Metabolism
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Summary - why do we need to eat and how do we survive between meals?
Objectives
By the end of this exercise you should be able to:
Explain why there is a need for metabolic energy even when at rest
Define Basal and Resting Metabolic Rate (BMR and RMR)
Define Physical Activity Ratio (PAR) and Physical Activity Level (PAL)
Explain how to measure BMR and energy expenditure in physical activity
Explain how measurement of oxygen consumption and carbon dioxide production permits estimation of the mixture of metabolic fuels being metabolised
Explain how it is possible to measure total energy expenditure using dual isotopically labelled water
Explain why there is an increase in metabolic rate after a meal
Explain why women have a lower BMR than men of the same age and body weight, and why BMR falls with increasing age, even if body weight remains constant
List the main metabolic fuels available to tissues in the fed and fasting states
State the desirable proportions of carbohydrate, protein and fat in the diet, and explain how to calculate the percentage of energy derived from each
Describe in outline the metabolic fate of the glucose coming from dietary carbohydrates in the fed state
Explain how the blood concentration of glucose is maintained in the fasting state, and which alternative fuels are provided to tissues to spare glucose for tissues that absolutely require it
Explain why free (non-esterified) fatty acids are transported in the bloodstream bound to serum albumin
Name the ketone bodies and explain their importance in the fasting state and starvation; explain why acetoacetate is largely reduced to hydroxybutyrate in the liver.
Describe in outline how insulin and glucagon act to regulate metabolic processes in the fed and fasting states
Explain how extra-hepatic tissues are prevented from taking up glucose in the fasting state, so sparing it for the brain and red blood cells