W2-L2: Biosynthetic Pathways + Energy Expenditure

Question 1

What are the Benefits of Endurance Training? (7)

Answer 1

1. ↑ number and size of mitochondria
2. ↑ concentration of glycolytic enzymes
3. Improved aerobic efficiency
4. Improved electron delivery to the ETC
5. ↑ ability of the muscle to oxidize lactate

Not as Relevent:

6. Improvements in the heart’s stroke volume and angiogenesis
7. Improved capillary density and capacity to transport fatty acids from plasma to muscle cells

Question 2

What is Gluconeogenesis?

Answer 2

Gluconeogenesis: creates glucose for the body from non carbohydrate precursors

• Amino acids enter the Krebs cycle
• Pyruvate
• Lactic acid – Cori cycle in liver converts lactic acid to glucose
• Glycerol – converted in the liver to glucose

Question 3

What molecules CANNOT be directly converted into Glucose?

Answer 3

Fatty acids cannot be converted directly to glucose (the pyruvate → acetyl-co A reaction cannot be reversed)

Question 4

Where does gluconeogenesis occur?

Answer 4

Main site of gluconeogenesis is
90% in liver; 10% in kidneys

Question 5

What is Glycogenesis?

Answer 5

Glycogenesis: assembles glucose molecules into branched chains for storage as glycogen

When demand for glucose ↓ , glycogen synthase activity ↑ and restores glycogen stores in liver and muscle

Question 6

What is Lipogenesis?

Answer 6

accelerated during times of excess calorie consumption; often
leads to the gain of fat tissue due to excess acetyl-CoA molecules

Question 7

What are the 3 principle components of energy expenditure?

Answer 7

1. Resting Metabolic Rate (RMR); 50 – 70% - maintain basic physiologic function
2. Thermic Effect of Food (TEF); 10%
3. Physical activity: Non-exercise activity thermogenesis (NEAT) + Physical activity. 15 – 30%

NOTE: Caloric intake and energy expenditure may not be identical on a daily basis but with weight stability it is balanced over time

Question 8

How can we measure free living energy expenditure?

Answer 8

• Direct calorimetry
• Indirect Calorimetry
• Doubly labelled water
• Activity Monitors
• Heart rate monitors
• Metabolic carts
• Prediction equations

Question 9

What is the Harris-Benedict Equation?

Answer 9

Calculates Basal Metabolic Rate (BMR), which is the amount of energy expended at rest.

Question 10

Used in this Class

What is the Mifflin-St Jeor Equation?

Answer 10

This is an updated version of the Harris-Benedict Equation and is often considered more accurate:

Question 11

What is the Katch-McArdle Equation?

Answer 11

more accurate for individuals who know their lean body mass (LBM), as it uses LBM instead of total body weight.

The formula is:

Question 12

How do we Adjust BMR based on activity level to estimate total daily energy expenditure (TDEE)?

Answer 12

TDEE = BMR × PAL (Physical Activity Level

Question 13

Calculate BMR using Mifflin Equation

Question 14

If a sedentary individual has a daily Energy requirement of 2100kcals (MSJ), How would it change if they were lightly active?

Answer 14

Energy requirement is now 2400kcals (MSJ) - will need to increase energy intake for weight maintenance

Question 15

PRACTICE EQUATIONS

For both individuals, calculate the energy requirements
(round to the nearest 50) for a physical activity level that is
A) Sedentary
B) Very Active