10 - Pulmonary Ventilation And Gas Exchange Flashcards
To reach the respiratory zone air must first pass through what? And what is this achieved by?
The conducting zone and reach the lungs, this is achieved by changing three dimensions of the thorax which increases the volume of the thoracic cavity and reduces the pressure inside
What is air passively drawn in by?
The pressure change
What allows the pressure change?
The ribs, intercostal muscles and diaphragm
What does inspiration involve?
The external intercostal muscles contracting to raise the ribs as the diaphragm contracts to bring the floor of the thorax down
What is expiration achieved by?
Relaxing these muscles and allowing the force of gravity to lower the ribs
What helps contract the lung tissue
The elastic tissue of the lungs and smooth muscle bands around the alveoli help to contract the lung tissue
What is atmospheric pressure around sea level?
Approximately 760 mm Hg
Is is special about the pressure inside the plural sac?
It is lower than the atmospheric pressure
What is the outer layer of the pleural sac attached to
The thoracic wall
What 2 ways is molecular O2 carried?
- 5% is dissolved in plasma
98. 5% is loosely bound to each Fe2+ of Hb in RBCs
What is each Hb molecule composed of
4 polypeptide chains, each with an iron-containing heme group
What heavily influences the binding and release of O2 with haemoglobin
P02
How is CO2 transported
7-10% is dissolved in plasma as Pco2
20% of CO2 is bound to the globin part of haemoglobin and called carbaminohaemoglobin
70% is transported as bicarbonate ions in plasma
What doers the carbonic acid-bicarbonate buffer system help resist changes in?
pH
What do slow shallow breaths cause
An increase in the CO2 of blood, resulting in a drop in pH
