integration and regulation of metabolism

Question 1

what are the
central unifying
core of
metabolism.

Answer 1

Glycolysis and the
TCA cycle are the
central unifying
core of
metabolism.

Question 2

RECALL - A fatty acid molecule is in a
more reduced state than a molecule of
glucose.

Answer 2

Thus, more
energy is
extracted from
the oxidation of
FA than CHO.

Question 3

Interconversion of the macronutrients

Answer 3

Protein, carbohydrate, fat
– fat (acetyl CoA) does not make glucose
– glucogenic and ketogenic (both) amino acids
– pyruvate central role
• In all figures:
– Anabolism “up”
– Catabolism “down"

Question 4

Overview of lipid metabolism,
emphasizing the central role of
acetyl CoA

Answer 4

Dietary Fat
• Excess Protein / Carbohydrate
– fat storage in adipose tissue
• Steroid and ketoacid production

Question 5

Amino Acid Metabolism

Answer 5

Interchanges of selected amino acids and
their metabolites among body organs and
tissue

Question 6

Central role of the liver in metabolism

Answer 6

• Metabolic pathways for glucose 6-phosphate in
the liver
– anabolic pathways pointing upward (liver glycogen, mucleotides, triacylglycerols, cholestrol, fatty acids)
– catabolic pathways pointing downward (pyruvate, acetyl coa, ribose -5- phosphate )
– distribution to other tissues, horizontally (blood glucose, glucose- -phosphate in the liver)
• Pathways of amino acid metabolism in the liver
• Pathways of fatty acid metabolism in the liver

Question 7

Macronutrient metabolism in the

fed state / early fasting

Answer 7

• Disposition, in the fed state, of
– dietary glucose, amino acids, and fat
• Insulin is an anabolic hormone
• Postabsorption flow of substrates in
tissues
– among the liver, CNS, adipose tissue, muscle,
and red blood cells

Question 8

Macronutrient metabolism in the

fasting and starvation

Answer 8

• Flow of substrates among the liver, CNS,
adipose tissue, muscle, and red blood cells
during fasting and starvation states.
– Broken lines indicate major substrate flow during
fasting, lasting about 2 days
– Solid lines reflect predominant substrate flow during
the starvation state
• Shift during starvation to fatty acid and glycerol
export from adipose tissue
– increased use of fatty acids and ketones as fuel by
CNS and muscle (sparing protein)

Question 9

Starvation

Answer 9

• ptn syn ↓ (ptn →CHO to brain etc)
• ptn bkd ↓ (N losses small)
- adaptative mechanism (loss of 3-4 g ptn/d)
- critical ptn maintained (eg, heart, kidneys)

Question 10

Stress Factor

Answer 10

• Stress alone

* Stress combined with starvation

Question 11

Infection/Stress

Answer 11

• ptn bkd ↑
– stress could be part of starvation
Eventually, organs weaken, ↓ immune fn,
↑ infections/disease, death