Respiratory Physiology Flashcards
What is the conducting zone?
No exchange of gases with the blood. The airways make up the conducting zone
What is the respiratory zone?
Exchanges gases with the blood
The alveoli that exchange gases with the blood make up the respiratory zone
-alveolar sacs are filled with air and are covered with capillaries for gas exchange
Difference between cell respiration and external respiration
Cell respiration-using O2 in cells during metabolism to produce ATP (also make CO2)
External respiration-is the exchange of gases between the atmosphere and the cells
What are the 4 steps of external respiration?
- Ventilation of gas exchange between the atmosphere and air sacs (alveoli) in the lungs by bulk flow
- Exchange of O2 and Co2 between air in the alveoli and the blood in the pulmonary capillaries by diffusion
- Transport of O2 and CO2 by the blood between the lungs and the tissues by bulk flow
- Exchange of O2 and CO2 between the blood in the systemic capillaries and the tissue cells by diffusion
Where are levels of O2 and CO2 highest and lowest?
O2 would be lowest where it’s being used in the cells and highest in the lungs where it’s brought in from the atmosphere
CO2 would be highest where it’s being made in the cells and lowest in the lung where it’s gotten rid of into atmosphere
What are the 3 layers of pleura ?
The visceral pleasure covers the surface of the lung
there is then a tiny gap that is the pleural cavity containing intrapleaural fluid
The parietal pleura lines the chest cavity
What is pleurisy
Inflammation of the pleura
Can have pleural friction rub-very painful
What is trans pulmonary pressure?
A trans mural pressure, an across the wall pressure difference
Transpulm=pressure in the alveoli - intrapleaural pressure
What creates the subatmospheric pressure?
In development the thoracic cavity becomes bigger than the lungs.
This means the lungs are always stretched to some degree and want to recoil
Causes pressure in intrapleaural space to be -4 mmHg compared to atmospheric pressure
What causes the lungs not to collapse
The pressure difference
Transpulmonary pressure keeps them open
If pleural cavity is punctured the transpulmonary pressure will be 0 and the lungs will collapse
Why does the lung collapse
Due to recoil and also surface tension
Surface tension of the alveolus wants to collapse (the watch molecules that line alveolus want to be closer together)
Surface tension resist expansion
The lung cells produce surfactant (produced by type 2 alveolar cells to reduce surface tension)
Acts like detergent to decrease attraction of water molecules
Why do clinicians tell you to take deep breaths after surgery?
Increased surfactant
Stretches type 2 cells and stimulates secretion
Surfactant increased lung compliance and makes lungs easier to expand
Lung compliance
C= change in volume/ change in transpulmonary pressure
A less compliant lung is a stiff lung. This means you have to increase chest size more to drop intrapleural pressure to increase the transpulmonary pressure
Respiratory distress syndrome of the newborn
Occurs in premature infants where type 2 cells do not mature and aren’t producing enough surfactant
Alveoli tend to collapse at expiration and makes inspiration very difficult
Therapy is surfactant into the trachea
Resistance of airways
F= change in pressure/ resistance
Change in pressure=difference between alveolar and atmospheric pressures
Resistance determined by radius of the airways
Normally resistance is very low so only small change in pressure 1 mmHg difference is needed in normal breathing
