Physiology Clinical Notes Flashcards
Achalasia
- Impaired peristalsis
- Incomplete lower esophageal sphincter (LES) relaxation during swallowing – results in back-up of food
- Elevation of LES resting pressure
Achalasia: Causes
- Decreased numbers of ganglion cells in myenteric plexus
- Degeneration preferentially involves inhibitory neurons producing NO / VIP
- Damage to nerves in the esophagus, preventing it from allowing food in the stomach
Achalasia: Symptoms
- Backflow of food in the throat (regurgitation)
- Difficulty in swallowing both liquids and solids (dysphagia)
- GERD
- Chest pain
GERD
- Occurs when there are changes in the barrier between the esophagus and stomach
- Persistent reflux and the resulting inflammation lead to this condition
- Backwash of acid and pepsin into the esophagus leading to heartburn and acid regurgiation
GERD: Causes
- Motor abnormalities that result in abnormally low pressures in the LES
- Increase in Intragastric pressure – commonly occurs after a meal, during heavy lifting, or during pregnancy
GERD: Complications
- GI bleed
- Irritation of the lining of the esophagus (esophagitis)
- Scar tissue in the esophagus (stricture of esophagus)
- Barrett’s esophagus
___ ___ ____ is the most common problem associated with disorders of gastric motility
Slow Gastric Emptying
Slow Gastric Emptying: Symptoms
- Fullness
- Loss of appetite
- Nausea
- Vomiting
Slow Gastric Emptying: Causes
- Gastric Ulcer (scar tissue)
- Cancer (physical obstruction)
- Eating disorders (anorexia, bulimia, obesity)
- Vagotomy
Gastroparesis
Slow emptying of stomach / paralysis of stomach in the absence of mechanical obstruction
Gastroparesis: Causes
- Diabetes Mellitus
- Injury to Vagus Nerve
Gastroparesis: Symptoms
- Nausea
- Vomiting
- Early feeling of fullness when eating
- Weight loss
- Abdominal bloating
- Abdominal discomfort
Chronic Constipation
Generally results from inadequate fiber or fluid intake, or from disordered colonic transit or anorectal function
Disordered Colonic Transit or Anorectal Function can be the result of:
- Neurological disorders
- Outlet obstruction to defecation
- Certain drugs (ex. Opioids inhibit gastric emptying and peristalsis, and increase anal sphincter tone which impairs the defecation reflex)
- Advanced age
- Systemic diseases that affect GI tract
- Metabolic disorders (ex. hypothyroidism, hypercalcemia)
Hirschsprung Disease: Cause
Ganglion cells absent from segment of colon; often present at birth
Hirschsprung Disease: Result
VIP levels low –> smooth muscle constriction / loss of coordinated movement –> colon contents accumulate
Hirschsprung Disease: Newborn Symptoms
- Difficulty in passing stool (congenital megacolon)
- Failure to pass meconium
- Poor feeding
- Jaundice
- Vomiting
Hirschsprung Disease: Adolescent Symptoms
- Constipation
- Swollen belly
- Malnutrition
Hirschsprung Disease: Treatment
Surgical resection of colon segment lacking ganglia
Cirrhosis
- Chronic liver disease in which normal liver cells are damaged and replaced by scar tissue
- Often caused by excessive alcohol intake
Alcohol misuse leads to accumulation of ___ within _____
- Fat
- Hepatocytes
Fatty Liver leads to ___
Steatohepatitis
Steatohepatitis
Fatty liver accompanied by inflammation, which often leads to scarring of liver and cirrhosis
Portal Hypertension
- Can be caused by liver cirrhosis
- Develops when there is resistance to portal blood flow, which most often occurs in the liver
Esophageal Varices
Swollen connections between systemic and portal systems at inferior end of esophagus
Caput Medusae
Swollen connections between systemic and portal systems around umbilicus
How can Liver dysfunction lead to Hepatic Encephalopathy?
(1) Decreased hepatic urea cycle metabolism in the liver due to cirrhosis or portosystemic shunting
(2) Accumulation of ammonia in systemic circulation
(3) Ammonia crosses BBB which results in increased brain water, direct neuronal toxicity, increased intracranial pressure, and altered neurotransmission
Jaundice (Icterus)
- Occurs due to hyperbilirubinemia
- Yellow pigmentation of the sclera, skin and mucous membranes
Hemolytic Anemia
- Form of anemia due to hemolysis (RBC destruction)
- Can lead to increased production of bilirubin – increased bilirubin level overwhelms liver’s capacity to produce conjugated bilirubin, resulting in increased unconjugated bilirubin
Physiological Neonatal Jaundice
- Due to increased un-conjugated bilirubin in the blood during the first week
- Typically resolves within the first 1-2 weeks after birth, depending on the maturation rate of bilirubin clearance systems
Physiological Neonatal Jaundice: 2 Main Causes
(1) Bilirubin production is elevated because of increased breakdown of fetal RBCs; shortened lifespan of fetal RBCs
(2) Low activity of UDP-Glucuronosyltransferase (UGT)
Crigler-Najjar Syndrome
- Increased levels of un-conjugated bilirubin in the blood
- Related to mutations in the gene that codes for UDP-Glucuronosyltransferase
- Two types
Crigler-Najjar Syndrome: Type 1 (CN1)
- Very severe
- No function of UDP-Glucuronosyltransferase
- Often results in Kernicterus
Kernicterus
- Form of brain damage that is caused by the accumulation of un-conjugated bilirubin in the brain and nerve tissues
- Permanent neurological sequelae of bilirubin-induced neurologic dysfunction
- Develops during the 1st year postnatal
Kernicterus: Major Clinical Features
- Cerebral Palsy
- Sensoryneural hearing loss
- Gaze abnormalities
Small Intestinal Bacterial Overgrowth (SIBO)
- Condition of colonic bacteria overabundance in the SI
- MMC is important for cleansing debris in SI and prevention of this condition
- Can result in impaired small bowel motility, nausea, anorexia, chronic diarrhea, and bloating
Crigler-Najjar Syndrome: Type 2 (CN2)
- Less severe type
- Less than 20% function of UDP-Glucuronosyltransferase
- Less likely to develop Kernicterus