Midterm - as per course syllabus Lectures 1a-6b inclusive-50 multiple choice-50 points One short answer question-10 points Lecture 5b 31 January 2018 Most of this lecture taken from Chapters 5,7 of Rolfes et al(Understanding Normal and Clinical Nutrition(Nutrition 2104/2106 text)

Outline of lectures 5a,b Lipids classified     -fatty acids     -saturation     -triglycerides     -phospholipids     -sterols

Outline of lectures 5a,b Lipids     -digestion     -absorption     -transport

Outline of lectures 5a,b Lipids in the body     -roles of triglycerides     -essential fatty acids

Outline of lectures 5a,b Preview of lipid metabolism

Outline of lectures 5a,b Lipid Metabolism     -fatty acid catabolism     -fatty acid anabolism     -triglyceride catabolism     -triglyceride anabolism     -cholesterol catabolism     -cholesterol anabolism     -phospholipid catabolism     -phospholipid anabolism     -regulation

More detailed comments

Lipids classified -phospholipids      example-choline containing phospholipids 2 fatty acids and a choline head group attached to glycerol                     -diagram  

 

Lipids classified -phospholipids -ethanolamine containing phospholipids                     -2 fatty acids and an ethanolamine head group attached to glycerol             -phosphatidylinositol                     -2 fatty acids and an inositol head group attached to           

Lipids classified -phospholipids             -phosphatidylserine                     -2 fatty acids and a serine head group attached to glycerol             -sphingomyelin                     -one fatty acid and 2 other groups attached to glycerol

-various hormones (eg estrogen, testosterone) made from cholesterol    Lipids classified -sterols             -cholesterol             -various hormones (eg estrogen, testosterone) made from cholesterol

Diag chol

Lipids     -digestion          -mouth             -lingual lipase                     -adults-minor role                     -infants- major role in digesting short and medium chain fatty acids

Lipids     -digestion             -stomach- gastric lipase-able to function in watery environment without bile             -small intestine- pancreatic lipase-digests fatty acids from triglycerides - intestinal lipases                                     -role of bile (figure 5-14, Rolfes)

Lipids -absorption             -glycerol, short and medium chain fatty acids go directly into blood             -monoglycerides and long chain fatty acids are formed into micelles which are moved into intestinal cells                      in intestinal cells ultimately get phospholipids and  triglycerides formed into chylomicrons  which are moved into lymph - from lymph go into blood

Lipids -transport lipoproteins   Lipids   -transport         lipoproteins             -fat protein particles-protein required to give water solubility to lipids             -chylomicrons             -very low density lipoprotein             -low density lipoprotein             -lipoprotein (a)             -high density lipoprotein             -albumin             -lipoprotein density affected by ratio of lipid to protein in a lipoprotein

Lipids in the body     -roles of triglycerides                -primarily energy                 -fat stores                 -participates in carbohydrate metabolism                 -protein sparing  

Lipids in the body     -essential fatty acids                 -linoleic                 -alpha-linolenic  

Preview of lipid metabolism                 -fat is made into fat                 -carbohydrate and protein can make fat                   

Lipid Metabolism     -fatty acid catabolism                 -fatty acids made into acetyl CoA                 -acetyl CoA follows TCA cycle                 -ATP is made

Lipid Metabolism   -fatty acid anabolism                 -acetyl CoA can be made into fatty acids                 -omega 6 and omega 3 pathways                 -ATP is used                    

Lipid Metabolism -triglyceride catabolism                 -to glycerol and fatty acids -triglyceride anabolism                 -fatty acids and glycerol make triglycerides

Lipid Metabolism -cholesterol catabolism                 -largely made into bile -cholesterol anabolism                 -acetyl CoA made into cholesterol

Lipid Metabolism -phospholipid catabolism                 -made into glycerol, fatty acids and head group (eg choline) -phospholipid anabolism                 -made from glycerol, fatty acids and head group (eg choline)

-regulation-closely linked to carbohydrate availability Lipid Metabolism -regulation-closely linked to carbohydrate availability    -lots of carbohydrate-favours fatty acid synthesis-due to lots of malonyl CoA which inhibits carnitine acyl transferase I that allows for transfer of fatty acids to carnitine for transport into mitochondria for oxidation to acetyl CoA- also if not enough carbohydrate for fatty acid synthesis but not so little that there is sufficient OAA-fatty acids are metabolised through the Krebs cycle (acetyl CoA from fatty acids joins with OAA to make citrate)              -little carbohydrate-favours fatty acid catabolism to ketones (acetyl CoA is converted to ketone as OAA is converted to glucose)