Short-term energy balance

Question 1

What is the main metabolic focus of the body?

Answer 1

To maintain uniform glucose blood level at 5mM or 90mg/dL

Question 2

Relationship between FA blood level and insulin level

Answer 2

Inverse relationship

Question 3

In postabsorptive state, levels of:
GLUT4?
glucose oxidation?
liver glycogenolysis and gluconeogenesis?
HSL activity in adipocyte?
ACC activity in liver?
FA synthesis in liver?

Answer 3

GLUT4? - low
glucose oxidation? - low, to maintain blood glucose
liver glycogenolysis and gluconeogenesis? - high to supply blood glucose
HSL activity in adipocyte? - high to increase FA release to blood
ACC activity in liver? - low, means low malonyl-CoA, means high CAT-1, means high FA oxidation
FA synthesis in liver? - low, oxidation is favored

Question 4

after balanced meal, levels of: 
GLUT4?
glucose oxidation?
liver glycogenolysis and gluconeogenesis?
HSL activity in adipocyte?
ACC activity in liver?
FA synthesis in liver?

Answer 4

GLUT4? - high
glucose oxidation? - high, to reduce blood glucose
liver glycogenolysis and gluconeogenesis? - low
HSL activity in adipocyte? - low
ACC activity in liver? - high, so low FA oxidation
FA synthesis in liver? - high, to use up blood glucose

Question 5

Why do sugars and protein get into the circulation faster than FA?

Answer 5

• sugars and protein leave the small intestine via the hepatic portal vein (HPV)
• HPV immediately passes through liver so liver gets first shot at glucose and AAs
• pancreatic vein empties into HPV so liver also gets insulin first
• transit to liver is rapid, so response to ingested glucose is rapid

Question 6

Why do FAs get into circulation slower than sugar and protein?

Answer 6

• FAs leave small intestine via lacteals which merge into thoracic duct
• thoracic duct empties into veins of neck
• heart is the first organ to see FAs
• entry of ingested fat into bloodstream takes hours

Question 7

What is basal metabolic rate and when do you take it?

Answer 7

• what it takes to keep your cells/organs going

- taken in morning (post-absorptive state) on an awake but sedentary individual

Question 8

BMR is highly proportional to:

Answer 8

non-fat body mass

Question 9

major contributors to BMR

Answer 9

1) skeletal muscle - 30-40% of body mass
2) brain, liver, and kidney use a lot of energy per unit mass
3) heart is always pumping
4) adipose tissue uses almost no energy in comparison
5) exercise and digestion drastically increase BMR so neither can be happening when measuring