?

A

Biliary adenocarcinoma

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222
Q

Hilar/perihilar tumor/bifurcation of right and left hepatic ducts from bile duct carcinoma is called what?

A

Klatskin tumor

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223
Q

What are the risk factors of carcinoma of the bile ducts?

A

• liver flukes
• sclerosing cholangitis
• fibropolycystic liver disease
• choledococysts (bile stasis and inflammation)
• hepatitis B and C/non-alcoholic liver disease
• gallstones

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224
Q

What does a cholangiocarcinoma look like grossly and histologically?

A

• gross: papillary, intraductal nodules, infiltrative, diffuse
• Histopathology: adenocarcinoma, transmural infiltration

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225
Q

What is the common histological findings of ampulla of Vater adenocarcinoma?

A

• signet ring morphology, colloid carcinoma
• bile duct dysplasia

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226
Q

What occurs during dry heaves?

A

Repeated herniation of the abdominal esophagus and cardia into the thoracic cavity due to negative pressure

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227
Q

What occurs during nausea and the urge to vomit?

A

Decrease gastric motility and increased tone in the proximal small intestine leading to reverse peristalsis: movement of contents of small intestine into stomach

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228
Q

What are the phases of emesis?

A
  1. Preparation and protection (close glottis, deep breath)
  2. Diaphragm contracts—> negative pressure in the thorax and opening of esophageal sprinter
  3. Muscles of the abdominal wall contract elevating intragastric pressure
  4. With pylorus closed, stomach and intestinal contents move into the esophagus (passive, no reverse peristalsis)
229
Q

What are the peripheral emetic stimuli?

A

• traditional sensory: nociception, olfaction, vision, inner ear
• G.I. sensory: drugs, radiation, bacteria, virus
• blood-borne emetics: chemoreceptive trigger zone

230
Q

What are the central emetic stimuli?

A

Fear, anticipation, memory

231
Q

Where is the chemoreceptive trigger zone, that detects blood-borne emetics?

A

Area Postrema

232
Q

Where is the vomiting center?

A

Medullary reticular formation: initiation and coordination of fixed motor pattern

233
Q

What are the 5HT3 antagonists?

A
  • SETRON, ondansetron
  • blockade of peripheral 5HT3 receptors on intestinal vagal afferent nerves
  • therapeutic use: prevention and treatment of chemotherapy induced nausea and vomiting
234
Q

What are the side effects of 5HT3 antagonist?

A

• well tolerated, excellent safety profile
• mild side effects of headache, dizziness, constipation
• prolongation of QT interval

235
Q

What are the D2 antagonists?

A

• droperidol, metoclopramide, and the phenothiazines: Prochlorperazine, promethazine
• blockage of the D2 and muscarinic receptors in the CTZ, counteracting reverse peristalsis and causing sedation
• therapeutic use: vomiting due to uremia, radiation sickness, cancer chemo, infection, labor/gravidrum

236
Q

What are the side effects of D2 antagonists?

A

• somnolence, nervousness, agitation, anxiety
• dystonia, parkinsonism, tardive dyskinesia (irreversible), increased prolactin release

237
Q

What is scopolamine?

A

• blockade of muscarinic and dopaminergic receptors in the cerebellum used to treat motion sickness
• side effect: dry mouth, eyes, blurred vision, constipation, increased GERED, urinary retention, cognitive problems/confusion

238
Q

What antihistamines are used as anti-emetics?

A

• dimenhydrinate, diphenhydramine, meclizine
• blockage of H1 and muscarinic receptors in the cerebellum, nonselective, sedative
• therapeutic use: motion sickness, hyperemesis gravidarum
• SE: anticholinergic

239
Q

What are the NK1 antagonists?

A

• aprepitant (oral) and fosaprepitant (IV)
• blockage of neurokinin receptor 1 (NKR1) in the CNS (analog of substance P)
• therapeutic use: acute and delayed phases of chemotherapy and use nausea and vomiting

240
Q

What are the cannabinoids used for nausea/vomiting?

A

• dronabinol, nabilone, medical marijuana
• activation of central cannabinoid receptors (intrinsic agonist of anandamide) in the CNS
• therapeutic use: cancer chemotherapy induced nausea/vomiting (combo with phenothiazines)

241
Q

What is a beneficial side effect of cannabinoids and dexamethasone for cancer patients?

A

Hyperphagia, increased appetite

242
Q

Uses of dexamethasone (corticosteroid) for anti-emesis purposes

A
  1. Anti-inflammatory effect (ICP)
  2. Direct central action in the nucleus of the solitary tract
  3. Indirect GCR interactions with 5HT and NK1 receptors
    • therapeutic uses: cancer, chemo, postop, increased ICP, opioid induced nausea/vomiting
243
Q

What is the preferred treatment for poisoning?

A

Whole bowel irrigation: with polyethylene glycol (osmotic cathartic)

• SE: allergic reaction, bloating, gas, stomach upset (rare: bloody diarrhea, rectal bleeding)

244
Q

What is responsible for 45% of pancreatitis?

A

Cholelithiasis, stones. They lodged in the pancreatic duct/ampulla of vater and cause an obstruction and subsequent extravasation of enzymes into the parenchyma

245
Q

What is responsible for 35% of pancreatitis?

A

Alcohol use:
1. Intracellular accumulation of digestive enzymes and premature release/activation
2. Increases the permeability of ductules, which allow enzymes to reach the parenchyma
3. Increases protein content in the pancreatic juice, decreases bicarbonate levels and trypsin inhibitor concentrations —> protein plugs

246
Q

What causes autodigestion in pancreatitis?

A
  • trypsin starts the premature release of enzymes
  • phospholipase A - causes ARDS
  • Elactase - vascular damage/hemorrhage
  • lipase - induces fat necrosis
  • chymotrypsin - causes edema/vascular injury
247
Q

What are the symptoms of pancreatitis?

A

• mid-epigastric pain in 95% that can radiate to the back or cause nausea/vomiting
• rapid onset (~ 30 min)

248
Q

What are the lab tests used to diagnose pancreatitis?

A
  • Amylase/lipase (lipase is more sensitive/specific)
  • increased WBC/glucose
  • dehydration, increased BUN/cr
  • decreased calcium
  • increased bilirubin, LDH, AST
  • decreased albumin
  • decreased oxygen
  • high CRP
249
Q

What are the three requirements to diagnose pancreatitis?

A
  1. Clinical symptoms (mid epigastric pain)
  2. Labs (lipase > 3x normal)
  3. Imaging + (US or CT)
250
Q

What can be seen on abdominal x-ray for pancreatitis?

A

A sentinel loop (not specific)

251
Q

What is the treatment for pancreatitis?

A
  1. IV hydration, 2L lactated ringers, 2 additional leaders in the first 24 hours
  2. Pain control, opioid/morphine
252
Q

What are the treatable causes of pancreatitis?

A

• causative medication
• cholelithiasis
• elevated calcium (ex. hyperparathyroidism)

253
Q

What are the treatments of pancreatitis?

A

• enzyme therapy for malabsorption (pancrelipase)
• reducing fat intake to 20g or less per day
• medium chain triglycerides (more easily digested)

254
Q

What are the complications of pancreatitis?

A

• Ascites
• pancreatic pseudocyst
• diabetes
• my absorption of fat/vitamins (A, D, E, K)

255
Q

At the time of diagnosis, what is the survival rate of pancreatic cancer?

A

5 years is <5% (typically diagnosed late)

256
Q

What type of bond is non-digestible for the human body?

A

Beta-1,4 (cellulose)

257
Q

What are lignins?

A

• branched polymers of phenolic subunits found in woody tissues like bark, stems, fruit seeds

258
Q

What is hemicellulose?

A

• a branched polymer abundant and brand, whole grains, and nuts
• xylose, mannose, or galactose backbone
• arabinose, glucuronic acid, or galactose side chains

259
Q

What are pectins?

A

• branched polymers abundant in apples, strawberries
• completely degraded by gut bacteria
• backbone: galacturonic acid

260
Q

What are gums?

A

• hydrocolloids secreted by plants to close wounds
• commonly food additives, completely fermented by gut bacteria

261
Q

What are beta-glucans?

A

• found an oats, barley, mushrooms. They are fermented by gut bacteria to short chain fatty acids
• typically homopolymers of glucopyranose subunits

262
Q

Glucans are an effective dietary intervention for what disease?

A

Hypercholesterolemia. The mechanism is increasing bile acid synthesis (7alpha-hydroxylase) and decreasing bile salt reuptake

263
Q

What are Fructans?

A

• poly fructose, found in asparagus, leeks, onions, garlic, tomato, and banana
• probiotics: promote the growth of bifodobacteria (G+ anaerobe)

264
Q

What is a fructan used as a fat substitute in foods like salad dressing?

A

Inulin

265
Q

What is psyllium?

A

• (Metamucil) structure similar to gums, indigestible and holds excessive water
• backbone of arabinose and xylose

266
Q

What are some types of resistant starches in the body?

A

inaccessible to amylose and amylopectin
* plant cell walls
* starch granules within cells
* retrograde starch (cooked then cooled)
* chemically crossing to starch

267
Q

What are the insoluble fibers found in the exoskeletons of insects and crustaceans?

A

Chitin and chitosan (structurally similar to cellulose, but with amino group substitutions on the glucoses)

268
Q

What is polydextrose?

A

A polymer of glucose and sorbitol used as a food additive to replace sugar. Soluble and partially fermented in the gut

269
Q

What are the functions of dietary fiber in the body?

A
  1. Delays gastric emptying
  2. Increases luminal volume
  3. Decreases nutrient absorption time (increases intestinal transit time)
270
Q

High fiber foods have a (high/low) glycemic index

A

Low — increase insulin sensitivity (GOOD)

271
Q

What are the benefits of having a diet high in fiber?

A
  1. Decreased lipid absorption
  2. Lowered serum cholesterol concentrations
  3. Healthier gut Microbiome (lactobacilli and bifodobacteria)
  4. Increase fecal bulk (decreased diverticulitis)
272
Q

Fermentation of dietary fiber by bacteria in a large intestine produces what?

A

Short chain fatty acids (SCFAs) including acetate, propionate, butyrate. They promote immune intolerance of a healthy gut microbe because they are a nutrient source for colonocytes and bacteria

273
Q

Are short chained fatty acids packaged in chylomicrons?

A

NO. They are transported through intestinal epithelial cells directly into the blood

274
Q

How does dietary fiber affect immune cells?

A

It acts as a ligand for GPR43, and it inhibits histone deacetylases (HDACs)

275
Q

Deactivation of GPR43 by SCFAs leads to what effects?

A

•adipose tissue: decreased insulin sensitivity, and decreased fat accumulation
•liver and muscle: increased insulin sensitivity

276
Q

What is an important and beneficial component of human breastmilk that is a complex carbohydrate?

A

Non-digestible human milk oligosaccharide (HMOs)

277
Q

What is lactose synthetase a dimer of, and what does it do?

A

• galactosyltransferase and lactalbumin
• it produces lactose. A disaccharide of galactose and glucose that is the main sugar in human breastmilk

278
Q

What is a unique characteristic of human milk oligosaccharide?

A

It can pass through the gut epithelium and is present in the infants blood. They can act as decoy receptors, preventing attachment of pathogens to cellular glycolipids and glycoproteins

279
Q

What is the dominant anion driving H2O transport in the distal colon?

A

SCFAs (proprionate, butyrate, acetate)

280
Q

What SCFAs promote intestinal gluconeogenesis?

A

Propionate and butyrate

281
Q

SCFAs are what type of signaling molecule?

A

Anorexigenic— promote feelings of fullness via activation of the hypothalamus, stimulation of vagal Erin in portal vein, and triggers release of PYY and GLP1 paracrine signaling in the fed state

282
Q

What is modified to allow tight junction permeability for paracellular fluid transmission?

A

Claudins (tight Junction proteins) regulated by cytokines, bacterial toxins, hormones

283
Q

How is fluid absorbed in the small intestine?

A

• cells at the tips of villi driven by sodium cup nutrient transport
• chloride and H2O follow paracellularly

284
Q

How is fluid secreted in the small intestine?

A

• cells in the crypts secrete fluid driven by chloride ions secretion through CTFR
• sodium and H2O follow paracellularly

285
Q

Regulation of luminal water content occurs via:

A
  • modulation of chloride transport, cGMP and cAMP impacting channels (CTFR, NHE3, etc) and prostaglandins
286
Q

How are chloride transport channels modulated to regulate luminal water content?

A

• disruption of the mucosa releasing 5HT from ECL cells —> release of ACh and/or VIP —> cAMP in crypt cells —> increased chloride secretion (CTFR)

287
Q

What is guanylin?

A

• a peptide hormone released by goblet cells that activates guanylyl cyclase C and increases cGMP (which increases the flow of chloride through CTFR)

288
Q

Why does secretory diarrhea occur?

A

• excess secretion of chloride and or inhibition of NaCl transport across the apical membrane
• commonly caused due to endocrine tumors, bile salt malabsorption, infection, inflammation

289
Q

What is osmotic diarrhea?

A

• changes in luminal contents (small sugars, ions) that result in water being pulled from the bloodstream
• increased osmotic gap > 75
• common causes include carb mall absorption, laxative abuse, malabsorption syndromes

290
Q

Teduglutide

A

• treatment for short bowel syndrome, GLP2 analog that binds to enteric neurons and endocrine cells —> releases tropic hormones that increase epithelial growth and enhance fluid/nutrient absorption

291
Q

Lubiprostone

A

• anti-constipation drug that is an activator of CIC-2
• increases chloride secretion leading to retention of water in the lumen and looser stool
• SE: fetal loss(?), diarrhea in infants

292
Q

Linaclotide, plecanatide

A

• anti-constipation medication’s that are activators of GC-C
• activate guanylyl cyclase and increase cGMP, leading to activation of CTFR and retention of water in the lumen (looser stools)
• SE: increase maternal death in animals/mortality of juvenile mice

293
Q

Crofelemer

A

• inhibitor of CTFR: voltage gated inhibition of CFTR and CIC2 leading to decreased chloride secretion, increased absorption of water and firmer stool
• commonly used for anti-HIV diarrhea medication

294
Q

Octreotide

A
  • somatostatin analog, mech includes:
    1. Decrease 5HT stimulated cGMP dependent chloride secretion
    2. Decreased neurotransmitter/hormone release
    3. Low doses Increase motility, high doses decrease motility
  • off label treatment of severe diarrhea due to AIDS (main mechanism is treatment of endocrine tumors)
295
Q

What are some therapeutic uses of ocreotide?

A

• severe diarrhea due to AIDS
• short bowel syndrome
• dumping syndrome— vagotomy (vagal nerve severance)

296
Q

What are the side effects of ocreotide (somatostatin analog)?

A

• nausea, abdominal pain, flatulence
• fat soluble vitamin deficiency
• gallstones
• hypo or hyperglycemia
• hypothyroidism leading to bradycardia

297
Q

Bismuth subsalicylate as a diarrheal medication

A

• salicylate decreases prostaglandin synthesis leading to decreased cAMP, decreased chloride secretion via CFTR, and increased absorption of water
• typically used for prevention of travelers diarrhea

298
Q

Osmotic cathartics: lactulose, magnesium hydroxide, sodium phosphate, polyethylene glycol

A

• increased retention of water in the lumen due to osmosis causing loser stool
• lactulose specifically can decrease plasma ammonia concentration (Tx of portosystemic encephalopathy)

299
Q

What is a side effect of sodium phosphate, an osmotic cathartic?

A

• intravascular volume depletion and electrolyte imbalances (hypocalcemia, hypernatremia, hypokalemia)

300
Q

What are the bile acid binding resins?

A

• cholestyramine, colestipol
• they caused the reabsorption of bile salts leading to secretory diarrhea. They can also impair the absorption of other drugs and fat soluble vitamins

301
Q

What SSRI are effective treatments for constipation predominant IBS?

A

Fluoxetine, paroxetine, sertraline: they decreased the reuptake of serotonin in EC cells leading to primary afferent vagal activity and increased peristalsis

302
Q

What are the bulk laxatives?

A
  • dietary fiber, methyl cellulose, psyllium
  • these are dependent on the normal function of the peristaltic reflex: increased distention on gut lumen stimulates receptors in the myenteric plexus
303
Q

What are contact cathartics?

A

• anthraquinone derivatives, castor oil, bisacodyl
• stimulate the peristaltic reflex via aggressive irritation
• can have significant side effects, including dependency and destruction of myenteric plexus

304
Q

What are the 5HT3 antagonists that decrease: motility?

A

• setron, where alosetron has a longer duration of action
• this causes afferent stimulation of peristalsis used for severe diarrhea prominent IBS
• SE: severe constipation is common, may develop ischemic colitis

305
Q

What are the 5HT4 agonists that increase colon motility?

A
  • tegaserod, cisapride
  • activation of presynaptic receptors which increases release of neurotransmitters from the myenteric neurons leading to increased peristalsis (treatment for constipation-predominant IBS and diabetic gastroparesis)
306
Q

What are the D2 receptor antagonists used for constipation?

A

• domperidone, metoclopramide
• inhibition of DA inhibition (double inhibition) leads to increased action of acetylcholine in the gut (increased motility)
• commonly used for decreased gastric emptying from vagotomy or diabetic gastroparesis. Metoclopramide is also an anti-emetic

307
Q

D2 receptor antagonist can lead to what side effects?

A

Nervousness, agitation, anxiety, dystonia, parkinsonism, tardive dyskinesia, increased prolactin release- impotence, menstrual disorders, galactorrhea

308
Q

What are the most effective antidiarrheal drugs for active diarrhea?

A

• opioids: diphenoxylate, eluxadoline, loperamide
• loperamide is the least likely to cross the blood brain barrier
• SE: toxic megacolon, toxic colitis

309
Q

What are the mu receptor antagonist used to treat constipation from postoperative ileus and chronic opioid therapy?

A

• alvimopan, methylnaloxone, nalox egol
• selective antagonists that do not cross the BBB that can increase motility of the G.I. system

310
Q

What are drugs that affect colonic function that are generally NOT used to treat diarrhea or constipation but theoretically couldbe used?

A
  • tricyclic antidepressants such as amitriptyline or desipramine: anticholinergic that decreases motility
  • atropine: anti-muscarinic that decreases motility
311
Q

What class of antibiotics stimulate the motilin receptors on smooth muscle?

A

Macrolides (ACE)

312
Q

What are common stool softeners?

A

• docusate: surfactant that increases mixing of water with stool
• mineral oil: lubrication (can cause lipid pneumonitis if aspirated)

313
Q

What are the three types of diarrhea/constipation medication and some examples of each?

A

1. Prokinetic: D2 receptor antagonist, macrolides, 5HT4 agonists
2. Antidiarrheals: opioids, eluxadoline, bile-acid binding resins, octreotide, bismuth subsalicylate, crefelemer
3. Laxative/cathartics: Bulk, osmotic, stimulant, stool softeners, opioid antagonist/agonists

314
Q

Pictures/graph/image of diarrhea/constipation medication classes

A
315
Q

What are the anti-inflammatory agents (aminosalicylates) used to treat IBD?

A

• balsalazide, mesalamine, sulfasalazine
• all variance of mesalamine (5-ASA), which is an NSAID that is poorly absorbed from the G.I. tract —> local COX inhibition

316
Q

Why does sulfasalazine have a high incidence of side effects?

A

Absorption of the sulfapyridine molecule: nausea, headache, arthralgia, bone marrow suppression, malaise, hypersensitivity reactions

317
Q

What are the cortical steroids used as immunosuppressive agents for IBD?

A
  • budesonide, prednisone, prednisolone
  • budesonide has a high first past metabolism so it has a local rather than systemic effect (good for GI)
318
Q

What are the anti-metabolites used for immunosuppressive action in IBD?

A

• azathioprine—> 6-mercaptopurine and methotrexate

319
Q

What are the anti-TNF-alpha antibodies used to treat IBD?

A

• adalimumab, certolizumab, infliximab
• works by dysregulation of the TH1 response where TNF-Alpha is the key proinflammatory cytokine
• 60% do not respond or become resistant to treatment due to antibody antibodies

320
Q

What is unique about infliximab and adalmumab?

A

their Fc portion of the antibodies can also promote complement activation and antibody-mediated destruction of inflammatory cells

321
Q

What is certolizumab?

A

• an anti-TNF alpha antibody consisting of an Fab component conjugated to polyethylene glycol (PEG)
• no complement activation and no placental transfer

322
Q

Anti-TNF-alpha antibodies can cause what reactions?

A

• infusion reactions: acute, type 1 or delayed, cytokine release storm
• type 3 hypersensitivity
• increased infections, reactivation of TB
• teratogen, third trimester abnormalities

323
Q

What are the rare but severe side effects of anti-TNF-alpha antibodies?

A

Severe hepatic reactions, demyelinating disorders, hematologic reactions and CHF, skin cancer, lymphoma

324
Q

What is the anti-interleukin 12/23 medication used in the treatment of IBD?

A
  • ustekinumab
  • works by inhibition of Treg cell activation (Th1 cells)
  • used in Crohn’s disease, psoriasis, psoriatic arthritis
325
Q

What are the anti-integrin medications used in the treatment of IBD?

A
  • natalizumab, alpha4betaX used in IBD
  • vedolizumab, alpha4beta7 used in MS and IBD
  • these work by inhibiting diapedesis of immune cells (entry through endothelial cells)
326
Q

Natalizumab can cause a reactivation of what disease?

A

Human polyomavirus (JC) which can progress to multifocal leukoencephalopathy (PML)

327
Q

What are the two main agents causing viral gastroenteritis?

A
  1. Norovirus
  2. Rotavirus

(Others: enteric adenovirus 40 and 41, sapovirus, astrovirus, aichi virus)

328
Q

What are the two main agents causing viral gastroenteritis?

A
  1. Norovirus
  2. Rotavirus

(Others: enteric adenovirus 40 and 41, sapovirus, astrovirus, aichi virus)

329
Q

Norovirus causing gastroenteritis:

A

• RNA virus, icosahedral nucleocapsid, non-envelopes, single-stranded + genome
• fecal-oral transmission, ready to eat food, confined areas
• incubation period: 24 to 48 hours
• symptom period: 24 to 48 hours

330
Q

What are the common symptoms of norovirus?

A

• vomiting/diarrhea, explosive
• rapid onset
• low-grade fever
• stomach pain

331
Q

What is rotavirus?

A

• double-stranded segmented RNA genome virus
• group A most infectious
• 48-hour incubation, disease course of one week
• primarily effects 6-24mo children

332
Q

What are the important pieces of the mechanism of rotavirus disease?

A

• 5-HT
• viral NSP4 is critical for the destruction of epithelial cells being rapidly replaced by immature ones that allow for over activation of cAMP and invasion

333
Q

What is the original formulation of rotavirus vaccine known for?

A

Causing intussusception

334
Q

What are the bacteria that generate pre-formed toxins and food?

A

• staphylococcus aureus
• bacillus cereus
• clostridium botulinum

335
Q

What causes Staphylococcus aureus food poisoning?

A
  • injection of toxin (not the bacteria) is what causes illness
  • can grow in 15 to 45°C Celsius and high concentrations of salt (resistant)
336
Q

What are the symptoms for s. Aureus food poisoning?

A

• incubation period of 1-7 hours
• nausea/vomiting/stomach cramps/diarrhea for 1-3 days: self-limiting

337
Q

What is bacillus cereus?

A

• boxcar shaped gram-positive rods
• produces biofilms set here easily to invasive devices (skin infection)
• spore forming, beta hemolytic
• Preformed enterotoxin that forms holes in the membranes of enterocytes

338
Q

B. Cereus food poisoning:

A

• 1-6 hour incubation period
• duration of 24 hours, self limiting
• nausea and vomiting, resemblance to s. aureus enterotoxin

339
Q

When can you commonly see bacillus cereus food poisoning?

A

In rice: spores can survive the rice cooking process

340
Q

What is clostridium botulinum?

A
  • gram-positive, spore forming rod (matchstick)
  • toxin is absorbed from G.I. tract into the bloodstream (preformed)
  • incubation period of 18 to 36 hours
  • illness can occur anywhere from 6 hours to 10 days post ingestion
341
Q

What are the symptoms of clostridium botulinum?

A

• all neurological symptoms because it enters the bloodstream: double vision, blurred vision, drooping eyelids, slurred speech, difficulty swallowing, dry mouth, muscle weakness

342
Q

What is the cause of the C. Botulinum neurotoxin?

A

• irreversibly blocks the release of acetylcholine from the motoric end plate which result in muscle weakness and paralysis

343
Q

What are the bacterial sources of foodborne illness in the United States (the big 3)?

A

• campylobacter jejuni: intestinal cell invasion
• salmonella enterica: intestinal cell invasion
• clostridium perfringens: enterotoxin

344
Q

What is clostridium perfringens?

A

• gram-positive, spore forming rod non-motile
• obligate anaerobe
• endotoxin binds to receptors in endothelial cell junctions, generates pores in host mucosa cells

345
Q

What are the symptoms of clostridium perfringens food associated illness?

A

• incubation of 6-24 hours
• symptoms last for 24 hours, less than three days
• diarrhea and abdominal cramps

346
Q

What is a common food to be inoculated with clostridium perfringens?

A

• food prepared and large quantities those kept warm for a long time before serving (reheated meat)

347
Q

What is campylobacter jejuni?

A

• gram-negative rod, comma/S-shaped
• motile, cold sensitive
• a zoonosis disease, transmitted to humans from animals or animal products (commonly poultry and eggs)

348
Q

What are the symptoms of campylobacter Jejuni foodborne illness?

A
  • incubation of 2 to 5 days
  • symptoms can last up to a week
  • diarrhea, cramping, bloody stools, vomiting, abdominal pain, fever
  • symptoms are an inflammatory response to cell division
  • positive stool culture
349
Q

What is a possible complication of Campylobacterosis?

A
  • Guillain-Barré syndrome: autoimmunity against peripheral nervous system. Symptoms of weakness/tingling sensation in the legs and symmetrical weakness/abnormal sensation spread to the upper extremities
350
Q

What are the most common salmonella variants?

A

• s. Enteritidis, s. Typhimurium
• gram-negative bacilli, non-spore forming, H2S+ and lactose -

351
Q

What are the symptoms of salmonellosis?

A

• 12 hour to 3 day incubation
• symptoms last 4-7 days
• diarrhea, fever, abdominal cramps, reactive arthritis
• infected from poultry, meat, eggs, reptilian pets (turtles)

352
Q

What is the most common cause of infant botulism?

A

c. Botulinum spores found in honey

Symptoms: lethargic, feeding poorly, constipated, weak cry, poor muscle tone

353
Q

What is listeria monocytogenes?

A

• gram-positive, rod shaped bacteria
• non-fastidious, flagellated, motile, non-spore forming, oxidize -

354
Q

What is listeriosis?

A

• listeria infection, mild G.I. infection
• more vulnerable: old adults, pregnant women, newborns, immune system
• can lead to muscle aches, stiff neck, fevers, chills, meningitis and sepsis particularly in pregnant women

355
Q

How does listeria spread, and what is a major target?

A

Spreads via immune cells (macrophages) and the liver is a major target

356
Q

What is cholera?

A

• diarrhea prominent disease caused by vibrio cholerae: gram-negative curved rod with single flagellum
• water is the primary reservoir

357
Q

What are the unique symptoms of cholera?

A

• rice water stools
• vomiting, tachycardia
• loss of skin elasticity, dry mucus membranes
• low blood pressure and thirst
• muscle cramps
• restlessness/irritability

358
Q

What are the common serogroups of vibrio cholerae?

A

O1 and O139 — they produce the cholera toxin

  • increased adenylate cyclase —> increased cAMP —> increased chloride excretion, water moves into lumen
359
Q

Is there a vaccine for cholera?

A

Yes: vaxchora, works against the O1 serotype

360
Q

What reagent turns oxidize positive bacteria purple?

A

• Kovac’s oxidase reagent (used for vibrio cholerae)

361
Q

What is the most common cause of traveler’s diarrhea?

A

E. Coli ETEC
* incubation 1-3 days
* illness typically lasts 3-4 days, less than 10
* profuse watery diarrhea and abdominal cramping, fevers, chills, nausea, loss of appetite

362
Q

Where can you find vibrio parahaemolyticus and what does it do in the body?

A

• in food you find in the water and do not cook (shellfish, sushi)
• bloody diarrhea, stomach cramps, fever, nausea, vomiting
• symptoms last less than a week but can spread in the blood in immunocompromised patients

363
Q

What are the entertoxins of vibrio parahaemolyticus?

A

• hemolysins, TDH and TRH
• pore-forming and red blood cells and epithelial cells disrupting gut homeostasis
• without these toxins it is not pathogenic

364
Q

What is Shigella?

A

• closely related to E. coli
• gram -, facultive anaerobe, non-motile, non-spore forming
• gain access through M cells via peyers patches
• invasive, can cause systemic disease

365
Q

What are the most common shigella organisms and how are they transmitted?

A

• s. Sonnei
• s. Flexnori
• s. Dysenteriae

~ transmitted via fecal oral route

366
Q

What are the symptoms of infection with shigella sonnei?

A

• diarrhea, bloody
• fever, stomach cramp
• incubation of 1-2 days
• resolves in 5 to 7 days

367
Q

What is dysentery?

A

Frequent, small bowel movements with blood and mucus accompanied by rectal pain and spasms (tenesmus)

368
Q

Shigella dysenteriae

A

• invasive, phage-born toxin
• most severe dysentery
• Shiga toxin producing E. coli (STEC)
• O157:H7

369
Q

Infection with Shiga toxin producing E. coli (STEC) O157:H7 causes what symptoms?

A
  • previous diarrhea, abdominal cramping, bloody diarrhea
  • fever, nausea, chills
  • 3-8 days incubation, illness lasts 3 to 4 days, less than 10
  • hemorrhagic colitis and or HUS can result as a complication
  • antibiotic treatment not recommended, can make disease worse
370
Q

What is the E. coli STEC AB5 toxic?

A

• toxins Stx1 and Stx2 on genes stxA and stxB on lambda bacteriophage
Very similar to Shigella dysentery

371
Q

What is yersinia enterocolitica?

A

• gram-negative, facultative anaerobe that is motile only at temperatures below the body temperature
• can cause acute gastroenteritis

372
Q

What are the symptoms/mechanisms of Yersinia enterocolitica?

A

• pseudo appendicitis: pain in the right lower quadrant
• 3-10 day incubation period may last 1 to 3 weeks
• zoonotic infectious organism from contaminated water or pet droppings. Pork, and daycare facilities also have outbreaks

373
Q

What is typhoid fever?

A

•s. Typhi from untreated water that can spread from the G.I. tract to the bloodstream causing very high fevers, weakness, headache
• spread in feces and can reside in gallstones— antibiotic treatment is recommended

374
Q

Inflammatory polyp or inflammatory pseudo polyp

A

• reactive and regenerative and non-neoplastic (not Pre malignant)
• associated with ulcerative colitis, Crohn’s disease
• histology: inflamed reactive and hyperplastic mucosa, irregular gland growth, alteration/erosion

375
Q

What is a hamartoma?

A
  • An abnormal growth forming a tumor or mass of mature tissues from the site of origin (not a topic). However, the architecture or growth pattern is abnormal and disorganized
376
Q

What are the hamartomatous polyps of the G.I. tract?

A

1. Juvenile polyps: colon predominant, cyst Stickley dilated mucus filled glands with inflamed stoma

2. Peutz Jeghers polyps: small intestine predominant, arborizating/branching polyps with smooth muscle in the stroma

377
Q

What is juvenile polyposis syndrome?

A

• autosomal dominant juvenile polyps found in the rectum—> all over GI tract
• SMAD4, or BMPRIA mutation
• increased risk of adenocarcinoma
• may also see hereditary hemorrhagic telangectasia, pulmonary AV malformation, macrocephaly, hypotonia

378
Q

What is Peutz Jegher’s polyps/syndrome?

A

• Autosomal dominant hamartomatous polyps throughout the G.I. tract from STK11 mutation
• multiple polyps in small bowel, greater than 90% have jejunal polyps
• arborizating/branching smooth muscle polyps
• mucocutaneous hyperpigmentation is also seen

379
Q

What is Cowden syndrome?

A

• non-hereditary mutation of PTEN presenting in childhood causing hamartomatous intestinal polyps, lipoma, etc.

380
Q

What is Cronkite-Canada syndrome?

A

• a rare, non-hereditary hamartomatous polyposis syndrome of unknown ideology
• malnutrition, G.I. bleeding, infection may occur—> mortality

381
Q

What are hyperplastic polyps?

A

• the most common small G.I. polyps found in the left side of the G.I. tract (descending colon, sigmoid colon, rectum)
• benign with no malignancy potential

382
Q

What is a chronic defecation disorder with failure of relaxation of the anal sphincter?

A

solitary rectal ulcer/rectal mucosal prolapse
• 20-50 y/o, bleeding, cramping, alternating diarrhea and Constipation
• fibromuscular hyperplasia

383
Q

What are the submucosal polyps?

A

• Leiomyoma (smooth muscle)
• ganglioneuroma (cowden)
• lipoma

384
Q

What is a traditional adenoma?

A

• dysplastic precursors to most colorectal carcinoma via APC gene mutation
• can be tubular, tubulovillous, villous

385
Q

Tubular adenoma is the:

A

Most common with the lowest risk

386
Q

Villous adenoma:

A
  • finger-like projections (villi) arranged in parallel, perpendicular to the mucosa
  • rare, large and sessile (flat).More dysplastic
387
Q

Lack of the APC gene results and what?

A

• uncontrolled division of the epithelial cells leading to neoplastic polyps
• continued growth can develop additional mutations leading to malignancy such as KRAS, p53

388
Q

What are the variants of familial adenomatous polyposis (FAP)?

A
  1. Attenuated FAP (autosomal recessive)
  2. Gardner’s syndrome: FAP with bone/connective tissue disorders, fibromas, desmoid tumors, and skull/jaw osteomas, CHRPE
  3. Turcot syndrome: FAP and CNS tumors (medulloblastoma, glioblastoma multiforme)
389
Q

A sessile serrated polyp (adenoma) is most likely where?

A

right side of the colon
* has gland architectural that looks like a boot/anchor

390
Q

Sessile serrated polyps (adenomas) can be related to what pathway?

A
  • microsatellite instability pathway: hyper methylation of MLH1 gene/BRAF mutation
  • high grade dysplasia and adenocarcinoma can occur
391
Q

The microsatellite instability pathway (serrated) comes from what genetic mutations?

A

MMR— MLH1, PMS2, MSH2, MSH6

392
Q

What is Lynch syndrome (hereditary non-polyposis colorectal cancer)?

A

• germline, autosomal dominant hereditary cancer syndrome
• one inherited defective allele and one acquired defective allele resulting in mismatch repair enzyme dysfunction (MLH1, MSH2, MSH6, PMS2)

• increased risk for endometrial carcinoma, small bowel carcinoma, sebaceous tumors of the skin, stomach cancer, liver, biliary tract, pancreas, ovary, uterus, renal pelvis, brain (turcot) cancers

393
Q

Neuroendocrine neoplasm of the G.I. tract:

A

• can affect any organ anywhere in the G.I. tract
• can secrete hormones with resulting symptoms
• stain chromogranin and synaptophysin +

394
Q

The grading of a G.I. neuroendocrine tumor is based off of what?

A
  1. Mitotic rate
  2. Ki-67 staining
395
Q

Neuroendocrine tumors/carcinoids have what features on histology?

A

• salt and pepper chromatin
• positive (Brown) IHC stain of chromogranin and synaptophysin
• located at the mucosal or submucosal layers

396
Q

Where is the most common place for a carcinoid to develop?

A

SMALL BOWEL

• foregut= cured by surgery, early symptoms
• midgut= multiple carcinoids and most aggressive, except appendix
• hindgut= usually benign, found incidentally and small

397
Q

Neuroendocrine tumors and their associations based off of where they’re located:

A

• stomach: atrophic gastritis, MEN1
• duodenum: MEN1, Zollinger-Ellison syndrome (gastrinoma)
• ilium/jejunum: aggressive, high stage
• cecum: rare, often large
• rectum: usually small and incidental/benign
• appendix: small and benign

398
Q

What are the systemic effects of carcinoid syndrome?

A

• release of serotonin and other vasoactive neuropeptides from a tumor
• carcinoid heart valve syndrome
• G.I. tumors secrete serotonin, liver metabolism (MAO) causing systemic symptoms

399
Q

Colorectal carcinoma is most commonly ____ sided

A

Left

400
Q

What is the most important prognostic feature of colorectal carcinoma?

A

• staging (TNM) regarding depth, lymph node status, metastatic sites

401
Q

What bacteria are associated with colorectal cancer?

A

• streptococcus bovis and streptococcus gallolyticus bacteremia and endocarditis

402
Q

What are the common symptoms of right sided (cecum, ascending colon, transverse colon) colon carcinoma?

A

• asymptomatic non-obstructing
• iron deficiency anemia
• Weight loss
• palpable mass (gets large)

403
Q

What are the symptoms of left sided (descending colon, sigmoid, rectum) colon carcinoma?

A

• obstructing: early presentation including changes in bowel habits, cramping, pain, blood stool, mucus, tenesmus
• grows in infiltrative napkin ring like lesions— Apple core lesion on radiology

404
Q

What are the molecular pathways of colorectal carcinoma?

A
  1. APC/KRAS pathway including traditional adenoma, sporadic adenocarcinoma, and FAP
  2. Microsatellite instability including DNA mismatched repair and hyper methylation/BRAF mutations causing sessile serrated adenomas and mucinous adenocarcinoma
405
Q

What molecular pathway is the most common cause of sporadic colon carcinoma?

A

APC/KRAS

406
Q

Non-mucinous versus mucinous adenocarcinoma

A
407
Q

What is the number one determinant for a patient outcome for adenocarcinoma of the G.I. tract?

A

Staging (TNM: tumor/lymph nodes/metastasis)

408
Q

Malignant lymphoma of the G.I. tract is typically found where and made up of what cell type?

A
  • Found in the stomach > small bowel > large bowel
  • B cell type
  • symptoms are based on sizing : polypoid masses, obstruction, bleeding
409
Q

What are the common histological types of malignant lymphoma of the G.I. tract?

A

• DLBCL
• MALT
• mantle cell lymphoma
• enteropathy associated T cell lymphoma
• Burkitt lymphoma

410
Q

Acute appendicitis is caused by what?

A

obstruction
• adults: fecalith
• children: lymphoid hyperplasia (yersinia can mimic)

411
Q

What are the symptoms of acute appendicitis?

A

• pain, nausea, vomiting
• vague paraumbilical pain and then sharp abdominal pain localized to McBurney’s point, 2/3 distance from umbilicus to right iliac spine

412
Q

Carcinoid/neuroendocrine tumors of the appendix:

A

• small, incidental, asymptomatic, benign
• still have salt and pepper chromatin

413
Q

What are the mucinous tumors of the appendix?

A
  1. Adenoma
  2. Low-grade appendiceal mucinous neoplasm (LAMN)
  3. Mucinous adenocarcinoma
  4. Pseudomyxoma peritonei
414
Q

What disease of the appendix is strictly a clinical diagnosis?

A

pseudomyxoma peritonei
• peritoneal dissemination of mucin (ascites or peritoneal deposits)
• abdomen/pelvis filled with mucus with tumor cell nests
• locally persistent with high morbidity common low-grade neoplasm (adenoma or LAMN)

415
Q

What is an anal fistula?

A

Enterocutaneous fistula from anal duct abscess—> abdominal wall that can be seen in Crohn’s disease

416
Q

What are the HPV related anal pathology diseases?

A
  1. Condyloma acuminatum/anogenital wart (HPV 6,11)
  2. Squamous dysplasia/anal intra-epithelial neoplasia (AIN 1-3 grades w/ high being associated with HPV 16»18)
  3. Invasive squamous cell carcinoma (high risk HPV types, 16»18)
417
Q

What could be found on an anal pap test?

A

• early detection of anal carcinoma, commonly associated with HPV 16
• risk factors: HIV/immunosuppression, smoking, receptive anal intercourse

418
Q

What are the protozoan G.I. parasites found in the United States?

A

• entamoeba
• Giardia
• cryptosporidium

419
Q

What are the two environments of Giardia lamblia?

A
  1. Water (cysts)
  2. Small intestine (trophozoites that are attached but do not penetrate- stay in GI)
420
Q

Who is the most common person to get Giardia?

A
  1. Developing countries
  2. Backpackers/hikers
421
Q

What are the symptoms of Giardia?

A

• incubation of 1-14 days, symptoms for one to two weeks or longer
• foul smelling diarrhea, flatulence, greasy stools, malabsorption

422
Q

What is the diagnosis and prevention of Giardia?

A

• diagnosed by cysts in a stool sample
• prevention is filtered water

423
Q

When is cryptosporidium parvum seen?

A

• often when sanitation systems fail: pool, waterpark, storms or issues with drinking water

424
Q

What are the symptoms of cryptosporidium parvum?

A

• incubation of 2 days to 2 weeks, symptoms (diarrhea) for one to two weeks and up to 30 days (waxes and wanes)
• occasionally has fever, nausea, oocysts seen in stool

425
Q

What are the two environments of cryptosporidium parvum?

A
  1. Water (acid fast + due to oocytes)
  2. Small intestine (sporozoites)
426
Q

What are the other coccidia species that cause human G.I. infection?

A

• cystoisospora belli
• cyclospora cayetanensis
~ both are also acid fast and auto fluorescent. Oocysts are larger.

427
Q

What is Entamoeba histolytica?

A

• causes amebiasis (amoebic dysentery, amoebic liver abscess)
• prevalent in tropical/subtropical climates with inadequate sanitation
• 80 to 90% of individuals are asymptomatic

428
Q

What is the difference between amoebic versus bacillary dysentery?

A
429
Q

Entamoeba can cause what types of tissue lysis?

A
  1. Colitis
  2. Flask shape ulcer
  3. Ingests RBCs in the trophozoite stage
430
Q

What three locations do entamoeba reside in?

A
  1. Water (cysts)
  2. Small intestine (trophozoites via excystation)
  3. Migrates to colon —> feces
431
Q

What are the invasion possibilities of entamoeba in the large intestine?

A

• blood vessel invasion: leading to amoebic hepatitis (abscess in right lobe presents with right upper quadrant pain, fever, weight loss)
• mucosal cell invasion: result in replication and cysts in the feces

432
Q

What are the anti-parasitic drugs that target G.I. protozoans?

A

• metronidazole/tinidazole
• Iodoquinol
• nitazoxanide
• paromycin

433
Q

What is the drug of choice to treat symptomatic Giardia infections?

A

Nitroimidazoles (metronidazole, tinidazole)

Toxicity: disulfiram-like reaction (flushing, tachycardia, hypotension) — avoid alcohol. Can also disturb normal GI flora

434
Q

What is the mechanism of nitazoxanide?

A

• essential to anaerobic energy metabolism, interferes with pyruvate:ferredoxin oxireductase enzyme-dependent electron transfer
• rapidly metabolize to tizoxanide

435
Q

When should cryptosporidium be treated?

A

In immunocompromised hosts it is treated with nitazoxanide. Used in combination with retroviral therapy for AIDS patients

436
Q

What is iodoquinol?

A

• works on local gut protozoa and is a luminal anti-parasitic (amebicide) because it is only 10% absorbed

• toxicity: loss of visual acuity, interferes with thyroid tests

437
Q

What is paromomycin used for?

A
  • an aminoglycoside that target ribosomal small subunit. Used for luminal anti-parasitic, minimal absorption after oral administration
  • toxicity: ototoxicity, nephrotoxicity, diarrhea and G.I. effects
438
Q

Why must we consider absorption and tissue distribution for treatment of protozoan infections?

A

• symptomatic infection indicates an organism has invaded into the tissue, but is still at the lumen. Luminal and tissue amebicide must be used
• luminal: iodoquinol, paromomycin
• tissue/systemic: metronidazole or tinidazole

439
Q

When is TMPSMX used?

A

It has a broad spectrum for many bacteria and is also effective against apicomplexa including Toxoplasma, cystisospora, and cyclospora

~ double inhibition of the folic acid synthesis pathway

440
Q

What are the two predominant molecular genetic types of colorectal cancer?

A
  1. APC mutation- Wnt/catenin pathway involving chromosomal instability
  2. Mismatch repair (MMR) gene pathway involving micro instabilities
441
Q

What’s the predominant cause of colorectal cancer?

A

Sporadic (followed by FAP and Lynch/HNPCC)

442
Q

What are the local and distant sites of metastasis for colorectal cancer?

A

Mesenteric lymph nodes is local, and liver/lung are the distant sites (often presents as numerous undetectable micrometastasis)

443
Q

What is a gold standard for colorectal cancer screening?

A

• colonoscopy: 100% accurate, 60% reduction and mortality
• other options: CT colon, flexible sigmoidoscopy, barium enema, stool DNA PCR analysis, fecal occult blood

444
Q

What factors increase your risk for colorectal cancer?

A

• older age/male
• African-American, Native American, Jewish
• obesity
• smoking/alcohol
• lack of exercise
• IBD
• personal or family history of CRC/polyps

445
Q

What factors decrease your risk for colorectal cancer?

A

• estrogen
• chemo preventative agents (NSAIDs, 5-ASA, statins)
• healthy diet
• exercise

446
Q

What is metabolic syndrome and how does it increase your risk of colorectal cancer?

A

• metabolic syndrome is defined as a set of common risk factors for cardiovascular disease and type two diabetes that includes: glucose intolerance, insulin resistance, dyslipidemia, obesity, hypertension

• 3x risk for colorectal cancer incidence and mortality

447
Q

How does an APC/CIN mutation lead to colorectal cancer?

A

• complete destruction of APC leads to the disruption of the WNT/beta-catenin pathway leading to chromosomal instability (CIN)
• typically the left side
• often loss of p53, increase KRAS activity
• hereditary syndromes seen with APC mutation such as FAP
• 85% of all CRC, poor prognosis

448
Q

How does an MMR/MIN mutation lead to colorectal cancer?

A

• complete loss of mismatch repair (typically MLH1 or MSH2) leading to micro satellite instability
• mostly right sided
• methylator phenotype common
• hereditary syndrome such as lynch/HNPCC seen with MMR mutations
• 15% of colorectal cancer, better prognosis (90% survival)

449
Q

What loss is considered the gatekeeper of chromosomal instability colorectal cancer?

A

APC: loss of this tumor suppressor MUST come first in order to proceed through adenoma—> carcinoma sequence overtime (loss of p53 and increase KRAS activity lead to carcinoma)

450
Q

How does APC typically work as a tumor suppressor?

A

• regulation of the beta-catenin/WNT pathway
• involved in cell adhesion, migration, cytoskeletal integrity, and chromosome fidelity

451
Q

What is currently the most clinically predictive biomarker for colorectal cancer?

A

KRAS: a key cell signaling molecule that acts downstream of receptor tyrosine kinases such as EGFR; activating KRAS mutations occur in about 40% of CRC and associated with poor prognosis and poor survival

452
Q

What drugs are ineffective in patients with activating KRAS mutations?

A

• anti-EGFR monoclonal antibody drugs such as cetuximab and panitumumab

453
Q

What is chromosomal instability, and how is APC affecting it?

A

• CIN causes aneuploidy (abnormal chromosome number)
• APC in colorectal cancer causes numerous large scale chromosomal changes including translocations, large scale deletions and insertions at a rate 100x greater than normal

454
Q

What is the only effective treatment for FAP due to APC mutations/CIN?

A

Colectomy. NSAIDs can also prevent some polyps

455
Q

What is AFAP (attenuated FAP)?

A

FAP characterized by relatively low polyp number presenting at a later age caused by mutations in the APC gene that occur at either extreme amino terminus or carboxy terminus ends. Tumors can be found in the proximal colon

456
Q

When do you typically see sporadic APC/CIN?

A

• 85% of colorectal cancer
• arises on average in the 60-70s

457
Q

What’s the most common cause of MMR deficient/MIN pathway of colorectal cancer?

A

Hypermethylation of MLH1 promoter. Dietary risk factors include high alcohol consumption, red meat, low folate intake

458
Q

MMR/MIN target genes in colorectal cancer that contain microsatellites in what coding regions?

A

• TGF-BR
• IGF
• BAX
~ MIN can be detected by PCR of bio marker such as BAT26

459
Q

What are the most common mutations in Lynch syndrome/HNPCC?

A

• MLH1, MSH2, MSH6, PMS2, MLH3, PMS1
• two-hit hypothesis: autism dominant inheritance, but 100% of patients have a sporadic second hit by genetic or epigenetic changes

460
Q

What is required for diagnosis of colorectal cancer?

A

Biopsy of tissue

461
Q

Staging of colon cancer picture/image/graph

A
462
Q

What is the three drug regimen used to treat stage three colorectal cancer?

A
  1. 5-fluorouracil
  2. Leucovorin
  3. Oxaliplatin
463
Q

What are the actionable genomic variants in stages one through three of colorectal cancer with proficient MMR?

A
  • MSH3, APC, PBRM1, ARD1A, BRCA2, BRAF, RNF43
464
Q

In order to treat patients with cetuximab or panitumumab, what wild type gene must they have?

A

KRAS (cannot have the mutated version)

465
Q

What are the common immunotherapies used to treat dMMR/SMI-H?

A

• nivolumab
• pembrolizumab
• regorafenib (harsh SE), inhibits VEGFR2 and TIE2

466
Q

What are used to prevent adenomas in FAP patients?

A

COX-2 inhibitors, aspirin with a family hx of colorectal cancer, and vitamin D

467
Q

What stages of colorectal cancer receive chemotherapy?

A

• typically only stages 3 and 4. Stage 2 may be considered, particularly staged 2B
• stage one is always surgery only only

468
Q

Does dMMR indicate high-risk or low risk status in a patient that is stage 2?

A

Low risk: typically do not receive therapy

469
Q

What is enterobius vermicularis (roundworm)?

A

• enterobiasis infection (pinworm)
• symptoms: perianal pruritis, insomnia, abd pain, anorexia
• acquired by ingestion of eggs

470
Q

What is enterobius vermicularis (roundworm)?

A

• enterobiasis infection (pinworm)
• symptoms: perianal pruritis, insomnia, abd pain, anorexia
• acquired by ingestion of eggs

471
Q

How do you test for pinworm (enterobius)?

A

• differential: anal itching
• appearance of worms 2-3 hrs after falling asleep
• scotch tape method
• sample under fingernails
• eggs not found in stool sample

472
Q

What is hookworm?

A

• Necator americanus/ancylostoma duodenale
• pruritic, papular, erythematous rash
• may cause iron deficiency anemia
• diagnosed by eggs in the stool

473
Q

What is the lifecycle of hookworm?

A

Larvae in soil —> skin penetration —> circulatory system —> lungs —> coughed and swallowed —> GI tract becomes permanent home

474
Q

What is strongilodiasis?

A

• strongolides stercoralis (roundworm)
• symptoms: dry cough, throat irritation, itchy skin, recurrent red raised rash along thighs and buttocks
• can see larvae in stool sample

475
Q

What is whipworm/trichuriasis?

A

• caused by trichuris trichiura (roundworm)
• light infection is asymptomatic but heavy worm load can cause frequent, painful stools with mucus, water, and blood, and tenesmus
• ingestion of embyronated eggs, stools of unembryonated eggs. In small and large intestine

476
Q

Heavy infection of trichuris trichiura in children can lead to what?

A

• iron deficiency anemia
• growth retardation
• impaired cognitive development

477
Q

What is giant roundworm?

A

• infection with ascaris lumbricodes
• 50% of population in tropical and subtropical regions are infected
• typically asymptomatic, but may cause discomfort or intestinal blockages. May cause cough from lung stage

478
Q

What is the life cycle of giant roundworm?

A
479
Q

What is raccoon roundworm?

A

• baylisascaris procyonis infection
• can affect the brain and spinal cord (neural larva migrans), the eyes, or other organs
• symptoms: nausea, tiredness, liver enlargement, loss of coordination, confusion, loss of muscle control, blindness and coma

480
Q

What are the anti parasitics targeting GI roundworm?

A
  1. Mebendazole and Albendazole
  2. Pyrantel pamoate
  3. Ivemectin

~ goal of Tx is to remove adult worms

481
Q

What are albendazole and mebendazole?

A

• benzimidazole antiparasitics used for roundworms and tapeworms
• albendazole is better absorbed if target tissue is tissue-migrating larvae
• mech: binds to parasitic beta-tubulin and inhibits the formation of microtubules

482
Q

What is pyrantel pamoate?

A

• a cholinergic antihelmintic
• mech: selectively opens a restricted subgroup of nematode acetylcholine receptor (AChR) ion channels in nematode nerve and muscle. Produces spastic muscle contraction causing parasite flushing

483
Q

Does pyrantel pamoate kill egg stages of pinworm?

A

NO

484
Q

What is Ivermectin?

A

• a macrocyclic lactone used against ascaris, strongyloides, and onchocerca (river blindness)
• mech: binds to glutamate-gated chloride channels in invertebrate nerve and muscle cells, causing deactivation of the channel
• resistance via efflux transporters

485
Q

What are the segments of tapeworms called?

A

Proglottid

486
Q

What are the different types of tapeworms (all zoonotic diseases)

A
  1. Taenia, typical human tapeworm, beef or pork (3-10m in length)
  2. Dipobothroum, fish tapeworm (up to 30 feet long)
  3. Echinococcus, disease of liver, lungs, or brain (tiny, few mm long)
487
Q

What is Diphyllobothrium (fish tapeworm)?

A

• found primarily in Canada, some of North America
• life cycle: eating the musculature of fish where larva have migrated
• symptoms: standard G.I. problems, anemia due to competition for B12
• diagnosis: stool contains eggs/proglottids

488
Q

What is taenia sp. (beef or pork tapeworm)

A

• worm disease acquired by eating pork or beef with cysticerci
• typical G.I. problems, stool containing eggs/proglottids
• cysticerosis can occur if migration to brain or other tissue (pork tapeworm specifically)

489
Q

What is echinococcus (a cestode)?

A

• a worm causing echinococcosis
• symptoms: typically no GI discomfort, some pain or discomfort in the upper abdominal region or chest, and hydatid cysts
• seen in sheep farmers, canine owners, and trappers (dog is definitive host)

490
Q

What is the number one treatment for symptomatic echinococcus?

A

Surgery

491
Q

What are the anti-parasitics that target tapeworms?

A
  1. Praziquantel
  2. Albendazole and Mebendazole
  3. Niclosamide
492
Q

What is praziquantel?

A

• mech: increased permeability of the parasite to divalent ketones leading to contraction of the worms musculature
• toxicity: dizziness, nausea. Rapidly absorbed
• spectrum: cestodes (tapeworms) and trematodes (FLUKES)

493
Q

What is niclosamide?

A

• mechanism: block glucose uptake by intestinal tapeworm
• toxicity: not well absorbed, stays in the lumen
• not available in the United States

494
Q

What are Schistosoma Manson and s. japonicum?

A

• flukes/trematodes that caused the disease schistomiasis
• two major forms: intestinal and urogenital (urogen caused by schist. Haematobium)

495
Q

Why is schistomiasis so severe?

A

Symptoms are caused by immune response to egg stage of schistosoma—> inflammation, scarring of the liver, intestine, spleen, lungs, bladder

  • within days of infection, rash or itchy skin appear
  • within 1-2 months fever, chills, cough, muscle aches occur
  • chronic: enlarged liver, blood in the stool, trouble passing urine, squamous cell carcinoma of the bladder
496
Q

Where does Schistosoma go in the body?

A

After skin penetration, schistosomulae find capillaries and migrate first to the lungs, second to the heart and third to the liver

497
Q

How is schistomiasis treated/prevented?

A

• treatment: praziquantel, steroids
• prevention: sanitation, do not swim in freshwater that may be contaminated

498
Q

What is cercarial dermatitis (swimmer’s itch)?

A

• human exposure during infected water entry
• bird hosts, eggs are passed in feces and hatching the water. Molluscan intermediate host

499
Q

Ulcerative colitis invades ________ , while Crohn’s disease invades _______.

A

• UC: only mucosa
• Crohn’s: all 4 layers (mucosa, submucosa, muscularis, serosa/Adventitia)

500
Q

What is the clinical presentation of ulcerative colitis?

A

• diarrhea, most with blood and mucus
• tenesmus
• abdominal pain/tenderness
• loss of appetite and weight
• fever/fatigue

501
Q

Severe ulcerative colitis can lead to:

A
  • fever, elevated WBC, unstable vitals
  • high risk of perforation with endoscopy or spontaneously
  • toxic megacolon —> surgical emergency
502
Q

Describe the involvement of ulcerative colitis in the G.I. tract:

A

• continuous inflammation
• colon only
• mucosal involvement only
• risk colorectal cancer and extra intestinal manifestations

503
Q

Describe the G.I. involvement of Crohn’s disease:

A

• patchy inflammation
• mouth to anus involvement, Skip lesions
• full thickness inflammation of all four layers
• cobblestone appearance
• fistula
• structures and surgery required
• extraintestinal manifestations

504
Q

What is the clinical presentation of Crohn’s disease?

A

• abdominal pain, weight loss, anorexia
• diarrhea/vomiting/rectal bleeds
• stunted growth and fevers
• perianal fistulizing disease

505
Q

Distinguishing features of Crohn’s disease: picture/image

A
506
Q

What are common extraintestinal manifestations of IBD?

A

• skin: erythema nodosum, pyoderma gangrenosum
• eyes: uveitis, episcleritis
• sclerosing colangitis (inflammatory obliterated fibrosis of the biliary tree)
• ankylosing spondylitis and joint inflammation

507
Q

What are medication’s typically used for IBD?

A

• 5-ASA and sulfasalazine
• immunomodulators: azathioprine, 6-mercaptopurine, methotrexate
• corticosteroids: prednisone, prednisolone, budesonide, hydrocortisone
• biologics

508
Q

What is a biological drug typically used for IBD?

A

• anti-TNF therapy
• infliximab, certolizumab pegol, adalimumab, ustekinumab

• JAK inhibitors
• tofacitinib

509
Q

What is the importance of anti-TNF, anti-integrin, and ustekinumab therapy and IBD?

A

• induce and maintain remission
• steroid sparing medications
• heal perianal fistulizing disease

510
Q

What are the surgical options for ulcerative colitis (Crohn’s disease cannot be treated surgically)?

A

• conventional ileostomy
• continent ileostomy
• ileal pouch-anal anastomosis
• ileorectal anastomosis

511
Q

Crohn’s disease versus alterative colitis table/image

A
512
Q

What enzyme inactivates GLP1 and GIP?

A

DPP-4

513
Q

What is glucagon like peptide-1 (GLP1)?

A

• a hormones secreted by enteroendocrine L cells of the small intestine
• lowers blood glucose by stimulating insulin secretion, reducing glucagon concentration, and delaying gastric emptying

514
Q

What is glucose dependent insulin inotropic peptide (GIP)?

A
  • a hormone secreted by enteroendocrine K cells of the stomach and proximal intestine
  • stimulates insulin secretion, reduces acid secretion, increases proliferation of osteoblast/inhibition of osteoclasts, functions as a neuromodulator
515
Q

What are the GLIPTINS drugs?

A

• DPP-4 inhibitors such as: linagliptin, saxagliptin, sitagliptin
• they competitively block DPP4, leading to increase insulin synthesis and secretion, and decrease glucagon secretion

516
Q

What are the GLP1 receptor agonist drugs?

A

• liraglutide, semaglutide, tirzepatide
• increases feelings of satiety in the hypothalamus

517
Q

What are the side effects of GLP1 agonists?

A

• nausea, vomiting, diarrhea
• hypoglycemia
• DDIs
• pancreatitis, renal impairment, acute renal injury, thyroidal C-cell tumors (rodent models)

518
Q

What are the physiological signs of the feeding cycle?

A

Hunger and satiation

519
Q

What are the psychological signs of the feeding cycle?

A

Appetite and satiety

520
Q

What releases Lepin to signal to the hypothalamus (arcuate and paraventricular nuclei) that a person is full?

A

Adipose tissue

521
Q

What is the purpose of ghrelin interneurons?

A

• in the hypothalamus, increase orexigenic signals and inhibits satiation (tips balanced toward hunger) .

522
Q

Where is ghrelin produced and what does it do?

A

• produced by the stomach (stomach endocrine P/D1 cells) and released into the blood when stomach is empty

523
Q

What decreases ghrelin secretion?

A

• stomach distention
• short-term regulation, increased activity of stomach mechanoreceptors leading to the inhibition of P/D1 cells

524
Q

What are the actions of ghrelin on hunger/preparation for feeding?

A

•increases orexigenic signal, decreases anorexigenic signals in the hypothalamus
• increases gastric motility and acid secretion
• stimulation of hedonic food reward circuit

525
Q

How does ghrelin modify energy output?

A

• decreases insulin secretion
• increases gluconeogenesis
• decreases adipogenesis

526
Q

Ghrelin acts as what during sleep?

A

A growth hormone

527
Q

Anorexigenic signals are relayed through what?

A

vagus nerve through the nucleus of the solitary tract to the hypothalamus
• chemo receptor/stretch receptors contribute to satiation
• CCK and GLP1 Signal that fat/protein is being processed

528
Q

What is peptide YY336?

A

Released by L cells of the distal gut (ileum and colon) in response to fat in the in the lumen

529
Q

What is pancreatic polypeptide (PP)?

A

Released from the pancreatic islet cells in response to a protein meal

530
Q

What reduces NPY release from neurons in the arcuate nucleus?

A

• polypeptide YY336 (PYY)
• pancreatic polypeptide (PP)

531
Q

What are the different types of bariatric surgery (pictures/image)?

A
532
Q

What has an increase effect on PYY and GLP1: gastric bypass (RYGB) or gastric banding (AGB)?

A

Gastric bypass increases PYY and GLP1

533
Q

What are ducts of Luschka?

A

Embryonic deformity leading to bile ducts coming directly from the liver

534
Q

What is the function of a gallbladder?

A
  1. Stores bile salts to aid in digestion of fats and fat soluble vitamins
  2. Contract system stimulation by cholecystokinin
  3. CCK released by duodenum when fat and protein are present— allows for breakdown of fats by bile salts
535
Q

What are the two types of gallstones?

A

1. Cholesterol: 80% of stones in Americans, hyper secretion of cholesterol, gallbladder hypomobility
2. Pigment: black pigment stones, cirrhosis or hemolytic anemia, thalassemia, sickle cell. Brown pigment stones common in Asian from biliary tract infections

536
Q

What is the name of a stone in the gallbladder?

A

Cholelithiasis almost entirely cholesterol stones

537
Q

What is the name of a gallstone in the bile duct?

A

Choledocholithiasis, mixed cholesterol and pigment stones

538
Q

What is the primary intrahepatic gallstone?

A

Brown stones (calcium bilirubinate)

539
Q

Factors contributing to cholesterol gallstones

A

• hepatic hypersecretion
• gallbladder hypomotility (stasis)
• intestinal factors (loss of terminal ileum)
• rapid phase transitions (weight loss)
• genetic factors (LITH gene)

540
Q

What are protective factors for gallstones?

A

• statins
• coffee
• vitamin C

541
Q

What is biliary pain?

A

• spasm of a gallbladder and cystic duct in the setting of obstruction
• often post prandial or nocturnal
• RUQ or epigastric pain can radiate to scapular region

542
Q

What is seen with acute cholecystitis?

A

• fever, abdominal pain more than six hours, leukocytosis normal AST/ALT
• biliary colic
• positive Murphy sign (RUQ tenderness, inspiratory arrest)
• palpable gallbladder
• non-visualization of gallbladder on a HIDA scan

543
Q

What is acalculous disease?

A

• sphincter of Oddi dysfunction causing biliary dyskinesia, acalculous cholecystitis, cholesterolosis, polyps, and adenomyomatosis
• typically presents after major surgery, trauma, severe burns
• unexplained fever, hypotension, leukocytosis, hyperamylasemia are only signs

544
Q

What is choledocholithiasis?

A

• stones in the common bile duct
• typically presents due to dilated CBD post cholecystectomy, duodenal reflux, parasitic colitis
• Tx: ERCP with stone extraction

545
Q

What are very strong predictors of choledocolithiasis?

A

• common bile duct stone seen on ultrasound
• clinical ascending cholangitis
• bilirubin greater than 4 mg/dL

546
Q

What is Charcot’s triad of choledocolithiasis?

A
  1. FEVER
  2. RUQ PAIN
  3. JAUNDICE
547
Q

Picture/image of area associated disease of the gallbladder/biliary tract

A
548
Q

What are the options for intermediate determination of CBD stone based on clinical predictors?

A

• laparoscopic IOC, laparoscopic US
• pre-operative US, MRCP
• post op ERCP
• laparoscopic common bile duct exploration
• laparoscopic cholecystectomy

549
Q

Transabdominal ultrasound is best for looking at what gallbladder disorder?

A

Cholelithiasis and cholecystitis

550
Q

CT is best at imaging what G.I. disorders?

A

• pancreatic cancer
• liver metastasis

551
Q

MRI and MRCP are best at imaging what?

A

Common bile stones and sclerosing cholangitis

552
Q

Endoscopic ultrasound (EUS) is most sensitive for visualizing what?

A

• stones/ microliths
• pancreatic, biliary tumors and regional adenopathy

553
Q

What is biliary dyskinesia?

A

• delayed gallbladder emptying resulting in an ejection fraction < 35% following CCK administration during HIDA scan

554
Q

What are the most common causes of colonic hematochezia?

A

• diverticular hemorrhage
• angiodysplasia
• neoplasm
• IBD
• ischemia
• infection
• radiation colitis/colopathy
• anorectal disorders
• post polyectomy

555
Q

What are the most common upper G.I. sources of hematochezia?

A

• peptic ulcer disease
• esophageal/gastric varices
• Dieulafoy lesion

556
Q

What are the small bowels causes of lower bleeding?

A
  • angioectasia/AVM
  • malignancy
  • Aortaenteric fistula
  • diverticular hemorrhage or Meckel’s diverticulum
557
Q

An acute diverticular hemorrhage is typically (painful/painless)?

A

Painless— also self limited, but reccurs frequently

558
Q

What is the most important treatment of diverticular hemorrhage?

A

• resuscitation (including reverse anticoagulation and transfusion)

559
Q

What is angoectasia (angiodysplasia)?

A

• torturous, dilated submucosal capillary/veins lacking smooth muscle
• most commonly found in the right colon presenting as over hemorrhage or anemia
• associated comorbidities: aortic stenosis, renal failure, LVAD, advanced age

560
Q

Ischemic colitis is typically (painful/painless)?

A

• painful— followed by self-limited hematochezia

561
Q

What is the most common place to get ischemic colitis?

A

The watershed area of the splenic flexure

562
Q

What is the common radiation effect in the lower G.I. tract?

A

• acute radiation proctitis: tenesmus, diarrhea, pain, bleeding

563
Q

What are the anorectal disorders?

A

• fissures (internal sphincter spasm, pain and bright red blood)
• hemorrhoids (dilated plexus of submucosal middle and superior hemorrhoidal veins- itchy/painful)
• solitary rectal ulcer (due to rectal prolapse, puborectalis spasm, constipation, older age)

564
Q

What is the best treatment for most anorectal disorders?

A

Fiber/ bulk laxatives

565
Q

Why does Meckel’s diverticulum cause bleeding?

A

It can release gastric acid in the colon leading to ulceration and bleeding

566
Q

Carcinoid syndrome diagnostic symptoms

A

Be FDR
• bronchospasm
• flushing
• diarrhea
• right sided heart failure

567
Q

Mucinous adenocarcinoma:

A

• >50% show extracellular pattern
• right sided more common
• large and high staged
• associated with sessile serrated adenoma and HNPCC pathway

568
Q

Anogenital wart: condyloma acuminatum

A

• cauliflower like growth, papillary formations and acanthosis of epithelium
• koilocytotic changes and parakeratosis

569
Q

FNA results of a pancreatic cyst

A

• CEA: 1200
• amylase: 80
• mucin and mucinous epithelial cell groups
• negative result for high-grade dysplasia or malignancy
• in the setting of a main pancreatic duct cyst, this is consistent with intraductal papillary mucus neoplasm

GI (3 decks)

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