28-31. Respiratory Flashcards
(33 cards)
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
