This lesson follows dietary fats from digestion in the small intestine to transport through the body and explains how stored triglycerides can be used to produce energy.
Dietary fats are mainly triglycerides. In the small intestine, bile salts emulsify fats, dispersing them into smaller droplets that enzymes can act on. Pancreatic lipases then break triglycerides down into free fatty acids and monoglycerides.
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What does cholecystokinin (CCK) do during fat digestion?
CCK stimulates pancreatic lipase release and gallbladder contraction, promoting the delivery of bile salts to the small intestine.
What are chylomicrons?
Lipid-carrying particles assembled in enterocytes that transport dietary triglycerides and cholesterol through lymph and blood.
What happens during lipolysis?
Triglycerides are hydrolyzed into glycerol and three fatty acids, which enter metabolism by different routes.
Why is carnitine needed for fatty acid oxidation?
Carnitine helps shuttle fatty acyl groups into the mitochondrial matrix, where β-oxidation can proceed.
How does citrate support lipogenesis?
Citrate carries acetyl units from mitochondria to the cytoplasm, where they can be used to make fatty acids.
Quiz questions
What is the role of bile salts in dietary fat digestion?Answer: They disperse fats into smaller droplets that lipases can act on.
How do most absorbed dietary triglycerides reach the bloodstream from enterocytes?Answer: They enter chylomicrons, which pass into lacteals and then through lymph.
After fatty acids are activated to fatty acyl CoA in the cytoplasm, what does carnitine help do?Answer: Transport fatty acyl groups into the mitochondrial matrix for β-oxidation.
Why can ketone bodies help maintain energy supply during glucose scarcity?Answer: The brain can use ketones as an alternative fuel.
How do acetyl units generated in mitochondria reach the cytoplasm for lipid synthesis?Answer: They are exported as citrate, which is converted back to acetyl CoA in the cytoplasm.
Based on Anatomy and Physiology 2e by J. Gordon Betts, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.