metabolic fuels

Question 1

metabolism

Answer 1

sum of chemical reactions taking place within each cell of a living organism

Question 2

dietary components are metabolised in cells through 4 main pathways:

Answer 2

biosynthetic, fuel storage, oxidative processes, waste disposal

Question 3

anabolic

Answer 3

synthesise larger molecules from smaller components (biosynthetic, fuel storage)

Question 4

catabolic

Answer 4

break down larger into smaller (oxidative)

• Waste disposal is either

Question 5

specialisation of tissues

Answer 5

• Adipose tissue – 85% fat, storage of energy-rich molecules
• Liver – metabolically active (e.g. gluconeogenesis, removal of toxins)
• Muscle – activity

Question 6

storage of dietary fuels

Answer 6

• Fat – adipose tissue (only 15% water)
• Carbohydrate – as glycogen in liver and muscles
• Protein – muscle (80% water)

Question 7

how does catabolism provide energy for anabolism?

Answer 7

primarily but not only via oxidative phosphorylation

Question 8

Basal Metabolic Rate (BMR)

Answer 8

• Energy needed to stay alive at rest
• A measure of the energy required to maintain non-exercise bodily functions such as; respiration, contraction of the heart muscle, biosynthetic processes, repairing & regenerating tissues, ion gradients across cell membranes

25-35 kCal

Question 9

conditions essential for measuring BMR

Answer 9

• Post-absorptive (12 hour fast)
• Lying still at physical and mental rest
• Thermo-neutral environment (27-29◦C)
• No tea/coffee/nicotine/alcohol in previous 12 hours
• No heavy physical activity previous day
• Establish steady-state (≈ 30 minutes)

Question 10

factors affecting BMR

Answer 10

Decreasing BMR 
•	Age
•	Gender
•	dieting/starvation
•	hypothyroidism  
•	decreased muscle mass 
increasing BMR
•	Body weight (BMI)
•	Hyperthyroidism 
•	Low ambient temp
•	Fever/infection/chronic disease 
Equation for estimating BMR; benedict equations, Schofield, Henry

Question 11

starvation

Answer 11

• Overnight fast; insulin down, glycogenolysis
• The brain requires about 15g of glucose a day
• After an overnight fast the liver only has about 80g glycogen
• During a longer period of fasting/starvation, glucose must be formed from non-carbohydrate sources – gluconeogenesis
• Insulin down, cortisol up
• Gluconeogenesis uses; lactate, amino acids, glycerol
• > 4 days ; liver →ketones from fatty acids, brain adapts to using ketones, lower BMR = accommodation

Question 12

malnutrition

Answer 12

A state of nutrition with a deficiency, excess or imbalance of energy, protein or nutrients, causing measurable adverse effects
Adverse effect are on tissue/body form (shape, size, composition), body function and clinical outcome

Question 13

re-feeding syndrome

Answer 13

Re-distribution of phosphate, potassium, magnesium etc due to insulin. Switch back to carbohydrates as the main fuel which requires phosphate and thiamine
Micronutrients – trace elements and vitamins (co-factors in metabolism, gene expression, structural components, antioxidants)

Question 14

prudent diet

Answer 14

e.g 5 + servings of fruit/veg, base meals around starchy carbs, don’t drink more than 14 units a week