2 - Key Organs in Metabolism Flashcards
Catabolism
Degradation phase of metabolism
Carbs / Fats / Lipids –> Small Molecules
–> Produce Energy
Anabolism
BIOSYNTHESIS
Small Precursors -> Complex Molecules
Use Energy
Liver
in Metabolism
-
Primary Site of Energy Storage
- Excess energy is stored as Glycogen
- when FULL –> lipid in adipose tissue
- Excess energy is stored as Glycogen
- Glucose & Lipid metabolism
- Glycolysis = Catabolism
- Gluconeogenesis (GNG) = Anabolism
Pentose Phosphate Pathway
G6P -> Nucleotides + NADPH
Liver Metabolism Pathways
-
Glycolysis
- Glucose -> Pyruvate + ATP -> Lactate in muscle
-
Citric Acid Cycle
- ATP + CO2
-
Pentose Phosphate Pathway
- Nucleotides + NADPH
What are the fates of Acetyl-CoA?
-
Catabolism:
- -> TCA -> ATP Energy Production
-
Anabolism:
- -> Cholesterol + FFA
Liver + Pancreas
HIGH blood Sugar
-
Pancreas -> Release Insulin
-
-> Stimulate formation of Glucagon @ Liver
- = Glycogenesis
- -> Stimulate Glucose UPTAKE from blood
- –> into Muscle / Kidney / Fat
- Lowers Blood Sugar
- –> into Muscle / Kidney / Fat
-
-> Stimulate formation of Glucagon @ Liver
Muscle
in Metabolism
-
“Selfish” Tissue
- Has large storage of Glycogen
- G6P encourage TRAPPING of glucose in tissue
- Major Fuels for the muscle are oxidized:
- Fatty Acids
- Ketone Bodies
- Carbohydrates
Order that Muscle Uses Its fuels
- Fatty Acids
-
Ketone Bodies
- only if FA’s are NOT available
- Carbs
Hexokinase Trapping of G6P
- Glucose -> Cytoplasm of cell (GLUT4)
-
Hexokinase + ATP converts glucose -> G6P
- G6P CAN NOT BIND TO GLUCOSE TRANSPORTERS
- CAN NOT LEAVE THE PLASMA MEMBRANE
-
Hexokinase + ATP converts glucose -> G6P
- How muscle keeps the energy source
Cori Cycle
- Prevents Lactic Acidosis in the Muscle
- under ANAEROBIC conditions
- Buildup of Lactic Acid –> Muscle Cramps
- Uses Lactate Dehydrogenase (LDH)
- in both MUSCLE & LIVER
Cori Cycle - MUSCLE
-
Anaerobic Glycolysis
-
G6P -> Pyruvate -> LACTATE
- -> Blood -> Liver
- LDH
-
G6P -> Pyruvate -> LACTATE
Cori Cycle in LIVER
-
Gluconeogenesis
- Lactate -> Pyruvate -> Glucose
- -> blood -> back to Muscle
- LDH
- Lactate -> Pyruvate -> Glucose
Lactate Dehydrogenase
LDH
- Integral to the Cori Cycle
- In Muscle:
- __Pyruvate -> Lactate
- uses energy (NADH)
- __Pyruvate -> Lactate
-
In Liver:
- __Lactate -> Pyruvate
Brain
In Metabolism
-
“Picky” tissue
- Uses 20-25% of body’s produced ATP
- Hormones tell brain whats going on with energy
- Uses mainly GLUCOSE as primary source of fuel
- In starvation uses Ketone Bodies
- produced by the liver
-
Fatty Acids are not used as fuel
- B/c they are bound to ALBUMIN in plasma
- –> can NOT cross the BBB
- B/c they are bound to ALBUMIN in plasma
Brain’s Hierarchyof Fuel
- Glucose
-
Ketoacids/ketobodies
-
produced in Liver
- __replaces glucose in starvation
- NOT converted to glucose in brain
-
produced in Liver
-
**Fatty acids are NOT used
- albumin bound and can not cross BBB
Adipose Tissue as Storage
-
Major Reservoir of metabolic fuel as Triacylglycerols
- FA’s + Glucose
-
FA’s are esterfied in the Liver
- -> transported to adipose tissue by lipoproteins
-
FA’s are esterfied in the Liver
- FA’s + Glucose
-
Lipases are stimulated by INSULIN to take up TG’s
- –> CoA derivatives are transferred as Glycerol
Lipoproteins
Transport Fatty Acids
that were esterfied in the liver
–> Adipose Tissue
High Glucose Levels inside adipocytes
- Indicate adipocytes to Synthesize TG’s
- Glucose (G6P) + FA’s (Fatty acyl-CoA)
- High Glucose = Increase TG Storage
Low (Paucity) Glucose Levels tell Adipocytes to?
- -> Release Fatty Acids -> the blood
- -> back to the Liver
Hormone Sensitive Lipase
- Stimulated by INSULIN
- Tells adipocytes to Break Down TG’s -> FA + Glycerol
-
Fatty Acids
- recycled within cell to make more TG’s
- -> return to Liver
-
Glycerol
- -> back to Liver to become glucose for energy
-
Fatty Acids
Kidney
in Metabolism
- Major role is to Excrete Waste in the form of urine
- Can also contribute to energy with
- _Gluconeogenesis during starvatio_n
-
Water-soluble materials are reabsorbed
- uses ENERGY to filter
Consumer Organs
Uses fuels to regenerate ATP consumed
Brain
Muscle
Maintainer Organs
Regulates the concentration of fuels in blood
Adipose Tissue
Liver / Pancreas
What does the Liver do during starvation?
- Senses the glucose is declining
-
Glycogenolysis
- Glycogen -> Glucose
- Glucose to feed the Brain
- Glycogen -> Glucose
-
Glycogenolysis
What does the Adipose Tissue do during starvation?
-
Lipolysis
-
Lipids -> FFA + Glycerol -> LIVER
- __FFA -> Ketone Bodies for brain
- FFA can also go to muscle for energy
- Glycerol -> Glucose for brain
- __FFA -> Ketone Bodies for brain
-
Lipids -> FFA + Glycerol -> LIVER
What does the Muscle do during starvation?
- Glycogen -> Pyruvate for energy
- Fatty Acids + Protein -> AA’s for energy
- Pyruvate / Lactate / AA’s –> Gluconeogenesis in Liver
- Glucose + Ketone Bodies to Brain for energy
What does the Brain do during starvation?
- Uses the Glucose from all sources
- Will use Ketone Bodies if all out of glucose
Types of Carbohydrates
as energy fuels
-
Glucose
- from diet or gluconeogenesis (AA / Glycerol)
-
Lactate
- metabolite of glycogen
- Cori Cycle
-
Pyruvate
- intermediate in glycolysis (uses ATP)
-
Glycerol
- Adipose tissue TG’s -> Glycerol + FFA
Types of FATS as energy fuels
-
Fatty Acids
-
Adipose
- TG’s -> FA’s + glycerol
-
Adipose
-
Ketoacids
-
Liver @ fasting
- FFA -> Ketoacids for brain
-
Liver @ fasting
-
TG’s
- Stored in Adipose / Muscle
-
Produced in liver
- __FFA / Glucose / AA’s -> TG’s
Amino Acids as an Energy Fuel
-
Liver
-
Converts Amino Acids into Glucose
- = gluconeogenesis
-
Converts Amino Acids into Glucose
