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GI 01


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Name the four general categories of morphology of GI diseases as they are manifested radiographically. Name two examples of pathologic processes for each category.
(1) Narrowing

e.g. inflammatory processes, neoplastic processes, infiltrative processes

(2) Dilating

e.g. obstruction, muscle thinning

(3) Projecting out

e.g. diverticular, ulcers / perforation

(4) Projecting in

e.g. polyps, neoplasms
gallstone ileus
a large calcified gallstone which erodes through the wall of the gallbladder, enters the intestine, and obstructs the distal small bowel.
in general left-sided colonic diverticula are associated with __________ and right-sided are associated with __________
in general left-sided colonic diverticula are associated with diverticulitis and right-sided are associated with bleeding
name the two inflammatory bowel diseases of the colon
ulcerative colitis and Crohn's colitis
contrast ulcerative colitis and Crohn's colitis
(1) rectum -- UC may involve it, Crohn's colitis typically spares it

(2) pattern

- UC starts at rectum and moves continuously back

- Crohn's shows a discontinuous pattern with intervening areas of normal bowel ("skip areas"); ulcerations and nodular mucosa are typical

(3) fistulas

UC -- no spread

Crohn's -- fistulas with other loops of bowel, the skin, and other abdominal structures can occur
radiographic appearance: calcified gallstones

usually multiple, rounded or oval, and located in the right upper quadrant of the abdomen
radiographic appearance: chronic pancreatitis calcifications

most common cause: drinking; rounded calcifications occur in the pancreatic ductal system; calcifications form the rough shape of the pancreas and indicate a chronically diseased organ
radiographic appearance: achalasia

dilated esophagus / little or no peristalsis; reason: lower esophageal sphincter doesn't relax; distal esophagus usually has a "bird's beak" appearance (tapers to a point)
radiographic appearance: benign gastric ulcer

occur on a backdrop of otherwise normal mucosa; ulcers may undermine the surrounding submucosa, leaving a thin rim of mucosa (Hampton's line)
radiographic appearance: malignant gastric ulcer

masses ulcerate; since ulcer is within mass, it does not project beyond the lumen of the stomach
radiographic appearance: small bowel Crohn's disease

usually seen in terminal ileum; folds may be distorted / truncated; mucosa may be ulcerated, nodular, and fistulae b/t adjoining loops can be ID'd; later stages: bowel narrowing
radiographic appearance: colonic diverticulosis

usually occur in the sigmoid colon; distinguishable from ulcerations because of the rounded configuration of their base; can become infected and result in microperforation of the diverticulum into the surrounding fat (diverticulitis)
radiographic appearance: ulcerative colitis

UC is a mucosal process, barium enema changes are typically subtle alterations in the mucosa pattern; called granularity; disease begins in the rectum and can spread continuously throughout the bowel back to the cecum; can cause larger ulcerations, foreshortening of the colon, and narrowing; if left untreated may result in colon cancer
radiographic appearance: colon carcinoma

arise from adenomatous polyps; rounded growths of tissue that project into the lumen on thin stalk; polyp head bigger --> irregular --> stalk shortens --> growth adheres to wall ("sessile") --> circumferential growth around colon ("apple core lesion")
radiographic appearance: primary sclerosing cholangitis

inflammatory process of the biliary ducts that is characterized by fibrosis and stricture formation; pattern: strictures of varying lengths in the intrahepatic and extrahepatic ducts; may be intervening areas of minimal dilation of the ducts with resulting "beaded" appearance
three stomach regions
- luminal secretion
- motility
(1) LES & cardia

- mucus, HCO3-
- prevention of reflux; entry of food; regulation of belching

(2) Fundus & body

- mucus, HCO3-, H+, intrinsic factor, pepsinogens, lipase
- reservoir, tonic force during emptying

(3) Antrum and pyloris

- mucus, HCO3-
- mixing, grinding, sieving, regulation of emptying
All three regions of the stomach secrete mucus, and HCO3-. Which region secretes something else too and what does it also secrete?
Fundus / body -- H+, intrinsic factor, pepsinogens, lipase
Do ACh, gastrin, and histamine inhibit or stimulate the parietal cell?
what does CCK do to gallbladder and sphincter of oddi?
CCK stimulates gallbladder contraction and sphincter of oddi relaxation by both neural and humoral pathways
three fxnal regions of small intestine
- secretion
- absorption
(1) duodenum

- CCK, secretin, GIP, HCO3-
- aborbed: Fe, ions, nutrients, H20

(2) jejunum

- no secretions
- absorbed: less ions, nutrients, H2O

(3) Ileum

- PYY, HCO3-
- absorbed: bile acids, B12, even less ions, nutrients, H2O
digestion of carbohydrate occurs where?
in the intestinal lumen and at the brush border
where in the GI tract does absorption of water primarily occur?
in the small intestine and colon
pharyngeal phase of swallowing
- how fast
VERY, up to 40 cm/s
esophageal phase of swallowing
- how fast
slower than pharyngeal, 2-4 cm/s
oral cavity / pharynx / cervical esophagus = voluntary / striated muscle
- innervation?
innervated by lower motor neurons that are carried in CNs including vagas -- are all excitatory in nature and release ACh at motor end plates
thoracic esophagus / LES = involuntary / smooth muscle
- innervation?
- extrinsic preganglionic fibers that are carried in the vagas nerves and intramural postganglionic neurons that are part of the myenteric plexus

excitatory pathway -- pregang/postgang cholinergic act by releasing ACh

inhibitory -- preganglionic cholinergic and postganglionic nitrergic neurons that exert inhibitory action on smooth muscle by releasing VIP and NO, respectively
upper esophageal sphincter
- anatomy
musculocartilaginous structure composed of the posterior surface of the thyroid and cricoid cartilage, the hyoid bone, and three muscles: cricopharyngeus, thyropharyngeus, and cranial cervical esophagus
lower esophageal sphincter
- anatomy
2-4 cm long high pressure zone of smooth muscle that straddles the diaphragm and is the major component of the anti-reflux barrier
lower esophageal sphincter
- innervation
at rest: tonic contraction due to intrinsic muscle activity and also slight vagal cholinergic control

upon swallowing: relax in response to initial neural discharge from the swallowing center mediated through the vagus nerve
what do fatty meals, smoking, gastric distention, CCK, and progesterone do to LES pressure?
all dec it
primary peristalsis
orchestrated by the premotor neurons in the solitary tract, which send projections to the dorsal motor nucleus of the vagus
secondary peristalsis
elicited by esophageal distention, is executed entirely by a local intramural reflex
transient LES relaxation (TLESR)
LES may relax without associated peristaltic contraction; may be elicited by gastric vagal afferent stimulation or stimulation of afferents in the superior laryngeal nerve with stimuli that are below the threshold for activating swallowing
oropharyngeal dysphagia
aka transfer dysphagia

commonly seen in older patients; caused by striated muscle (including UES) diseases, or neurological disorders and various local structural lesions
esophageal dysphagia
aka transport dysphagia

mechanical or motility causes
pain with swallowing
globus sensation
a feeling of a lump of tightness in the throat, unrelated to swallowing
_________ are the most efficacious medical therapies for GERD with regard to symptom relief and healing of esophagitis
Barrett's esophagus
metaplastic columnar epithelium replaces the normal squamous epithelium of the distal esophagus
Rome III diagnostic criteria for IBS
recurrent abodminal pain or discomfort at least 3 days per month in the last 3 months associated with 2 or more of the following:

(1) improvement with defecation

(2) onset associated with a change in frequency of stool

(3) onset associated with a change in form of stool

- and symptom onset at least 6 months prior to diagnosis
avg length of esophagus
16 cm
hiatal hernia
stomach slides up and protrudes above the diaphragm creating a bell shaped dilation
paraesophageal hernia
stomach rolls along side of the lower esophageal sphincter; vascular supply may strangulate or obstruct
glucose and galactose enter the enterocyte via which transporter?
SGLT 1 (energy / sodium dependent)
fructose enters the enterocyte via which transporter?
GLUT 5 (facilitated diffusion)
glucose, galactose, and galactose leave the basolateral surface of enterocytes via which transporter?
Menetrier disease
gastric secretions contain abundant mucus and usually little acid due to glandular atrophy

diarrhea, weight loss and sometimes bleeding
Zollinger-Ellison syndrome
expansion of the acid secreting portion of the stomach as a response to gastrin-secreting neuroendocrine tumors

ulcers present with duodenal ulcerations predominating
main pathologic feature of achalasia
Main pathologic feature is loss of myenteric ganglion cells, resulting in a lack of ability to relax upon swallowing and progressive dilatation with chronic stasis and hypertrophy of the musculature.
Scleroderma is a CT disease that affects SM only -- therefore the distal 2/3 of the esophagus (SM part) is involved. In this disorder atrophy and fibrosis of smooth muscle occurs, resulting in dysfunction of the LES and reflux esophagitis.
three functions of gastric acid
(1) facilitates the digestion of protein

(2) facilitates the absorption of iron, B12, and calcium

(3) prevents enteric infection and bacterial overgrowth
oxyntic gland
hallmark: parietal cell

fundus / body
pyloric gland
hallmark: secretes gastrin

what do somatostatin cells do to the secretion of gastrin and acid / histamine?
inhibit parietal (acid), ECL (histamine) and gastrin-producing cells
myenteric plexus general function
innervates the circular and longitudinal layers and regulates gastric motility
submucosal plexus
innervates the mucosa and regulates secretion

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