GI General Principles Flashcards
Retroperitoneal structures; mnemonic?
SAD PUCKER; suprarenal gland, aorta and IVC, duodenum (2,3,4), pancreas (except tail), ureters, colon (ascending and descending), kidneys, esopahgus, rectum
Falciform ligament…connects?…contains?
Liver and abd wall…contains ligamentum ters hepatis (remnant of fetal umbilical vein)
Heptoduodenal ligament…connects?…contains?
Liver and duodenum…Portal triad (common bile duct, portal vein, heptatic artery)
Gastrohepatic ligament…connects?…contains?
Liver and less curvature of stomach…Gastric arteries…cut this to gain access to lesser sac during surgery
Gastrocolic ligament…connects?…contains?
Greater curvture and transverse colon…gastroepiploic arteries
Gastrosplenic ligament…connects? Contains?
Greater curvature and spleen…Gastric and gastroepiploic arteries
Splenoreal ligament…connects….contains?
Spleen to posterio wall…splenic artery and vein and tail of pancreas
Basal electric rhythm of stomac, duodenum and ileum
Stomach 3/min, duodenum 12/min => ileum 8-9/min
Layers of gut wall (inside to outside)
MSMS - mucosa, submucoasa, msucularis externa, Serosa
Mucosal layer…functions?…contains?
epithelium (think donut), lamina propria, muscularis mucosa…absorption, support, motility (resp.)
Submucosa…functions?…contains?
Submusocal nerve plexus….Meissner’s plexus (parasympathetic) which innervates the muscuaris mucosa (for motility)
Muscularis Externa….functions? Contains?
Myenteric nerve plexus aks Auerbach’s (sympathetic and parasympathetic) which controls GI tract motility
Serosa…functions? Contians?
Support and can help connect to abd. Walls, etc. (aka adventitia
Histology of Esophagus
Nonkeratinized squamous
Histology of Stomach
Gastric glands
Histo of duodenum
Villi and microvilli (for absorption), Brunner’s glands (secretes HCO3- and mucus), crypts of Lieberkuhn (secretes intestinal digestive enzymes)
Hidto of jejunum
Plicae circulares (folds in mucosa) and crypts of Leiberkuhn
Histology of ileum
Peyer’s Patches (in lamina prop and submucosa…which help with immunity …M-cells, with T-cells and B-cells…lymph nodes of the GI?), Plicae circulares, and crypts of Lieberkuhn…MOST GOBLET CELLS IN SMALL INTESTINE FOUND HERE
Histo of colon
Crypts but no villi, lots of goblet cells
Celiac Trunk….comes off of? Branches? Supplies? At the level of?
Abd. Aorta, main branhces are: splenic artery, left gastric (which also gives esophageal branch), common hepatic artery (which also gives hepatoduodenal artery; supplies: stomach, pancreas, spleen, proximal duodenum, gall bladder, liver; Level = T12
SMA…Level? Supplies?
comes off below the celiac (at L1), distal duodenum up to 2/3 of transverse colon
IMA…level? Supplies?
L3…supplies distal 1/3 of transverse colon down to upper rectum
Anastamosis of the stomach blood supply?
Left and right gastric arteries; left and right gastroepiploic arteries…concept: collateral circulation occurs in the “pairs of arteries”: Superior epigastric with infereior epigastric, middle colic with left colic…superior rectal with middle and inferior rectal
Three main portosystemic anastamoses
Esophagus (left gastric with esophageal veins), umbilical (paraumbilical with sup and inf epigastric), rectal (superior rectal with middle and inf rectal veins)
Clinical signs of portal hypertension (anastamoses)
Esophageal varices (can lead to bleeding, hemoptysis), caput medusa (umbilical), INTERNAL hemorrhoids
Pectinate/dentate line…define?…differences in clinical?
Where endoderm becomes ectoderm near the anus…above line we get INTERNAL hemerrhoids and adenocarcinoma (not painful because it receives visceral innervation)…below line we get external hemeerhoids and squamouc cell carcinoma (painful because of pudendal)
Is the inner muscular layer circumferential or longitudinal?
Circumferential
Order of contents of the femoral triangle
Lateral to medial; nerve-artery-vein-lymphatics
Contents of femoral sheath
Vein and artery and lymph nodes; NOT the nerve
Gastrin source
G-cell of stomch antrum
Gasrin action
Increase gastric acid secretion (via ECL cells), increase gastric mucosa, increase motility
Gastrin regulation
Increas release due to stomach distention, alkalinization, amino acids, peptides, vagus nerve. Decrease due to acidic stomach pH.
What two aminoacids are potent stimulators of gastrin?
Phenylalanine and tryptophan
CCK source
I-cells of duodenum/jejunum
CCK action
Increase pancreatic protein secretion, increase gallbladder contraction, decrease gastric emptying, relaxes sphincter of Oddi
CCK regulation
Increased by fatty acids, amino acids
Secretin source
S cells of the duodenum
Secretin action
Increase pancreatic HCO3 secretion, decrease gastric acid secretion, increase bile (liquid) secretion
Secretin regulation
Increased by fatty acids and acid in lumen of duodenum
What pH do pancreatic enzymes work at ideally?
Basic
Somatostation source
D_cells (pancreatic islet,s GI mucosa)
Somatostatin action
Decrease gastric acid and pepsinogen secretion; decrease pancreatic and small intestine fluid secretion, decrease gallbaldder contraction and decrease insulin/glucagon release
Somatostation regulation
Increased by acidity and decrease by vagal stimulation
Glucose-dependent insulinotropic peptide (GIP) source
K-cells (duodenum, jejunum)
Glucose-dependent insulinotropic peptide (GIP) action
Exocrine: decrease gastric H+ secretion; endocrine: increase insulin release
Glucose-dependent insulinotropic peptide (GIP) regulation
Increased by fatty acids, amino acids, oral glucose (NOT INJECTED GLUCOSE)
Vasoactive intestinal polypeptide source
Parasympathetic ganglia
Vasoactive intestinal polypeptide action
Increase intestinal watre and electrolyte secretion, relaxation of smooth muscles and sphincters
Vasoactive intestinal polypeptide regulation
Increased by GI distention and vagal stimulation; decreased by adrenergic output
Nitric oxide effect on LES
Decreases tone; loss of NO is implicated in achalasia
Motilin source
Small intestine
Motilin action
Produces migrating motor complexes (MMCs)
Motilin regulation
Increases in fasting state
Intrinsic factor source
Parietal cells
Intrinsic factor action
Binds B12 in duodenum, uptake at terminal ileum
Gastric acid source
Parietla cells in gastric body
Gastric acid regulation
Increased by hiastmine, Ach, gastrin; lowered by somatostatin, GIP, prostaglandin, secretin
How does gastrin increase HCL (gastric acid)?
It is secreted into circulation and then hits ECL cells (Enterochromaffin-like cells) which then release histamine which signals pariental cells to secrete HCL and intrinsic factor
Pepsin source
Chief cells in gastric body
Pepsin regulation
Increased by vagal stimulation, local acid
What converts pepsinogen to pepsin?
Stomach acidity, then autocatalyzation
Normal saliva tonicity
Hypotonic
Effect of high flow rates on saliva tonicity
Isotonic
Saliva ionic composition
High bicarb, low K, increase in Cl and Na as flow rates increase, decrease K+
Pancreatic juice ionic composition
High Na, inverse relationshpi between HCO and Cl as flow rate increases, low K
How do vagal cells stimulate G-cells?
Via GRP, NOT Ach - muscarinic antaognists have no affect!
What ist he tonicity of pancreatic fluid?
Isotonic
Level of CL and HCO3 in pancreatic fluid with low and high flow
Low flow => high Cl, high flow => high HCO3
Enzyme composition of pancreatic secretions
amylase, lipase, phospholipase A, colipase; tryspin, chymotryspin, elastase, carboxypeptidase
Where is trypsinogen activated?
Brush border by enterokinase/enteropeptidase
Amylase hydrolyzes what bonds? Produces what sugar type?
Disaccharaides; maltose and alpha-limit dextras; hydroylyzes 1-4 alpha glycosidic linkages
Where is iron absorbed
Duodenum
Where is folate and B12 absorbed?
Folate - jejunum, B12 in Ileum with intrinsic factor
In what form are the carbs absorbed in the GI tract?…catalyzed by which enzyme and important of this step?
Borken down from oligosacc and Absorbed as monsacc. Or disacchrides…catalyzed by oligosaccharide hydrolase (it is the rate limiting step)
What transporter uptakes glucose from the GUT lumen
SGLT
What transporter moves glucose from gut epithelial cells to the blood
GLUT 2
What transporter uptakes fructose from the GUT lumen
GLUT 5
What does the D-xylose absorption test tell you?
Distinguiishes GI mucosal damage from other causes of malabsorption
Liver anatomy…Zone 1, 2, 3 conatins what?
1- Hepatic artery and portal vein (aka periportal zone…drains blood and it goes through the canniculi in Zone 2. Zone 3 has the central vein (that goes to systmic circulation and is now “clean”
Viral hepatitis affects which liver zone first?
Zone 1
Which liver zone is affected by ischemia first?
Zone 3
Which liver zone has P450 system and is sensitive to toxic injury the most?
Zone 3
Bilirubin metabolism…quick:
In macrophages: RBCs—> heme—> unconjugated bilirubin…..In blood: Uncong. Bilirubin binds with albumin…In Liver: UDP glucuronosyl transferase conjugates bilirubin…In gut: gut bacteria convert to urobilogen…80% goes to poop…20% goes back into circ and goes to pee
