GI Flashcards
ventral pancreatic bud gives rise to
- pancreatic head and main pancreatic duct, and uncinate process
annular pancreas
- the ventral bud abnormally encircles 2nd part of the duodenum, forms a ring of tissue around the duodenum that can cause narrowing
pancreas divisum
- ventral and dorsal pancreas fails to fuse at 8 weeks
midgut development timeline
- exits through the umbilical ring week 6
- returns to abdominal cavity + rotates around the SMA week 10
retroperitoneal structures
SAD PUCKER
- suprarenal (adrenal) glands
- aorta and IVC
- duodenum (2nd - 4th parts)
- pancreas (except tail)
- ureters
- colon (ascending and descending)
- kidneys
- esophagus (lower 2/3)
- rectum
which ribs overly the spleen, kidneys and liver
- left 9-11 – spleen
- right 8-11 – liver
- left 12 - left kidnet
borders of the pleura
- 7, 10, 12
- 7th in midclavicular line, 10th in midaxillary, and 12th in paravertebral
falciform ligament - structures contained
- ligamentum teres hepatis (derivative of fetal umbilical vein)
- derivative of ventral mesentery
hepatoduodenal ligament - structures contained
- portal traid: hepatic artery, portal vein and CBD
- pringle maneuver - clamp this to prevent bleeding
gastrohepatic - structures contained/significance
- gastric arteries
- separates greater and lesser sac on the right
gastrosplenic ligament - structures contained and signficance
- short gastrics, left gastroepiploic vessels
- separates greater and lesser sac on the left
splenorenal ligament - structures contained
- splenic artery and vein, tail of pancreas
layers of the gut wall - inside to outside
- MSMS
- mucosa (epithelium, lamina propria and muscularis mucosa)
- submucosa (include submucosal nerve plexus – Meissner)
- muscularis externa (includes myenteric nerve plexus – Auerbach)
- serosa
crypts of Lieberkuhn
- simple tubular glands that rest atop muscular mucosa
- present in the duodenum, jejunum, ileum and colon
Brunner glands
- secrete alkaline mucus into the crypts, then into the lumen
- present in the duodenal submucosa
- hypertrophy seen in peptic ulcer disease
peyer patches
- present in the ileum
plicae circularis
- in the jejunum and ileum
goblet cells
- in the ileum and colon
- larges number in the small intestine are in the ileum
SMA syndrome
- when the transverse portion of the duodenum is entrapped between the SMA and aorta, causing intestinal obstruction
- angle diminishes to < 20 degrees
- precipitated by conditions that lower mesenteric fat (low body weight, severe burns, bed rest, pronounced lordosis)
esophageal varices connect
- left gastric vein (portal) and esophageal veins (systemic)
caput medusae connects
- umbilical veins (portal) and epigastric veins (systemic)
rectal varices connect
- superior rectal vein (portal) to inferior/middle rectal veins (systemic)
- will drain into internal pudendal veins and internal iliacs to react IVC
Zone 1 of the liver (periportal)
- affected first by viral hepatitis and ingested toxins
Zone 3 of the liver (centrilobular)
affected 1st by ischemia, contains cytochrome p450 system, most sensitive to metabolic toxins, site of alcoholic hepatitis
CCK
- produced in the I cells in the duodenum + jejunum
- actions: inc pancreatic secretions, inc gall bladder contraction, inc sphincter of Odi relaxation, and decrease gastric emptying
- increased by fatty acids, amino acids
- CCK acts on neural muscarinic pathways to cause pancreatic secretion
gastrin
- G cells (antrum of the stomach)
- actions: increase gastric H+ secretion, growth of gastric mucosa, increased gastric motility
- regulation: increased by stomach distention, alkalinization, amino acids, peptides and vagal stimulation, decreased by stomach pH < 1.5
- increased in Zollinger-Ellison syndrome, PPI use and pernicious anemia
- phenylalanine and tryptophan are potent stimulators
glucose dependent insulinotropic peptide (GIP)
- secreted by K cells (duodenum, jejunum)
- actions: exocrine – decreases gastric H+ secrtion, endocrin – increases insulin release
- regulation: increased by fatty acids, amino acids, oral glucose
- this is why oral glucose is more rapidly utilized than IV glucose
motilin
- source: small intestine
- actions: produces MMCs
- increases in fasting state
- motilin receptor agonists (erythromycin_ are used to stimulate intestinal peristalsis
secretin
- source: S cells in the duodenum
- actions: increase pancreatic HCO3-, decrease gastric acid secretion and increase bile secretion
- regulation: increased by acid and fatty acids in the lumen of the duodenum
somatostatin
- inhibitory hormone secreted by D cells in the pancreatic islets and GI mucosa
- decreases gastric acid and pepsinogen secretion, decreased gallbladder contraction, decreases insulin and glucagon release
- increased by acid, decreased by vagal stimulation
- has anti-growth effects
- H pylori leads to chronic antral inflammation that decreases the number of D cells
VIP
- source: PS ganglia in the sphincters, gall bladder and small intestine
- increases intestinal water and electrolyte secretion, increased relaxation of intestinal smooth muscle and sphincters
- increased by distention and vagal stimulation, decreased by adrenergic input
VIPoma
- non-alpha, non-beta islet cell tumor that secretes VIP
- copious Watery Diarrhea, Hypokalemia, and Achlorhydia (WDHA)
intrinsic factor
- source: parietal cells (stomach)
- vitamin B12 binding protein required for uptake in the terminal ileum
- AI destruction of parietal cells –> chronic gastritis and pernicious anemia
gastric acid
- secreted by parietal cells in the stomach
- action – decreases stomach pH
- secretion increased by histamine, Ach and gastrin
- secretion decreased by somatostatin, GIP, prostaglandin, secretin
gastrinoma
gastrin secreting tumor that causes high levels of acid secretion and ulcers (duodenal and jejunal) refractory to medical therapy
pepsin
- secreted by chief cells of the stomach
- action - protein digestion
- regulation - increased by vagal stimulation, local acid
- inactive pepsinogen in cleaved to pepsin by H+
cells in the body of the stomach
chief cells and parietal cells
cells in the antrum of the stomach
G cells, mucous cells and D cells
cells in the duodenum
I, S and K cells
gastric parietal cell mediators
- Ach (via M3) and gastrin (via CCKb) stimulate Gq and increases IP3/Ca, which increases H/K ATPase activity
- histamine binds H2 receptor and increases cAMP through Gs, which increases H/K ATPase activity
- prostaglandins, misoprostol and somatostatin decrease cAMP via Gi, decreasing H/K ATPase activity
trypsinogen
- converted to trypsin (protease) by enterokinase/enteropeptidase and then goes on to cleave/activate other enzymes
- enteropeptidase deficiency: impaired trypsin formation leading to diarrhea, growth retardation and hypoproteinemia
- serine peptidase inhibitor secreted by acinar cells (trypsin inhibitor)
D-xylose absorption test
distinguishes GI mucosal damage from other causes of malabsorption
- would be normal in pancreatic insufficiency/after pancreatic surgery
carb absorption
- glucose and galactose taken up by SGLT1
- fructose taken up by GLUT5
- all transported to the blood by GLUT 2
iron absorbed in the ….
duodenum
- so pts s/p gastrojejunostomy will need Fe supplements
folate absorbed in the ….
jejunum and ileum
B12 is absorbed in the …
terminal ileum along with bile acids, requires IF
peyer patches
- in the lamina propria and submucosa of the ileum
- contain M cells that sample antigens
- IgA secreting plasma cells produce secretory IgA that deal with the intraluminal antigen
bile
- made by cholesterol 7-a hydroxylase
- functions: digestion and absorption of lipids and fat-soluble vitamins, cholesterol excretion, antimicrobial activity (via membrane disruption)
heme oxygenase
- breaks heme down to biliveridin
- responsible for the green discoloration of bruises
pleomorphic adenoma
- benign mixed tumor (stromal and epithelial)
- the most common salivary gland tumor, usually involves the parotid gland
- painless, well-circumscribed, mobile mass
- recurs if incompletely excised, which happens a lot because it has irregular borders
warthin tumor
- aka pupillary cystadenoma lymphomatosum
- benign cystic tumor with germinal centers (lymphoid tissue)
- usually involves the parotid gland
mucoepidermoid carcinoma
- most common malignant tumor and has mucinous and squamous components
- typically presents as painless, slow-growing mass
- commonly involves the parotid and affects the facial nerve
achalasia
- inability to relax the LES because of loss of the myenteric (Auerbach) plexus
- progressive dysphagia to solids and liquids
- increased risk of SCC
- can be 2/2 Chagas disease
eosinophilic esophagitis
infiltration of eosinophils in the esophagus in atopic pts
- food allergens –> dysphagia, heartburn, strictures
- unresponsive to GERD therapy
esophagitis
- associated with reflux, infection in immunocompromised or chemical ingestion
- candida - white psuedomembrane
- HSV-1 - punched out ulcers
- CMV - linear ulcers
Plummer Vinson Sydnrome
- triad of dysphagia (due to esophageal webs), iron deficiency anemia and glossitis (beefy red tongue)
barrett esophagus
- glandular metaplasia that replaces nonkeratinized squamous epithelium with intestinal epithelium (nonciliated columnar with goblet cells)
- increased risk for esophageal adenocarcinoma
esophageal carcinoma
- adeno most common in the US, squamous everywhere else
- adeno on the bottom 1/3
- adeno RF: barretts, cigarettes, fat, GERD
- squamous RF: alcohol, cigarettes, hot drinks, lye ingestion, esophageal webs, diverticula, achalasia
- squamous on the top 2/3
- nodes they go to: upper 1/3 –> cervical nodes, middle 1/3 –> mediastinal, bottom 1/3 –> celiac/gastric
acute gastritis
- disruption of the mucosal barrier leads to inflammation
- can be caused by stress, NSAIDs, alcohol, uremia, burns (Curling ulcer), brain injury (Cushing ulcer), and chemo
Curling Ulcer
- due to severe burns –> decreased plasma volume –> sloughing of the gastric mucosa
Cushing ulcer
- due to increased ICP –> increased vagal stimulation –> increased Ach action on parietal cells –> increased acid
type A chronic gastritis
- autoimmune attack on parietal cells, pernicious anemia, and achlorhydria (low acid production by the stomach leads to increased gastrin secretion and G cell hyperplasia in the antrum)
- associated with other AI disorders
type B chronic gastritis
most common type, associated with H pylori infection
- increased risk of MALT lymphoma, gastric adenocarcinoma and ulcers
mentrier disease
- gastric hypertrophy with protein loss, parietal cell atrophy, and increased mucous cells
- precancerous
- rugae of the stomach are so hypertrophied that they look like brain gyri
stomach cancer - intestinal type
- associated with H pylori, nitrosamines, tobacco, achlorhydria, AI chronic gastritis
- commonly on lesser curvature, looks like ulcer with raised margins
- pts with blood type A have higher risk
stomach cancer - diffuse type
- not associated with H pylori
- signet ring cells
- will infiltrate the stomach wall and cause thickening/leathery appearance (linitis plastica)
gastric ulcer
- pain Greater with meals
- usually on the lesser curvature - if they bleed it comes from the left gastric artery
- H pylori 70% of the time, also NSAIDs
- increased risk for carcinoma, happen in older people
duodenal ulcer
- pain Decreases with meals
- H pylori almost always
- associated with Z-E syndrome
- generally benign
- can see hypertrophy of the brunner glands
- if they bleed it is the gastroduodenal artery
