Pressure and Gases Flashcards
Millimetres of mercury (mmHg) is typically a unit of measurement used in measuring what?
Blood pressure and inspiratory and expiratory pressures
Centimetres of Water (cmH2O) is typically a unit of measurement used in measuring what?
Central venous pressure
Pounds per square inch (Psi) is typically a unit of measurement used in measuring what?
The pressure of compressed gases and direct pressure on an object
What property of fluids does the Bernoulli effect describe?
As the speed of a moving fluid increases, the pressure decreases and vice versa
What property of gases does Boyle’s law describe?
In a closed system at constant temperature, if the occupied volume of a gas increases, the pressure decreases and vice versa
What property of gases does Dalton’s law describe?
In a mixture of gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gasses
What is a partial pressure of a gas in a mixture?
The pressure that gas would exert if it occupied the total volume of the mixture
What property of gases does Henry’s law describe?
The mass of a gas that will dissolve in water at a given temperature is proportional to the partial pressure of the gas and it’s solubility coefficient
How is oxygen able to diffuse into the bloodstream within the lungs?
Oxygen in the bloodstream has a lower partial pressure than oxygen in the alveoli, creating a pressure gradient which allows oxygen diffusion from the alveoli into the bloodstream
How is oxygen carried in the bloodstream from the lungs to the rest of the body?
Most of the oxygen binds to haemoglobin molecules (4 oxygen molecules per haemoglobin), while a small percentage is dissolved in blood plasma.
How does oxygen from the blood enter the interstitial fluid and eventually cells?
Oxygen diffuses along a pressure gradient into the interstitial fluid and cells
An oxygen saturation level is a measure of what? What can it be an indicator of?
A measurement of the proportion of haemoglobin molecules with oxygen attached. Indicates respiratory function and potential anaemia (as Iron is what binds oxygen in haemoglobin)
How does oxygen therapy increase oxygen concentration in the blood?
Concentrated oxygen increases the partial pressure of oxygen in alveolar air. This increases the oxygen concentration/pressure gradient between alveoli and capillaries and makes more oxygen available for diffusion into the blood
