Lecture 12

Question 1

What is the key role of ventilation?

Answer 1

Maintain arterial O2 saturation and remove CO2.

Question 2

What happens to ventilation during exercise?

Answer 2

Breathing frequency increases and tidal volume increases.

Question 3

What happens when respiratory muscles fatigue?

Answer 3

A chemoreflex takes place which decreases active muscle blood flow making them fatigue quicker.

Question 4

What are the other roles of ventilation?

Answer 4

Controls acid-base balance (CO2 blown off increases pH)

Fluid and temperature balance are affected (not very important)

Question 5

What is the significance of water loss through ventilation at high altitudes?

Answer 5

Rate of ventilation at high altitudes is fast and so water is lost quickly.

Question 6

What determines VO2?

Answer 6

VO2 is primarily determined by exercise intensity.

Question 7

What does the ventilation vs intensity graph look like?

Answer 7

Linearly increases with 2 thresholds for ventilatory increase.

Question 8

How does ventillation increase with a rise in metabolic activation?

Answer 8

Increase of metabolic activation results in more CO2 production and ventilation is controlled by CO2. With increase in lactate production the carbonic anhydrase buffer releases more CO2 resulting in higher rate of ventilation.

Question 9

Why can it be said that ventilation rate is affected by factors other than CO2 as well as CO2?

Answer 9

Lungs are effective at maintaining constant arterial oxygen and CO2 saturation. At the higher intensities the ventilation increases significantly which causes the arterial CO2 to drop. This indicates that other factors also affect ventilation.

Question 10

What pH drives ventilation?

Answer 10

Decrease in arterial pH drives ventilation.

Question 11

What happens to dead space during ventilation?

Answer 11

Dead space during exercise doesn’t change much but ventilation rate does increase.

Question 12

What is the significance of ventilatory drift?

Answer 12

Ventilatory drift causes increase in VO2.

Question 13

What is the difference between minute ventilation and alveolar ventilation?

Answer 13

Minute ventilation and alveolar ventilation differ by dead space.

Question 14

What aspects of ventilation increase during exercise?

Answer 14

Tidal volume increases but most of increase in ventilation is due to increase in ventilation frequency.

Question 15

What is the partial pressure of oxygen in the atmosphere at sea level compared to atmospheric pressure?

Answer 15

oxygen in atmosphere is about a fifth of 760 mm/hg

Question 16

How does blood take up oxygen from the alveoli?

Answer 16

arterial blood equilibrates to alveolar PO2 at the alveoli. This is a very effective process.

Question 17

What is the problem with exercising at high altitudes?

Answer 17

Diffusion gradient at high altitude is much less than at sea level which limits diffusion meaning exercise is more difficult at high altitudes.

Question 18

What happens to lung structure as a response to training?

Answer 18

Lungs don’t adapt to exercise training and surface area does not increase.

Question 19

What is the major cause of exercise induced hypoxemia?

Answer 19

Major cause is the diffusion limitation due to large increase in cardiac output not allowing enough time for oxygen to diffuse into the pulmonary blood vessels.

Question 20

What is exercise induced hypoxemia?

Answer 20

When at VO2 max and the arteries are no longer saturated with oxygen.

Question 21

What are some minor causes of exercise induced hypoxemia?

Answer 21

Regional mismatch between the ventilation and the perfusion.

ventillation/cardiac output inequality

Expiratory flow limitation causing the expiration to be suboptimal and so oxygen concentration in lung is suboptimal for diffusion.

Shift to the O2 dissociation curve

Question 22

What causes the diaphragm to fatigue?

Answer 22

diaphragm only fatigues during intense exercise

Question 23

What is the respiratory muscle metaboreflex?

Answer 23

The type 3 and type 4 afferent fibers (bloke still says fibers. FIBERS. STILL) of the diaphragm send a message to the brain which vasoconstricts blood vessels to the exercising muscles causing them to fatigue. (protective

Question 24

What are the control factors involved in regulating ventilation?

Answer 24

Pons and Medulla regulate ventilation. inspiratory neruons and expiratory neorons fire intermittently. central and peripheral chemoreceptors feedback at the brain

stretch and pressure receptors and mechanoreceptors.

Most respiratory work is done by the diaphragm

Question 25

What causes exercise hyperpnea?

Answer 25

Motor cortical activation

Muscle afferents

Co2 flux to the lung

Increased K+, H+, and lactate

Elevated catecholamines and temperature

No role for O2

Question 26

What happens to ventilation vs intensity curve with training?

Answer 26

adaptation to training is a right shift in ventilation curve. Max ventilation is slightly lower.

Question 27

What do lower lactate levels show?

Answer 27

Lower lactate levels indicate higher threshold which shows that aerobic pathway is being utilized.

Question 28

Why does K+ levels decrease in blood following training?

Answer 28

training increases amount of sodium potassium pumps in muscles which decreases amount of potassium released.

Question 29

What happens to blood pH in trained individuals?

Answer 29

pH tends to follow lactate curve.

Question 30

Why is ventilation rate lower following training?

Answer 30

Lower blood lactate/H+

Lower plasma K+

Lower plasma catecholamines

Reduced activation of muscle afferents?

Reduced central drive?