Flashcards in Lecture 12 Deck (30)
What is the key role of ventilation?
Maintain arterial O2 saturation and remove CO2.
What happens to ventilation during exercise?
Breathing frequency increases and tidal volume increases.
What happens when respiratory muscles fatigue?
A chemoreflex takes place which decreases active muscle blood flow making them fatigue quicker.
What are the other roles of ventilation?
Controls acid-base balance (CO2 blown off increases pH)
Fluid and temperature balance are affected (not very important)
What is the significance of water loss through ventilation at high altitudes?
Rate of ventilation at high altitudes is fast and so water is lost quickly.
What determines VO2?
VO2 is primarily determined by exercise intensity.
What does the ventilation vs intensity graph look like?
Linearly increases with 2 thresholds for ventilatory increase.
How does ventillation increase with a rise in metabolic activation?
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.
Why can it be said that ventilation rate is affected by factors other than CO2 as well as CO2?
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.
What pH drives ventilation?
Decrease in arterial pH drives ventilation.
What happens to dead space during ventilation?
Dead space during exercise doesn't change much but ventilation rate does increase.
What is the significance of ventilatory drift?
Ventilatory drift causes increase in VO2.
What is the difference between minute ventilation and alveolar ventilation?
Minute ventilation and alveolar ventilation differ by dead space.
What aspects of ventilation increase during exercise?
Tidal volume increases but most of increase in ventilation is due to increase in ventilation frequency.
What is the partial pressure of oxygen in the atmosphere at sea level compared to atmospheric pressure?
oxygen in atmosphere is about a fifth of 760 mm/hg
How does blood take up oxygen from the alveoli?
arterial blood equilibrates to alveolar PO2 at the alveoli. This is a very effective process.
What is the problem with exercising at high altitudes?
Diffusion gradient at high altitude is much less than at sea level which limits diffusion meaning exercise is more difficult at high altitudes.
What happens to lung structure as a response to training?
Lungs don't adapt to exercise training and surface area does not increase.
What is the major cause of exercise induced hypoxemia?
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.
What is exercise induced hypoxemia?
When at VO2 max and the arteries are no longer saturated with oxygen.
What are some minor causes of exercise induced hypoxemia?
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
What causes the diaphragm to fatigue?
diaphragm only fatigues during intense exercise
What is the respiratory muscle metaboreflex?
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
What are the control factors involved in regulating ventilation?
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
What causes exercise hyperpnea?
Motor cortical activation
Co2 flux to the lung
Increased K+, H+, and lactate
Elevated catecholamines and temperature
No role for O2
What happens to ventilation vs intensity curve with training?
adaptation to training is a right shift in ventilation curve. Max ventilation is slightly lower.
What do lower lactate levels show?
Lower lactate levels indicate higher threshold which shows that aerobic pathway is being utilized.
Why does K+ levels decrease in blood following training?
training increases amount of sodium potassium pumps in muscles which decreases amount of potassium released.
What happens to blood pH in trained individuals?
pH tends to follow lactate curve.