Small Intestines

Question 1

Duodenal atresia

Answer 1

failed to canalize

bilious vomiting, stomach distended

XR: double bubble - stomach w/ gass proximal to pyloris
-distention in blind duodenal pouch

Assoc w/ down syndrome

Question 2

Conditions clogging biliary ducts

Answer 2

sludging of fluid - biliary sludge
gallstones
pancreatic tumor

Question 3

ERCP

Answer 3

Endoscopic retrograde cholangiopancreatogram

Inject contract into ampulla of Vater to visual biliary tree

can cause pancreatitis w/ reversal of flow

Question 4

Cholecystokinin (CCK)

Answer 4

I cells of duodenum

“pro duodenal”

• decrease gastric emptying
• increased pancreatic secretion
• Gallbladder contraction

Question 5

Secretin

Answer 5

S cells in duodenum

facilitates pancreatic HCO3- secretion neutralizes gastric acid

decreased gastric acid production - inhibit parietal cells

Question 6

Gastric Inhibitory Peptide (GIP)

Answer 6

K cells
Decreased gastric acid production
increase insulin release - why PO glucose taken up by cells faster than IV glucose

Question 7

Brunner glands

Answer 7

secrete alkaline mucus to neutralize gastric acid

hypertrophy w/ excess acid

only in duodenal submucosa

Question 8

Somatostatin

Answer 8

Inhibit secretion of:
gastrin
CCK
secretin
GIP
VIP
insulin
glucagon

D cells in GI and delta cells in pancreas

Question 9

Vasoactive intestinal peptide (VIP)

Answer 9

Produced by sm.m. of GI and parasympathetic ganglia and enteric nervous system

relaxes sm.m. and sphincters throughout GI tract

increased secretion of electrolytes and water –> watery diarrhea

VIPoma of pancreas –> high volume rice water diarrhea like cholera

Question 10

Motilin

Answer 10

produces migrating motor complexes

Question 11

Ileus

Answer 11

no peristalsis

post op
stroke
septic shock

Question 12

Prokinetic agents for ileus

Answer 12

Goal: increase ACh, Increase 5-HT (carcinoid syndrome), decrease D2

Cholinergic agonists - Bethanechol
Aceytlcholinesterase inhibitors - neostigmine

Metoclopramide (Reglan) - stimulates 5HT4, inhibits D2

• used in gastroparesis of DM pts
• SE: seizures, drug induced parkinsonism

Macrolides - stimulate sm.m. motilin receptors

Question 13

Carbohydrate digestion and absorption

Answer 13

salivary amylase

pancreatic amylase –> disaccharides
Intestinal brush border enzymes –> monosaccharies

Glucose and galactose –> sodium dependent transporter

Fructose –> facilitated diffusion

Question 14

Protein digestion and absorption

Answer 14

Pancreatic proteases –>

aa –> sodium dependent transport

di-, tri-peptides –> H+ gradient = faster

Question 15

Trypsinogen

Answer 15

autoactivation or enterokinase in brushborder –> trypsin

cleaves arginine and lysine

Question 16

Lipid digestion and absorption

Answer 16

salivary lipase and stomach –> triacylglycerol

pancreatic lipase –> FA, 2-monoacylglycerol

Bile salts emulsify hydrolized products –> micelles –> triglycerides, cholesterol –> chylomicrons –> liver

Question 17

pancreatic lipase deficiency

Answer 17

chronic pancreatic inflammation –> decreased lipase = decreased lipid digestion

Question 18

Iron absorption and deficiency

Answer 18

duodenum

cause: antacids and certain abx; gastric bypass sx

Question 19

Folate absorption and deficiency

Answer 19

duodenum
jejunum

Def: poor nutrition (e.g. alcoholism)
Infants exclusively fed goats milk

Question 20

B12 absorption and deficiency

Answer 20

terminal ileum - requires intrinsic factor

Def: malnutrition, pernicious anemia

Question 21

Abetalipoproteinemia

Answer 21

AR
Lack apoB –> defective chylomicron assembly

apoB48 tells chylomicron to leave enterocytes - without it it accumulates

Acanthocytes - star shaped RBCs

Presents early childhood:
steatorrhea
malabsorption - ADEK deficient
failure to thrive
ataxia

Question 22

Lactase deficiency

Answer 22

lactase in tips of microvilli
-gastroenteritis can blunt microvilli –> temporary lactose intolerance

sx: bloating, cramping, diarrhea

supplement enzyme or avoid lactose

Question 23

Tropical sprue

Answer 23

likely infectious cause
can affect entire small bowel

vitamin deficiency
Megaloblastic anemia

not better w/ removal of gluten

better with abx

Question 24

Whipple disease

Answer 24

Tropheryma whipplei

wt loss
LAD
hyperpigmentation
cardiac sx
arthralgias
neurological sx

PAS+ foamy macrophages laden w/ t. whipplei in intestinal lamina propria

Older white males

Tx: PCN, ampicillin, tetracycline x 1-2 YEARS!
less than 1 yr tx has 40% relapse rate

Question 25

Bacteria overgrowth of small intestine

Answer 25

N/V/D
bloating
malabsorption

signs of inflammation on histo

dx: aspirate from jejunum - grow out –> excess growth

risk:
dysmotility
fistulas
diverticula
ileocecal valve resection
gastroenteritis
Meds: PPIs

Tx:
Abx/probiotics - contraversial
Intermittent as relapse common

Question 26

Pancreatic insufficiency

Answer 26

d/t chronic pancreatitis, CF, obstruction of duct (gallstones, cancer)

fat malabsorption - ADEK def
steatorrhea

Question 27

Meckel’s diverticulum

Answer 27

MC congenital anomaly in GI
Incomplete obliteration of omphalomesenteric duct (vitilline duct)

five 2's
-2 inches long
2 feet from ileocecal valve
2% of population
first 2 years of life
2 types of tissue- pancreatic and gastric

It causes:
Melena
RLQ pain
intussusception
volvulus
obstruction

Question 28

Intussusception

Answer 28

telescoping of sm. bowel into itself
MC abdominal emergency under 2 yo
Near ileocecal junction
unusual for adults

75% idiopathic
Viruses - esp adenovirus

Currant jelly stools
sudden severe abdominal pain, V

US: “bull’s eye” or “coiled spring”

Question 29

Intestinal ileus

Answer 29

Lack peristalsis in GI tract
post op or severe illness

d/t decreased blood flow to gut - diverted to areas of healing

Question 30

Meconium ileus

Answer 30

meconium not passed in first days after birth

causes: CF, hirschsprung dz

Question 31

Necrotizing enterocolitis

Answer 31

Premature - bowel necrosis, orally fed

sx: feeding intolerance, increaed gastric residuals, abdominal distention, bloody stools
- -> perforation

XR: dilated loops of bowel
paucity of gas
pneumatosis intestinalis - gas in wall of small or large intestine

Tx: bowel rest, parenteral nutrition

Question 32

Intestinal ischemia

Answer 32

Mesenteric ischemia - small intestine
-has chronic form d/t atherosclerosis; typically pain after eating in older male

Ischemic colitis - large intestine

Causes:
Inadequate blood supply
-watershed of splenic flexure at risk

Splanchnic vasoconstriction
Acute arterial occlusion
Venous thrombosis
hypoperfusion of mesenteric vasculature

Typically elderly patient w/ abdominal pain out of proportion to exam findings

Labs: nonspecific
Plain XR: dilated loops of bowel and bowel wall thickening
CT angio diagnostic

Tx underlying cause:
Venous thrombosis - anticoagulation
Arterial embolism - early surgical laparotomy w/ embolectomy
nonocclusive d/t vasoconstriction - remove vasoconstrictive drugs
bowel necrosis - resect

Question 33

Angiodysplasia

Answer 33

small vascular malformation in GI
Tend to bleed - unxplained GI bleeding and anemia

Cecum or ascending colon

Dx: colonscopy, angiography

older patients

Question 34

Irritable bowel syndrome (IBS)

Answer 34

chronic abdominal pain and altered bowel habits
abd pain: crampy w/ variable intensity - improves with defecation

Diarrhea, constipation or alternating

Other sx: GERD, dysphagia, early satiety, nausea, and chest pain

Non GI: urinary frequency and urgency, dysmenorrhea, dyspareunia, fibromyalgia

tx: diet modificaiton (lactose or gluten), fiber supplement, antispasmodics (dicyclomine and hyoscyamine) antidepressants (TCA, SSRI), guanylate cyclase agonists (IBS w/ constipation)

NOT associated: rectal bleeding nocturnal abdominal pain, wt loss, anemia, elevated inflammatory markers, electrolyte abnormalities

Question 35

Common causes of SBO?

Answer 35

XR: dilated loops of bowel

ABCs
Adhesions - surgical 75%
Bulge - hernia
Cancer - tumors - mets colorectal cancer

Other less common:
volvulus, intussusceptions, Crohn’s dz, gallstone ileus, bezoar, bowel wall hematoma from trauma, inflammatory stricture, congenital malformation, radiaiton enteritis

Question 36

Carcinoid tumor

Answer 36

neuroendocrine –> hormone secretion
-Histamine, prostaglandin
Most importantly serotonin

50% of small intestinal tumors
Appendix, ileum, rectum, lung
sx d/t excess serotonin –> carcinoid syndrome

If in intestine only liver metabolizes serotonin via first pass, no sx.
Mets outside of GI or primary lung cause sx

Question 37

Carcinoid syndrome

Answer 37

BFDR
Bronchospasm
Flushing
Diarrhea
Right sided valvular heart disease (edema, ascities)