Ris
Healthy-ojas
Custom Search
   Blood glucose diabetes | Hyperlipidemia Cholesterol | Hypertension | Hypotension | Eye defects  | Sleep disorders
Cholesterol Information
Cholesterol Risks & Symptoms
Cholesterol Causes
Cholesterol Screening Tests
Cholesterol Diagnosis Test
Therapeutic lifestyle changes
Cholesterol lower Medication
Cholesterol alternative medicine
Cholesterol Complications
Social Book Marking
Bookmark and Share
Subscribe to RSS feed
Subscribe in a reader
Email friend about this site
Email

Fat metabolism | Lipid metabolism

The lipid transport can be divided into the exogenous pathway, which refers to the metabolism of intestinally derived lipoproteins, and the endogenous pathway, which refers to hepatic-derived lipoproteins.

In fact, dietary cholesterol represents only about one-third of total intestinal cholesterol pool, while endogenous sources, the bile and to some extent intestinal mucosal cholesterol account for the remaining two-thirds.

Fat metabolism - exogenous pathway

  • When fat food enters into the duodenum, mucosal cells in duodenum will releases cholecystokinin (CCK).
  • CCK stimulates gallbladder contraction and realizes bile acids, into the small intestine.
  • Bile acids chemically resemble detergent molecules, which can dissolve fat and disperse it in small packets called as emulsification (mixture of fat and water).
  • Small packets of fats are further digested by pancreatic lipase. Enzyme lipase acts only at oil-water interfaces and requires a large surface area. Lipase hydrolyses fat and yield monoglyceride and fatty acids.
  • Monoglycerides and fatty acids associated with bile acids, phospholipids to form a complex structure called micelles.
  • Micelles present in the border of small intestine enterocytes is taken up into the epithelial cells.
  • Intestinal cells resynthesize triglycerides then packaged into Chylomicrons (triglyceride packed with protein). Chylomicrons in enterocytes are transported via the lymphatic system and enters bloodstream for circulation.
  • Cholesterol in bloodstream is utilized, otherwise taken up and stored in the liver for future use.

Pile acids recycle in fat metabolism

Adequate quantity of bile acid is a must for fat metabolism, it is maintained by
  • The liver, about 0.6 g of new bile acid is produced daily from cholesterol.
  • This is added to the total bile acid pool of 3.0 g, which cycles 6 to 10 times daily.
  • Approximately 96% of the bile acid is re-absorbed in each cycle; the balance is lost in the stool.

Fat metabolism by Liver - endogenous pathway

The liver is capable of removing cholesterol from the blood circulation as well as manufacturing and releasing cholesterol into the blood circulation.
  • After a meal, fat is digested and released into the blood stream.
  • Liver removes excess chylomicrons (triglyceride or fat packed with protein) from the blood circulation.
  • Removed chylomicron is stored into the liver for future requirements.
  • In between meals or during fasting, the liver manufactures fat from storage and releases cholesterol back into the blood circulation when needed.
  • Even if there is no fat in dietary food, liver can produce the required quantity of fat from carbohydrates or protein foods.

Next Cholesterol Risks & Symptoms

Last modified date 2nd July 2009
    Copyright © 2009 Healthy-ojas.com All rights reserved.   
All information is intended for your general knowledge only and is not a substitute for medical advice or treatment for specific medical conditions. You should seek prompt medical care for any specific health issues and consult your physician before starting a new fitness regimen.
This website is certified by Health On the Net Foundation. Click to verify. This site complies to the HONcode standard for trustworthy health information: verify here.