lecture 17 - the work of breathing Flashcards
what is boyles law
the pressure of a gas is inversely related to its volume
what is intrapulmonary pressure
pressure inside the lungs
what is the stiffness of the lungs related to
compliance and surface tension
what is compliance in the lungs
the magnitude of the change in lung volume produced by the given change in pressure
change in V / change in P
what does low compliance of the lungs mean
“stiff lungs”
this means more energy is needed / more work must be done for the lungs to expand
what is surface tension
the tendency of a fluid surface to occupy the smallest possible surface area
what must be overcome and where is it for the lungs to expand
surface tension must be over come
- alveoli are lined with fluid that exert surface tension + walls of alveoli are very thing = enhancing this effect
what reduces surface tension in the alveoli and what produces this
surfactant = produced by type 2 pneumocytes
how does surfactant reduce surface tension
reduces attractive forces between fluid molecules lining alveoli
where does most of the resistance to airflow arise
in the bronchi
what is the tidal volume
volume of air moved in and out of the lungs during normal quiet breath
what is the inspiratory reserve volume
extra volume that can be inhaled over and above the tidal volume
what is the expiratory reserve volume
extra volume that can be exhaled voluntarily after completion of a normal, quiet respiratory cycle
what is the residual volume
volume remaining in the lungs after maximal exhalation
what is the minimal volume
volume remaining in the lungs if they collapsed
