Metabolic fuels Flashcards
What is metabolism?
Metabolism refers to the sum of the chemical reactions that take place within each cell of a living organism.
Catalysed by enzymes
How are dietary components metabolised?
(4 main pathways)
Biosynthetic
Fuel storage
Oxidative processes
Waste disposal
What is anabolic and give the pathways:
Anabolic – synthesise larger molecules from smaller components
Eg. Biosynthetic, fuel storage, waste disposal
Requires energy
What is catabolic and give the pathways:
Catabolic – break down larger into smaller
Eg. Oxidative, waste disposal
How is energy provided for anabolic processes?
Catabolic reaction of oxidation of carbs, lipids and proteins, produces energy in form of ATP, then used for anabolic processes and becomes ADP + Pi
Name the reactants of Kreb’s cycle:
Acetyl CoA
Citrate - 6C
3 NAD+
FAD
ADP
Name the products of Kreb’s cycle:
CoA
3 NADH H+
2 CO2
ATP
FADH2
What are co factors?
Macronutrients that enzymes require in order to function.
Eg. Thiamine / B1
Needed for acetyl CoA into krebs cycle
What is the specialisation of adipose - liver - muscle tissues?
Adipose tissue – 85% fat, storage of energy-rich molecules.
Liver- metabolically active (e.g. Gluconeogenesis, removal of toxins).
Muscle – Activity
What are the electron accepting coenyzmes:
NAD+ – NADH+
NADP+ – NADPH
FAD – FADH
What happens to the NADH and FADH2 in ETC?
They are oxidsed and this releases energy used to produce ATP.
What are the 3 main dietary energy sources?
Carbohydrates
Lipids
Proteins
Oxidation equation?
Carb/Lipid/Protein + O2 = ATP + CO2 +H2O
What types of carbohydrates are there?
Monosaccharides - glucose, fructose
Disaccharides - sucrose (plant), lactose (milk)
Glycogen is branched
Explain the dietary component in proteins:
Amino acids in chains, contain carbon, hydrogen, oxygen & nitrogen
Maintains nitrogen balance - when starving/dieting, there is a decrease in proteins thus decrease in nitrogen and that affects cell functions
Explain the dietary component in lipids:
3 fatty acids esterified to one glycerol mostly - most efficient energy source
Explain the dietary component in alcohol:
Typically ethanol, highly energetic
How is excess energy stored?
Lipid - Stored as triglycerides, approx 15kg
Glucose - Stored as glycogen, approx 200g in liver & 150g in muscle
Protein - Stored as protein, approx 6kg
How much is each dietary component per gram?
Carbohydrates - 4kcal/g
Protein - 4kcal/g
Alcohol - 7kcal/g
Lipid 9kcal/g
How much is carbs and lipids as ATP production?
Carbs - 30% of ATP production at rest
Lipids - 70% of ATP production at rest
Proteins are often used in longer periods of starvation
What is BMR?
Basal Metabolic Rate
Amount of energy needed to keep the body alive in the
rest state.
Energy needed to maintain non exercise bodily functions
eg. respiration, heart muscle contraction, biosynthetic processes, repairing & regenerating tissues, ion gradients across cell membranes.
How is BMR measured?
BMR = 1kcal/kg body mass/hr
Adult requires approximately 0.8g/kg ideal body weight protein per day
What are the conditions essential for measuring BMR?
- Post-absorptive (12 hour fast)
- Lying still at physical and mental rest
- Thermo-neutral environment (27 – 29C)
- No tea/coffee/nicotine/alcohol in previous 12 hours
- No heavy physical activity previous day
- Establish steady-state (~ 30 minutes)
What factors decrease BMR?
- Age, as you get older, BMR decreases,
- Gender, female have lower BMR since they have less metabolically active tissues,
- Dieting/Starvation
- Hypothyroidism, less thyroid hormone = lower BMR
- Decreased muscle mass
What factors increase BMR?
- High BMI
- Hyperthyroidism
- Low ambient temperature
- Fever/infection
- Pregnancy, due to increase in weight and thyroid hormone
- Exercise
What is malnutrition?
A state of nutrition with a deficiency, excess or imbalance of
energy, protein or other nutrients, causing measurable adverse effects
Adverse effects - Tissue/body (shape, size, composition), body function
What are essential nutrients?
Essential amino acids
Essential fatty acids
Vitamins - Vitamin C, Vitamin B12
Minerals
What are micro nutrients and what are they important in?
Trace elements and vitamins
- Co-factors in metabolism
- Gene expression
- Structural components
- Antioxidants
What is Vitamin C for?
AKA Ascorbic acid, found in fruit and vegetables
For: Collagen synthesis, improve iron absorption, antioxidant
What is Vitamin B12 for?
Found in: milk, meat, eggs
For: Protein synthesis, DNA synthesis, regenerate folate (and therefore – cell division), fatty acid synthesis, energy production
