Diseases Flashcards
What are the GI manifestations of Scleroderma/Progressive Systemic Sclerosis (PSS)?
Obliterative small vessel vasculitis, smooth muscle atrophy and gut wall fibrosis, weak peristalsis.
Is peristalsis preserved in spastic disorders of the esophagus?
Yes
What are some clinical manifestations of gastroparesis?
Nausea, vomiting, early satiety, and postprandial abdominal distention and pain
Describe Chronic Intestinal Pseudo-Obstruction (CIPO)
Signs and symptoms of mechanical obstruction of the small bowel without a lesion obstructing flow. Characterized by presence of dilation of bowel on imaging.
What is a major complication of Chronic Intestinal Pseudo-Obstruction (CIPO)?
Bacterial overgrowth.
What is a Sitz marker?
Colonic transit study. 24 radiopaque markers in capsule given on day 1. Plain abdominal x-ray on day 5.
Describe a normal Sitz marker study result?
Sitz marker: What does >5 markers in recto-sigmoid suggest?
Defecatory disorder
Sitz marker: What does >5 markers scattered throughout colon suggest?
Slow transit
Which reflex is absent in Hirschsprung’s disease?
Recto-anal inhibitory reflex
Describe the pathophysiology of Hirschsprung’s disease
Congenital absence of myenteric neurons of the distal colon (neuropathic motility disorder). Absence of recto-anal inhibitory reflex.
Describe pelvic floor dysfunction
Dyssynergia of the pelvic floor and external anal sphincters.
What is the treatment for pelvic floor dysfunction?
Biofeedback therapy
Where is B12 and IF absorbed?
Ileum
Describe the alkaline tide? What is a possible consequence of this?
Lots of acid secretion raises the pH of venous blood leaving the stomach because of HCO3- transport. Can cause HTN in some.
Describe how ACh activates HCl secretion in a parietal cell
ACh binds to muscarinic receptors on the basolateral membrane which activate a G protein. Intracellular Ca increases. Ca activates distinct protein kinases which phosphorylate and activate H/K-ATPase.
Describe how histamine activates HCl secretion in a parietal cell
Histamine binds to H2 receptors on the basolateral membrane. Adenylate cyclase activity is increased which raises intracellular cAMP which activates distinct protein kinases which phosphorylate and activate H/K-ATPase.
How doe ACh and gastrin affect histamine?
They potentiate histamine release from enterochromaffin-like (ECL) cells –> More HCl secretion (indirect pathway).
Describe the basal phase of gastric acid secretion
Between meals. Follows a circadian rhythm. Acid secretion is lowest in morning and highest in evening.
Describe the cephalic phase of gastric acid secretion
The smell, sight, taste, and swallowing of food initiates cephalic phase (mediated by vagus nerve). 30% of total acid secretion.
Describe the gastric phase of gastric acid secretion
Entry of food into stomach stimulates gastric phase. Distention activates vagovagal reflex as well as local ENS reflexes. Gastrin is secreted. 50-60% of total acid secretion.
In absorption, which nutrients enter the venule of a villus and which enter the lacteal?
Products of fat digestion enter the lacteal and all other nutrients enter the venule.
What is the purpose of secreting zymogens instead of active enzymes?
So that the enzymes don’t digest pancreatic membranes and each other before they are needed.
Where and how is trypsinogen activated?
In duodenum, activated by enteropeptidase (aka enterokinase).
What converts most zymogens to active enzymes?
Trypsin
What is the largest single source of carbohydrates in most human diets?
Amylopectin
Can polymers of sugars be absorbed?
NO!! Only simple monomers can be absorbed by intestine.
What is the difference between amylose and amylopectin?
Both are glucose polymers. Amylose consists of simple straight chain polymers and amylopectin contains branched chains.
Which enzyme is the final step of small-intestinal digestion of branch points of starch to glucose?
Mucosal sucrase-isomaltase (SI)
Which enzyme is the final step of small-intestinal digestion of linear forms of starch to glucose?
Mucosal maltase-glucoamylase activity (MGA)
What does SGLT1 transport and where?
Glucose, galactose, and Na. From lumen to cell.
What does GLUT5 transport and where?
Fructose (not Na). From lumen to cell.
