Lecture One And Two Flashcards
Define the components of your daily energy expenditure
- Basal metabolic rate - the minimum energy required to sustain life
- Energy for voluntary physical activity (+30/65/100%)
- Diet-induced thermogenesis - energy required to process the food we eat
Give approximate values for your daily energy expenditure:
Assuming moderate physical activity:
- a 70kg man = 12,000 kJ
- a 58kg woman = 9,500 kJ
What are the essential dietary components?
Why are they essential?
Explain the clinical consequences of protein deficiency in humans:
Kwashiorkor:
- symptoms include: apathetic, lethargic, anorexic
- There is generalised oedema and the abdomen is distended
- Serum albumin is low and anaemia is common
Explain the clinical consequences of energy deficiency in humans:
Marasmus:
- The child (typically under 5) looks emaciated with obvious signs of muscle wasting and loss of body fat
- There is no oedema
- Symptoms: thin and dry hair, diarrhoea , anaemia
What is the formula for BMI?
BMI = weight (kg) / height2 (m2)
What are the BMI values?
- Underweight = <18.5
- Desirable weight = 18.5-24.9
- Overweight = 25-29.9
- Obese = 30-34.9
- Severely Obese = >35
Define obesity
- excessive fat accumulation in the adipose tissue which impairs health
- result of energy intake exceeding expenditure over a period of years
Describe the factors involved in body weight regulation
Energy Expenditure = Energy Intake
- if intake exceeds expenditure, weight will increase
- if expenditure exceeds intake, weight will decrease
Define cell metabolism
The chemical processes that occur within a living organism in order to maintain life.
Explain the functions of cell metabolism:
- Oxidative pathways - convert food into energy
- Fuel storage and mobilisation - mobilise energy stores (glycogen) when not eating but increased energy required
- Biosynthetic pathways - produce basic building blocks for cells
- Detoxification pathways - remove toxins
Describe the relationship between catabolism and anabolism
Catabolism - break down larger molecules into smaller ones, releasing energy, H atoms, and reducing power. They are oxidative pathways.
Anabolism - synthesise larger important molecules, using energy and H atoms from catabolism. They are reductive pathways.
Why do cells need a continuous supply of energy?
There is a limited amount of ADP and ATP in the cell and the [ATP] is only sufficient for a few seconds of energy. Therefore ATP must be rapidly resynthesised from ADP using the free energy released during catabolism of fuel.
The rate of cellular ATP turnover is very high.
Explain the roles of redox reactions within metabolism
- Oxidation is the loss of a hydrogen atom/electrons
- Reduction is the gain of a hydrogen atom/electrons
- These reactions always accompany one another
- When fuel molecules are oxidised, H atoms are initially transferred to carrier molecules which become reduced.
Explain the roles of H-carrier molecules in metabolism
- Carrier molecules must cycle between ox and red processes to maintain cell function so act as carriers of reducing power
- OX FORM - NAD+, NADP+, FAD
- RED FORM - NADH + H+, NADPH + H+, FAD2H
Explain the biological role of ATP
- the main source of energy within cells (currency)
- this is due to the high energy of bond hydrolysis of the phosphate groups
- it is stable is the absence of specific catalysts so the flow of energy can be controlled
Explain the biological role of creatine phosphate (phosphocreatine)
- an energy store that can quickly be mobilised to increase metabolic activity
- creatine + ATP <—> creatine phosphate + ADP
- if [ATP] falls suddenly, the reaction reverses providing short-term boosts
Explain the biological role of creatine kinase
- useful clinical marker of muscle damage - appears in blood after cell damage
- usually found in the cytoplasm of cells
Explain the biological role of creatinine
- a breakdown product of creatine and creatine phosphate, usually produced at constant rate
- of muscle is wasting or damaged, it is excreted via the kidneys as urine
- can be used to assess kidney function and provide a measure of muscle mass
What are the high energy signals?
- ATP
- NADH
- NADPH
- FADH2
Reduced forms of the molecules
Explain the roles of high energy signals in the regulation of metabolism
Activate anabolic pathways as there is sufficient energy in the cell for its requirements.
What are the low energy signals?
- ADP/AMP
- NAD+
- NADP+
- FAD
Oxidised form of molecules.
Explain the roles of low energy signals in the regulation of metabolism
Activate catabolic pathways to generate more energy
- AMP is a very strong low energy signal
- with the help of adenylate kinase can increase ATP generation by glycolysis (2ADP —> ATP + AMP)
- also an activator of AMP kinase that regulates genes expression switching from anabolic to catabolic pathways
