GI Flashcards
What makes up the GI tract?
Oral cavity
esophagus
stomach
small intestine
large intesting
What does the stomach acid do?
What else happens in the stomach?
Denatures proteins and kills most pathogens
adds or removes water until bolus is isotonic
What are the anatomical and motor disorders of the esophagus?
- Hiatal hernia
- achalasia
- esophageal varices
What is a hiatal hernia?
- stomach protrudes up into diaphragm
- sliding- food enters stomach from esophagus and gets caught in the pouch above the diaphragm
- symptoms:
- Heart burn
- regurgitation
- **can cause barrets esophagus and then cancer
- increases with age
Achalasia
- Food gets stuck in your esophagus
- food that sits there then starts to errode the esophagus
- lower esophageal sphinctor doesn’t open properly
- or has increased resting tone
- usually happens more to older people
- symptoms
- dysphagia
- mucous membrane errosion
- barrets esophagus –>squamus cell carcinoma
What are esophageal varices?
What is the big problem with these?
- Varicose veins in esophagus
- caused by impaired hepatic portal blood flow
- associated with alcoholic cirrhosis (~2/3 of cirrhosis patients)
- big problem is rupture
- hematemesis- vomiting blood
- 20-30% die on each episode of rupture
- 70% recurrence rate
- *often also have coagulopathies related to liver disease
What is Mallory-Weiss Syndrome?
severe and prolonged (traumatic) vomiting can cause tears in esophagus
*usually not a huge problem because if they dont have cirrhosis, then they will not have coagulophathies and will stop bleeding.
Reflux esophagitis
- When the lower esophageal sphinctor doesnt close properly
- causes heartburn and barret esophagus
- contributing factors
- obesity
- hiatal hernia
- vagal nerve abnormalities
What is barrett esophagus?
- replacement of normal stratified squamus mucosa with metaplastic columnar epithelium with goblet cells
- Can lead to cancer
What are the two esophageal cancers?
- Squamous cell carcinoma- occurs where you have normal esophageal tissue (no barretts)
- caused by tobacco, alcohol, achalasia, very hot tea (>65 C)
- Adenocarcinoma
- caused by barrett esophagus
- symptoms: dysphagia and obstruction
What is Zenker’s Diverticulum?
- part of food bolus gets trapped in the pouch
- more common in pts over 60
- symptoms
- dysphagia
- regurgitation
- cough
- halitosis (food rots in the pouch, causing bad breath)
- usually painless
- may cause infection and perforation (rare)
What is Chronic gastritis?
- Usually caused by H. pylori
- will start to errode stomach lining
- usually asymptomatic
- maybe stomach discomfort, N/V
- Can continue to becme peptic ulceration
What are peptic ulcers?
- Chronic lesions that can be anywhere in GI tract but 98% are in proximal duodenum and stomach (4:1)
- H. pylori is involved in 70-90% of duodenal ulcer and 70% of gastric ulcers
- Only 10-20% of ppl w/ H. Pylori get ulcers
What aggravates peptic ulcers?
- NSAIDS
- smoking
- alcohol
- corticosteroids
- high stress personality??
- gastrinoma (zollinger-ellison syndrome)
What problems do peptic ulcers cause?
- epigastric pain
- nausea and vomiting
- hemorrhage and perforation
- generally do NOT progress to cancer
- ** usually just impair quality of life rather than shorten it
- 15,000 deaths/year attributed to complications of peptic ulcers
Why do NSAIDS exacerbate ulcers?
decrease prostaglandins which decreases mucous layer
(prostaglandins stimulate mucousal production)
What is a gastrinoma?
a hormone producing tumor
What is acute (stress) gastritis?
- Completely different from chronic and does not progress to chronic
- Causes:
- heavy NSAID use
- excessive alcohol
- heavy smoking
- chemo
- uremia
- systemic infections
- severe stress (trauma, burn, surgery)
- ischemia and shock
- ingestion of caustic agents (acids or bases)
- mechanical trauma (nasogastric intubation)
- Problems:
- epigastric pain with N/V
- Hematemesis and/or melena (bloody stool)
How did we cure stomach cancer?
refrigeration
*before refrigerators ppl ate all smoked or pickled foods for winter
What are the two types of stomach cancers?
- Intestinal-type adenocarcinoma (the type of cancer cured with refrigeration)
- caused by nitrites, preservatives
- smoked food
- excessive salt
- decreased fruit and veg consumption
- chronic gastritis
- H. pylori
- Diffuse carcinoma
- risk factors poorly understood; we have not cured this type
What is the third leading cause of cancer death worldwide?
gastric carcinoma
1st- lung
2nd- liver
How are carbohydrates, proteins, and fats digested?
(chart)
What part of GI tract is most at risk for ischemia if there is a shortage (shock)?
splenic flexure
What is Hirschsprung disease?
- Neural crest cells don’t make it all the way to the end of the colon (caudal migration) during fetal formation leaving an aganglionic segment
- distal colon lacks both meissner and auebach myenteric plexus
- no peristalsis past where there are no nerves
- Problems
- obstruction
- enterocolitis
- perforation
- Fixed by removing the aganglionic segment
What is ischemic bowel disease?
- acute occlusion or hypoperfusion can result in infarction
- Mucosal- not a big deal, make for mucous
- mural- More severe, but not the worst
- Transmural infarction- Goes all the way through the intestinal wall
- becomes friable- easy to perforate, like trying to suture a wet tissue; whatever was in the lumen is now in the abdomen
*
- becomes friable- easy to perforate, like trying to suture a wet tissue; whatever was in the lumen is now in the abdomen
What are the causes of ischemic bowel?
- arterial thrombosis
- arterial embolism
- venous thrombosis
- nonocclusive ischemia
- cardiac failure, shock, dehydration, vasoconstrictive drugs
- mechanical obstruction
- volvulus, stricture, herniation
What is the mortality of transmural bowal infarction?
90%!
They were probably already sick when the bowel infarcted
What causes hemorrhoids?
- straining during defecation- strain causes increased venous pressure
- pregnancy- later in pregnancy
- portal hypertension- similar to esophageal varices
What causes cholera?
- Secretory (cholera)- produces toxin that causes chloride to leak into lumen, prevenitn Na from being reabsorbed. Water goes to lumen. Difficult to keep this person hydrated
What are osmotic causes of diarrh
- Gut lavage- goal to clean out the GI tract
- too much golytely causes dehydration with some kind of electrolyte imbalance
What are all the major causes of diarrhea?
- Secretory- cholera
- osmotic- golytely
- exudative- IBD (crohn’s and UC)
- Infectious- shigella, salmonella, campylobacter, C.diff
- C.diff can take over after antibiotics
- Malabsorption- defective absorption (lactose, gluten)
- Deranged motility- surgery, hyperthyroidism
What is irritable bowel syndrom?
- chronic “crummy tummy”
- IBD is WAY worse than IBS
Where does UC start?
- Ulcers in colon
- Starts at the anus and goes back from there. Amount of colon involved depends on extent of disease
- Pseudopolys- part of tissue wall stays forward as all the neighboring tissue becomes ulerated and errodes back
What part of the bowel does crohn’s disease affect?
- some parts are affected, others are normal (skip lesions)
- causes deep fissures that go through mucosal layer and can even cause fistulas from lumen of intestine to abdomen
- structures form, making intestine walls thicker
What are the different smptoms of Crohn’s vers UC?
(chart)
What are the common symptoms between Crohn’s and UC?
Diarrhea
loss of appetite
painful bowel movement
frequent bowel movement
weight loss
fatigue
Whats this?
- The hook worm!! A possible cure for crohn’s?!?
- causes hemorrhagic anemia with no bleeding
- the hook worm “turns off” the pts immune system so that it can survive
What is the lifecycle of the hookworm?
- lives in intestines, sucks blood, lays eggs
- eggs come out of body in feces, get into soil and hatch
- larva bore into the ground and then bore into a person’s foot when they walk over that ground
- the larva make their way into person’s lungs, get coughed up in sputum and then swallowed into GI tract to start cycle again
What is the other high yuck factor medical treatment discussed in class?
- Fly maggots
- eat dead flesh but not live tissue
- can be sprinkled on a necrotic wound and a few days later it is nice and clean
- alternative to amputation
What is diverticulosis/diverticulitis?
What causes it?
Where does it usually occur?
symptoms?
prevention?
- Diverticulosis- pouches that protrude out of the bowel
- occur in about 50% of ppl over 50 years old and increase with age
- diverticulitis- inflammation of the pouches
- occurs mostly in descending colon where the stool is very thick and difficult to move along
- Left lower quadrant pain
- prevent by eating more fiber, avoid food with small seeds
What are the different types of mechanical bowel obstructions?
- hernias- intestine seeps through inguinal canal; bolus can’t get through easily and neither can blood
- adhesions- scar tissue binds bowel together so it cant move as well
- intussusception
- vulvulus- twisting
What are some pseudo obstructions?
- paralytic ileus- bowel doesnt work so content just builds up
- bowel infarction- muscle damage prevents peristalsis
- myopathies and neuropathies (herschsprung)
Which intestine has the greater occurance of cancer?
large intestine
Definitions:
polyp
pedunculated
sessile
- polyp- a tumorous mass protruding into the lumen
- pedunculated- having a stalk
- sessile- not having a stalk
adenoma
neoplastic polyp arising from epithelial proliferation and dysplasia
adenocarcinoma
- cancer arrising from adenomatous polyps (98% of colorectal cancers)
Carcinoid tumor
tumors of neuroendocrine cells, found in stomach, intestines, and lung
What are the differences between a cancer on the right side vs left side?
-
right- fatigue, weakness
- iron deficient anemia
- blood on guiac, but wont see it in stool
- Left- no anemia because pt will see blood in stool and will get checked
