Tri B - Energy Metabolism

Question 1

Describe catabolism and anabolism

Answer 1

Catabolism - Breakdown reactions releasing energy
Anabolism - Synthesis reactions consuming energy

Question 2

Describe how energy is released from ATP

Answer 2

Energy stored in phosphate bonds
Released when bonds are broken

Question 3

Describe the Krebs Cycle

Answer 3

Reactions occur in mitochondria
2 molecules of ATP are directly produced
Produces NADH and FADH2
- Donate to electrons to electron transport chain

Question 4

Describe the Electron Transport Chain

Answer 4

Controlled release of energy
Carrier molecules - cytochromes
Electrons move from carrier to carrier –> from high energy to low energy

Question 5

Name some uses of energy

Answer 5

Muscle contraction
Protein synthesis
Active transport

Question 6

Describe energy balance

Answer 6

If intake > use, energy stored as fat
- Positive energy balance
If intake < use, fat stores mobilised
- Negative energy balance
If intake = use, energy balanced

Question 7

What are the 4 sources of energy?

Answer 7

1. Carbohydrate - 3.75 kcal/g
2. Fat - 9 kcal/g
3. Protein 4 kcal/g
4. Alcohol - 7 kcal/g

Question 8

Why is energy balance important

Answer 8

Obesity is a serious issue
BMI can measure
below 18.5 - underweight
Over 24.9 - overweight

Question 9

What are some health risks of obesity?

Answer 9

Cardiovascular disease
Type 2 diabetes
Some cancer (breast, colon)
Problems with weight bearing joints
Respiratory problems

Question 10

Name and describe some eating disorders

Answer 10

Anorexia nervosa - not eating enough
Bulimia - binging, making self sick
Binge eating disorder - losing control of eating

Question 11

How much energy do we need?

Answer 11

25 yr female - 2080 kcal/day
25 yr male - 2600 kcal/day

Question 12

What are the 3 components of energy expenditure?

Answer 12

1. Basal Metabolic Rate
2. Physical Activity
3. Thermic Effect of Food

Question 13

Describe how Basal Metabolic Rate uses energy

Answer 13

Minimum energy to survive
Accounts for 60-70% of total energy used

Question 14

Describe how Physical Activity uses energy

Answer 14

Energy to move (standing, exercise)
Accounts for 15-30% of total energy used
Depends on duration and intensity

Question 15

Describe prevalence of inactivity

Answer 15

69% of men and 59% of women meet current guidelines for physical activity (150 mins/week)
Sedentary behaviour - risk for cardiovascular disease and type 2 diabetes

Question 16

Describe how the Thermic Effect of Food uses energy

Answer 16

Increased energy use after eating due to digestion and absorption of food
Accounts for ~10% of total energy use

Question 17

Name and describe some factors effecting BMR

Answer 17

Body weight - more weight, higher BMR
Body composition - higher fat %, lower BMR
Age - BMR highest in kids (growth)
Gender - BMR higher in males
- other factors : thyroid, genes, pregnancy

Question 18

Describe direct calorimetry

Answer 18

Heat given off is measured by temp in water
Very accurate but costly and doesn’t represent real life

Question 19

Describe indirect calorimetry

Answer 19

Based on relationship between energy production and O2 uptake
More energy required, more O2 uptake