Lecture 44 11/29/23 Flashcards
(41 cards)
What are the sources of carbohydrates?
-starches and polysaccharides
-glycogen
-disaccharides
-fiber
What are the possible fates of carbohydrates in the body?
-metabolized to produce ATP
-stored in liver and muscle as glycogen
-converted to fatty acids and stored as triglycerides in adipose tissue
What are the steps of glucose metabolism?
-glycolysis converting glucose to pyruvate
-conversion of pyruvate to acetyl-CoA
-citric acid cycle converting acetyl-CoA to CO2
-electron transport chain to create ATP from released energy
What are the characteristics of anaerobic glycolysis?
-converts pyruvate to lactate
-occurs in the absence of oxygen
What are the characteristics of glucose storage?
-primarily stored in liver and muscle as glycogen
-liver stores are available for all tissues
-muscle stores are only available for muscle
-liver stores affect blood glucose levels
What happens after a carbohydrate-containing meal?
-glucose enters portal circulation and liver hepatocytes
-insulin is released by pancreas
-insulin stimulates glycogen synthase to convert glucose to glycogen in glycogenesis
What are the steps of glucose storage in adipose tissue?
-excess glucose is converted to fatty acids
-fatty acids are converted to triglycerides
-triglycerides are converted to adipose tissue
What are the characteristics of glycogenolysis?
-break down of glycogen to release glucose
-stimulated by glucagon and epinephrine
What are the characteristics of gluconeogenesis?
-formation of glucose from non-carbohydrate substrates
-occurs mostly in liver and somewhat in kidneys
-occurs when blood glucose levels are low
Which types of fats are ingested?
-triglycerides
-phospholipids
-cholesterol esters
What are saturated fatty acids?
fatty acids with no double bonds
What are unsaturated fatty acids?
fatty acids with one or more double bonds
What are omega 3 polyunsaturated fatty acids?
fatty acid in which the third bond from the methyl end is the first double bond present
What are omega 6 polyunsaturated fatty acids?
fatty acid in which the sixth bond from the methyl end is the first double bond present
What are the characteristics of fatty acid oxidation?
-fatty acids are broken down into acetyl-CoA, which enters citric acid cycle
-occurs in the mitochondria
-carnitine required for fatty acids to enter mitochondria
When does ketone formation occur?
when glucose metabolism is low
What are the characteristics of ketone formation?
-liver forms beta-hydroxybutyrate and acetoacetate from acetyl-CoA
-ketones are converted to acetyl-CoA when entering the Kreb’s cycle to produce energy
Where do the FFAs used to form ketones come from?
lipolysis
What are the general characteristics of plasma lipids?
-free fatty acids bound to albumin
-major lipids do not circulate in free form
What are the characteristics of chylomicrons?
-transport dietary lipids
-very large lipoproteins created in enterocytes
-cleared by lipoprotein lipase/LPL on the surface of capillaries
What is the function of LPL?
-breaks down the triglyceride in chylomicrons and VLDLs
-produces free fatty acids and glycerol
What are the characteristics of VLDLs?
-deposit triglycerides into tissue
-become IDL after LPL removes triglycerides
What are the characteristics of IDL?
-removes cholesterol esters from HDL via cholesterol ester binding protein (CETP)
-eventually becomes LDL cholesterol
Why are dogs and cats not prone to heart attacks?
they lack cholesterol ester binding protein
