Digestion - Post Stomach Flashcards
What leaves the stomach and in what state is it in?
Chyme Hypertonic Acidic Only partially digested
Why does chyme get more hypertonic as digestion continues?
As more things are broken down into solutes
What state is chyme in once it’s leaving the duodenum
Isotonic Neutral as Bicarbonate corrects the pH
What cells make up a pancreatic duct?
Acinar- Digestion. Produce enzymes, stimulated by Vagus and CCK Centroacinar Cells Duct Cells- Neutralise acidic chyme. Secrete isotonic aqueous components, HCO3-
What Do Pancreatic Ducts Secrete
Trypsin Elastase Carboxypeptidase Chymotrypsin Active- Amylase and Lipase Packages as zymogen granules
What is the role of the large intestine?
Absorbing water, electrolytes and nutrients
What is the difference between a bile acid and a bile salt?
A bile acid is an acid synthesised in the liver. Not soluble in duodenal pH Bile salts are bile acids which are conjugated with amino acids (Taurine and Glycine) Ampithatic and soluble at duodenal pH Emulsify fat into smaller droplets
Name the 2 main bile acids and their general properties
Cholic Acid Chenodeoxycholic Acid Generally not soluble in duodenal pH
What do bile acids do in the duodenum?
Form micelles with products of lipid breakdown for transport into the lumen. Absorbed through the gut wall (Lipids then reform into original form then are packaged into chylomicrons)
Lipid Metabolism: How do Chylomicrons travel?
Too large for capillaries Travel in lymphatic system Enter lymph capillaries (lacteals) Re-enter vascular at thoracic duct
Once used, what happens to bile salts?
They remain in the lumen and are reabsorbed at the terminal ileum, returned to liver via portal blood Liver extracts and reuses (95%)
What does CCK do?
stimulates contraction of the common bile duct relaxes the sphincter of Oddi
What is a bile pigment?
An Excretory product e.g Biliruben
What is Steatorrhoea?
What fat appears in faeces (pale, float and smell foul) If bile salts/lipases aren’t secreted normally
