Energy Metabolism Flashcards
what is energy metabolism?
the combined process of energy storage and energy production from various nutrient sources
what is the most energy demanding organ?
brain
how many grams of glucose does the body use each day and how many of those grams are used by the brain?
160g total
120g used by brain
what happens when there is too much glucose?
glycolysis
glycogenesis
what is glycolysis?
converts glucose to puruvic acid
what is glycogenesis?
combines glucose to form glycogen
what happens when glucose is low?
glycogenolysis
gluconeogenesis
what is glycogenolysis?
hydrolyses glycogen to glucose monomers
(chemicall breaks down glycogen)
what is gluconeogenesis?
forming glucose from noncarbohydrate precursors
what are some other sources used for gluconeogenesis?
lactate
glycerol
amino acids
what becomes the major source of ATP production when glucose levels fall?
fatty acids
what tissues uses fatty acids overy glucose for ATP production?
liver
cardiac muscle
resting skeletal muscle
why can’t the brain use fatty acids directly?
due to blood brain barrier
what is a blood brain barrier?
a filtering mechanism of the capillaries that carry blood to the brain and spinal cord tissue
blocks certain substances
what is the process involved in lipid metabolism when glucose levels fall?
1) triglycerides undergo lypolysis (breaking down of glyceryol and fatty acids)
2) glycerol that has been broken off from fatty acids can be used in gluconeogenesis to make glucose
3) fatty acids are broken down to acetyl-CoA molecules
(beta-oxidation)
what is beta-oxidation?
the breaking of the fatty acid bonds, between the 2nd and 3rd chain to produce aceytol-CoA molecules to enter kreb’s cycle
what can happen in the liver?
gluconeogenisis
what is involved for the main reaction in gluconeogenisis?
oxaloacetate
what is oxaloacetate?
4 carbon compond that acetyol CoA binds to
used in liver for gluconeogeneisis
what happens under extended fasting?
all of the oxaloacetate from the kreb’s cycle is shunted toward gluconeogenesis
= acetyl CoA produced from fatty acids have no where to go
what happens when there is an excess of acetyl CoA?
production of ketone bodies by the liver
what are the 3 ketone bodies produced?
1) acetoacetate
2) 3-hydroxybutyrate
3) acetone
produced by 2 acetyol CoA combining together
what is the process of ketone bodies to other body parts?
- ketone bodies leave the liver and gets transported to other tissues in the body (brain)
- when arrived at tissues, they are converted back to acetyol CoA and used for energy
(except fot acetone)
why is ketone body production important?
minimize gluconeogenesis
save protein catabolism
what happens with an accumulation of ketone bodies?
increases acidity of the blood = ketoacidosis
what is ketoacidosis?
too much accumulation of ketone bodies that increases the acidity in the blood
can be deadly
what can ketoaidosis be a result of?
starvation
lack of carbs
uncontrolled diabetes mellitus
what does deaminated mean?
the removal of amino froup from amino acid to change CO2 to urea in the liver
what happens when there is an excess of amino acids?
becomes deaminated
what is the carbon skeleton used for?
cellular respiration
lipid production
gluconeogenesis
what happens to amino acid during fasting?
amino acid catabolism provides oxaloacetate for gluconeogenesis
what minimalizes amino acid catabolism?
use fo fatty acids and ketone bodies
