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?: stimulate
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
odynophagia: 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: PPIs
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?: GLUT 2
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: 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

antrum
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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