11- Respiratory system 2 Flashcards
The rate of airflow and the amount of effort needed for breathing depends on what 4 factors?
Pressure changes
Alveolar surface tension
Compliance of the lungs
Airway resistance
what is surface tension?
a measure of the contractive tendency that allows liquids to resist deformation by an external force
what is a surfactant?
a compound that reduces surface tension when added to a liquid
What does lung compliance depend on?
the effort required to stretch the lungs and chest wall
the elasticity of the lungs and surface tension
explain high and low lung compliance
High compliance: Lungs and chest wall expand easily
Low compliance: Lungs resist expansion
Pulmonary air volumes exchanged in ventilation are:
Tidal volume — 500ml
Inspiratory reserve volume — 3100ml
Expiratory reserve volume — 1200ml
Residual volume — 1200ml
what is Minute Ventilation (MV) and how is it calculated?
the total volume of air inhaled and exhaled each minute
MV = respiratory rate x tidal volume.
In a person with 12 respiratory rate and tidal volume 500 ml — MV=12 breaths/min X 500 mL/breath = 6 litres/min.
what does a spirogram measure?
the volume of air exchanged during breathing and the respiratory rate
how does the exchange of oxygen and carbon dioxide occur between alveolar air and pulmonary blood?
passive diffusion
what is Boyle’s Law?
Gases diffuse from areas of higher partial pressure to areas of lower partial pressure.
The greater the difference in partial pressure, the faster the rate of diffusion.
what is Henry’s Law?
the quantity of a gas that will dissolve in a liquid is proportional to the partial pressure of the gas and its solubility —
the higher the partial pressure of a gas over a liquid and the higher the solubility, the more gas will stay in solution.
4 factors that affect the rate of diffusion
Partial pressure difference of gases in air
Surface area available for gas exchange
Diffusion distance
Solubility and molecular weight of gases
what is external respiration?
gas exchange between the alveoli of the lungs and pulmonary blood capillaries
(blood oxygenation)
what is internal respiration?
gas exchange is the exchange of O2 and CO2 between systemic capillaries and tissue cells
(Oxygenated into deoxygenated blood)
