21. Exercise

Question 1

Respiratory exchange ratio equation and approximate value at rest

Answer 1

= CO2 production/ O2 consumption

~ 1

Question 2

Respiratory exchange ratio for lipid and protein metabolism

Answer 2

< 1
Generates less CO2 for same amount of O2 consumed
Lungs don’t have to work as hard

Question 3

Respiratory quotient (RQ)

Answer 3

Carbon dioxide : Oxygen ratio

Question 4

Theoretical maximum for RQ

Answer 4

1

>1 you would be generating CO2 but not consuming O2 (so some of metabolism must be anaerobic)

Question 5

O2 requirements at rest

Answer 5

3.5 ml/min/kg of oxygen

1 metabolic equivalent (MET)

Question 6

Max. HR

Answer 6

220 - Age

Question 7

Saturation of blood returning to lung at peak exercise

Answer 7

50% saturated as muscles extract more O2

vs at rest saturation is ~75%

Question 8

How does tidal volume and breathing frequency change on increased ventilation?

Answer 8

The more you ventilate, the more you increase tidal volume until it reach a plateaux, then you increase breathing frequency

Question 9

What drives ventilation during exercise?

Answer 9

CO2 production

Question 10

How do we deal with the potential acidosis caused by anaerobic metabolism?

Answer 10

Lactate generates protons
Buffered by bicarbonate
Increased CO2
Increased ventilation
pH remains relatively stable