Gastrointestinal Tract Flashcards
(36 cards)
Discuss how to differentiate the jejunum and the ileum
Wall: - jejunum have thicker walls with larger diameter Location - jejunum located in left quadrant - ileum located in right lower quadrant Vascularity - jejunum have greater vascularity so appear darker - vasa recta are long in jejunum Mesenteric fat - jejunum have less mesenteric fat Circular Folds - jejunum have tightly packed circular folds Villi - jejunum have more numerous villi Lymph node - ileum have Peyer's patches
Discuss the differences in tissue above (visceral) and below (somatic) pectinate line
Embryology
- visceral is endoderm where somatic is ectoderm
Innervation
- visceral is autonomic
- somatic is pain sensation from in rectal nerve
Blood supply
- visceral is superior rectal artery and vein from IMA/V
- somatic is inferior rectal artery from internal iliac and middle/inferior rectal vein from IVC
Lymphatics
- visceral pattern
- somatic have body wall drainage
Discuss the digestion and absorption of proteins in the GI tract
Stomach
- proteins denatured by gastric acid
- pepsinogen secreted by chief cells activated by gastric acid cleave protein into peptides
Duodenum
- pancreatic proteases (trypsinm chymotrypsin) cleave peptide into oligopeptides
- brush border enzymes (-peptidase) cleave oligopeptides
Small Intestine
- absorbed by enterocytes via co-transport with Na
Blood
- leave epithelial cell by diffusion
Discuss the digestion and absorption of carbohydrates
Mouth - salivary amylase break starch - simple sugars can be absorbed by mouth Duodenum - pancreatic amylase break down starch Small Intestine - brush border enzymes break disaccharide into monosacchride Absorption - glucose and galactose absorbed with co-transport of Na
Discuss the digestion and absorption of fat
Mouth and Stomach
- mastication break down fat
- gastric lipase break down fat
Duodenum
- bile salts emulsify fat to break it down into fat droplets
- pancreatic lipase cleave triglyceride into fatty acids
- pancreatic phospholipase break phospholipids into fatty acids
- pancreatic cholesterol esterase break cholesterol into sterol
- cleaved fatty acids, monoglyceride, choline and sterol form micelle with bile salt
Small Intestine
- micelle diffuse into enterocyte where can reform triglyceride to form chylomicron which can exit and enter lymphatic
List the risk factors for a hernia
- body habitus which increases intra-abdominal pressure: obesity, pregnancy, ascites
- activities which increase intra-abdominal pressure: chronic cough, constipation, straining, heavy lifting
- congenital anomaly with patent processus vaginalis
- male increased risk for indirect inguinal hernia due to opening in inguinal canal
- female increased risk for femoral hernia
Differentiate between a indirect and direct inguinal henia
Indirect
- herniation originating deep inguinal ring lateral to inferior epigastric artery that descends into scrotum or labia majora
Direct
- herniation through Hesselbach’s triangle medial to inferior epigastric artery
- Hesselbach triangle is medial= lateral margin of rectus, lateral=inferior epigastric artery, inferior=inguinal
Discuss what is a femoral hernia
- herniation into femoral canal, medial to femoral vein
- greatest risk for incarceration
Discuss the presentation and management of a hernia
Presentation
- fullness at hernia site with enlarging mass with valsava with disappearance when supine
- aching sensation in area, worse at end of day
- incarcerated have painful, non-reducible mass with symptoms of bowel obstruction
- strangulated have irreducible hernia with symptoms of bowel obstruction and fever/peritonitis
Investigation
- CT or ultrasound
Management
- usually have surgical repair within 1 month of hernia unless it is minimally symptomatic and first occurence
Discuss the presentation and management of peptic ulcer
Etiolgy - H Pylori infection - NSAID - gastric cancer Presentation - dyspepsia (gastric worse with food and duodenal improve) - hemetemesis - melena - epigastric tenderness Management - if H pylori positive then quadruple therapy of PPI, bismuth, tetracycline, metronidazole) - discontinue NSAID Surgical Indications - refratory to medical management - hemorrhage - perforation - obstruction
Discuss the presentation and management of an acute surgical abdomen
Presentation - acute, severe abdominal pain - unstable vital signs - peritonitis: guarding, rigidity, rebound tenderness, tenderness to percussion Investigations - routine bloodwork - AXR for possible perforation or obstruction - CT Management - stabilize - early surgical intervention
Discuss the pathophysiology of a bowel obstruction
- have disruption of the normal flow of contents leading to upstream dilatation and downstream collapse
- dilatation can interrupt blood supple leading to ischemia and bowel wall edema
- Venous congestion impairs normal bowel absorption leading to increased intra-luminal fluid and fluid loss into peritoneal cavity causing electrolyte imbalances
List the differential for a small bowel obstruction
Intraluminal - intussusception - gallsontes Intramural - Chron's - radiation stricture - adenocarcinoma Extramural - Adhesions - hernia - peritoneal carcinomatosis
Discuss the presentation and management of a small bowel obstruction
Presentation - nausea and vomiting - bloating - diffuse abdominal pain - constipation and obstipation - distended abdomen with hyper-resonance Investigations - AXR: distended small bowel loops with air fluid level - thicker wall, pliacae circularis, and located in middle abdomen and are smaller Management - NG tube decompression with bowel rest - surgery if no resolution in 2-3 days, complete obstruction
List the differential for a large bowel obstruction
Intraluminal - constipation Intramural - adenocarcinoma - diverticulitis - IBD striction - radiation stricture Extramural - volvulus - adhesions
Discuss the presentation and management of a large bowel obstruction
Presentation
- history of colorectal cancer (melena, blood per rectum, decreased caliber of stool with incomplete emptying and soiling)
- same as small bowel obstruction
Investigation
- larger diameter with thinner walls and haustra that do not go all the way across
- closed loop if competent ileocecal valve blocking air from going into small bowel
- open loop if incompentent valve and small bowel dilated
Management
- surgical management
Discuss the presentation and management of a bowel perforation of the colon or rectum
Presentation - nausea and vomiting - severe, diffuse abdominal pain - fever and unstable vitals - peritoneal signs Investigations - air under diaphragm Management - aggressive resuscitation - ceftriaxone and flagyl or pip-tazo - surgery for correction
Discuss the presentation and management of toxic megacolon
Etiology - IBD - bacterial colitis Pathophysiology - inflammation extending to smooth muscle resulting in paralysis of peristalsis leading to dilatation Presentation - abdominal distention and tenderness - hematochezia - peritoneal signs Investigations - >12cm in right colon, >6cm in transverse or >9cm in left colon - thumb printing Management - stabilize - NPO and NG tube - empiric broad spectrum antibiotics - treat undrlying cause with possible surgery if fail to improve over 48-72hrs
Discuss the presentation and management of volvulus
- rotation of bowel segment (most common is sigmoid and then cecum) around the mesenteric axis
Presentation - bowel obstruction symptoms
Investigations - coffee bean with central cleft pointing to LLQ with sigmoid
- coffee bean with central cleft pointing to RLQ in cecum
Management - sigmoid get flexible sigmoidoscopy decompression and insertion of rectal tube past obstruction with elective surgery in future
- cecum get colonoscopy for derotation and decompression with elective surgery
List the risk factors for colonic volvulus
- Elderly
- high fiber
- chronic constipation
- laxative abuse
- pregnancy
- institutionalization
List the risk factors for colon cancer
- familial history
- > 50 years old
- presence of adenomatous polyp
- inflammatory bowel disease
- familial adenomatous polyposis, Peutz-Jeghers syndrome, Lynch syndrome
- diet high in fat, red meat and low in calcium and folate
Discuss the presentation and management of adenocarcinoma of the colon
Presentation - right sided have occult bleeding with iron deficient anemia - left sided have obstructive symptoms and hematochezia - altered bowel pattern - weight loss - tenesmus Investigation - CEA - CXR and bone scan Management - stage 1 and 2 get surgery - stage 2 and 3 get surgery with adjuvant chemotherapy (5-FU) - stage 4 get palliative chemotherapy
Discuss the pathophysiology of diverticular disease
- diverticulum is abnormal sac protruding from the colon
- occur where colon mucosa herniate through submucosa at weakness of muscle layer where blood vessel penetrate
- have stasis and obstructiction at neck -> bacterial overgrowth and tissue ischemia -> lead to micro-perforation and subsequent inflammation and infection
Discuss the risk factors for diverticulosis
- age >60
- low fiber diet
- NSAIDs
- physical inactivity
- smoking
