PROTEIN SECTION LECTURE #3 (Part 2)

Question 1

What is the role of amino acids in muscle mass?

Answer 1

Amino acids are the building blocks of muscle, essential for the growth and repair of muscle tissue.

Question 2

Besides amino acids, what other factors are involved in skeletal muscle growth?

Answer 2

Other factors involved in skeletal muscle growth include hormones such as insulin, which prevents muscle breakdown, and growth hormone and testosterone, which increase muscle hypertrophy.

Question 3

What does the term ‘anabolic’ refer to in the context of muscle mass?

Answer 3

Anabolic refers to the state of building tissue and storing nutrients, which is associated with muscle growth and increased muscle mass.

Question 4

How does cortisol affect muscle mass?

Answer 4

Cortisol, often released in response to stress, can lead to a catabolic state, which breaks down muscle tissue to provide amino acids for protein synthesis in other parts of the body, potentially leading to muscle atrophy.

Question 5

What is the effect of insulin on muscle tissue?

Answer 5

Insulin helps to prevent muscle breakdown, thus supporting muscle maintenance and growth.

Question 6

What hormones are known to increase muscle hypertrophy?

Answer 6

Growth hormone and testosterone are known to increase muscle hypertrophy.

Question 7

What is the difference between anabolic and catabolic processes in muscle metabolism?

Answer 7

Anabolic processes involve building up muscle tissue and storing nutrients, while catabolic processes involve the breakdown of muscle tissue, often leading to muscle atrophy.

Question 8

What is nitrogen balance?

Answer 8

Nitrogen balance is a measure of the relationship between the amount of nitrogen taken into the body through food and the amount of nitrogen leaving the body through excretion in urine, feces, skin, hair, nails, etc. Since protein is the primary nutrient that contains nitrogen, this balance is an indicator of protein status.

Question 9

What does it mean if your nitrogen intake is equal to nitrogen excretion?

Answer 9

If nitrogen intake is equal to excretion, it means you are in nitrogen balance, indicating that the amount of protein consumed meets the body’s current needs.

Question 10

What is a negative nitrogen balance and what can cause it?

Answer 10

A negative nitrogen balance occurs when nitrogen excretion exceeds intake, meaning the body is losing more protein than it is consuming. This can be caused by factors such as stress, illness, or inadequate protein intake.

Question 11

What is a positive nitrogen balance and when might this occur?

Answer 11

A positive nitrogen balance occurs when nitrogen intake exceeds excretion, indicating that the body is retaining more protein, which is often seen in situations like pregnancy, body-building, growth spurts, and healing.

Question 12

What is the RDA for protein and how is it determined?

Answer 12

The RDA (recommended dietary allowance) for protein is the amount considered sufficient for the body to prevent disease. The RDA values are derived from nitrogen balance studies.

Question 13

How is nitrogen balance typically measured?

Answer 13

Nitrogen balance is measured by having subjects consume a diet of known protein levels and then collecting all excreted nitrogen in urine, feces, and sweat over a period of 3-14 consecutive days.

Question 14

What is the EAR in the context of protein requirements?

Answer 14

EAR stands for Estimated Average Requirement, which is the average daily nutrient intake level estimated to meet the requirement of half the healthy individuals in a particular life stage and gender group.

Question 15

How is the RDA for protein determined from the EAR?

Answer 15

The RDA for protein is determined by adding two standard deviations (SD) above the EAR to cover the needs of 97-98% of the population.

Question 16

What are some challenges associated with the nitrogen balance technique?

Answer 16

The challenges with the nitrogen balance technique include difficulty in collecting all nitrogen excreted, the high cost of the process, time consumption, and compliance issues with the participants.

Question 17

Why might the nitrogen balance technique lead to an underestimation of protein requirements?

Answer 17

The technique might underestimate protein requirements because it tends to underestimate the output of nitrogen, which leads to an underestimation of total protein needs.

Question 18

What is the Indicator Amino Acid Oxidation (IAAO) method?

Answer 18

The IAAO method is a technique used to determine protein requirements by isotopically labeling an essential amino acid (EAA) and measuring its oxidation, detected in breath CO2, under different intakes of protein.

Question 19

How does the IAAO method work?

Answer 19

In the IAAO method, when protein intake is low, the labeled essential amino acid will be oxidized and detected in breath CO2 because it’s not incorporated into body proteins due to insufficient amino acids to make body proteins. As protein intake increases, the labeled amino acid will be incorporated into new proteins, and less will be oxidized.

Question 20

What does a ‘break point’ on the IAAO graph indicate?

Answer 20

The ‘break point’ in the IAAO graph indicates the protein requirement for that person, which is the point at which further increases in protein intake do not result in less amino acid oxidation.

Question 21

Why is the IAAO method useful for assessing protein requirements?

Answer 21

The IAAO method is useful because it provides a direct and quantifiable measure of how dietary protein intake influences the metabolism of an essential amino acid, which reflects the body’s protein needs.

Question 22

What does it mean when less labeled amino acid is detected in breath CO2?

Answer 22

When less labeled amino acid is detected in breath CO2, it suggests that more of the amino acid is being used for protein synthesis rather than being oxidized for energy, indicating adequate protein intake.