Respiratory 2 Flashcards
What is boyle’s law?
The pressure that a gas exerts is inversely porprtional to its volume.
-eg increase volume of gas in container, pressure of that gas decreases
What is dalton’s law?
The total pressure of a gas mixture is the sum of all the pressures of individual gases
What is Charle’s law?
The volume occupired by a gas is directly related to the absolute pressure
What is Henry’s law?
the amount of gas dissolved in a liquid is determined by the pressure of the gas and it’s solubility in the liquid
What are pleural membranes?
- parietal + visceral
- Parietal covers the lung and the visceral lines the inner walls of the ribcage
- inbetween them, thin layer of intrapleural fuid
Function of intrapleural fluid
- produced by pleural membranes + acts as a lubricant, hence reducing friction.
- Allows membranes to glide along eachother + ‘stick’ + holds the lungs against ribs + diaphragm.
What is pleurisy?
-Inflammation of the pleura
Describe the diaphragm’s role in inspiration and expiration in terms of thoracic volume
Inspiration = diaphragm contracts ( flattens) + thoracic volume increases Expiration= diapgragm relaxes ( dome shape) + thoracic volume decreases
Describe asthma
- overeactive constriction of bronchial smooth muscle, hence increasing resistance.
- Expiration phase is most afected
What is the intra-thoracic(alveolar) pressure?(PA)
The pressure inside the thoracic cavity ( inside lungs)
-negative or positive depending on inspire/expire
What is the intrapleural pressure(Pip)?
The pressure inside the pleural cavity (negative in healthy lungs)
-Always less than intra thoracic(alveolar) pressure
What is the Transpulomonary pressure(PT)
The difference between the alveolar pressure and intra-pleura pressure
- PT = PA – Pip.
- positive
Describe how the intrapleural pressure and transpulmonary pressure is formed
Lungs are stretched and are attempting to recoil and the chest wall is compressed and attempts to move outward, creating a subatmospheric intraplural pressure, and hence transpulmonary pressure that opposes the forces of elastic recoil
-natural recoil of lungs inwards also caused by:
surface tension of alveolar fluid which pulls alveoli inwards
What is the alveolar pressure at the end of an unofrced expiration
Patm=PA
Describe pneumothorax
Pleural cavity is opened to atmosphere and air flows in. The ung collapses and the relationship between the pleural membranes become lost.
