by agawhd


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The body prefers glucose which is used for ATP production - amino acid synthesis – glycogen synthesis and triglyceride synthesis.
Glucose catabolism takes place in four steps, a.k.a cellular respiration
1-Glycol sisaka anaerobic cellular respiration. Glucose is broken down to two pyretic acid molecules
(2)Formation of acetyl coenzyme A: takes place in matrix? of mitochondria, acetyl CoA is needed for the next step.
(3)Krebs cycle occurs in matrix of mitochondria, prepares the Acetyl CoA to enter the electron transport chain; generally six molecules of CO2 (three from each pyruvate).
(4)Electron transport chain: e- are transferred through a series of e- carriers to produce lots of ATP if O2 is present. The Krebs cycle and the e- transport chain are referred to as aerobic respiration.
Lipid Metabolism
Lipids are not soluble in water and so must be transported usually by proteins forming lipoproteins. There are four major classes:
(1)Chylomicrons
Transport dietary lipids to adipose tissue for storage
(2)Very low-density Lipoproteins (VLDLs
Form in hepatocytes from endogenous lipids, stored in adiposities as LDLs.
(3)Low-density Lipoproteins (LDLs)
Used by the body to repair membranes, synthesize steroid hormones and site salts. If in excess LDLs deposit on artery walls and form plaques which can ↑ risk for coronary artery disease. This is “bad” or “lousy” cholesterol.
(4)High-density Lipoproteins (HDLs)
Remove excess cholesterol from cells to the liver for elimination. This is “good” cholesterol.
Inhibited by insulin Lipogenesis – Lipid Anabolism
Lipids are synthesized by liver and d dispose cells from excess dietary carbohydrates, proteins and fats – all are converted into triglycerides.
Essential Amino Acids
Amino acids that cannot be synthesized by the body and must be taken in in the diet.
Non-essential Amino Acids
Can be synthesized by the body.
Absorptive State Rxns
-About 50% of glucose from a meal is used to produce ATP -Most glucose is absorbed by hepatocytes is stored as glycogen -Some fatty acids and triglycerides synthesized in liver stay there but most are packaged as VLDLs and sent to adipose tissue for storage -Adipocytes also pick up any ‘left over’ glucose and convert it into triglycerides. -Most dietary lipids are stored as adipose tissue -Absorbed amino acids are used to synthesize proteins or stored, after conversion as fatty acids.
Fasting and Starvation
-Fatty acids in blood ↑ -Hepatocytes produce ketone bodies from breakdown of fatty acids; ketone -fuel body by brains and cells
Proteins and carbs provide four calories of energy.
Fats provide nine calories of energy.
Fat soluble Vitamins
A, D, E and K need bile salts and dietary lipids to be absorbed; stored in liver of adiposities.
Water soluble
– Dissolved in body fluids; not stored so excess is excreted in urine.
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