Background Lecture and Nutrition, Diet & Body Weight Flashcards
What is metabolism?
A set of processes which derive energy and raw materials from foodstuffs and use them to support repair, growth and activity of the tissues of the body to sustain life.
What are catabolic processes?
Those that break down molecules to release energy in the form of ‘reducing power’ (oxidative - release H atoms), which drives anabolism?
What is anabolism?
A set of processes which use energy and raw materials to make larger molecules for growth and maintenance.
Fuel molecules are metabolised to provide what?
Building block materials, organic precursors, biosynthetic reducing power and energy for cell function.
What is energy?
The capacity to do work, whether it be biosynthetic, transport or specialised, such as mechanical, electrical or osmotic work.
What is the standard international unit for energy and how is this different when discussing nutrition?
Joules/kJ, but ‘calories’ are more commonly used by patients when referring to kilocalories. 1kcal = 4.2kJ.
Fat has the most, then alcohol, carbohydrates and proteins.
What happens to the excess if energy intake>energy required?
It may be stored as growth with the synthesis of new tissue as a means of repair, or new material for children or pregnant women. Alternatively it is stored as adipose tissue.
How long can a person survive with just water?
20-70 days.
Energy exists in interconvertible forms, which type is used predominantly by the body?
Chemical bond energy drives energy requiring activities. It is used directly without prior conversion to heat, as man in isothermal.
Which type of reactions release energy and which require it?
Endergonic reactions, found in anabolism, require energy whereas exergonic reactions found in catabolism release it.
How can you tell which reactions will be spontaneous?
Mostly catabolic reactions with free energy(delta G)<0. Transition stage does need to be reached first though.
How are standard free energy changes measured?
In kJ/mol or kcal/mol under standard conditions of 1 Atmosphere of pressure, 25 degrees celcius with 1 Molar concentrations of reactants/products and offer at a pH of 7.
It does not indicate rate.
How is energy released from chemical bonds?
Via oxidation reactions - removal of electrons &/ protons.
What happens when fuel molecules are oxidised?
Electrons/protons are transferred to carrier molecules e.g. Nicotinamide adenine dinucleotide or Flavin adenine dinucleotide.
H carriers are complex and contain B vitamins; they are converted to their reduced form by adding 2Hs (then 1 H+ dissociates into solution - not with FAD).
What is meant by a ‘high energy’ bond of hydrolysis?
The phosphodiester bond in adenosine triphosphate(ATP), where energy is stored and released from when it is hydrolysed to make ADP + Pi.
What’s the importance of cycles in metabolism?
There is a finite number of ADP and H carrier molecules in their reduced state, so these must be recycled to maintain a constant concentration in the cytosine or energy can’t be captured properly from exergonic reactions.
Why is it important that ATP is stable in the absence of specific catalysts?
So the flow of energy can be controlled.
When ATP concentrations are high, what does this mean for metabolic reactions?
Anabolic pathways are activated (converse is true for catabolic processes).
What does adenylate kinase do?
Catalysts reaction when high concentrations of low energy signal ADP.
2ADP –> ATP + AMP
Name two polymer macromolecules that energy may be stored in when supply exceeds demand.
Glycogen and triacyglycerol.
What is skeletal muscle’s reserve of high energy stores that can be used immediately?
Creating phosphate.
What does creating kinase do and how is it used as a diagnostic marker?
Catalysed reaction: creatine + ATP PCr + ADP. When ATP concentration is high, ‘phosphate bond energy’ may be stored in PCr.
Creating kinase is a marker of MI as it’s made of 2 subunits with different isoform combinations in different tissues. CK in a specific combination is released from damaged cardiomyocytes and may be seen in the blood after a few hours.
What is creatinine and how is it used?
Creatinine is the product of the spontaneous breakdown of PCr/Cr at a constant rate and is excreted via the kidneys.
It can be used as a measure of muscle mass, as excretion per 24hrs is proportional to muscle mass of an individual. Also the concentration in urine is a marker of dilation and it can be used to measure true urinary loss of many substances, e.g. pregnancy hormones.
Name the 7 essential components of nutrition and explain their purpose.
Carbohydrates - supply energy
Water - keeps hydrated
Fibre - necessary for normal function of GI tract
Vitamins - essential for life
Minerals - electrolytes to establish gradient/signal etc.
Protein - supply energy and amino acids
Fats - supply energy and essential fatty acids
