165 Questions
What is the primary function of the stomach in the GI tract?
Mixing food with digestive enzymes
Which of the following pathologies is related to the gastric mucosal mechanisms of acid secretion and mucosal protection?
Peptic ulcers
What is the primary mechanism of digestion and absorption in the GI tract?
Chemical breakdown of food by enzymes and acids
Which of the following is NOT a pathology related to the stomach's function?
Irritable bowel syndrome
What is the primary clinical sign of a GI pathology?
Patient-reported symptoms
Which part of the brain is responsible for the vomiting reflex?
Medulla oblongata
What is the term for bloody stools?
Hematochezia
What is the most common mechanism of abdominal pain in gastrointestinal disorders?
Mediators of the inflammatory response
Which layer of the gastrointestinal tract is most commonly affected by pathology?
Mucosa
What is the term for a connection between the trachea and esophagus?
Tracheo-esophageal fistula
Which of the following is NOT a mechanism of gastrointestinal dysfunction?
Hyperplasia
What is the term for the sensation of nausea associated with a number of conditions?
Nausea
Which of the following is a complication of gastrointestinal bleeding?
Hypochloremia
What is the term for the passage of bright red blood per rectum?
BRBPR
Which of the following is a congenital anomaly that can affect the esophagus?
Tracheo-esophageal fistula
What percentage of adults in developed countries are infected with H. pylori?
1/6
What is the primary effect of H. pylori infection on the cardia?
Decreased mucus production
What is the primary effect of H. pylori infection on the antrum?
Increased gastrin production
What is the primary effect of H. pylori infection on the fundus and body?
Decreased acid and pepsin production
What is the term for the clinical combination of duodenal ulcers and a pancreatic gastrin tumor?
Zollinger-Ellison syndrome
What is the term for a gastrin-secreting tumor that can occur in the pancreas or the duodenum?
Gastrinoma
What is the primary effect of somatostatin on HCL production?
Inhibition
What is the primary effect of anticholinergics on HCL production?
Inhibition
What is the primary effect of H2 blockers on HCL production?
Inhibition
What is the condition characterized by delayed gastric emptying?
Gastroparesis
What percentage of Europeans continue to produce lactase enzyme throughout their lives?
90+%
What is the result of bile salt deficiency in the small intestine?
Poor absorption of lipids, steatorrhea, diarrhea, and loss of fat-soluble vitamins
What is the common characteristic of lesions in Ulcerative Colitis?
Continuous lesions limited to the mucosa
What is the primary treatment for dumping syndrome?
Eat frequent small meals, high in protein and low in carbohydrates
What is the result of malabsorption of vitamin B12 and folic acid in Crohn Disease?
Anemia
What is the characteristic appearance of lesions in Crohn Disease?
Skip lesions with a cobblestone appearance
What is the primary complication of bile salt deficiency?
All of the above
What is the treatment for bile salt deficiency?
Increase medium-chain triglycerides in the diet
What is the common characteristic of Inflammatory Bowel Disease?
Chronic, relapsing/recurring bowel inflammation
What is the primary manifestation of dumping syndrome?
All of the above
What is the fate of amniotic fluid during fetal development?
It is absorbed in the fetal GI tract, flows through the bloodstream to the kidneys, then through the ureters and bladder to arrive back into the amniotic cavity
What is the primary predisposing factor for the development of gastroparesis?
Poorly-controlled diabetes
What is the term for the narrowing of the esophagus, typically caused by mucosal inflammation and scarring?
Esophageal stricture
What is the term for the mass of hardened, undigested food or other material trapped in the digestive system?
Bezoar
What is the primary cause of esophagitis?
Regurgitant stomach acid
What is the term for the growth of columnar epithelium with goblet cells in the lower esophagus, typically caused by chronic acid reflux?
Barrett's esophagus
What is the primary mechanism by which the kidney responds to decreased blood volume and pH imbalances in pyloric stenosis?
Release of renin by the juxtaglomerular cells
What is the primary function of mucous cells in the stomach?
To produce mucus
What is the term for the obstruction of the opening between the stomach and duodenum, which can be acquired or congenital?
Gastric outlet obstruction
What is the primary site of delivery for the pancreas, liver, and gallbladder?
Descending duodenum
What is the term for the inflammation of the gastric mucosa?
Gastritis
What is the primary cause of peptic ulcer disease?
Decreased mucus production
What is the term for the hypertrophy of the pyloric sphincter, which can occur in babies and adults?
Pyloric stenosis
What is the function of the spleen in the immune system?
Mechanical filtration of aging erythrocytes
What is the term for the abnormal connection between the esophagus and trachea?
T-E fistula
What is the symptom of esophageal achalasia that is characterized by a distended 'megaesophagus' with disordered, ineffective movement?
Cachexia
What is the term for the classic symptom of pyloric stenosis in babies, characterized by vomiting that is non-bilious and projectile?
Projectile vomiting
What is the primary area affected in Crohn Disease?
Entire intestinal wall
What is the term for the condition in which the stomach empties slowly, leading to delayed gastric emptying?
Gastroparesis
What is the primary site of acid neutralization in the small intestine?
Duodenum
What is the term for the sensation of incomplete emptying after a bowel movement?
Sensation of incomplete emptying
What is the term for the physical sign of pyloric stenosis in adults, characterized by a mass in the epigastric region?
Olive sign
What is the term for the blockage of the small or large bowel, resulting in the inability of contents to pass through?
Mechanical Bowel Obstruction
What is the term for hard, dry stool retained in the rectum?
Fecal impaction
Which of the following is a risk factor for Mechanical Bowel Obstruction?
All of the above
What is the term for the connection between the gut and the peritoneum, which can occur in Mechanical Bowel Obstruction?
Peritonitis
What is the location of the pancreatic head in relation to the duodenum?
It is nestled within the 'C' curve of the duodenum.
What is the primary function of Brunner's glands in the proximal duodenum?
To release bicarbonate and mucous to neutralize chyme.
What is the characteristic of retroperitoneal organs?
They are located behind the parietal peritoneum and do not have a mesentery.
What is the length of the pancreas?
15-25 cm (7-10 inches)
What is the primary function of the pancreatic duct system?
To release pancreatic enzymes in an inactive form.
What is the result of zymogens activating early in the pancreas?
Pancreatic injury and/or pain.
What is the characteristic of pancreatic pain due to the retroperitoneal location?
Mid-epigastric pain and back pain.
What is the consequence of a ductal blockage in the pancreas?
Pancreatitis due to early activation of zymogens.
What is the histological feature of the gallbladder?
It has a mucosa with folds that allow it to enlarge.
What is the result of pancreatitis?
Portions of the pancreas can autolyze and pancreatic enzymes escape into the bloodstream.
What is the primary function of the muscularis externa in the gallbladder?
To contract and relax the gallbladder
What is the primary route of bile entry into the gallbladder?
Via the cystic duct from the right and left hepatic ducts
What is the primary composition of cholesterol gallstones?
Bile salts and cholesterol
What is the primary risk factor for the development of gallstones?
Increased cholesterol composition of bile
What is the primary complication of symptomatic gallstones?
All of the above
What is the primary difference between maldigestion and malabsorption?
Maldigestion is enzyme-related, while malabsorption is inflammation-related
What is the primary cause of lactose intolerance?
Inability to break down lactose into glucose and galactose
What is the primary treatment for maldigestion due to pancreatic insufficiency?
Lipase supplements
What is the primary effect of 'gallbladder sludge' on gallstone formation?
It increases the risk of gallstone formation
What is the primary consequence of a blocked exit in the biliary tree?
Bacterial overgrowth and inflammation
What is the primary characteristic of anorexia nervosa?
Decreased food intake leading to starvation
What is the term for a condition that prevents proper digestion or absorption, or significantly increases metabolic consumption?
Secondary malnutrition
Which of the following is a symptom of bulimia nervosa?
Recurrent episodes of binge eating
What is the primary cause of malnutrition?
Inadequate amounts of calories, protein, vitamins, or minerals
Which of the following is NOT a characteristic of anorexia nervosa?
Recurrent episodes of binge eating
Which vitamin is particularly prone to deficiency in individuals with alcoholism?
Thiamine
What is the primary source of energy for the brain?
Glucose
Which vitamin is essential for the coagulation of blood?
Vitamin K
Which mineral is required for the oxygen-carrying capacity of red blood cells?
Iron
What is the term for the deficiency of vitamin C?
Scurvy
Which of the following is a high-risk population for vitamin D deficiency?
All of the above
What is the primary function of vitamin K in the body?
Coagulation and bone development
What is the recommended supplementation for all neonates within 1 hour of birth?
Vitamin K
Which of the following is a clinical sign of a nutritional deficiency?
All of the above
What is the primary effect of thiamine deficiency on the brain?
Impaired glucose metabolism
What is the primary function of vitamin C in the human body?
All of the above
What is the primary cause of vitamin B12 deficiency in patients with a history of gastric bypass surgery?
Malabsorption of vitamin B12 in the terminal ileum
What is the primary function of folic acid in the human body?
All of the above
What is the primary cause of thiamine (vitamin B1) deficiency?
Inadequate dietary intake of thiamine
What is the primary manifestation of Wernicke's encephalopathy, a degenerative brain disorder caused by thiamine deficiency?
All of the above
What is the primary function of vitamin C in the absorption of nonheme iron?
Improves the absorption of nonheme iron
What is the primary cause of folate deficiency in patients with celiac disease?
Impaired absorption of folate in the jejunum
What is the primary effect of vitamin B12 deficiency on the nervous system?
All of the above
What is the primary function of intrinsic factor in the stomach?
Absorption of vitamin B12 in the terminal ileum
What is the primary cause of iron deficiency in patients with intestinal disease?
Malabsorption of iron in the small intestine
What is the purpose of exposing lymphocytes to 'self' during education?
To eliminate cells that do not bind to 'self'
Which type of T cell regulates the immune response?
Helper T cells
What is the function of cytotoxic T cells?
To destroy infected cells
Where do B cells mature?
Bone marrow
What is the function of regulatory T cells?
To suppress or limit the immune response
Where do T cells mature?
Thymus
What type of immunity is primarily responsible for protection against many bacteria and viruses?
Humoral immunity
What is the primary function of Helper T-cells?
To send signals that direct other immune cells to fight infection
What type of receptors are found on the surface of B-cells?
Antibody-bound receptors
What is the primary function of Cytotoxic T cells?
To attack enemy cells and infected cells
What is the term for the process by which B-cells mature into plasma cells and start producing antibodies?
Maturation
What is the primary function of IgM in the early stages of B-cell mediated immunity?
To eliminate pathogens in the early stages of B-cell mediated immunity
What is the function of the variable region of an antibody?
To provide specificity to the antigen-binding site
Which class of antibody is responsible for neutralizing antigens in the early stages of B-cell mediated immunity?
IgM
What is the primary function of IgA in the body?
To provide defense against pathogens in the skin and mucous membranes
What is the primary mechanism of IgE-mediated immunity?
Anaphylaxis
What is the primary function of the constant region of an antibody?
To define the class of antibody
What is the primary function of T cells?
To recognize and destroy infected cells
What is the role of MHC Class II molecules?
To present exogenous antigens to CD4 T cells
What is the function of IgE antibodies?
To bind to allergens and trigger histamine release
What is the role of professional antigen-presenting cells (APCs)?
To present antigens to T cells
What is the difference between MHC Class I and MHC Class II molecules?
MHC Class I presents endogenous antigens, while MHC Class II presents exogenous antigens
What is the function of cytotoxic T cells?
To recognize and destroy infected cells
What is the role of helper T cells?
To activate B cells and produce cytokines
What is the function of natural killer cells?
To recognize and destroy infected cells
What is the term for the molecules that are unique to each individual and help to identify cells as 'self'?
Human Leukocyte Antigens (HLA)
What is the role of IgA antibodies?
To prevent the colonization of mucosal areas
What is the primary function of NK cells in the immune system?
To kill infected cells or tumor cells using antibodies
What is the significance of IgM and IgG antibodies in the immune response?
IgM is produced in the primary response and IgG is produced in the secondary response
What is the primary function of memory B cells in the immune system?
To retain immunologic memory and provide long-term protection against future infections
What is the significance of the secondary immune response?
It is a faster and stronger response compared to the primary response
What is the primary difference between IgM and IgG antibodies?
IgM is produced in the primary response and IgG is produced in the secondary response
What is the primary function of helper T cells in the immune system?
To activate B cells and provide humoral immunity
What is the significance of affinity maturation in the immune response?
It is a process that occurs in the secondary response and results in a stronger immune response
What is the primary function of Fc receptors on NK cells?
To bind to IgG antibodies and activate the killing mechanism
What is the primary difference between the primary and secondary immune responses?
The primary response is slower and weaker than the secondary response
What is the significance of memory cells in the immune response?
They are produced in the secondary response and provide long-term protection
What type of immunity is acquired through the introduction of a microorganism or its antigens, inducing an immune response and production of memory cells?
Active immunity
What type of antibodies are produced in response to vaccination, providing long-term immunity?
IgG
What is the specific antigen used in the Hepatitis B vaccine?
HBsAg
What is the main difference between active and passive immunity?
Duration of immunity
What is the function of immunologic memory?
To recognize and respond to pathogens
What is the result of having low titers of IgG antibodies against Hepatitis B?
Vulnerability to Hepatitis B
What happens when someone with type A blood receives a transfusion of type B blood?
Transfusion reaction occurs
What is the term for the immunologic disorder that occurs in an Rh-negative patient carrying an Rh-positive fetus?
Rh Isoimmunization
What is the most important carbohydrate system for transfusion reactions?
ABO system
What is the universal donor blood type?
O negative
What is the percentage of cases of Rh Isoimmunization caused by D antibodies?
More than 90%
What is the term for the symptoms of a transfusion reaction, including itchiness, hemolysis, allergy, and alloimmunization?
No specific term
What is the primary mechanism of immune tolerance during fetal and early postnatal life?
Clonal deletion or clonal inactivation
What is the primary function of Helper T cells in the immune response?
To make IL-2 and activate B cells
What is the primary characteristic of autoimmune diseases?
A failure to develop self-tolerance
What is the target of the Human Immunodeficiency Virus (HIV)?
CD4+ Helper T cells
What is the primary effect of HIV on the immune system?
A decrease in CD4+ Helper T cells
What is the primary mechanism of immune response against Hepatitis B infection?
Production of IgM against HBcAg and HBsAg
What is the primary consequence of a failure to develop immune tolerance?
Autoimmune diseases
What is the primary function of B cells in the immune response?
To produce antibodies against antigens
What is the primary characteristic of immunodeficiency diseases?
An underactive immune response
What is the primary cause of chronic Hepatitis B infection?
A failure to produce IgG against HBcAg and HBsAg
Study Notes
GI Pathophysiology
- Clinical signs of a GI pathology are not directly observable in pictures.
- Clinical manifestations of GI dysfunction:
- Anorexia (loss of appetite)
- Nausea (subjective experience associated with multiple conditions)
- Vomiting (forceful emptying of the stomach and intestinal contents through the mouth)
- Pain (can be caused by stretching, inflammation, or ischemia)
- Constipation
- Diarrhea
- GI Bleeding (upper and lower GI bleeding)
GI Pathophysiology Mechanisms
- Stenosis (narrowing or stricture of an area)
- Regurgitation or insufficiency (backflow or pass-through when it should not occur)
- Abnormalities of Movement (too fast or too slow, think neurological)
- Inflammation/Trauma (can affect absorption, secretion, and bleeding)
Esophagus
- Connects pharynx to stomach
- Secrets some mucous, but no absorption occurs here
- Job: conduit for food, mechanical digestion
- Anatomically indistinct but physiologically demonstrable upper and lower esophageal sphincters
- Mechanisms of pathology:
- Stenosis (e.g., esophageal stricture, esophageal achalasia, T-E Fistula)
- Regurgitation or insufficiency (e.g., GERD, esophageal dysmotility)
- Abnormalities of Movement (e.g., esophageal dysmotility)
- Inflammation/Trauma (e.g., esophagitis, Barrett's Esophagus, Malory-Weiss tear)
Stomach
- Normal gastric secretory epithelium:
- Cardia (mucous-secreting cells)
- Fundus (acid-producing parietal cells, pepsin-producing chief cells)
- Pylorus (hormone production, e.g., gastrin)
- Gastric glands:
- Mucous cells (mucus production)
- Parietal cells (HCl production)
- Chief cells (pepsin production)
- Enteroendocrine cells (gastrin production)
- Mechanisms of pathology:
- Stenosis (e.g., pyloric stenosis)
- Regurgitation or insufficiency (e.g., GERD)
- Abnormalities of Movement (e.g., gastroparesis)
- Inflammation (e.g., gastritis, PUD)
Pyloric Obstruction/Stenosis
- Blocking or narrowing of the opening between the stomach and duodenum
- Can be acquired (GOO) or congenital (pyloric stenosis)
- Clinical manifestations:
- Epigastric pain and fullness
- Nausea
- Vomiting
- Malnutrition and dehydration
- Treatment:
- Gastric drainage (NG Tube)
- IV fluid and electrolytes
- Proton pump inhibitors or H2 blockers
- Surgery or stenting
Intestines
- Duodenum:
- Superior, Descending, Horizontal, and Ascending segments
- Site of delivery for stomach (L1)
- Acidic chyme must be neutralized here
- Site of delivery for pancreas, liver, and gallbladder
- Anatomic features:
- Shortest segment of the small intestine
- Starts at the pyloric sphincter and ends at the Ligament of Treitz
- Almost completely retroperitoneal
- Its segments:
- Superior: releases hormonal triggers for the gallbladder and pancreas
- Descending: pancreatic duct and common bile duct empty here
- Horizontal: digestion occurs here
- Ascending: continued digestion
Pancreas
- Gland with both exocrine and endocrine functions
- Retroperitoneal, arises from the wall of the duodenum
- Parts:
- Head
- Neck
- Body
- Tail
- The Pancreatic Ducts:
- Main pancreatic duct runs the entire length of the pancreas
- Empties its exocrine products at the Ampulla of Vater
- A portion of the head of the pancreas usually drains via a different duct (the accessory pancreatic duct) at the Ampulla of Santorini
Pancreatic Juice
- Secretion of pancreatic enzymes in a clear alkaline medium
- Enzymes are produced by the exocrine cells of the pancreas
- Alkaline mucousy liquid from the pancreatic ductal cells
- Flows to the duodenum via the pancreatic duct system
- Enzymes typically are released in inactive form and are activated by membrane-bound activators in the duodenum### Anatomy of the Gallbladder
- The gallbladder has three layers: simple columnar epithelium, muscularis externa, and adventitia.
- The muscularis externa layer is responsible for gallbladder contractions.
- The adventitia layer holds the gallbladder in place.
The Normal Biliary Tree
- Bile exits the liver via the left and right hepatic ducts.
- Bile can travel into the gallbladder via the cystic duct.
- Bile then leaves the gallbladder via the cystic duct and enters the common bile duct.
- There is only one way into and out of the gallbladder.
- The sphincter of Oddi is used by both the gallbladder and pancreas to enter the duodenum.
Gallbladder Problems
- Common problems include duct blockage, inflammation, and infection.
- Duct blockage can lead to gallstone pancreatitis, gallstone liver inflammation, and an increased risk of liver and pancreatic cancer.
- Symptoms after a cholecystectomy (gallbladder removal) may include fatty stools, poor tolerance of high-fat meals, dyspepsia, and nausea/vomiting.
Cholelithiasis (Gallstones)
- Gallstones are crystallized or solidified stones of gallbladder content.
- They are typically made of bile salts, cholesterol, and other substances.
- Cholesterol gallstones are yellow-gold in color, while pigment gallstones are darker.
- The pathogenesis of cholesterol gallstones involves either more cholesterol in bile than can be dissolved or bile in stasis for longer than normal.
- "Gallbladder sludge" is a risk factor for gallstones, and decreased gallbladder motility can increase the risk of gallstones.
- Estrogen increases the cholesterol composition of bile and decreases gallbladder motility, which is why pregnancy increases the incidence of gallstones.
Malabsorption Syndromes
- Malabsorption is a problem with the mucosa's ability to absorb nutrients into the bloodstream.
- Diseases that interfere with nutrient absorption, such as Crohn's disease and ulcerative colitis, can cause malabsorption.
- Maldigestion is a problem with the processes that get nutrients digested down to the monomer level, often due to an enzyme issue.
- Pancreatic insufficiency can cause maldigestion, particularly fat maldigestion, which can lead to steatorrhea and weight loss.
- Lactose intolerance occurs when the lactase enzyme ceases to be produced, leading to the inability to break down lactose into glucose and galactose.
- Bile salt deficiency can cause malabsorption, particularly of lipids, and can lead to steatorrhea, diarrhea, and a loss of fat-soluble vitamins.
Inflammatory Bowel Disease
- Inflammatory bowel disease is a chronic, relapsing-recurring bowel inflammation of unknown origin.
- The two main types are ulcerative colitis and Crohn's disease.
- Ulcerative colitis causes ulceration of the colonic mucosa, particularly in the sigmoid colon and rectum, and is characterized by continuous lesions with no skipped lesions.
- Crohn's disease causes granulomatous inflammation of the GI tract, which can affect any part of the digestive tract, and is characterized by skip lesions and a "cobblestone" appearance.
Mechanical Bowel Obstruction
- Mechanical bowel obstruction occurs when there is a blockage in the small or large bowel, preventing contents from passing "downstream".
- Risk factors include prior surgery, diseases causing gut inflammation or stricture, volvulus, and intussusception.
- Symptoms include abdominal pain, nausea, and vomiting, and can lead to peritonitis and bowel perforation.
Constipation
- Constipation is defined as infrequent or difficult defecation, with fewer than three bowel movements per week.
- Clinical definitions include straining with defecation, lumpy or hard stools, sensation of incomplete emptying, and manual maneuvers to facilitate stool evacuation.
- Pathophysiology involves transit times and muscular function, with normal transit (functional) constipation, slow-transit constipation, and pelvic floor dysfunction.
- Treatments include diet, exercise, bowel retraining, enemas, and biofeedback.
Diarrhea
- Diarrhea is defined as increased frequency of bowel movements, with three or more per day.
- Types of diarrhea include osmotic, secretory, and inflammatory diarrhea.
- Treatment depends on the physiologic type of diarrhea present.
This quiz covers the normal physiology of the GI tract, including neural control, digestion, and absorption, as well as pathologies related to stomach function. It also explores the secretory functions of different organs and potential disorders.
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