Respiration - Lecture 6 Flashcards
What does the chest wall include?
the rib cage, diaphragm and the abdominal wall
What happens to the visceral pleura when the lungs fill the chest?
it comes in contact with the parietal pleura
How do the lung and chest operate together?
in series with one another
Are the lungs directly attached to the chest wall?
no
How are the visceral and parietal pleura coupled together?
by a thin layer of liquid that fills the intrapleural space
What is the function of the liquid inside the intrapleural space?
it allows the lungs to slide against the internal wall of the chest during breathing and to follow the change in thoracic configuration
What is pleural pressure?
the pressure that can be measured in the liquid-filled space between lung and chest
At rest, what sign is the pleural pressure?
negative
Why is the pleural pressure negative at rest?
because of the opposing forced acting on the lung and the chest wall
What happens if a hole is punctured through the chest wall?
the lungs collapse and the chest springs outwards (pneumothorax)
What do we measure to evaluate the elastic properties of the respiratory system?
changes in the recoil pressure of each separate structure for a given change in lung volume
How are pressures measured for the respiratory system?
manometers or pressure transducers
What does “negative pressure” indicate?
a pressure below atmospheric pressure
What does “positive pressure” indicate?
a pressure above atmospheric pressure
What is the recoil pressure defined as?
the pressure difference between the inside and outside of the structure
What is the trans-chest-wall pressure?
the difference between the pleural pressure and the pressure at the body surface
How can we measure pleural pressure?
using a flexible balloon introduced into the esophagus
Why does esophageal pressure provide a close approximation of pleural pressure?
because the esophagus is located between the two pleural spaces
What is the formula for trans-chest-wall pressure?
Pw = pleural pressure - body surface
How is the transpulmonary pressure measured?
Pl = Palv - Ppl
How is the transrespiratory system pressure measured?
Prs = Palv - Pbs
Prs = Pl + Pw
How can we calculate Pbs?
Pbs = Ppl - Pw
How can we calculate the Palv?
Palv = Pl + Ppl
What is the compliance of the lungs?
a parameter that refers to the ease with which each of these structures can be distended
