Gastrointestinal: Part 2 Flashcards
Specialized structures on the folds that further increase surface area and contain blood vessels and lacteal (lymph vessels), which play a role in the absorption of nutrients.
Villi
Form the brush border and increase surface area even more
Microvilli
Microenvironment for enzyme release and digestion and reabsorption
Brush Border
Where is bile made?
Liver
Where is bile stored and concentrated?
Gallbladder
Where is bile released to?
Duodenum
What two things can stimulate the release of bile from the gallbladder?
Cholecystokinin
Vagus Nerve
What is bile made of?
Mostly Water
Bile Salts (50%)
Cholesterol (4%)
Bile Pigments (2%)
Phospholipids (40%)
What do bile salts help to do?
Emulsify Fats
(break down)
Principal bile pigment released by the liver.
Bilirubin
Type of bilirubin that is secreted into the intestines with bile.
Conjugated bilirubin
Type of bile that is broken down into urobilirubin and stercobilin in the small intestines and may be reabsorbed or secreted in feces.
Conjugated Bilirubin
Where are most senescent (old) red blood cells broken down?
Liver
What is bilirubin derived from?
Heme of recycled red blood cells
Type of bilirubin that is stuck to protein in the blood and is not soluble.
Unconjugated Bilirubin
Type of bilirubin that is released from albumin and is soluble in bile.
Conjugated (Direct Bilirubin)
Where is bilirubin conjugated?
Liver
Where are bile salts made?
Liver
What is the primary function of bile salts?
Emulsify Fats
Bile salts are amphipathic, meaning they have a hydrophilic and hydrophobic portion. This property allows that to act as what?
Emulsifiers
What is the fate of bile salts that are released into the small intestine?
Reabsorbed
(in the Ileum)
What breaks down fats into monoglycerides and fatty acids stored in micelles?
Pancreatic Lipase
Inside cells, cholesterol, monoglycerides, lysolecithin (an emulsifier) mix with Free Fatty Acids and apolipoproteins. Triglcyerides are then reassembled from monglycerides, cholesterol is esterfied to an inactive form, and phopholipids reassemble. All of this together forms what?
Chylomicron
How does absorption of lipids take place?
Brought in inside of a micelle, everything is put back together and then turned into a chylomicron.
Made by intestinal cells and carry digested lipids from the intestine to adipose tissue and other cells.
Chylomicrons
How do chylomicrons leave the intestinal environment?
Lymph Vessels (Lacteals)
Lipoprotein that carries mostly triglycerides made in the liver and takes them to adipose tissue.
Very-low-density Lipoprotein
(VLDL)
Main carrier of cholesterol to “needy” cells.
Low-Density Lipoprotein
(LDL)
Lipoprotein that removes excess cholesterol from cells and vascular membranes.
High-density Lipoprotein
What type of cholesterol is considered “bad” because it leaves deposits on vessels walls as they take lipids to cells?
Low-density Lipoprotein
What type of cholesterol is considered “good” because they clean up deposits in the blood as well as removing lipids from cells?
High-density Lipoprotein
Specialized vasculature that delivers absorbed nutrients to the liver for processing before they enter the general systemic circulation.
Hepatic Portal System
Blood from the digestive system carries absorbed material to the liver through what?
Hepatic Portal Vein
What is a potential consequence of liver cirrhosis or other hepatic obstructions to portal blood flow (portal hypertension).
Varices
Where are most gastrointestinal flora found?
Colon
What are some products of intestinal flora?
Gases
Vitamins (B12 and K)
Where is most water reabsorbed?
Small Intestine
(large intestine plays a role as well)
