Tri B - Energy Metabolism Flashcards
Describe catabolism and anabolism
Catabolism - Breakdown reactions releasing energy
Anabolism - Synthesis reactions consuming energy
Describe how energy is released from ATP
Energy stored in phosphate bonds
Released when bonds are broken
Describe the Krebs Cycle
Reactions occur in mitochondria
2 molecules of ATP are directly produced
Produces NADH and FADH2
- Donate to electrons to electron transport chain
Describe the Electron Transport Chain
Controlled release of energy
Carrier molecules - cytochromes
Electrons move from carrier to carrier –> from high energy to low energy
Name some uses of energy
Muscle contraction
Protein synthesis
Active transport
Describe energy balance
If intake > use, energy stored as fat
- Positive energy balance
If intake < use, fat stores mobilised
- Negative energy balance
If intake = use, energy balanced
What are the 4 sources of energy?
- Carbohydrate - 3.75 kcal/g
- Fat - 9 kcal/g
- Protein 4 kcal/g
- Alcohol - 7 kcal/g
Why is energy balance important
Obesity is a serious issue
BMI can measure
below 18.5 - underweight
Over 24.9 - overweight
What are some health risks of obesity?
Cardiovascular disease
Type 2 diabetes
Some cancer (breast, colon)
Problems with weight bearing joints
Respiratory problems
Name and describe some eating disorders
Anorexia nervosa - not eating enough
Bulimia - binging, making self sick
Binge eating disorder - losing control of eating
How much energy do we need?
25 yr female - 2080 kcal/day
25 yr male - 2600 kcal/day
What are the 3 components of energy expenditure?
- Basal Metabolic Rate
- Physical Activity
- Thermic Effect of Food
Describe how Basal Metabolic Rate uses energy
Minimum energy to survive
Accounts for 60-70% of total energy used
Describe how Physical Activity uses energy
Energy to move (standing, exercise)
Accounts for 15-30% of total energy used
Depends on duration and intensity
Describe prevalence of inactivity
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
Describe how the Thermic Effect of Food uses energy
Increased energy use after eating due to digestion and absorption of food
Accounts for ~10% of total energy use
Name and describe some factors effecting BMR
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
Describe direct calorimetry
Heat given off is measured by temp in water
Very accurate but costly and doesn’t represent real life
Describe indirect calorimetry
Based on relationship between energy production and O2 uptake
More energy required, more O2 uptake
