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PHGY350 - GI
N/A
130
Physiology
Undergraduate 3
12/17/2011

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Term
3 basic processes of GI tract
Definition
Ingestion, Digestion (secretion/absorption), Motility
Term
What is skeletal muscle needed for in the GI tract?
Definition
Continence @ sphincters, chewing, initiation of swallowing
Term
Difference between skeletal & smooth muscle
Definition
Smooth muscle has graded contractions, is mononucleated, can contract autonomously
Term
Characteristic contraction of GI smooth muscle
Definition
SLOW and MAINTAINED; have a resting tone to GI smooth muscle
Term
What does the ENS control?
Definition
Regulate motility, secretion, absorption
Complete sensory and motor pathways - NOT PAIN
Term
Key symptom of pathology relating to the ENS?
Definition
PAIN - it is not sensed by the ENS, and indicates pathology
Term
Where do external pain fibers run to/from the GI tract?
Definition
Nociceptive fibers run from DRG to mucosa of GI tract to mediate pain
Term
Likely reasons for pain in the GI tract
Definition
High luminal pressure
Wall distension
Term
What is true of all inflammatory conditions targeting the epithelium of the GI tract?
Definition
DECREASE SURFACE AREA
Therefore see decreased absorption, secretion, and barrier function
Term
What forms physical barrier between GI lumen and the body?
Definition
Mucosa (epithelium)
Term
Type of epithelium in intestines?
Definition
Simple columnar
Term
Where are immune cells present in the GI tract?
Definition
Mucosa (lamina propria)
Term
What type of immune cells are seen in the GI tract?
Definition
Eosinophils, neutrophils, monocytes, T cells
Mast cells primed with IgE (type I hypersensitivity)
Term
What is the acute response to inflammation in the GI tract?
Definition
Emesis, diarrhea (clear out contents)
Localized pain to inflamed area & loss of function
Term
General characteristics of gastroenteritis
Definition
Nausea, cramps, diarrhea
Term
Acute vs. Chronic Inflammation
Definition
Acute - short lived response to presence of irritant
Chronic - LONG term response to persistent stimulus OR persisting in the absence of any stimulus (e.g. IBD)
Term
Regions of the stomach
Definition
Fundus (proximal), body, antrum (distal)
Term
Vomiting
Definition
Evidence of CNS and GI involvement
Many stimuli
Usually a symptom of a larger pathology
Term
Process of vomiting
Definition
Stimulation of vomiting centers in medulla
Hypersalivation from parasymp innervation and glottis closes to protect airway; relaxation of LES, reverse peritalsis & contraction of abdominal muscles
Term
What type of inflammation is seen in gastritis?
Definition
CHRONIC inflammation of the stomach
Term
Different causes of gastritis (chronic inflamm)
Definition
H. pylori infection - leads to ulceration (compromised mucosal defense barrier)
NSAID injury (ischemia caused by NSAIDs)
Excess HCl secretion
Gastric cancer
Term
How can you treat excess acid secretion leading to gastritis?
Definition
Proton pump inhibitors, H-channel blockers
Term
Gastric Emptying
Definition
"Dumping" syndrome - early dumping into duodenum
Vomiting, diarrhea
May be due to decreased gastric volume from BARIATRIC surgery; other is idiopathic
Term
Gastroparesis
Definition
Delayed emptying - imbalance of luminal and neural signals
Associated with DM - chronic DM causes peripheral neuropathy in ENS
Term
Pyloric Stenosis
Definition
NO emptying
Congenital defect in pyloric sphincter - no inhibitory innervation to sphincter (always contracted)
Use myectomy to enlarge pylorus
Term
Types of bariatric surgery
Definition
Restrictive Operations - reduce gastric VOLUME; much more common
Malabsorptive Operations - bypass small intestine to reduce ABSORPTION
Term
3 major types of restrictive bariatric surgery
Definition
Roux-En-Y
Gastric Banding
Sleeve Gastrectomy
Term
Roux-En-Y
Definition
40% of restrictive operations
Good for comorbidities (DM II)
Connect piece of small intestine to fundus (bypass rest of stomach) to reduce gastric volume
Term
Gastric Banding
Definition
43% of restrictive surgeries
Minimally invasive (laproscopic)
Tie band around fundus to reduce gastric volume
Term
Sleeve Gastrectomy
Definition
4% of restrictive operations
Stomach is stapled and sleeve placed over top to limit expansion
Term
Description of PUBLICALLY funded bariatric surgery
Definition
21 month wait time
Roux-En-Y is performed (small intestine attached to fundus)
Better for comorbidities
Major surgery & highly invasive - risks
Term
Description of PRIVATELY funded bariatric surgery
Definition
1 month wait time - $16k (median cost)
Gastric banding performed (minimally invasive)
Safer procedure, ambulatory
Term
Most common comorbidity to obesity
Definition
DM II
Term
What is the primary role of the liver?
Definition
Secretion of bile acids/salts (fat absorption)
Term
Why is the liver tolerant of insult?
Definition
Because of its regenerative capacity; only visceral organ which can regenerate
Term
Different name for biliary colic
Definition
Gall stones
Term
Where can the blockage in biliary colic occur?
Definition
Either in bile outflow duct from gallbladder or in the duct emptying into duodenum
Term
Type of pain seen in biliary colic
Definition
TRANSIENT, periodic pain
Term
Complications of biliary colic?
Definition
Jaundice & cirrhosis
Term
Treatment of biliary colic
Definition
Surgical removal of stone or gall bladder
Lithotripsy to break down
Drugs to dissolve
Term
3 different causes of JAUNDICE:
Definition
Overall it shows excessive bilirubin levels in blood
May be too much is produced - hemolysis of RBCs
Not enough removed BY liver - key aspect of HEPATITIS
Not enough removed FROM liver - obstruction
Term
Hepatitis A
Definition
Caused by HAV
Highly contagious; have vaccine
Contracted from water/environment; ACUTE
Term
Hepatitis B
Definition
Caused by HBV; "serum" hepatitis
Blood borne disease
Chronic
Term
Hepatitis C
Definition
Caused by HCV; blood-borne (like B)
Chronic w/ associated cancer risk
Term
Hepatitis D
Definition
Requires B to be co-morbid for HDV to infect
Blood borne; ACUTE
Term
Hepatitis E
Definition
Not present in USA; caused by HEV
Blood/environment spread; ACUTE
Term
Non-viral causes of hepatitis?
Definition
Chemical - acetominophen, EtOH, benzene
Cancer - liver is main site of cancer formation; common site of metastasis
Term
What is cirrhosis considered to be?
Definition
The outcome of CHRONIC liver damage
Term
Pathology associated with cirrhosis
Definition
Loss of hepatocyte function
Increased circulating bilirubin (jaundice), but decreased bile production (decreased fat absorption)
Impaired detoxification of N-compounds
Encephalopathy
Term
Which symptoms are common to both hepatitis and cirrhosis?
Definition
Loss of hepatocyte function - jaundice from increased bilirubin in blood and decreased bile production; also get decreased fat absorption
Term
What causes the loss of hepatocyte function in cirrhosis?
Definition
FIBROSIS - scar tissue forms in the liver
Term
At what point(s) can liver damage be reversed?
Definition
If EtOH intake stops at fatty liver OR alcoholic hepatitis, damage may be reversed
However, if cirrhosis is reached, then damage is PERMANENT
Term
What are the vascular effects of cirrhosis?
Definition
Fibrosis impedes blood flow leading to PORTAL HTN - restricts flow entering liver, get-back up
Because of backup get systemic HTN in veins
Get ascites and varices
Term
What are side-effects which occur because of portal HTN seen in cirrhosis?
Definition
Ascites (fluid accumulation in peritoneum)
Varices in the spleen leading to splenomegaly
Term
2 main functions of pancreas
Definition
Exocrine enzyme secretion & HCO3-
Endocrine secretion of insulin & glucagon
Term
Types of pancreatitis
Definition
Gallstone
Alcoholic
Infectious
Term
Gallstone Pancreatitis
Definition
Blockage of pancreatic outflow by gallstone, get autodigestion by enzymes
Treat by gallbladder removal
Term
Alcoholic Pancreatitis
Definition
Triggers early activation of pancreatic enzymes = autodigestion; feed-forward process causes mass enzyme activation
Term
Infectious Pancreatitis
Definition
Due to bacterial infection of pancreas
Term
Symptoms of General Pancreatitis:
Definition
Decreased pancreatic function
SEVERE pain (unrelenting)
Complications = sepsis, perforation, peritonitis
Term
Main functions of small intestine?
Definition
Absorption/secretion, motility, neutralize gastric HCl
Term
Main functions of large intestine?
Definition
Storage & H2O absorption
Term
What are the main functions of intestinal epithelium?
Definition
Barrier for protection, secretion/absorption, constant proliferation, enzyme secretion
Term
Daily fluid load
Definition
About 9 L in total (8 L secreted into GI lumen by epithelium); need to balance with reabsorption
Term
How is the pathology of intestinal mucosa prevented?
Definition
Constant challenge - sampling of luminal contents by immune system
Term
What is the immune response in celiac disease?
Definition
Antibodies formed against GLIADIN (gluten byproduct)
Immune reaction causes inflammation of villi and flattening of them - FLAT MUCOSA
Term
What occurs to the mucosa in Celiac disease?
Definition
Get FLAT MUCOSA - villi are all flattened
B/c of mucosal pathology, enzyme and absorption functions are decreased
Term
What does NOT occur in Celiac disease?
Definition
NO enzyme deficiency or digestive block
NOT an autoimmune condition
Term
Lactose Intolerance
Definition
NOT an allergy (not type I hypersensitivity mediated by IgE)
Bacterial response to undigested lactose (lactase deficiency)
Term
What causes the symptoms of lactose intolerance?
Definition
Bacteria fluorish on undigested lactose present because of a lactase deficiency
Actually, lactase deficiency is very common (most people are, just have varying degrees)
Term
What causes food allergies?
Definition
Antigen recognition by mast cells primed w/ IgE
Term
Symptoms of food allergy?
Definition
Gut is the primary target, then reaction goes systemically
Pain, diarrhea, hives, anaphylaxis
Term
What is used to determine sensitivity to an allergy?
Definition
Oral challenge b/c primed mast cells located under tongue
Term
Amount of microbes present in GI tract?
Definition
10^5 in ileum
10^9 in colon
Term
Bad E. coli?
Definition
O157 H7 - enterohemorrhagic E. coli (EHEC)
Term
Where is O157H7 E. coli native to, and what are its symptoms in infection of us?
Definition
Native to the gut of cattle
Causes - pain, bloody, diarrhea, vomiting, hemolysis, kidney damage
Term
What is the worst case scenario to treat infection of the gut?
Definition
Antibiotics - throws off the normal probiotic environment of the gut
Term
C. difficile Colitis
Definition
C. difficile is NORMAL FLORA of GI tract, BUT when given certain antibiotics increases C.D population in gut which causes toxin secretion
Possible treatment w/ stool transplant - replace unbalanced flora w/ normal flora
Term
Two different causes of diarrhea
Definition
Increased H2O secretion into lumen
Decreased H2O absorption from lumen
BOTH caused by ion imbalance (underlies fluid movement)
Term
What does an increased fluid volume in the gut cause?
Definition
Increased motility
Term
Treatment of Traveler's diarrhea
Definition
Immodium - anti-motility agent, reduce cramping
Pepto Bismol - decreased frequency of stool and duration
Antibiotics - worst case scenario
Term
Main symptoms of appendicitis
Definition
Pain in RLQ (can be episodic or unremitting); unremitting pain post-rupture
Rupture forms abscess, but may be walled off by omentm
Term
What occurs if a ruptured appendix is NOT walled off by the omentum?
Definition
Peritonitis
Term
Types of mechanical intestinal obstructions
Definition
Intussusception
Volvulus
Adhesions
Strangulation
Term
Intussusception
Definition
"Telescoping of gut" b/c of loose mucosa
Mucosal folding traps mesentery & compresses BV's - ischemia, necrosis, peritonitis if ruptures
Colicky, cramping pain; jelly diarrhea
Term
Volvulus
Definition
Twist in loop of gut (like kink in garden hose)
Due to defective mesentery
See dilatation of gut where volvulus is
Colicky cramping pain
Term
Adhesions in Intestines
Definition
Mechanical obstruction - inappropriate connections
Occurs because of something WITHIN INTESTINE - inflammation, surgery
Dilatation upstream of adhesion due to obstructed movement
Term
Strangulation of Intestine
Definition
Mechanical obstruction - complete ischemia to region causing NECROSIS
Associated w/ INGUINAL hernia - loop of intestine may herniate through muscle, entrap and constrict
Term
Type of pain involved in obstruction of intestine?
Definition
COLICKY, CRAMPING Pain (associated with peristaltic contractions)
Term
Two types of congenital obstructive disorders
Definition
Atresia - blind end of intestine
Hirschprungs - colonic aganglionosis
Term
Intestinal Atresia
Definition
Blind ended intestine; non continuous
Need surgical resection
Term
Hirschprung's Disease
Definition
Aganglionosis in distal colon
Tonic contraction in affected region b/c of no inhibitory input
Obstruction, upstream back-up, megacolon
Term
What is a failure in gut motility known as?
Definition
ILEUS
Term
What is the progression of a mechanical obstruction of the gut?
Definition
Start w/ vomiting, cramping pain, diarrhea - increased secretions and blockage leads to EDEMA
Complete obstruction completely inhibits absorption, get a lack of fluid movement leading to bacterial overgrowth - ischemia & necrosis, possibly leading to ulceration/abscess
Term
What does a complete gut obstruction result in?
Definition
Failure of gut motility = ILEUS
Lose all bowel sounds
Risk of perforation and peritonitis from bacterial infection
Term
Characteristic symptoms of ileus
Definition
No bowel sounds
No reflex contractions
No colicky pain
Term
What is associated with onset of ileus (what causes it)?
Definition
GI pathology OR following a GI surgical procedure (due to ENS, get quick recovery)
Term
What is unique about the omentum and its involvement in healing?
Definition
Omentum can rapidly mobilize to wall off an abscess or perforation/inflammation
Term
Why is bacterial infection in the peritoneal cavity ideal?
Definition
Because the peritoneal cavity is not supported by the immune system
Term
Key symptoms of peritonitis
Definition
GUARDING - board like abdomen (reflex); UNREMITTING PAIN (NOT colicky like in obstructive conditions)
Ascites - fluid accumulation in peritoneal cavity
Ileus & systemic infection
Term
In the presence of a perforation of the gut due to bacterial infection/ileus, what can be done to prevent peritonitis from occurring?
Definition
Mobilization of the omentum to wall off the perforation/site of inflammation
Term
Different phases of swallowing?
Definition
Voluntary - mastication, tongue movement
Pharyngeal - trigeminal & pharyngeal nerves commence
Term
Achalasia
Definition
Failure of LES relaxation (always constricted)
Defect in inhibitory ENS innervation
Term
What is the primary symptom in GERD?
Definition
PAIN due to acid reflux into lower esophagus
Term
Different origins of GERD:
Definition
Lax LES (open too often)
Excess HCl secretion
Hiatal hernia (often due to increased abdominal pressure) - fundus protrudes through hiatus in diaphragm
Term
What can long-standing GERD be a risk factor for?
Definition
Esophageal cancer (Barret's esophagus) - premalignant condition associated with prolonged GERD
Term
Differentials of different types of blood in the stool:
Definition
Fresh = local source
Black/Tarry = upper GI source
Cryptic = detected chemically
Term
Where are intestinal tumors most common (which cell type)?
Definition
Epithelial tumors (b/c constant proliferation)
Term
What type of blood in the stool is present with a hemorrhagic adenoma?
Definition
Often see bright red blood if present in the colon (fresh source)
Term
Why can you resect segments of the intestine WITHOUT a loss of function?
Definition
Because normally, the intestinal epithelia is functioning well below its maximum - after resection can increased absorption/secretion to continue normal GI function
Term
What is one thing you need to be weary about after any major GI sx?
Definition
ILEUS
Term
Most common cause of overt blood stool?
Definition
Hemorrhoids
Term
Haustra
Definition
Contractions of CIRCULAR smooth muscle to form ring-like segments of the colon
Term
Diverticulosis
Definition
COMPLETELY NORMAL (no associated pathology)
Small outpockets of colonic wall through mucosa
May be due to low fiber diet
Term
Diverticulitis
Definition
Inflammation of diverticula
Difficult cause to establish (foods with small seeds?)
Acute pain (unremitting), signs of abscess/perforation (may lead to peritonitis)
Term
What is unique about the IBS diagnosis?
Definition
Diagnosis by EXCLUSION - diagnose IBS in the absence of a noticeable pathology
Term
Inclusive criteria for IBS
Definition
Pain relieved by defecation
Duration of several months
Alternating nature of symptoms
"Trigger" factor
Term
What is the most frequently encountered disease in GI practice?
Definition
IBS
Term
What is the objective & subjective evidence for the existence of IBS?
Definition
Differing patterns of haustra
Increased sensitivity to balloon distension in the gut (HYPERSENSITIVITY to distension)
Term
Symptoms of IBD
Definition
Pain, bloody stool, diarrhea, fever, leukocytosis (high WBC), weight loss, etc.
Term
2 distinct diseases of IBD?
Definition
Crohn's disease
Ulcerative colitis
Term
Similarities between Crohn's & UC?
Definition
True chronic inflammation (persists in absence of known cause)
Idiopathic & have no cure
Treatment is symptomatic (treat symptoms)
Term
Treatment of IBD (for both Crohn's & UC):
Definition
ASA's, antibiotics - reduce inflammation
Glucocorticoids/immunosuppressants
anti-TNF antibodies
Term
Crohn's Disease - Characteristics
Definition
Can range from anywhere from mouth to anus (ileum most common)
Affects full thickness of wall (transmural)
See skip lesions (patches of inflammation) and cobblestoning (patterns of inflammation around normal mucosa)
Term
What are 2 outcomes of transmural inflammation, seen in one type of IBD?
Definition
Seen in Crohn's disease
Abscess and adhesions; FISTULA = adhesion
Fibrosis & stricturing - obstructs affected segments
Term
Treatment for Crohn's?
Definition
Resectioning of gut - often RECURRENT (need multiple sx)
Need multiple sx, so get short gut syndrome (decreases absorption of Vit B12)
Term
What symptoms are unique to UC?
Definition
Occurs only in colon (colitis)
Affects only the mucosa (NOT transmural)
Term
Difference in disease prognosis in CD vs. UC?
Definition
Crohn's - often recurrent, need multiple resectionings
Ulcerative Colitis - does NOT reappear after resection; can live w/o colon
Term
What occurs to the affected portion of the wall in Crohn's?
Definition
See wall thickened in affected segment
Term
UC is associated with an elevated risk of?
Definition
Adenocarcinoma formation in the colon
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