Gastrointestinal Flashcards
1
Q
Regarding extrinsic innervation to the GI tract, efferent fibers do what?
A
Carry information from brainstem and spinal cord to GI tract
2
Q
Regarding extrinsic innervation to the GI tract, afferent fibers do what?
A
Carry sensory information (chemoreceptors and mechanoreceptos) from the GI tract to the brainstem and spinal cord
3
Q
The parasympathetic nervous system is (excitatory/inhibitory) to the GI tract
A
Excitatory
4
Q
Sympathetic nervous system is (excitatory/inhibitory) to the GI tract?
A
Inhibitory
5
Q
What is the intrinsic innervation to the GI tract (enteric nervous system)?
A
Coordinates and relays information (parasympathetic and sympathetic) to the GI tract.
Uses local reflexes to relay information within the GI tract
6
Q
What is the enteric nervous system composed of?
A
- Myenteric plexus (Auerback plexus) - Primarily controls the motility of GI smooth muscle
- Submucosal plexus (Meissner plexus) - Primarily controls secretion and blood flow
7
Q
What does the myenteric plexus (Auerbach plexus) control?
A
Motility of GI smooth muscle
8
Q
What does the submucosal plexus (Meissner plexus) control?
A
Secretion and blood flow
9
Q
What is the other name for the myenteric plexus?
A
Auerbach plexus
10
Q
What is the other name for the submucosal plexus?
A
Meissner plexus
11
Q
What cells secrete gastrin?
A
G cells of pyloric ANTRUM
12
Q
What are the effects of gastrin? (2)
A
Increased gastric H+ secretion
Stimulates growth of gastric mucosa
13
Q
What cells release cholecystokinin (CCK)?
A
I cells of duodenum and jejunum
14
Q
What are the effects of cholecystokinin (CCK)? (4)
A
Stimulates gallbladder contraction and relaxation of sphincter of Oddi
Increased pancreatic enzyme and bicarb production
Increased growth of pancreas/gallbladder
Inhibits gastric emptying
15
Q
What cells secrete secretin?
A
The S cells of the duodenum
16
Q
What are the effects of secretin?
A
Increased pancreatic bicarb (HCO3-) secretion
Increased biliary bicarb (HCO3-) secretion
Decreased gastric H+ secretion
Increased bile production
17
Q
Where is glucose-dependent insulinotropic peptide secreted?
A
K cells of duodenum and jejunum
18
Q
What does glucose-dependent insulinotropic peptide do?
A
Increased insulin secretion
Decreased gastric acid secretion
19
Q
What cells secrete motilin?
A
M cells of duodenum and jejunum
20
Q
What does motilin do?
A
Stimulates gastric and intestinal motility
21
Q
Which cells secrete acid in the stomach?
A
Parietal cells
(Remember parietal cells also secrete intrinsic factor for B12)
22
Q
What are stimuli for secretion of gastrin?
A
Small peptides/amino acids in the stomach
Distention of the stomach
Vagal stimulation (mediated by gastrin-releasing peptide)
23
Q
What is gastrin-releasing peptide?
A
Peptide stimulated by vagal tone. Stimulates gastrin release.
24
Q
Does atropine block vagally-mediated gastrin release?
A
No - Because vagal gastrin release is mediated by gastrin-releasing peptide and not Ach
25
What inhibits gastrin release?
H+ in the lumen of stomach (negative feedback)
Somatostatin
26
What is a gastrinoma?
AKA Zollinger-Ellison syndrome
Gastrin-secreting PANCREATIC tumor (non-beta cell)
27
What stimulates CCK secretion?
Small peptides and amino acids
Fatty acids and monoglycerides
28
Can triglycerides stimulate CCK release?
NO - triglycerides do not cross intestinal cell membrane
29
What are stimuli for secretin release?
H+ in the lumen of the duodenum
Fatty acids in the lumen of the duodenum
30
What stimulates glucose-dependent insulinotropic factor?
Fatty acids, amino acids, and carbohydrates
31
What does leptin do to appetite?
Decreases appetite
32
What does ghrelin do to appetite?
Increases appetite
33
What are the GI paracrine hormones?
Somatostatin
Histamine
34
What are the GI endocrine hormones?
Gastrin
CCK
Secretin
Glucose-dependent insulinotropic peptide
35
What are the effects of somatostatin on the GI tract?
Inhibits release of all GI hormones
36
What cells secrete somatostatin in the GI tract?
Cells throughout the GI tract in response to H+ in the lumen
37
What cells secrete histamine in the GI tract?
Mast cells in gastric mucosa
38
What are the effects of histamine in the GI tract?
Increases gastric H+ secretion directly and by potentiating the effects of gastrin and vagal stimulation
39
What are slow waves?
Oscillating membrane potentials inherent to GI smooth muscle. Occur spontaneously.
40
Where do slow waves originate from?
Interstitial cells of Cajal (pacemaker cells of GI smooth muscle)
41
Are slow waves action potentials?
NO - but they determine the pattern of action potentials
42
What is the mechanism for production of slow waves?
Cyclic opening of Ca2++ channels (depolarization)
followed by opening of K+ channels (depolarization)
43
When do spike action potentials occur in the GI?
During depolarization of slow waves
44
Is the frequency of slow waves influenced by neural or hormonal input?
No - but the frequency of action potentials is
45
Which part of the GI tract has the lowest frequency of slow waves?
Stomach (3/min)
46
Where in the GI is the frequency of slow waves the highest?
The duodenum (12/min)
47
What part of the CNS coordinates swallowing?
Medulla
48
What is a primary peristaltic contraction in esophagus?
Contraction behind the food bolus - propulsing bolus
49
What is secondary peristaltic contraction in esophagus?
Clears any remaining food
50
What neurocrine promotes lower esophageal relaxation?
vasoactive intestinal peptide
51
What is achalasia?
esophageal sphincter does not relax during swallowing
52
When is gastric emptying the fastest?
When the stomach contents are isotonic
53
How does fat inhibit gastric emptying?
By the production of CCK
54
What do segmental contractions in the SI do?
mix intestinal contents
55
How are peristaltic contractions controlled in the SI?
By the enteric nervous system:
Food in the intestine is sensed by **enterochromaffin cells**, who release serotonin.
**Serotonin** binds to afferent neurons, which initiate peristaltic reflex
56
What is the composition of saliva at the acinus and salivary ducts?
Acinus - Produces isotonic saliva
Ducts - Reabsorb Na+ and Cl-, makingit hypotonic. Ducts also secrete K+ and HCO3-
57
When is saliva most similar to plasma? At low flow rates or high flow rates?
At high flow rates (not as much time to remove Na and Cl and excrete bicarb and K+)
58
What is unique about regulation of saliva production?
Saliva production is increased by both sympathetic and parasympathetic activity
59
What cranial nerves provide parasympathetic stimulation to salivary glands?
VII - Facial nerve
IX - Glossopharyngeal
60
What do the chief cells of the stomach produce?
Pepsinogen
61
What are the parietal cells of the stomach stimulated by?
Gastrin secreted by G cells
62
What do parietal cells of the stomach absorb into the bloodstream?
Bicarb (HCO3-) via carbonic anhidrase
63
How is H+ secreted into the stomach by the parietal cells?
Via the H+-K+ ATPase pump
64
How does omeprazole work?
Inhibits H+-K+ ATPase pump
65
What is the "alkaline tide?"
HCO3- produced by parietal cell of stomach is absorbed to venous blood, pH increases
66
How does cimetidine work?
Blocking the effects of histamine on H+ secretion (H2 receptors)
67
True or false: Pancreatic secretions are always isotonic/
True - regardless of flow rate
68
What does it mean that bile salts are amphipathic?
Molecules of bile have both hydrophilic and hydrophobic portions
69
What are the primary bile acids?
Cholic acid
Chenodeoxycholic acid
70
What are secondary bile acids?
Bacteria in the intestine convert primary bile acids to secondary bile acids:
Deoxycholic acid and lithocholic acid
71
Which amino acids are used to transform bile acids into bile salts?
Taurine and glycine
72
What portion of the small intestine absorbs bile acids? Via what cotransporter?
Terminal ileum - Na+-bile contransporter
73
Ileal resection results in what?
Steatorrhea - decreased absorption of bile acids, depleted bile acid pool and impaired fat absorption
74
Who transforms hemoglobin to bilirubin?
Reticuloendothelial system
75
What enzyme conjugates bilirubin?
UDP glucuronyl transferase - Conjugates bilirubin with glucuronic acid
76
What happens to bilirubin once it's conjugated?
Some is excreted in urine, and some is secreted into bile
77
What substance is secreted from neurons in the GI to produce smooth muscle relaxation?
Vasoactive intestinal peptide
78
Where are the parietal cells located?
Gastric FUNDUS
79
Where in the stomach is gastrin secreted?
Antrum (G cells)
80
What bacteria has been associated with histiocytic ulcerative colitis (boxer colitis)
Enteroinvasive E. coli
81
How is histiocytic ulcerative colitis (boxer colitis) diagnosed?
Fluorescence in situ hybridization **(FISH)** can be performed to detect intramucosal colonization of *E. coli.*
Culture recommended due to resistance
82
How is Tritrichomonas foetus diagnosed?
Fecal smear - low sensitivity
Best sensitivity - PCR on colonic flush or fresh colonic sample
83
Which test offer the best sensitivity for Giaridia
ELISA
84
What is heterobilharzia americana? How is it best diagnosed?
Trematode that causes schistosomiasis in dogs. Lives in the mesenteric veins. Best diagnosed with PCR of feces
85
What is folate and where is it absorbed?
A water soluble B vitamin.
Absorbed in the duodenum
86
How does intestinal dysbiosis cause increased folate?
Synthesized by many bacteria- suspected that dysbiosis may lead to increased folate
87
In addition to intrinsic factor, what other proteins are involved in the absorption of B12?
Dietary protein
R protein
Intrinsic factor
88
Where is intrinsic factor produced mostly in dogs and cats?
Dogs - Exocrine pancreas mostly, parietal cells of stomach (a little)
Cats - Exocrine pancreas only
89
What is used as an estimate of protein loss in the GI tract? Used for diagnosis of PLE
Fecal Alpha1-Proteinase Inhibitor Concentration
90
When is fecal **alpha-1 proteinase inhibitor** concentration indicated?
Indicated in dogs *without* clinical signs of gastrointestinal disease and where an extra-gastrointestinal source of *protein loss* cannot be identified
91
What is an acute phase reactant that is increased in dogs with IBD?
Serum C-Reactive Protein Concentration (CRP)
92
What two medications can cause gingival hyperplasia?
Calcium channel blockers
Cyclosporines
93
What infectious agents have been implicated in feline stomatitis?
Feline calicivirus
Feline herpesvirus (FHV-1)
94
What are two autoimmune oral conditions?
Pemphigus vulgaris - Lesion is suprabasilar (intercellular clefting) _with formation of acanthocytes._
Bullous pemphigoid - subepidermal _without formation of acanthocytes_
95
What are the clinical signs of masticatory muscle myositis?
Fever, regional lymphadenopathy, muscle swelling/pain OR atrophy (if chronic), exophthalmos, **resistant to opening mouth.**
96
What is the pathophysiology behind masticatory muscle myositis?
_Autoantibodies to myosin component of the_ **_type 2M fibers_** _of the temporal, masseter, pterygoid muscles_
97
How is masticatory muscle myositis diagnosed?
_Serum type 2M fiber Ab titer_
98
What is sialoadenosis?
_Non-inflammatory_ enlargement of a salivary gland. Neurogenic cause.
99
How is sialoadenosis treated?
Phenobarbital
| (neurogenic mechanism)
100
Can pharyngeal weakness be the only sign in myesthenia gravis?
Yes - 1% of dogs with MG
101
How is cricopharyngeal achalasia diagnosed?
prominent thickened cricopharyngeus muscle _(_*_cricopharyngeal “bar”)_*
102
How is cricopharyngeal achalasia treated?
_cricopharyngeal myotomy or myectomy_;
less invasive tx = botulinum toxin injection
103
What is the treatment for persistent right aortic arch?
surgical ligation of the ligamentum arteriosum
104
Esophageal sarcomas have been associated with what parasite?
Spirocerca lupi infection - due to transformation of esophageal granulomas
105
What percentage of cases of myastenia gravis have megaesophagus as the only clincal sign?
25-30%
106
Cisapride and metoclopramide work on (striated/smooth) muscle?
Smooth
107
(Cisapride/metoclopramide) is better at tightening the lower esophageal sphincter
Cisapride
108
What is microbiota?
Microbes living in the intestine
109
What is a major source of energy for colonocytes?
Butyrate - short chain fatty acid produced by colonic bacteria
110
What are the M cells of the gut?
Specialized epithelial cells that overlie lymphoid follicles, sample luminal antigens and deliver producers to dendritic cells and other APCs
111
How do you differentiate between gastrointestinal stromal tumor (GIST) and leiomyosarcoma?
Immunohistochemistry (IHC) - GIST expresses c-KIT (CD117) and DOG1
112
What changes are observed with serum cobalamin and folate in patients with small intestinal bacterial overgrowth (SIBO)?
Increased folate
Low cobalamin
113
In IBD, what are the cobalamin and folate profiles?
Decreased Folate - Proximal inflammation (duodenum)
Cobalamin - Distal inflammation (ileum)
114
What are the fat-soluble vitamins?
A, D, E, K
115
What is the ideal diet for PLE?
Highly digestible, mod to high protein (20-25%), low fat (\<10%), \<5% insol fiber
116
What test is used to differentiate feline lymphoma from IBD?
PARR
117
What is the gold standard test for exocrine pancreatic insufficiency?
Serum Trypsin-Like Immunoreactivity
118
How much of the pancreas' excretory capacity needs to be lost before symptoms of EPI occur?
\>90%
119
What type of toxicity predominates in cats with acetaminophen toxicity?
hematologic toxicity (methemoglobinemia) predominates over liver toxicity
120
What is the most consistent hepatic biochemical changes in cats with hepatic lipidosis?
**ALP** \>\>\>\>\>\> ALT
GGT usually normal
121
What is a confirmatory test for hepatic lipidosis?
FNA of the liver when there is clinical suspicion of HL
122
What are IV fluid considerations for cats with hepatic lipidosis?
Dextrose containing fluids CONTRAINDICATED
Impaired lactate metabolism - try to avoid lactate containing fluids
123
What type of diet is ideal for cats with hepatic lipidosis?
HIGH protein diet
124
What is the pathophysiology behind coagulopathies in cats with hepatic lipidosis?
Decreased absorption of vitamin K1 rather than decreased production of clotting factors (because they respond well to vit K supplementation)
125
How does **hypokalemia** exacerbate hepatic encephalopathy?
**Causes hypokalemic alkalosis** - Hypokalemia promotes a shift of potassium from the intracellular space to the extracellular space in exchange for hydrogen. The resulting extracellular alkalosis and intracellular acidosis cause ammonia to freely move into cells, including neurons, where it becomes ionized to form NH4+. **NH4+ becomes trapped within the cells (e.g. neurons), making them one-way scavengers of ammonia**
126
What are precipitating factors for hepatic encephalopathy?
1. GI hemorrhage
2. Hypokalemia
3. Hyponatremia
4. Metabolic alkalosis
5. Renal failure
127
What drugs should be avoided in hepatic encephalopathy?
Benzodiazepines, opioids, other sedatives - Because stimulation of benzo/opiod receptors may be part of pathophys of HE
128
What is the best treatment for acute exacerbation of hepatic encephalopathy?
Cleansing enema
129
How does lactulose help in the treatment of encephalopathy?
Bacteria transform lactulose to short chain fatty acids - makes environment more acidic, trapping ammonia in the GI
130
How is ALP cleaved from the biliary membrane?
**Bile acids** cleave ALP and releases AL from membranes resulting in increased ALP activity in serum/plasma
131
Gallbladder filling is (active/passive)
Passive
132
What are the three types of cholecystitis?
Class I - Necrotizing cholecystitis
Class II - Acute necrotizing cholecystitis with rupture
Class III - chronic cholecystitis
133
Patients with extrahepatic biliary obstruction can be (hypocoagulable/hypercoagulable)
Hypocoagulable - need vitamin K supplementation
134
When performing mechanical dilation of esophageal strictures, what is more effective?
Balloon dilation
Rigid bougienage
Balloon dilation
135
What TLR recognizes LPS?
TLR4
136
What TLR recognizes flagellin?
TLR5
137
What is the only clotting factor not made by the liver?
von Willebrans subtype of Factor VIII
138
What is protein C?
Vitamin K activated **anticoagulation** factor
139
In what liver condition is protein C low? (PSS or microvascular dysplasia)
PSS
140
Biacarbonate is exchanged for what in the distal ileum?
Cl-
141
What is the most specific indicator of cholestasis?
GGT
142
What inhibits glucagon?
Somatostatin
143
Where do the hepatic ducts join to secrete produced bile?
Common bile duct
144
How much of the bile salts are re-absorbed?
94%
145
What are Brunner's glands?
Secrete bicarb in duodenum
146
How is glucose absorbed in the intestine?
SGLT-1
147
How is fructose absorbed in the intestine?
GLUT-5
148
What emulsifies fats in the small intestine?
Bile salts
Lecithin (phospholipid)
149
What is responsable for post prandial hyperlipidemia?
Chylomichrons
150
Why do cats lose a large amount of Cobalamin in the intestine as compared to dogs?
Cats don't have transcobalamin
151
What B vitamin can be produced by the intestinal flora?
Folate
152
True or false - Most dogs with microvascular dysplasia are asymptomatic.
True
153
Can biopsy differentiate between PSS and MVD?
No
154
What is more common PSS or MVD?
MVD
155
What is different in the morphology of PSS in small vs. large breed dog?
Small breed - Single extrahepatic shunt
Large breed - Intrahepatic shunt (patent ductus venosus)
156
What blood test can you use to differentiate between PSS and MVD?
1. **Protein C activity:**
1. **normal dog= 100%**
2. **portal vein hypoplasia\>/= 70%**
3. **PSS = \<70%**
157
What is a positive prognostic indicator in PSS?
Higher BUN
158
What is the cause of gallbladder mucocele?
Likely due to **primary disease of the mucous secreting glands** of the gallbladder
159
How is copper taken up by the liver?
Copper transporter 1 (CTR-1)
160
What is ceruloplasmin?
Copper-dependent oxidase - It Fe2+ to Fe3+ for transport
161
How is copper excreted?
In the bile by COMMD1 (MURR)
162
Where is copper stored in Bedlinton Terriers?
Zone 3 - centrilobular
163
What is the most common chem abnormality in Bedlinton terriers with copper storage disease?
Increased ALT = first and most consistent change
164
How are bedlinton terriers diagnosed with Cu hepatopathy?
Biopsy
MURR gene test
165
Copper storage secondary to cholestatic hepatopathy happens where?
Zone 1 - Periportal
166
What is the major circulating bile acid in dogs and cats?
Tauracholate
167
What is the most toxic bile acid?
Lithocholic acid
168
Copper is stored as what?
**_metallothionein_**
169
What is a liver disease in cats that results in ascites?
Lymphocytic cholangitis
