Chapter 9: Respiratory System Under Stress Flashcards
By what amount can oxygen consumption increase during exercise?
Ten-fold or more, from 300mL/min to 3000mL/min (6000mL/min in trained athletes!)
What happens to the respiratory exchange ratio during exercise?
Instead of sitting at 0.8, it increases to 1.0 or even slightly higher
How can the respiratory exchange ratio exceed 1.0?
Production of lactic acid during exercise drives the respiratory exchange ratio higher
What level of exercise is required to raise blood lactate concentrations?
Severe exercise
What is the first and best response to high altitude hypoxia?
Hyperventilation
What long-term compensation does the body engage in to acclimatize to high altitude?
Increased RBC production (hypoxia induces erythropoietin release from the kidney)
What is the downside of altitude-induced polycythemia?
Sludgy blood
Other than hyperventilation and polycythemia, name two other physiological changes at high altitude
Increase the number of capillaries per unit volume in peripheral tissues and alter oxidative enzymes inside cells
What does the combination of alveolar hypoxia-induced pulmonary vasoconstriction and polycythemia bring about?
Pulomonary hypertension - right ventricular hypertrophy
What effect does breathing a helium-oxygen mixture have on a diver’s risk of decompression sickness?
Decreases it
Is it easier or harder to breather a helium-oxygen mixture versus atmospheric air?
Easier - helium much less dense than nitrogen
What happens to the risk of inert gas narcosis when breathing a helium-oxygen mixture?
Decreases it
What happens to venous return in an astronaut experiencing 0g?
Increases, no pooling of blood in legs or other hydrostatic edema
How does blood flow in the lung change in 0g?
More uniform perfusion of upper and lower lobes
Where do large particles get filtered by breathing?
Stokes Law - large particles (>1.0 micron) traverse stream lines of uniform flow when the stream lines bend radically (such as in the back of your nose). These particles are impacted into the mucosal lining, where they stick. Some make it into the bronchi, but not very far
Where and by what mechanism do medium-sized particles (0.1-1.0 micron) get filtered?
Medium sized particles sediment out of inspired air and deposit in the small airways (terminal and respiratory bronchioles), more or less at the point where flow transitions from bulk to diffuse due to exponentially increasing airway cross section
Where does coal miner’s lung manifest?
Terminal and respiratory bronchioles
Where do the smallest particles (
Some deposit in the alveoli by simple diffusion, others are breathed back out with expired air
Which increases more during exercise, heart rate or alveolar ventilation?
Alveolar ventilation increases from 7.5 L/min to up to 120 L/min, while heart rate maybe only triples in rate.
Why does heart rate increase so much less than ventilation during exercise?
Moving liquid is much harder. Also, analysis using the Fick equation shows that since you can’t increase the O2 content of inspired air, increasing O2 in the lungs has to happen through increased ventilation. Oxygen delivery to the tissues increases both by increasing O2 gradient upstream and downstream of target tissues and by increasing flow rate, a twofer.
What happens to pulmonary vascular resistance on a newborns first breaths? Why?
Decreases when the smooth muscles relax
What happens to systemic vascular resistance on a newborns first breaths? Why?
Increases when the parallel placental flow goes away, decreasing the number of paths around the blood flow circuit
