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Energy - what is metabolism all about?

This set of exercises introduces the main metabolic fuels that are available, and the concepts of metabolic pathways and coenzymes, as well as the idea that the energy-yielding metabolism of carbohydrates, fats and proteins is one of oxidation to provide metabolically useable energy (in the form of ATP) for the various energy-requiring activities of the body.

The following exercises are available in this section:

A respiratory physiology practical class - and beyond (Oxygen consumption, oxidation and metabolic water)

An early morning jog (RQ, estimation of fuels being oxidised, provision of fuels in fed and fasting states)

Starving to slim (Fasting state, ketone bodies, energy yield of adipose tissue)

Poisoned by unripe ackee fruit (Uses of ATP: ion transport, endothermic reactions and muscle contraction; coenzyme A)

Overheating after overdosing on E - and slimming by taking dinitrophenol (Oxidative phosphorylation, mitochondrial electron transport chain and ATP synthesis)

Summary - why do we need to eat and how do we survive between meals? (Calorimetry and energy expenditure, RQ, estimation of fuels being oxidised, provision of fuels in fed and fasting states)

The following programs may run directy by clicking on the linbk, or may need to be dowloaded, depending on your browser software

Estimating energy requirements from an activity diary

Practice calculations on weight loss through dieting and exercise

Practice calculations on weight loss in a patient with advanced cancer


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After working through these exercises you should be able to:

Describe the chemical features of the macronutrients that provide most of our metabolic energy: fatty acids and triacylglycerols, glucose, starch and glycogen, amino acids and proteins

Distinguish between anabolic (biosynthetic) pathways that are energy requiring (endothermic)and catabolic (degradative) pathways that are energy yielding (exothermic)

List the main metabolic fuels and how their concentrations in the bloodstream vary between the fed and fasting states and into starvation

Describe in outline the hormonal changes that regulate fuel availability and utilisation in the fed and fasting states

Explain the importance of blood glucose, and how its concentration is maintained in the fasting state and starvation

Describe the role of ATP in endothermic reactions and how its production is linked to exothermic reactions by mitochondrial oxidative phosphorylation

Explain what is meant by a coenzyme and describe how small amounts of coenzymes have a rapid turnover in tissues

Define the key terms in energy metabolism: BMR, PAR, PAL, DIT and TEE

Explain how BMR, energy expenditure in activity and total energy expenditure can be measured