20. Metabolic aspects of stress in protein and energy metabolism

Question 1

What is the primary reaction of the body with stress? What can it conflict with?

Answer 1

at first, there is a non-specific reaction by the body. Lot of energy available to have the body to react.
 Stress reaction can react in conflict with homeostasis (barely eat with heart break)

Question 2

What does homeorhetic control of stress mean?

Answer 2

keep homeostasis, but metabolism changes.

Question 3

What is the first organ to be affected by stress? What happens?

Answer 3

First organ to be affected by stress: brain.
GH released:
1. Protein synthesis increases
2. Fat breakdown increases

3. Little effect compared to release of ACTH. Acts on adrenal glands and does a lot of things: monomers circulating in stress response. Re-prioritisation & repartitioning

Question 4

Fructose dose:
What happens with glucose with HD?
What happens with fructose oxidation HD vs LD?

Answer 4

Fructose-derived glucose is higher in high dose of fructose (small effect in overall glucose appearance)
High dose of fructose: less glucose produced by the body
Fructose oxidation does not differ between low and high dose fructose.

Question 5

Reprioritization of hepatic protein synthesis, three clinical aspects?

Answer 5

• Decreases carrier proteins
• Increase immuno-active proteins (APP: acute phase proteins)
• Increase synthesis of gluthatione, collagen (for wound)

Question 6

Characteristics APP (acute phase proteins)?

Answer 6

• Primarily synthesised by the liver
• Released into the circulation
• Various (partly unknown) functions
• Specific amino acid composition
• Up to 70 gram per day (= 20% of daily capacity):

Question 7

Over 10 days, you may lose X% of total body protein depending on the trauma (even when just having fever)

Answer 7

6-7%

Question 8

Why is there protein loss in response to trauma?

Answer 8

• APP are synthesized which are disproportionally rich in certain amino acids
• This depletes tissue pools of these amino acids, leaving an unbalanced amino acid mixture which cannot be used for protein synthesis.

Question 9

Cellular stress response can exist of..

Answer 9

• Heat, anaerobic situations, radicals, etc
• Protection for surcical
• HSP (molecular chaperones)
• Glucose regulated proteins (metabolic problems, atp, heat)

Question 10

What is the cross stressor adaptation hypothesis?

Answer 10

Sport and health:
A regular metabolic stress caused by physical activity could help to overcome other stressors.
This might involve HSP

Question 11

What is shielding?

Answer 11

Shielding = body is shielded from stressful environmental conditions.
Shielding is to avoid stress, not overcome it for a very short time. Stress tolerance in general is lower.
You still have the stress, but body decides to avoid it. E.g. start worrying day before exam, if you start earlier you gradually build it up and are better tolerated or something

Question 12

 Costs for protein synthesis (kJ/gr) are part of (A) GE (B) DE (C) ME (D) none of above

Answer 12

(D) none of above

Question 13

 Protein synthesis is a very complex and well-programmed metabolic process. How much heat is produced during the synthesis of 1 gr of protein? (A) 23.6 kJ/gr (B) 18.4 kJ/gr (C) 5.2 kJ/gr (D) 4.0 kJ/gr

Answer 13

(D) 4.0 kJ/gr

Question 14

 The complete oxidation of 1 gram muscle protein within the body (with urea as end product) yields? (A) 4 kJ/gr (B) 17 kJ/gr (C) 18.4 kJ/gr (D) 23.6 kJ/gr

Answer 14

(C) 18.4 kJ/gr

Question 15

 PASSAGE RATE: in monogastrics (one stomach), an (articifial) increase of protein through the digestive tract will NOT influence the …. Energy (kj/gr) of the ingested protein. (A) gross (B) digestible (C) metabolizable (D) none of above.

Answer 15

(A) gross
Gross energy is associated with protein, when passage rate is increased you affect how much protein is absorbed/metabolized.

Question 16

 Protein structure and digestion: for proteins we distinguish different structures. Which of these structures is the main target for the proteolytic enzymes from the exocrine pancreas? (A) primary (B) secondary (C) tertiary (D) quaternary.

Answer 16

(A) primary
From secondary on, they change structure already with pH.

Question 17

 Technological treatment of dietary protein that improves the metabolic utilization of that protein in the body has caused: (A) improvement of the amino acid pattern (B) improvement of the digestibility of protein (C) A + B true (D) A + B false.

Answer 17

(C) A+B true

Better pattern = different production of energy (more energy with other aa that enter TCA cycle differently)

Question 18

 Protein synthesis in the body can be used for different purposes with regard to maintenance, adaptation and net synthesis of body proteins.

Give a ranking of these purposes with regard to the relative amount of dietary proteins required to support them.

(A) maintenance > adaptation > net synthesis (B) net synthesis > maintenance > adaptation (C) adaptation > net synthesis > maintenance (D) net synthesis > adaptation > maintenance

Answer 18

(D) net synthesis > adaptation > maintenance

Question 19

 The metabolic half-life of protein is important for their renewal rate. How much time is minimally required for a >90% renewal of proteins with a half-time of 6 hrs? (A) 6 hrs (B)12 hrs (C) 18 hrs (D) 24 hrs

Answer 19

(D) 24 hrs