GI Flashcards
The esophagus is lined by _____cells
Squamous cells
The GI tract consists of
Mouth, esophagus, stomach, small intestines, large intestines.
The esophagus is ______ strong
Mechanically
Stomach acid does what?
Kills most bacteria, denatures proteins.
Makes an isotonic slurry
Small intestines tonicity is greater than, less than, or equal to the tonicity of blood?
Equal to.
What controls the pyloric sphincter?
The pH of the duodenum. Has to be pH ~8, when pH is high enough duodenum will signal pyloric sphincter to relax and let out more chyme
The large intestine reabsorbs
Na+, Cl-, water
Feces is mostly bacteria. What type?
Bacteroides, e.coli.
The appendix serves as
Reservoir for bacteria, immune organ (where immune cells can find their antigens)
The stomach can absorb what?
Water, alcohol, ASA. It can also lose water. (Ingest a gallon of water, will absorb more to increase concentration in the stomach)
The duodenum absorbs these 9 things
Fe2+, Ca2+, mg2+, Na+, water, protein, fat, sugar, vitamins
The jejunum absorbs (2)
Sugar, protein
The ileum absorbs (3)
Bile salts, vitamin b12, Cl-
The colon absorbs (4)
Water, Na+, Cl-, HCO3-
Three anatomical/motor esophageal disorders are:
Hiatal hernia, achalasia, esophageal varices
Two types of esophagitis
GERD, Barrett esophagus
Two types of esophageal cancer
Squamous cell, adenocarcnoma
95% of hiatal hernias are
Sliding hernia
What is hiatal hernia?
Stomach protrudes into esophageal hiatus. (Food can get stuck in the portion of stomach that is above the diaphragm)
T/F hiatal hernias decreases with age
False- increases with age
Achalasia is a problem with the lower esophageal sphincter (LES) and it’s inability to _____properly
Open/ relax
Achalasia presents with these 3 things
- Aperistalsis
- Incomplete relaxation of LES
- Increased resting tone of LES
Achalasia can lead to
- dysphasia
- mucosal inflammation/ulceration
- squamous cell carcinoma
Esophageal varices result from
Portal hypertension
Or impaired portal blood flow
Esophageal varices are most common in these patients
Alcoholic cirrhosis
Esophageal varices are present in how many of all cirrhosis patients?
2/3
What are some issues with esophageal varices rupturing?
1- hematemesis
2- 20-30% death rate with episode
3- 70% chance of rebleed if they aren’t the 20-30% that died
GERD is when the LES does not ____ properly
Close
Contributing causes of GERD
Obesity, hiatal hernia, vagal nerve abnormalities
Problems with GERD
Heartburn, Barrett esophagus (if left untreated)
What happens in GERD
Stomach acid backs up through open sphincter, erodes esophagus
Barrett esophagus has what type of cells
Metaplastic columnar epithelium with goblet cells. (Acid destroys the normal stratified squamous cells)
Barrett esophagus can lead to cancer T/F
True. Leads to adenocarcinoma.
With Barrett esophagus the goblet cells protect the esophagus because it secretes mucus. Does this solve the problem?
No, still have reflux and heartburn. Fix the reflux!
Squamous cell carcinoma is caused by:
Tobacco/alcohol, achalasia, hot tea
Adenocarcinoma of the esophagus is caused by:
Barrett esophagus. Most common in US
s/s of esophageal adenocarcinoma?
Dysphasia and obstruction. (Occurs late in progression)
Chronic gastritis is caused by:
H. Pylori
Acute gastritis is resolved by
Treating the underlying cause
Peptic ulcers result from
Chronic gastritis
How does the stomach protect itself from it’s own HCl?
The cells are deep in the gastric pits and crypts, the mucous layer also protects them
Which cells secrete HCl?
Parietal cells
What is the one equation we should all know?
CO2+ H2O —- H2CO3 ——
HCO3- + H+
H+ is pumped into the stomach lumen in exchange for?
K+ via the H+/K-ATPase pump.
Since H+ is now in the lumen, what ion follows it?
Cl-
Cl- is pumped into the cell in exchange for what?
HCO3-
If your blood is slightly alkaline, how do you fix it?
dump the HCO3 you just picked up into the duodenum
What is the alkaline tide?
when bicarb is transported into the interstitial fluid, slightly increasing the pH.
Chronic gastritis is symptomatic/asymptomatic, and is a result of
usually asymptomatic. A result of chronic inflammation caused by H. Pylori
What are s/s of chronic gastritis?
- upper abdominal discomfort
- n/v
- ulcers
Peptic ulcers are
chronic lesions anywhere in GI tract exposed to acid peptic juices.
Peptic ulcers are commonly found where
98% proximal duodenum, and stomach 4:1
T/F people with H.Pylori infections get peptic ulcers
False. only 10-20% of people with H.Pylori get gastric ulcers. 70% of the population carry H.Pylori.
Aggravating factors of peptic ulcers:
- NSAIDS
- Smoking
- Alcohol
- Corticosteroids
- High stress personality? / spicy foods (not on the list but he keeps talking about it)
S/S of peptic ulcers
- epigastric pain
- n/v
- Hemorrhage and perforation
T/F: Peptic ulcers can lead to cancer
false. Peptic ulcers impair quality of life, they don’t shorten it.
Acute Gastritis is caused by (10)
- Heavy NSAID use (aspirin)
- Excess ETOH use
- Heavy Smoking
- Chemotherapy
- Uremia
- Systemic infections
- Severe stress (trauma, burns, surgery)
- Ischemia and shock
- ingestion of caustic agents (acid or base)
- mechanical trauma (NG tube placement
s/s acute gastritis
epigastric pain with n/v, hematemesis and/or melena
treatment for acute gastritis
get rid of the underlying cause. Gastric mucosa will recover if you get rid of the culprit.
Acute gastric ulcers result from
mucosal defects from severe stress. (focal)
causes of acute gastric ulcers include (4)
- severe trauma (sepsis, major surgery)
- extensive burns
- trauma to CNS or intracerebral bleed
- gastric irritants (NSAIDS)
Stomach cancer was mainly caused by what during the 1930s?
Salting, smoking and pickling foods. (refrigeration has caused a significant decline in stomach cancers today)
Gastric Carcinomas account or what percentage of all stomach cancers?
> 90%
Causes of intestinal type adenocarcinomas (decreased in frequency now)
- nitrites/nitrates to preserve meat
- smoked food
- pickled food, excess salt
- decreased fruit/veggies in diet
- Chronic gastritis
- H. Pylori infection
T/F: Diffuse carcinomas are caused by H.Pylori
false, usually absent. Diffuse carcinomas rare, risk factors poorly understood.
Gastric Carcinoma is the ___ leading cause of cancer death worldwide.
2nd. Lung Ca is 1st.
Developmental anomaly of the intestines is:
Hirschsprung disease: congenital megacolon
Vascular d/o of the intestines include
ischemic bowel dz and hemorrhoids
Diarrheal dz of the intestines include
infectious enterocolitis, malabsorption syndromes
Idiopathic inflammatory bowel diseases are
Ulcerative colitis, Crohns
The enteric plexus of the SI includes ____ and ____ and they ______
Myenteric (between circular and longitudinal muscle layer) and submucosal (between circular muscle and submucosa) and plexus innervate the muscles of the SI.
The muscularis of the SI has how many layers? They are :
- Circular layer, longitudinal - for peristalsis
The intestinal mucosa is made of what 3 layers
- mucous epithelium - simple columnar goblet cells
- lamina propria
- muscularis mucosae - causes villi to move
Describe the small and large intestines in terms of villi
Duodenum, tall villi, deep crypts. moving toward large intestines have shorter villi. Microvilli are on all of the cells. Villi = increased surface area
Starch is broken down into ____ and ____ by _______ (what enzyme?)
Dextrins and oligosaccharides by salivary amylase
_____(enzyme) breaks dextrin and oligosaccharides into ___, ____ and ____
pancreatic amylase breaks dextrin and oligosaccharides into lactose, maltose, and sucrose.
Brush Border enzymes (lactase, maltase, sucrase) breaks down lactose, maltose and sucrose into what?
Galactose, glucose and fructose
Proteins are broken down into _____ and ____ by (what enzyme) in the presence of HCl?
proteoses and peptones by pepsin in the presence of HCl
Proteoses and Peptones are broken down into small polypeptides and dipeptides by which pancreatic enzymes?
trypsin, chymotrypsin, carboxypeptidase
Brush Border enzymes break down small polypeptides and dipeptides into what?
Amino acids ( brush border enzymes are aminopeptidase and dipeptidase)
Unemulsified fats are broken down into ______ and fatty acids and _____ and fatty acids
monoglycerides and glycerol
emulsifying agents are:
bile acids, fatty acids, monoglycerides, lecithin, cholesterol and protein.
what other enzymes help break down unemulsified fats?
pancreatic lipases
Monoglycerides are absorbed by ____ in the villi and transported to the liver in the systemic circulation which receives lymphatic flow from ____ or _____
Lacteals. lymphatic flow from thoracic duct or hepatic portal vein.
glycerol and short chained fatty acids are absorbed by _____ in the villi and transported to the liver by _____
capillaries. transported by the portal vein
The ____ of the large intestines receives the least amount of blood flow.
splenic flexure
The superior mesenteric artery supplies what?
ascending and transverse colon to the splenic flexure
the inferior mesenteric artery supplies what?
descending colon from the splenic flexure to the rectum
blood supply to the sigmoid colon returns to central circulation via ____
the hepatic portal system
blood supply from the rectum returns to central circulation via ____
the IVC
Congenital disease where part of the colon is aganglionic
Hirschsprung or congenital megacolon
Hirschsprung lacks ____ and _____ plexuses
Meissner and Auerbach myenteric
Problems that can occur with Hirschsprung
obstruction, enterocolitis, perforation
how is Hirschsprung fixed?
remove aganglionic portion. (small section okay, can cause diarrhea if a large portion is removed.
Where does Hirschsprung “begin”?
at the anus and travels “back” upwards.
Ischemic bowel disease occurs most commonly in what section of bowel?
Splenic flexure
_____ or _____ can result in infarction of the bowel
acute occlusion or hypoperfusion
Causes of ischemic bowel disease
- arterial thrombosis
- arterial embolism
- venous thrombosis
- nonocclusive ischemia (cardiac failure, shock, dehydration, vasoactive drugs)
- mechanical obstruction (volvulus, stricture, herniation)
Hemorrhoids are the result of ______
persistent elevated venous pressure in hemorrhoidal plexus and causes vatical dilations
You can get hemorrhoids by
straining during defecation, pregnancy, hepatic portal hypertension
the types of diarrhea are:
Secretory, osmotic, exudative, malabsorption, deranged motility
Vibrio Cholerae (cholera) is what type of diarrhea?
secretory
destruction of the epithelial layer by shigella, salmonella and campylobacter is what type of diarrhea?
exudative
Malabsorption diarrhea is caused by
Giardia, lymphatic obstruction, defective absorption (lactose intolerance)
Golytely will cause what type of diarrhea
Osmotic
Deranged motility is caused by
surgery, hypothyroidism
Bacterial cells dump Cl into the intestinal lumen, and causes water to stay in the intestines. this is caused by what?
Secretory diarrhea from vibrio cholera.
Vibrio cholerae is seen in places close to
lakes, rivers, estuaries. raw seafood from these places can cause cholera.
idiopathic inflammatory bowel disease consists of
Crohns and ulcerative colitis
_____ has skip lesions
Crohns
Pseudopolyps are present in ___
Ulcerative colitis
____ begins at the rectum and is contiguous
ulcerative colitis
Fistulas can form from deep chiasms that become transmural in ____
crohns
You can determine if a pt has ___ by colonoscopy or sigmoidoscopy
ulcerative colitis
Fever is common in UC or Crohns
crohns
abdominal pain is present in UC or Crohns
crohns
rectal bleeding is present in UC or Crohns
UC
