TEST 5: GI Flashcards
Functions of GI tract
(Lecture, p.1285)
- Food ingestion
- Propulsion of food/waste from mouth to anus
- Secretion of mucous, water, enzymes
- Mechanical/ chemical digestion of food
- Absorption of digested food
- Elimination of waste
- Immune and microbial protection against infection
What controls the GI tract?
(Lecture)
- Muscle control (chewing, swallowing; defecation)
- Hormonal control through the autonomic nervous system (GI motility, secretion of substances that aid in digestion)
GI anatomy overview
(Lecture)
Upper GI: mouth, stomach, esophagus, duodenum
Lower GI: small and large intestine, colon
Sphincters: between organs that assist in gut compartmentalization
Gut wall: organized into well defined layers that contribute to functions of certain regions
GI blood flow
(Lecture)
Arterial blood supply:
-Celiac artery
-Mesenteric artery
Venous blood supply:
-Flows through the gut to hepatic circulation via portal vein
-Liver blood flow
-From liver via hepatic vein to IVC after detoxification
Hepatic circulation
(Lecture, p. 1304)
-Blood flows through liver sinusoids where reticuloendothelial cells (Kupffer cells) remove toxins, bacteria, and metabolic waste products
In addition to detox:
-Water soluble nutrients are absorbed by gut and hepatic circulation
-Reticuloendothelial cells and reproduces absorb and store the nutrients
-Intermediate chemical processing of nutrients occurs in liver
Countercurrent blood flow in villi
(Lecture)
-Arterial and venous blood vessels are close to each other but with opposite directionality
-O2 diffuses out of arterial blood into venules (shunting) before perfusing villi tips
-With normal blood flow this isn’t a problem but in states of low perfusion villi tips become oxygen decisive and cells die—> decrease absorptive capacity + gut bacterial flora translocate into blood stream (increased infection risk)
Motility disorders- Constipation
(Lecture, p.1319)
-Difficult/ infrequent stooling
-Individualized definitions based on a persons stool patterns (2-3 day- weekly)
Primary:
-Functional: normal motility but difficult to pass stool
-Slow transit: slow colon transit and accumulation of stool in sigmoid colon
-Pelvic floor dysfunction: failure of pelvic floor or anal sphincter muscle relaxation
Secondary:
-Opioid induced, stroke, Parkinson’s, hirschsprung disease
-Manifestations that last 3+ months:
-Straining with stooling, lumpy/hard stools, sensation of incomplete emptying, and/or use of manual maneuvers to facilitate stooling >25% of the time, <3 stools per week
Motility disorders- Diarrhea
(Lecture, p. 1320)
-Less than or equal to 3 loose, watery stools per day
-Categorized as acute, persistent, chronic
-Osmotic: ingestion of high solar substances that pull water in and increase stool weight and volume
-Ions (mag, phosphate)
-sugars (sorbitol)
-lactose
-tube feeding formulas
-Treatment revolves around dietary changes to avoid offending substances
Secretory: increased secretion of chloride or bicarb rich fluids or decreased sodium reabsorption
-infection (e coli, c diff, rotavirus)
-inflammatory bowel disease (UC, crohns)
-Treatment revolves around addressing infectious or hormonal agent
GI bleeding
(Lecture, p. 1322)
-Classified as either upper or lower based on origin of bleed
-Upper: esophageal or gastric varices, Mallory Weiss tear, cancers peptic ulcer, medications
-Lower: polyps, IBD, diverticular disease, cancer, hemorrhoids
Manifestations:
-Increased peristalsis (emesis or diarrhea)
Upper:
-Hematemesis: bloody (fresh bright red), coffee ground (dark, grainy, digested)
Lower:
-Melena: black, tarry, foul smelling stool
-Hematochezia: fresh, bright blood via rectum
-Occult blood: trace amounts in normals appearing stool or gastric secretions
Ulceration
(Lecture, p.1331)
-Peptic ulcer disease: a break in the lining of the esophagus, stomach, or duodenum
-Risks: H. Pylori, ASA and NSAID use, alcohol, smoking, pancreatitis, COPD, obesity, 65+, low socioeconomic status
Gastric ulcers
(Lecture, p. 1333)
-50-70 years old
-Stress increases risk
-Increases risk for cancer
-60-80% are H. Pylori, associated with increased gastric and gastritis
-Pain: intermittent, with food, relieved with antacids
Duodenal ulcers
(Lecture, p. 1331)
-25-50 year olds, family history
-Ulcerogenic drug use increases risk
-H. Pylori 95-100%, increased parietal cell mass and acid production, NOT associated with gastritis
-Pain: intermittent, nocturnal, remission and exacerbation of pain
Inflammatory bowel disease
(Lecture, p. 1336)
-Relapsing, chronic disease
-Prevalent in white and Ashkenazi Jews
-Causes: genes, environment, alteration in epithelial cells, altered immune response to intestinal microflora (T cell mediated)
-Increases risk for developing colon cancers
Ulcerative colitis
(Lecture, p. 1336)
-Risk factors: 10-40 years old, NO family
History, idiopathic
-Patho:
-Continuous lesions common in colon and rectum
-Affects the mucosal layer ONLY
-Manifestations:
-Diarrhea with bloody stools and presence of antineutrophil cytoplasmic antibodies (hallmark of diagnosis)
Crohn’s Disease
(Lecture, p.1338)
-Risk factors: 10-30 year olds, WITH family history
-Patho:
-“Skip” lesion common in ileocecal region, small intestine, and colon
-Affect ENTIRE intestinal wall
-Common to have fistulae, strictures, obstruction
-Manifestations:
-Abdominal pain, mucous diarrhea, abdominal mass, Malabsorption
Irritable bowel syndrome
(Lecture, p. 1340)
-Brain gut interaction with abdominal pain and altered bowel habits
-Risks: youth and middle age, women, also with anxiety and depression
-NO structural or biochemical causes known
-Possible causes: Visceral hypersensitivity, abnormal Motility, post inflammatory, changes in gut microbiome, food allergy, epigenetic
-Manifestations: spectrum of severity of symptoms (pain and bloating, fecal urgency and incomplete emptying but does not impact sleep)
Diverticular disease of the colon
(Lecture, p. 1340)
Diverticulosis: saclike outpouching (hernias) of the mucosal layer of colon through the muscle wall
Diverticulitis: inflammation of diverticula
Risks: older age, genetics, obesity, smoking, lack of activity, NSAIDS, lack of dietary fiber
Manifestations: cramping, diarrhea, constipation, distention, flatulence
-Fever, leukocytosis, LLQ tenderness associated with common location for diverticula to develop
-Treatment: increase dietary fiber, antibiotics if inflamed
Bowel obstructions
(Lecture)
-Anything that blocks normal flow or motility of intestines
Can be:
-Acute or chronic
-Partial or complete
-Intrinsic or extrinsic
-Mechanical (needs surgical intervention) or functional
Common causes:
-Herniation, constriction from adhesion, volvulus, intusseption
Bowel obstruction— large vs small intestine
(Lecture, p. 1326)
Small intestine:
-Leads to distention and decreased absorption with increased fluid accumulation (proximal to obstruction) which causes emesis, dehydration and electrolyte abnormalities
-Presents as colicky pain associated with peristaltic waves
-Once ischemia occurs, pain increases and is more constant
Large intestine:
-Less common, often related to cancer
-Presents with hypogastric pain and distention, bowel sounds usually still present
-Vomiting is considered a LATE sign
Risk with bowel obstruction: Perforation= results from distention and abdominal wall tension that decreases arterial blood flow—> ischemia
Appendicitis
(Lecture, p. 1341)
-Inflammation of the appendix (projection at the apex of the cecum)
-Pathophysiology is unclear
-Manifestations: epigastric or periumbilical pain (increases in intensity over time)
-MAY subside and then RLQ pain with rebound tenderness
-N/ V/ fever
-Treatment : surgery or antibiotics
Cholelithiasis (gallstones)
(Lecture, p. 1353)
-Causes obstruction and inflammation of the gallbladder
-If the obstruction is in the cystic duct = cholecystitis
-Risks: female, obesity, age over 40, on oral contraception, white
-Patho: stones result from impaired metabolism of cholesterol, unconjugated bilirubin, fatty acids, calcium carbonates and phosphates (hepatocytes secrete bile that is super saturated in cholesterol)
Manifestations: asymptomatic until blocking duct, then;
-epigastric pain (30 mins to hours after eating), intolerance of fatty foods
-Vague: heartburn, epigastric discomfort, jaundice
-Obstruction: fever, jaundice
