Respiratory Systems 18 - Exercise Test

Question 1

What is the respiratory quotient (RQ)?

Answer 1

Carbon dioxide to oxygen ratio

Question 2

List the RQ in different types of metabolism.

Answer 2

• Lipids 0.70
• Protein 0.82
• Glucose 1.00
• Anaerobic respiration >1.00

Question 3

What is a MET?

Answer 3

• 1 Metabolic Equivalent

- At rest, humans need 3.5ml/min/kg oxygen

Question 4

What is the muscles response to exercise?

Answer 4

• Stored energy is used for muscular contraction
• Inorganic phosphates (ADP/creatine) drive oxidative phosphorylation
• Oxygen consumption at the muscle increases (10-15 fold)
• CO2 production initially slightly increases, and then rises to match O2

Question 5

How does the heart respond to exercise?

Answer 5

• First there is an increase in stroke volume, and then an increase in heart rate
• This overall results in higher cardiac output (4-7 fold increase)
• Stroke volume starts to decrease while heart rate is still increasing

Question 6

How much oxygen can be extracted during exercise?

Answer 6

Up to 85%

Question 7

How does ventilation-perfusion matching change due to exercise?

Answer 7

• At rest ventilation-perfusion matching is not ideal

- In early exercise the ventilation-perfusion matching improves

Question 8

In exercise, why does oxygen uptake at the tissues increase?

Answer 8

• Higher concentration gradient (more oxygen in the blood)

- Bohr Effect - the oxygen dissociation curve shifts left, so more oxygen is released at the cells.

Question 9

How does exercise affect blood pH?

Answer 9

• Initially pH decreases due to lactate
• Bicarbonate buffers this, as a result more CO2 is produced (isocapnic buffering)
• H+ eventually exceeds HCO3- (ventilatory compensation point)
• This causes hyperventillation (respiratory compensation)