Define basal metabolic rate and describe factors that influence it (70% of marks).
How could you measure metabolic rate? (30% of marks)
Metabolism is all the chemical reactions in all the cells of the body. Metabolic rate is usually
described in terms of rate of heat liberation. Candidates often confused basal with
metabolism during activity.
A good answer was expected to outline conditions under which basal metabolic rate is
measured (no food for 12 hours, after a night of restful sleep, person is at rest in reclining
position for 30 minutes, all psychic or physical factors that cause excitement eliminated, at
a controlled comfortable temperature), and the mention of and an explanation of the
methods by which metabolic rate is measured (eg direct and indirect calorimetry). Any
validated technique of determining the BMR was rewarded with marks, with oxygen
consumption methods being the easiest to explain. No candidate mentioned any ‘normal’
value for the BMR.
Candidates were expected to briefly mention and explain how factors affecting metabolic rate
(eg exercise, specific dynamic action of protein after a meal is ingested,, age, thyroid
hormone, sympathetic stimulation, fever, gender, hormonal, climate, sleep, chronic
malnutrition, trauma, inflammatory response, etc).
Questions with more than one part will have an indication of the proportion of the total mark
that will be allocated to each part. It is important that candidates apportion their allocated
time and content accordingly.
Syllabus: K 2a, b
Reference Text: Guyton Chp72