FATTies (lipids) Flashcards
3 primary functions of lipids
- energy
- essential FAs for FA synthesis
- absorption of essential fat-soluble vitamins
3 non-primary functions of lipids
- precursor for steroid hormones
- structural component of cell membranes
- signaling molecule and electrical insulators
AMDR of lipids
20-35% of daily energy intake (greater than 35% not recommended)
how much of your total energy consumption should be from saturated fat?
less than 10%
how do lipids travel through the bloodstream, given that they are hydrophobic?
they attach to binding proteins like albumin or lipoproteins
3 classes of lipids
triglycerides
sterols
phospholipids
triglycerides
- aka triacylglycerol
- primarily a source of energy
- composed of 3 fatty acids and a glycerol (bonded by esterification)
esterification
- the bonding of fatty acids to glycerol to make triglycerides
- occurs in liver, enterocytes and adipocytes
fatty acid lengths and number of Cs
- short chain: less than 6
- medium chain: 6-12
- long chain: greater than or equal to 14
ways to categorize fatty acids
short, medium, or long
saturated or unsaturated
trans or cis
what is saturated (re fatty acids)?
all carbons in the fatty acid chain are saturated with hydrogens: no double bonds between Cs
what is unsaturated (re FAs)?
one or more double bonds between Cs: monounsaturated (1 db) or polyunsaturated (2+ db)
how are polyunsaturated acids classified?
omega-3 and omega-6: based on position of first double bond after the omega carbon.
alpha-linolenic acid (ALA): omega 3 or 6? essential or nonessential? inflammatory or anti-inflammatory?
omega 3. essential. anti-inflammatory effect.
linoleic acid (LA): omega 3 or 6? essential or nonessential? inflammatory or anti-inflammatory?
omega 6. essential. inflammatory in excess.
why is ALA important/distinct?
it is a precursor to other fatty acids, like DHA and EPA
how are synthetic trans fatty acids created and why?
- by adding H to liquid vegetable oils (MUFA or PUFA)
- to make them more solid, to better texture and taste, for frying, and to increase shelf life
how are trans fatty acids listed on labels?
- hydrogenated or partially hydrogenated
- if less than 0.5g, they can say “0 trans fats”
why are trans fats bad?
they raise LDL and lower HDL
what class of dietary fat is cholesterol?
sterol
is cholesterol essential or nonessential?
nonessential: synthesized in the liver
what are dietary sources of cholesterol?
animal products like eggs
functions of cholesterol
- component of all cell membranes
- needed for production of testosterone, estrogen, adrenal hormones, and vit D
- needed for production of bile (to digest fats)
phospholipids: essential or no?
nonessential nutrient
what are dietary sources of phospholipids?
most plants and animals contain them in their cell membranes.
functions of phospholipids
- cell membranes (phospholipid bilayer)
- supply fatty acids for cellular metabolism
- incorporated into the outer surface of lipoproteins (lipid transporters)
what class of dietary fat is lecithin?
phospholipid
3 enzymes (i think?) used to break down lipids
- lingual lipase
- pancreatic lipase
- bile from gallbladder
what are triglycerides broken down to by lipase and bile? what form do these products take?
monoglycerides and free fatty acids. they form micelles.
what would happen if a person didn’t make bile?
lipid absorption would drop from 97% to 50%
how are monoglycerides and fatty acids absorbed into the enterocytes?
via passive diffusion
what happens to MGs and FAs once they enter the enterocytes?
they are esterified back into triglycerides in the endoplasmic reticulum of the enterocytes. then they are combined with cholesterol, apolipoprotein, and phospholipid to form a chylomicron (a type of lipoprotein)
chylomicron
- a lipoprotein made of TG, cholesterol, apolipoprotein, and phospholipid
- formed in the enterocyte
- allows for the transport of dietary TGs in aqueous environment of the blood and lymph (phospholipid heads and proteins are hydrophilic)
- short-lived: metabolized a few hours after a meal
lipoprotein vs apolipoprotein
lipoprotein is a particle; apolipoprotein is a protein (part of lipoprotein particle)
where does a chylomicron go once it’s formed in the enterocyte?
they leave the enterocyte, enter the lymphatic system, and then drain into the venous system via the subclavian vein (takes 3 hours)
where do chylomicrons change from lymph to blood?
the subclavian vein
what types of fatty acids are not included in the chylomicron, and how do they enter the bloodstream?
SCFAs and MCFAs, and they enter the blood directly from enterocytes (kinda like monosaccharides)
while chylomicrons are floating around the bloodstream, who do they need to bump into to get absorbed into cells?
lipoprotein lipase (LPL)
what is lipoprotein lipase? where is LPL located? what does it do?
it is an enzyme found in the capillaries of adipose, muscle and liver tissues. LPL stimulates lipolysis, which breaks down TG into glycerol and FAs, which can then enter these cells
lipolysis
the breakdown of TG into FA and glycerol, which can then enter muscle and adipose cells.
what happens to FAs in muscle cells?
they can be used as a source of energy, or they can combine with glycerol (esterification) to form intramuscular triglycerides (IMTG)
what happens to FAs in adipose cells?
they combine with glycerol to form TGs (esterification)
in what form are fatty acids sent to the liver from enterocytes/the bloodstream?
chylomicron
4 types of lipoproteins
- chylomicrons
- LDL
- HDL
- VLDL
VLDL
- very low density lipoproteins
- synthesized in the liver
- transports endogenous fats (as opposed to dietary fats): mostly TG made in the liver from excess glucose
- once TG are released, VLDL are converted to LDL
LDL
- low-density lipoproteins
- synthesized in the liver
- transports cholesterol
- high levels of LDL increase risk of CVD, because if there’s too much LDL, it will deposit cholesterol into the blood vessel walls
- “bad” cholesterol
HDL
- high-density lipoproteins
- synthesized in the liver
- removes cholesterol, decreases risk of CVD
- “good” cholesterol
what is the leading cause of death globally (32% of all deaths)? (1 in 4 deaths)
heart disease (aka cardiovascular disease)
what conditions count as CVD?
- blood vessel disease (ie coronary artery disease)
- arrhythmias
- congenital heart defects
- heart valve disease
- heart infections
coronary artery disease
atherosclerosis (plaque build up in arteries) in the arteries that carry blood to the heart
pectoris angina
chest pain (from restricted blood flow because of atherosclerosis)
thrombosis
blood clot from when plaque ruptures and clotting is needed to stop the internal bleeding. stationary in the artery walls.
embolus
a thrombosis that dislodges from the blood vessel and is carried in the blood (depending on where it lands it can cause a heart attack or stroke)
myocardial infarction
heart attack
what are the 4 main coronary arteries?
- right coronary artery
- left coronary artery
- left anterior descending artery
- left circumflex artery
what are the 3 layers of the artery wall?
- intima (inside)
- media (middle)
- adventitia (outside)
occlusion
when a thrombosis (blood clot) completely blocks the artery
between which layers of the artery does a fatty streak/plaque develop?
the intima and media
dyslipidemia
abnormal blood lipid levels:
- low HDL
- high LDL (most important)
- high total cholesterol
- high TG
what type of medication lowers LDL? what are other lifestyle ways to lower it?
statins. aerobic exercise and diet modification.
how does aerobic exercise help with lipid levels?
- lowers LDL
- lowers TG
- raises HDL
what are dietary modifications to improve lipid levels?
- fiber-rich diet
- reduce saturated fat intake
- avoid trans fats
- fatty fish/fish oil
- moderate alcohol consumption
- replace full fat dairy with low fat
what does saturated fat do to lipid levels?
it raises LDL (specifically pattern A type, which is not linked to coronary heart disease), but it also raises HDL
does pattern A or B LDL increase risk factor for CVD?
pattern B LDL
foods high in monounsaturated fats
- nuts and seeds
- olive oil
- canola oil
- avocado
- peanut oil
- sesame oil
- high oleic oils
what are the 3 types of omega-3 FAs? health benefits of omega-3 PUFAs
ALA (plant sources), DHA and EPA (fish sources): essential fatty acids
- all 3 are cardioprotective: DHA and EPA are most potent
- lower TGs
- increase HDL
- prevents blood clotting
- lowers blood pressure
- decreases arrhythmia
- anti-inflammatory
