Lecture 11 Flashcards
(28 cards)
What are the functions of fat?
- Major energy store and fuel source.
- Required for transporting fat soluble vitamins.
- Provide essential fatty acids - linoleum and alpha-linolenic acid.
- Important for insulating and protecting the body.
What are the most common type of lipids found in the body and in food?
Triglycerides.
What does each triglyceride consist of?
Three fatty acids bonded to glycerol.
Describe stearic acid?
18 carbon saturated fatty acid.
Describe oleic acid?
18 carbon monounsaturated fatty acid.
Describe linoleic acid?
18 carbon polyunsaturated fatty acid.
What are the physical properties of saturated fats?
Solid at room temperature.
More resistant to oxidation - longer shelf life.
What are the physical properties of unsaturated fats?
Polyunsaturated fats are liquids at room temp.
Monounsaturated fat is slightly less susceptible to spoilage.
Polyunsaturated fat spoils most readily.
Hydrogenation: protects against oxidation, therefore prolonging shelf life and alters texture.
What are the most saturated fatty acids?
Animal fats and tropical oils of coconut and palm.
Coconut oil, butter, beef tallow, palm oil and lard.
What are rich in monounsaturated fatty acids?
Vegetable oils such as olive and canola.
Olive oil. canola oil and peanut oil.
What are rich in polyunsaturated fatty acids?
Many vegetable oils.
Safflower oil, flaxseed oil, walnut oil, sunflower oil, corn oil, soybean oil and cottonseed oil.
What products do you fine cholesterol?
Meat, eggs, fish, ultra and dairy products = exogenous products.
What is cholesterol?
A sterol.
What can plant-based sterols do?
Interfere with cholesterol absorption.
What does sterol’s do?
Material for bile acids, hormones.
What occurs in the mouth in regards to fat digestion?
Some solid fats begin to melt and the sublingual salivary gland secretes lingual lipase. These lingual lipase (enzymes) then start the breakdown of fats.
What occurs in the stomach in regards to fat digestion?
Acid stable lingual lipase imitates lipid digestion. Muscle contractions then disperse the fat into smaller droplets. The fat is then exposed to gastric lipase.
What occurs in the small intestine in regards to fat digestion?
Cholecystokinin (CCK) signals the gallbladder to release bile.
Bile turns fat into emulsified fat. Then pancreatic and intestinal lipase - pancreatic cholesterolesterase - turns emulsified fat into monoglycerides, glycerol and fatty acids.
What occurs in the large intestine int regards to fat digestion?
Some fat and cholesterol, trapped in fibre and exit in faeces.
What do large lipids do in regards to absorption in the intestine?
Monoglycerides and long-chain fatty acids combine with bile, forming micelles that are sufficiently water soluble to penetrate the watery solution that bathes the absorptive cells. There the lipid contents of the micelles diffuse into the cells.
What do small lipids do in regards to absorption in the intestine?
Move directly into the bloodstream.
Describe the exogenous pathway (chylomicrons)?
- Dietary triglycerides, phospholipids and cholesterol absorbed into enterocytes of the small bowel. They become chylomicrons.
- Fatty acids are cleaved off (LDL) and it is still a chylomicron.
- Reuptake of chylomicron into the liver via a remnant receptor.
Describe familial dysbetalipoproteinemia?
A person cannot reuptake a chylomicron remnant into the liver for synthesis of cholesterol.
Describe the reverse transport pathway (HDL)?
- Cholesterol is synthesis in the liver.
- HDL picks up cholesterol in the tissues.
- a. HDL can then go on to be reused as HDL in the bloodstream, and vice versa.
- b. Cholesterol is delivered to tissues that need it or to other lipoproteins.
