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137 Cards in this Set
- Front
- Back
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Major Functions of Fats |
1) Energy Use 2) Energy Storage 3) Protection 4) Structure of cell membranes 5) Maintain Body Temp 6) Precursors for hormones 7) Regulate stomach emptying 8) Palatability and satiety 9) Nutrient absorption and transport |
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How much ATP is gained from beta oxidation of one glucose |
38 ATP |
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What tissues of the body DO NOT use fatty acids as a source of energy |
Brain, RBC's, skin and the renal medulla |
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T/F Unoxidized fatty acids get stored as subcutaneous fat, which can later be accessed and used as energy |
True |
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What is the major storage form of fats? |
Triglycerides |
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How is dietary fat stored? |
Adipose cells (increase 50x in weight) |
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How is fat used as protection? |
Fat surrounds organs TG insulates and protect Fills space that would allow organs to slide downward |
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T/F Fatty acid shape physically regulates membrane function |
True |
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Essential fatty acids are substrates for what molecules? |
Prostaglandins (hormone like substance) |
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What does cholesterol help the body synthesize? |
Steroid hormones in the gonads and adrenal glands |
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Examples of steroid hormones |
Glucocorticoids Mineralocorticoids Androgens Estrogens Progestogens |
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T/F Steroid hormones are water soluble |
False - fat soluble |
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What does the fat in the stomach regulate in digestion? |
Enterogastric reflex- keeps the food in stomach longer thus allowing greater digestive action |
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How does dietary fat regulate secretions of the stomach? |
Depresses gastric secretions, slows gastric emptying Stimulates binary and pancreatic flow = digestion |
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T/F Since fat keeps food in the stomach shorter, fast allows satiety signals to reach the brain |
False - keep food in stomach shorter which causes satiety |
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What important textural properties do fast have in food? |
smoothness and tenderness and makes food more satisfying |
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How do fats affect gallbladder secretions? |
Dietary fats provide the stimuli for bile salt secretion and are crucial for the absorption of fat soluble vitamins and nutrients. |
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Examples of Simple lipids |
Fatty acids Natural fats Mono-Do-Triglycerides waxes |
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Examples of Compound lipids |
Phospholipids/gycerophospholipids Glycosphingolipids Glycolipids Lipoproteins |
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Examples of phospholipids and glycerophospholipids |
Lecithin and cephalins |
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Examples of glycosphingolipids |
Sphingomyelins and ceramides |
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Examples of glycolipids |
cerebrosides and gangliosides |
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Examples of Derived and misc. lipids |
Eicosanoids Steroid and sterols Trans-fats Vitamins A,D,E & K |
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What do most natural fats consist of ? |
98 to 99% TG's composed of fatty acids |
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What are the two essential features of a fatty acid? |
1) a long hydrocarbon chain (4 to 30 carbons) typically linear with an even amount of carbons 2) A carboxylic head group |
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What is the bond called between a fatty acid and a neutral or polar lipid? |
Ester linkage ( Esterified) |
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20:5w3 What does each number/symbol mean? |
1) 20 = number of carbons 2) 5= number of double bonds 3) omega means the location of the double bond from the methyl end. ( delta is location from the COOH end) |
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Number of carbons in a SCFA |
less than 6 carbons i.e. butanoic acid (4), hexanoic (caproic) acid (6) |
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Why is butyrate so important? |
SCFA major metabolite in the colon lumen arising from bacterial fermentation of dietary finer and has been shown to be a critical mediator of the colonic inflammatory response. Counteracts inflammation-mediated ulcerative colitis and colorectal cancer |
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Food sources of SCFA |
butter and milk (especially goat and sheep) |
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Number of carbons in MCFA |
8-12 carbons i.e. caprylic acid (8), capric acid (10) |
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Why are MCFA so unique? |
Do not require carnitine for transport into the mitochondria. This can be important for people who have compromised digestion and absorption. Can be absorbed directly into circulation regardless of intestinal integrity |
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Food sources of MCFA |
"EASY ENERGY" Coconut oil, milk, palm kernel oil |
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How many carbons are in a LCFA |
14-27 i.e. palmitic acid, arachidonic acid, auric acid |
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What are LCFA highly involved in synthesizing? |
Prostaglandins |
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What fatty acids do LCFA include? |
essential and non-essential fatty acids (omega 3 and 6 and 9) |
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Food source of LCFA |
Primarily animal products |
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Saturated fatty acids (SFA) |
do not have any double bonds Non-essential Solid at room temp implicated in CVD and inflammatory conditions |
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Food sources of SFA |
meat and dairy. Coconut oil |
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Unsaturated fatty acids (USFA) |
At least one double bond (CIS-lowers mp) Includes mono/polyunsaturated and essential fatty acids (omega 3,6,9) |
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Monounsaturated Fatty Acids (MUFA) |
Only one double bond non-essential Reduce LDL and cholesterol deposits in the arteries |
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Example of MUFA |
Olei acid |
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Food sources of MUFA |
olive oil, avocado, almond ,canola, sesame |
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What does the mediterranean diet consist of? |
MUFA = and they have low incidence of heart disease |
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Polyunsaturated Fatty Acids (PUFA) |
At least 2 double bonds Found in cell membrane Unstable - susceptible to oxidation Reduces both HDL and LDL |
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Examples of PUFA |
linoleic acid arachidonic acid |
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Food sources of PUFA |
safflower oil, walnuts, sunflower, soy, whole grains, cold water fish, and small amounts of dairy and meats |
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Essential Fatty Acids (EFA) |
Omega 3 and 6 Cannot be synthesized by the body Humans can only place the double bond as low as n-9 carbons. |
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Omega 3 |
Alpha-linolenic acid becomes - EPA - DHA |
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Food sources of omega 3 |
flax, canola, hemp, walnut, pumpkin, soy, cold water fish |
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Omega 6 |
Linoleic acid becomes - GLA - DHGLA (PGE1) - Arachidonic acid (PGE2) |
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Food sources of omega 6 |
corn, safflower oil, sunflower, grains |
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Desaturates and elongase enzymes |
Synthesis of other MUFA and PUFA as well as further desaturation of dietary denied n-6 and n-3 fatty acids |
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What happens if the delta-6-desaturase enzyme is saturated by omega 6 fatty acids? |
Prevents the manufacturing of anti-inflammatory prostaglandins (ALA - EPA and DHA)even when omega-3 fatty acids are available |
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Why is it recommended to consumer more omega 3 fatty acids? |
Omega 6 can saturate delta-6 desaturase enzyme |
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T/F Monoglycerides and diglycerides tend to be more water soluble |
True Are often added to foods to enhance their texture - ice cream and candies |
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Esterification |
The process of puttying fatty acids on the glycerol backbone |
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Characteristics of storage TG's |
saturated and relatively unsusceptible to oxidative damage |
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Removing of fatty acids from TG's is called? |
De-esterification
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Reattaching a fatty acid is called? |
re-esterification |
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What happens to a TG every time it crosses a cell membrane? |
Broken down or de-esterified |
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What happens to fatty acids when they enter the cell? |
Re-esterified into TG's again |
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Short and Medium chain triglycerides |
TG's whose glycerol has 3 short or medium chain FA (less than 12 carbons) Water soluble and require less bile salt for breakdown |
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T/F Short and medium chain TG's are not absorbed directly into the bloodstream |
False - they do not have to go into the lacteals or be re-estrified in the enterocyte so they are absorbed directly into the bloodstream |
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T/F Short and medium chain TG's a great, quick, and efficient sources of energy |
True |
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T/F Short and Medium Chain TG's are stored in the adipose tissue |
False- they are not stored but instead oxidized to acetic acid. |
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When are Short and Medium Chain TG's prescribed to people? |
People who have fat malabsorption ( AIDS or cancer patients) |
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Food sources of Short and Medium Chain TG's |
Found in milk fat, coconut oil |
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Phospholipids |
TG's that contain a phosphate group at the 3rd position |
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Phospholipids and the effect of the head group? |
Head group determines the function choline, glycerol, serine, inositol, or ethanolamine |
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Membrane phospholipids usually contain what fatty acids? |
One SFA at C1 and PUFA and C2( usually an essential fatty acid) |
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Important functions of the phospholipid membrane |
1) Maintain optimal membrane fluidity 2) Lipid barrier to unregulated transport of water-soluble substances 3) EFA's are cleaved from bilayer to synthesize prostaglandins, leukotrienes, and thromboxjnes 4) Receptors for hormones and transporters |
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Lecithin |
AKA - phosphatidylcholine Made by the liver from arachidonic acid and secreted into the small intestine via the gallbladder to EMULSIFY FATS Forms MICELLES Component of lipoproteins |
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Food sources of lecithin |
liver, egg yolk, soybeans, peanuts, legumes, spinach, and wheat germ |
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Glycosphingolipids |
lipid esters attached to a sphingosine base |
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Where are glycosphingolipids found? |
Nervous system |
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Example of a glycosphingolipid |
sphingomyelin - 25% of the myelin sheath |
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Glycolipids |
Have a sphingosine base |
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Where are glycolipids found? |
Component of nerve tissue and cell membrane - lipid transport |
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Example of a glycolipid |
Cerebroside (galactose ) and gangliosides (glucose) |
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What is a lipoprotein |
Contains both lipids and a protein and cholesterol |
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Lipoprotein functions |
They allow fats to move through the water inside and outside our cells They transport lipids - especially cholesterol |
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Lipoprotein classes include: |
Chylomicrons (largest) VLDL IDL LDL HDL (smallest) |
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Chylomicrons |
Take lipids from SI through the lymph cells |
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T/G The less protein a lipoprotein contains the less "dense" it is considered |
True |
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LDL |
"Bad cholesterol" higher percentage of cholesterol and fat than protein Tranports cholesterol from liver to the Peripheral tissues |
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Why is LDL considered atherogenic |
When in excess LDL can promote the build up of plaque in artery walls and is also prone to oxidation |
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What will raise LDL in the diet? |
Saturated fats |
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How is LDL taken up by the cells? |
Via endocytosis in cell via the LDL-receptor sites Major pathway for delivery of cholesterol |
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HDL |
"Good cholesterol" Higher percentage of protein that fat and cholesterol Very dense Transports fats and cholesterol from tissues back to the liver for excretion and catabolism |
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How is HDL used in the liver? |
Can be used as a substrate for bile acid synthesis |
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Apolipoproteins |
Proteins that bind lipids to form lipoproteins Responsible or surface recognition of lipoprotein particles by cell receptors |
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T/F Higher levels of apolipoprotein A & B has been found to be more highly correlated to heart disease than LDL cholesterol |
True |
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Eicosanoids Function |
Paracrine (localized) signalling |
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How are eicosanoids made? |
oxidation of EFA's |
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How are EFA's accessed to be used in the eicosanoid synthesis pathway? |
EFA's are typically bound in the phospholipid bilayer and are cleaved by the enzyme phospholipase A2 in response to inflammatory mediators or injury. |
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T/F The kind of eicosanoid produced depends on the type of PUFA cleaved from the membrane. |
True |
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Can arachidonic acid cause chronic inflammation? |
Yes, if metabolized in excess it can promote chronic inflammation and is considered pro-atherogenic. When it is undersupplied though the body become unable to support itself in times of injury or infection` |
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Eicosanoids include: |
Prostaglandins Thromboxane's Prostacyclin Leukotrienes |
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Thromboxane function? |
Clot formation |
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Prostacyclin function? |
Inhibit plates activation Vasodilators |
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Leukotrienes |
Heal wounds and injuries In excess can promote inflammation |
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Prostaglandin Subtypes |
PGE 1 & 3 - Anti-inflammatory PGE 2 - Pro-inflammatory |
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PGE 1 & 3 sources and effects |
Omega 3 & 6 Have heart and artery protective effects |
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PGE 2 sources and effect |
Omega 6 - in excess can cause pain and inflammation and encourage blood clot formation |
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Eicosanoid hormone funtions: |
Alter the size and permeability of blood vessels
Alter the activity of platelets and blood clotting Change and modify the inflammation process |
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How is membrane cleavage of eicosanoid inhibited? |
By cortisone & prostaglandin synthesis and aspirin. |
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Steroids |
Lipids derived from four-membered saturated ring |
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Important steroid derivatives include: |
Glucocorticoids & mineralcorticoirs made in adrenal gland Androgens and estrogens made in testes and ovaries Bile acids made in the liver Vitamin D made when UV rays cleave cholesterol in subcutaneous fat to form D3 |
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Cortisol is a.. |
Glucocorticoid |
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Aldosterone is a |
Mineralcorticoid |
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Androgens are |
Testosterone |
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Phytosterols |
groups of lipids found in plants - inhibit absorption of cholesterol |
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Cholesterol |
Waxy sterol fat Carried by lipoproteins |
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Cholesterol function: |
1) Builds and maintains cell membranes 2) Determines membrane permeability 3) Production of various steroid hormones and Vit. D 4) Aids in the production of bile and fat-soluble vitamin metabolism 5) Insulates nerve fibers 6) Antioxidant |
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Major ares of fat digestion |
Mouth - lingual lipase Stomach - gastric lipase Proximal SI - Major are of fat digestion |
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How are fats digested in the proximal small intestine |
Via peristaltic action and 1) Bile 2) Pancreatic lipase - TG's into glycerol, FA's and mono and diglycerides |
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What is the composition of gallbladder bile? |
97% water 0.7% bile salts 0.2% bilirubin 0.5 % cholesterol, fatty acids, and lecithin |
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How are bile salts formed? |
Bile acid is conjugated with taurine or glycine |
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What hormones are released when fats reach the duodenum |
CKK and GIP/somatostatin which delay gastric emptying |
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CCK |
made by the cells of the small intestine and induce the secretion of pancreatic digestive enzymes (lipases) and bile from the gallbladder |
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Where are Micelles broken down |
At the brush border of the intestines by pancreatic lipase which act to cleave off FA's from the TG's in the micelles |
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How do fatty acids and monoglycerides enter the enterocytes? |
Via Passive diffusion or a protein carrie mediated transport system |
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What happens to the bel salt that are released from the micelles? |
Returned to the lumen of the SI and actively reabsorbed in the ileum and recycled via enterohepatic circulation |
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What are transport truck for TG's |
Chylomicrons |
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where does re-esterification of TG's inside the intestinal cell occur? |
The ER |
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Once TG's are re-esterified in the intestinal cells after absorption what happens to the chylomicrons? |
Form into lipid droplets coated with cholesterol, phospholipids and apolipoproteins and then further processing in the golgi apparatus Once compete the chylomicrons are released by the enterocyte into the lacteals of the villi and are transported by the lymph Once they reach the thoracic duct they are released into the bloodstream/general circulation Then they are carried to the liver where they are repackaged into lipoproteins and transport to adipose for storage. |
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What cells primarily do beta oxidation? |
SKM, heart muscle & liver |
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What controls the breakdown of fatty acids? |
Hormone sensitive lipase |
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How do adipocytes breakdown chylomicrons? |
lipoprotein lipase |
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What can the glycerol be used for from the TG's? |
gluconerogensis or transported back to the liver for TG synthesis |
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Hormones that control lipogenesis |
Insulin Increase lipogenesis Decreases the activity of hormone sensitive lipase which breaks don the TG's stored in fat tissues |
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Thyroid hormone |
Increase lipolysis and cellular metabolism |
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Glucocorticoids (ACTH and Cortisol) |
Increases lipolysis Increase the rate of HSL and the permeability of fat cell membranes to fatty acids |
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Epinephrine and norepinephrine |
increase the activity of HSL |
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Growth hormone |
Lipolytic effects |
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Why is adipose considered an endocrine organ? |
Secreted leptin, adiponectin and resistin which influence energy metabolism and modify appetite. |
