Flashcards in REVISION GUIDE LIVER: FAT Deck (69)
what are lipids?
they are esters of fatty acids and glycerol or other compounds (cholesterol)
what is the structure of a tri(acyl)glyceride (TAG)?
1 glycerol molecule esterified to 3 fatty acid chains at their carboxyl heads
what are the storage areas of fat in the body?
what are fatty acids?
they are the building blocks of lipids
what is the difference between saturated and unsaturated fatty acids?
saturated = single C-C bonds - they line up
unsaturated = at least 1 C=C double bond - they kink and need more space
what proportion of western diets is fat?
dietary fats are on average 1/3 of western diet
what type of fats are the majority that are found in western diets?
90% of dietary fats are triglyerides
what are the different types of of fats found in diets?
what are the functions of lipids?
structural - part of cell membranes
how are lipids involved in hormone metabolism?
cholesterol is the backbone of adrenocorticoids and sex hormones
how is cholesterol esterified?
it is esterified intracellularly in lipoprotein by:
acyl-CoA (cholesterol acyltransferase)
lecithin (cholesterol acyltransferase)
where is the majority of cholesterol processed in the body?
in the liver
what proportion of cholesterol is endogenous and what proportion is derived from diet?
90% of cholesterol is endogenous
10% of cholesterol is dietary
how is cholesterol excreted from the body?
through bile in enterohepatic circulatory system
how do triglycerides and cholesterol travel in blood?
bound to lipoproteins
which molecules provide the most energy in the body?
almost all energy is provided through oxidation of lipids
lipids > carbohydrates > proteins
how much energy do lipids yield?
what are the different energy reserves in the body?
- blood glucose
- glycogen stores
- muscle protein
- lipid reserve
how much energy is stored in blood glucose and how long does it last for?
lasts for a few minutes
how much energy is stored in glycogen stores and how long does it last for?
approx. a day
how much energy is stored in muscle protein and how long does it last for?
how much energy is stored in lipid reserve and how long does it last for?
where is the main storage place for glycogen?
what is the structure of lipoproteins?
- a core containing TGs and cholesterol esters
- a surface monolayer of phospholipids, cholesterol and specific protein (eg apoproteins)
what determines the density of lipoproteins?
the protein to lipid ratios
what is the role of chylomicrons?
they carry lipids from the gut to muscle and adipose tissue
what happens to chylomicron remnants in blood?
the remnants are taken up by the liver via receptor mediated endocytosis - there is recognition of ApoE by hepatocyte surface receptors
what is the structure of chylomicrons?
largest and lowest density lipoprotein
has high lipid to protein ratio
has highest triglyceride content
what is the structure of VLDL?
is 2nd highest in triglycerides as a percentage of their weight