GI absorption Flashcards
Where is iron absorbed?
Absorbed as Fe2+ in the duodenum
Where is folate absorbed?
In small bowel
Where is b12 absorbed?
Absorbed in terminal ileum along with bile salts, requires intrinsic factor
What are Peyer’s patches?
Lymphoid tissue w/in the gut
Where are Peyer’s patches found?
Lamina propia and submucosa of the ileum
What do the M cell’s of Peyer’s patches do?
Sample and present antigens to immune centers
What is IgA from Peyer’s patches generated?
B-cells are stimulated in germinal centers of Peyer’s patches, then differentiate into plasma cells that secrete IgA. IgA+ protective secretory component transported across the epithelium into the lumen to deal with intraluminal antigen
What are bile salts?
Bile acids conjugated to glycine or taurine to make them water soluble
What is bile composed of?
Bile salts, phospholipids, cholesterol, bilirubin, water and ions.
What enzyme is the RLS of bile synthesis?
Cholesterol 7-alpha hydroxylase
What is the function of bile?
- Digestion and absorption of fat soluble lipids and fat soluble vitamins
- Cholesterol excretion (body’s only method of eliminating cholesterol)
- Antimicrobial activity (via membrane disruption).
What is heme composed of?
Iron and protoporphyrin?
How is bilirubin produced?
heme is metabolized by heme oxygenase to biliverdin –> reduced to uncongugated bilirubin
Is indirect bilirubin water soluble? How is is transported in the blood?
No. Transported with albumin to bloodstream
What is bilirubin conjugation?
UDP glucoronosyl transferase conjugates indirect bili with glucuronic acid; becomes water soluble
