28-31. Respiratory Flashcards
What are the 2 principle physiologic functions of the lung?
- O2 in
- CO2 out
Define ventilation.
Moving air in/out of lungs
What is the main energetic difference between the mechanics of breathing at rest vs. during exercise?
- At rest = active inhalation, passive exhalation
- During exercise = active inhalation and exhalation
What are the 3 pre-conditions of oxygen transport system?
- Respiratory system is predicated on diffusion gradients
- Only facilitation is pumping fluids faster
- Gears must turn in concert
What 2 lung volumes add up to form the total lung capacity?
- Residual volume
- Vital capacity
How do residual volume and vital capacity differ in regard to ventilation?
- Residual volume = extra air that sits in airways and lung that never leaves
- Vital capacity = max air in + max air out
Roughly how big is the volume of a non-exchanging tubing in the lung?
30%
What is the main determinant of the portion of each breath wasted on dead space ventilation?
Depth of breath
What are the factors that influence the rate of a gas’ diffusion across a membrane
- Surface area
- Thinness of barrier
- Pressure differential
Describe the concept of Va/Q. What is the normal Va/Q ratio in humans?
- Va = ventilation of alveoli
- Q - cardiac output through lung
- These 2 flows must be proportional
- In humans = 0.8
What would happen to the balance of perfusion and ventilation in a lung where half of the alveoli had filled up w/ fluid and pus? Would the PaO2 be elevated or depressed?
- Less perfusion
- Half venous blood and half alveolar blood going back into the body
- PaO2 would decrease
How does ventilation and diffusion combine to move O2 from outside the body to the tissues and CO2 from the tissues to the environment?
- Ventilation moves air through pulmonary system
- Diffusion brings O2 into blood and CO2 out of blood based on differential pressure gradients
How does mitochondrial uptake of O2 drive O2 uptake?
Mitochondrial uptake blood more –> lung needs to uptake more O2 to reoxygenate blood
What percentage of its working capacity does the lung use to meet the demands of rest?
10-20%
Out of Ve, PaO2, PaCO2, pH. Which are regulated variables? Which are controlled?
- Regulated = PaO2, PaCO2, pH
- Controlled = Ve
Define hypoxemia.
Low levels of arterial O2 (PaO2
Define eupnea.
Ventilation appropriate to body’s needs
Define hyperpnea.
Elevated ventilation usually appropriate to need (exercise)
Define hyperventilation.
Ventilation beyond that needed to maintain blood gases
Define hypocapnea.
Low blood CO2 from too much breathing
Define hypercapnea.
Increased arterial CO2 often due to insufficient ventilation (asthma attack)
Define eucapneic hyperpnea.
Ventilatory response to exercize
What is normal PaCO2?
40 mmHg
What ventilation pattern leads to hypocapnea?
Hyperventilation
What is the equation for oxygen consumed?
VO2 = total ventilation x (ambient O2 - expired O2)
What are 3 major ways that CO2 travels in the bloodstream from the working muscles to the lungs?
- Dissolved in plasma
- Bound to hemoglobin
- In the form of bicarbonate
What percentage of a person’s resting oxygen consumption is being used by ventilatory muscles like the diaphragm and intercostals?
1-2% at rest
During submaximal exercise, what percentage of VO2 is being used to power ventilation? How does this change at high intensity work?
- 4%
- Can get above 10% during high intensity work
What is CLCP?
Critical lactate clearance point = highest workload at which lactate blood concentration can be stabilized
How is RER defined?
Amount of CO2 produced / amount of O2 consumed
What is the meaning of a resting RER of 0.7? 1.0?
- 0.7 = mostly fat is being metabolized
- -1.0 = only metabolizing CHO
How can RER go beyond 1.0? Where does the extra CO2 come from?
-More CO2 produced than O2 consumed
Excess CO2 comes from increase in lactate and increase in buffering of blood lactate by bicarbonate
How is it possible that an Olympic endurance athlete could take 3 months off from training and still have a higher VO2max than well-conditioned college athletes?
50% of VO2 max is genetic
