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28 Cards in this Set
- Front
- Back
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2 metabolic states and what drives them |
*absorptive: period when ingested nutrients are entering the blood, up to 4hrs posts meal *postabsorptive: period when GI tract is empty of nutrients and energy must be supplied from catabolism of body stores |
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Difference between digestion and absorption |
digestion: breakdown of food into molecules small enough to be absorbed absorption: movement of food molecules from GI into the blood (digestion before absorption) |
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Describe carb and protein absorption |
*absorbed by DI directly into the blood, circulates to the liver via portal vein, and then into systemic circulation |
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How are ingested fats transformed? |
*emulsified by bile salts (forming micelles) *gut cells transform ingested fat into chylomicrons |
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What is a chylomicron? |
*one major group of lipoproteins that enable fats to move within water-based solution of blood |
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How do chylomicrons move after their formation in the gut? |
travel through the lacteals (lymph vessels) to enter blood via the thoracic duct |
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Describe the breakdown of chylomicrons in the blood, and then in the liver |
*as they enter capillaries of adipose tissue and muscle cells they are broken down into fatty acids and chylomicron remenant *remenant taken up by the liver and re-packaged as very low density lipoprotein (VLDL) and then resecreted into the blood |
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What is the role of chylomicrons and VLDLs in the blood? |
deliver the fatty acids in their core to adipose tissue for storage or muscle tissue for energy. |
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name the main lipoprotein types |
chylomicrons VLDLs LDLs HDLs |
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what is the role of LDLs in the blood |
carry most of the body's cholesterol and deliver it to cells that need it |
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what is the role of HDLs in the blood? |
*remove excess cholesterol from endothelial lining of blood vessels |
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what is the main source of energy during the absorptive state? |
glucose |
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what happens to glucose during the absorptive state? |
*catabolized to produce ATP within cells *turned into glycogen in muscle or liver *turned into fat in adipose tissue after filling glycogen stores |
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What happens to glucose in the liver (3)? main thing first |
*packaged to form VLDLs to ultimately for stored as triglyceride in adipose tissue *made into glycogen (100g) *processed to form triglycerides (small storage) |
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What breaks down absorbed triglycerides? What else is broken down by these? |
lipoprotein lipase breaks down chylomicrons into fatty acids, monoglycerides, and chylomicron remnants VLDLs are also broken down into fatty acids and monoglycerides |
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What does absorbed fat ultimately become |
fat in adipose tissue |
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What happens to most absorbed amino acids? |
majority are taken up by cells for protein synthesis |
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What happens to absorbed amino acids in the liver? |
*make liver proteins *make plasma proteins *be converted into keto acids |
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What can keto acids be used for? |
converted to energy or stored as fat |
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How do you account for the net gain of protein in the absorptive state? |
It is replacing protein lost during the post absorptive state (excess protein makes fat) |
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What is the main goal in the postabsorptive state? |
maintain blood glucose levels, despite no glucose absorption from the GI tract |
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2 main events that maintain normal plasma glucose levels |
*processes that provide source of blood glucose *increased fat utilization |
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Name the processes that provide sources of blood glucose (3) |
*glycogenolysis *gluconeogenesis from fat *gluconeogenesis from protein |
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When do amino acids become the source of blood glucose? |
a few hours into postabsorptive state |
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which portion of a triglyceride goes through gluconeogenesis? |
gycerol |
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How does glycogenolysis in the muscle provide blood glucose? |
via the Cori cycle |
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What macronutrient is preferentially utilized in the post absorptive state? |
fat |
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What is utilization of fat instead of glucose called? What allows this to happen |
glucose sparing via accelerated lipolysis |
