Metabolism 1

• good cholesterol


  HDL
• bad cholesterol 


  LDL
• path 1

  • provide energy to all tissues - meet energy demand

  path 2

  • conversion to glycogen in muscle

  path 3

  • conversion to glycogen & triglycerides in liver

  path 4

  • stored as triglycerides/fat in adipose tissue


  glucose (galactose, fructose) in absorptive state
• path 1

  • stored as monoglycerides in adipose tissue


  triglycerides in absorptive state
• path 1

  • conversion to protein in all tissues (constantly synthesizing proteins)

  path 2

  • conversion to urea, CO2 + H2O + energy, triglycerides in liver


  amino acids in absorptive state
• general trend is anabolic (building things)


  absorptive state
• most energy comes from absorbed glucose

  absorptive state
• most excess nutrients are stored as triglycerides


  absorptive state
• energy is provided primarily by absorbed carbohydrates in a typical meal


  nutrient metabolism during absorptive state
• there is net uptake of glucose by the liver


  nutrient metabolism during absorptive state
• some carbs stored as glycogen in liver and muscle, but most carbs and fats in excess of that used for energy are stored as triglyceride in adipose tissue


  nutrient metabolism during absorptive state
• some synthesis of body proteins from absorbed amino acids; remaining amino acids in dietary protein are used for energy or used to synthesize triglycerides


  nutrient metabolism during absorptive state
• the absorptive state


  image:

  
• the post-absorptive state


  image:

  
• path 1:

  • glycogen -> glucose

  path 2:

  • lactate -> glucose

  path 3:

  • amino acids -> glucose

  path 4:

  • glycerol -> glucose


  glucose from liver -> blood glucose -> glucose to energy in nervous tissue (post-absorptive state)
• 4-6 hours post-meal


  "fasted state"
• path 1:

  • triglycerides in adipose converted to fatty acids
  • fatty acids converted to energy + CO2 + H2O in all tissues except nervous

  path 2:

  • triglycerides in adipose converted to fatty acids
  • fatty acids converted to energy and ketones in the liver

  path 3:

  • triglycerides in adipose converted to fatty acids
  • fatty acids converted to energy and ketones in the liver
  • ketones converted to energy + CO2 + H2O in all tissues except nervous


  triglycerides in the post-absorptive state
• general trend is catabolic


  post-absorptive state
• most energy comes from stored triglycerides

  post-absorptive state
• glucose sparing occurs:

  • most tissues reduce glucose utilization saving it for neural tissue


  post-absorptive state
• ketones derived from fatty acids provide neural energy in prolonged fasts:

  • spares protein catabolism


  post-absorptive state
• glycogen, fat, and protein syntheses are curtailed, and net breakdown occurs


  nutrient metabolism during post-absorptive state
• glucose is formed in the liver both from the glycogen stored there and by gluconeogenesis from blood-borne lactate, pyruvate, glycerol, and amino acids; the kidneys also perform gluconeogenesis during a prolonged fast


  nutrient metabolism during the post-absorptive state
• the glucose produced in the liver (and kidneys) is released into the blood, but its utilization for energy is greatly decreased in muscle and other nonneural tissues


  nutrient metabolism during the post-absorptive state
• lipolysis releases adipose-tissue fatty acids into the blood, and the oxidation of these fatty acids by most cells and of ketones produced from them by the liver provides most of the body’s energy supply


  nutrient metabolism during the post-absorptive state
• the brain continues to use glucose but also starts using ketones as they build up in the blood


  nutrient metabolism during the post-absorptive state