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33 Cards in this Set

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What are the four storage forms of fats in the body?
1.Triglycerides
2.Phospholipids
3.Cholesterol
4.Fat-soluble vitamins
What two essential fatty acids are derived from triglycerides?
Linoleic and a-linolenic acids.
What are the fat-soluble vitamins important to human health?
A,D,E, and K
From where does the liver receive blood?
It receives venous blood from the portal vein and arterial blood from the hepatic artery.
What are four ways in which the liver acts as a buffer between the intestines and the systemic circulation?
1.Kuppfer cells phagocytize any debris or microorganisms.
2.Cytochrome pathways detoxify compounds.
3.Substances may secreted through the bile ducts for fecal excretion
4.Nutrients are stored to prevent a flood of material into the bloodstream.
What stimulates duct cells in the bile canaliculi to secrete an alkaline electrolyte solution?
Secretin
What are the 6 components of bile?
1.Water
2.Bile salts
3.Phospholipids
4.Cholesterol
5.Bile pigments
6.Xenobiotics
What are bile salts made from? How is their synthesis regulated?
They are synthesized from cholesterol. Regulation occurs by feedback control of the first enzyme: sterol 7-hydroxylase.
Are bile salts hydrophobic or hydrophilic at normal pH?
At normal pH bile salts are strongly ionized and are amphipathic.
Which components of bile are solubilizers and which are insoluble?
Solubilizers include the bile salts and phospholipids. Bile pigments and cholesterol are insoluble.
What is enterohepatic circulation? What adaptations in the intestine and liver aid this process?
Bile salts are reclaimed in the intestine and transported back to the liver for re-use. High affinity transporters in the terminal ileum and liver assist.
How much of the body's bile salts is excreted in urine? In feces?
None is excreted in the urine and ~1% is excreted in the feces. The rest are reclaimed and used again.
Where does bilirubin come from? How does it travel in the blood?
It is a breakdown product hemeglobin that travels bound to albumin.
What is the basic cause of gall stones? Why might they be seen Crohn's disease patients?
*Due to an imbalance between solubilizers and insoluble components, bile becomes insoluble and forms a precipitant
*Chrohn's may be treated by resection of the terminal ileum which reduces the ability to reclaim bile salts and thus increases de novo synthesis
What symptoms are seen when the hepatic duct is blocked by a gall stone? The common duct?
*pain, inflammation, and jaundice
*pain, inflammation, jaundice, pancreatitis, steatorrhea, high serum pancreatic amylase, possible diabetes due to inadequate production of insulin and glucagon
What are three ways gall stones are treated?
1.Cholecystectomy
2.Lithotripsy
3.Oral bile salt replacements
Why is it important that fats be solubilized in mixed micelles?
This provides an interface for action of aqueous lipases, thus allowing the fats to be broken down into smaller components.
T/F:
After mixed micelles containing solubilzed fats are transported across the apical membrane, the micelles are recycled back to the lumen while the fats are made into lipoproteins.
False! The micelles never leave the lumen - they deposit solubized fats at the brush border.
What happens to short chain fatty acids in the columnar cells?
They are able to diffuse across the basolateral membrane without further modification.
Where in the columnar cell are lipoproteins assembled? What are some examples of these lipoproteins?
*Golgi apparatus
*chylomicrons, VLDL, HDL
What happens to lipoproteins after they cross the basolateral membrane of the columnar cells?
They are taken up by lacteals and transported through the lymphatic system to be released into systemic circulation through the thoracic duct. From there they are taken up by adipose, muscle, and liver.
Describe the transport of glucose and galactose across the apical membrane of columnar cells. How are these sugars transported across the basolateral membrane?
These sugars are moved via SGLT-1 which is a high energy driven process. They cross the basolateral membrane by facilitated diffusion through GLUT-2.
Describe the transport of fructose across the apical membrane of the columnar cells. What happens to it once inside the cell?
This sugar is transported by facilitated diffusion through GLUT-5. It is then rapidly converted to glucose.
How does pancreatitis affect carbohydrate digestion?
It may result in a deficit of amylase thus reducing the breakdown of starch.
What is the defect in lactose intolerance? How is symptomatic diarrhea generated?
There is a deficiency in lactase and thus lactose is not broken down at the brush border. Accumulation of lactose in the lumen creates an osmmotic gradient that draws in water, thus causing diarrhea.
Describe the transport of amino acids, small peptides, and intact proteins across the apical membrane of columnar cells.
Smalll peptides have a specific transporter. Amino acids are moved by one of seven transporters. Intact proteins are not taken up, except by M cells for antigen sampling purposes.
What is Hartnup's disease? What nutritional deficiencies are seen?
A defect in the transporter that moves neutral amino acids. No nutritional deficiencies are seen because these amino acids can be moved by the small peptide transporter.
How are amino acids moved across the basolateral membrane?
There are three individual transporters.
Where are triglycerides typically stored?
In white adipose tissue.
How are bile salts cleared by the kidney?
They are not cleared by the kidney - they are filtered but totally reabsorbed.
What are the two basic types of gall stones?
*Cholesterol stones
*pigment stones
How are fats digested in the mouth?
Not very well - lingual lipase is released but is maximally active at a pH range of 2-6.
In what segment of the GI tract does most fat digestion take place?
In the jejunum.