Respiratory physiology 2 Flashcards
Boyle’s law
Pressure of a gas is inversely proportional to the gas volume. P1V1=P2V2
Dalton’s Law
Total pressure of gas mixture of the sum of partial pressures of the individual gases.
Charles Law
Volume occupied by gas is directly related to the absolute temperature.
Henry’s Law
Amount of gas dissolved in a liquid depends on the partial pressure of the gas and its solubility in the liquid.
Define partial pressure of a gas
Partial pressure = Pmixture x % of gas
What is the direction of gas movement ?
From high pressure to low pressure.
What is the role of intrapleural fluid?
It allows gliding movement between parietal and visceral membrane and holds the lung tight to the thoracic wall.
What happens in pneumothorax?
Loss of relationship between the the two membranes, air enters the thoracic cavity, lungs collapse and the chests expands slightly.
What is intrapleural pressure?
It is pressure inside neural cavity, it is always negative -3 mm Hg. It decreases further during inspiration. It stops lungs from recoiling.
What muscles are used on inspiration?
Diaphragm and external intercostal muscles.
Describe the action of external intercostal muscles.
They act as pump handle increasing anterior -posterior dimensions and as buckle handle increasing mediolateral dimensions.
What keep airways open?
Physical forces of inspiration and expiration.
Define intra-thoracic pressure
Pressure inside the cavity, relative to the atmospheric pressure, it can be negative or positive. It is 0 between breathing.
What is the intra-thoracic (alveolar) pressure on inspiration, expiration and between the breath.
In inspiration the pressure is -1 mmHg, expiration +1 mmHg and 0 between.
What is intrapleural pressure?
Pressure inside pleural cavity, it is always negative. It is -3 mmHg during inspiration, -6 mmHg between breaths. During exercising it can reach -8 mmHg. It is created during the embryonic development.
What is transpulmonary pressure?
It id difference between the intrapleural and intra-thoracic pressure. It is always positive.
What is average breath volume ?
500 mL
What affect build flow of air?
Bulk flow of air is proportional to the difference between alveolar and atmospreric pressure and inversely proportional to the airways resistance, F = (Patm-Pa)/R
What opposes the force of elastic recoil of lungs?
Transpulmonary pressure
The volume of lungs is dependent upon ?
Transpulmonary pressure and how stretchable the lungs are
Which muscles are used on inspiration?
Diaphragm and external intercostal muscles
Which are accessory inspiratory muscles ?
Scalenes and sternocleidomastoid muscles
Which muscles are used for expiration?
Expiration is passive, inspiratory muscles stop contracting, on forced expiration internal intercostal muscles and abdominal muscles are used.
