PASS Wk7

PASS Wk7

​Recap

• ​Lung physiology

  • Mechanisms of breathing

  • Gas exchange

  • Boyle's, Ohm's, Dalton's and Henry's laws

• Lung volumes​

Multiple Choice

During inspiration....

• Lung volume increases, resulting in an increase in lung pressure

• Lung volume increases, resulting in a decrease in lung pressure

• Lung volume decreases, resulting in an increase in lung pressure

• Lung volume decreases, resulting in a decrease in lpressure

Multiple Choice

What would happen to the pressure in cylinder if the volume was halved (no other changes)?

• The pressure would be halved

• The pressure would be 1/16th of what it was

• The pressure would be doubled

• The pressure would be 16x greater

Multiple Choice

The law that describes the relationship between pressure and volume is called:

• Boyle's law

• Ohm's law

• Dalton's law

• Henry's law

Multiple Choice

With respect to respiratory physiology, which of these describes Ohm's law?

• $$F=\frac{\Delta P}{R}$$  

• $$F=\frac{\Delta P}{R^4}$$  

• $$I=\frac{V}{R}$$   

• $$F\propto\frac{1}{R^4}$$  

​Using Ohm's Law

If a tube has a change in pressure of 250 and a airway resistance of 15, what is the flow rate of air through the tube?

Multiple Choice

How does a change in diameter affect air flow through a tube?

• A small decrease in diameter will cause a large increase in flow

• A small decrease in diameter will cause a small decrease in flow

• A small decrease in diameter will cause a small increase in flow

• A small increase in diameter will cause a large increase in flow

Using Ohm's Law +​

If the diameter of a tube is doubled (no other changes), how would this affect the:

• Resistance

• Change in pressure

• Flow rate​

Multiple Choice

Which of these is TRUE about lung compliance?

• It allows the lung volume to expand easily

• Low compliance can lead to airways collapsing

• Lungs are generally not very distensible

• Lung compliance is the degree to which your lungs obey you

Using Dalton's Law

If air is 21% oxygen gas and has a total pressure of ​760 mmHg at sea level, what is the partial pressure of O₂?

​

If a container contains two gases of partial pressures 200 kPa and

450 kPa (and no other gasses), what is the total pressure in the container?​

Multiple Choice

Henry's law states that....

• Decreasing a gas' partial pressure will increase the rate it diffuses across membranes

• Increasing a gas' partial pressure will increase how much of it can be dissolved

• Decreasing a gas' partial pressure will increase the partial pressure of other gasses

• Decreasing a gas' partial pressure will decrease the overall pressure of a system

Multiple Choice

How is O₂ predominantly carried in the blood?

• As a dissolved gas in the plasma

• Bound to protein

• Dissolved as oxalic acid

• Along the vessel epithelium

Multiple Choice

How is CO₂ predominantly carried in the blood?

• As a dissolved gas in the plasma

• Bound to haemoglobin

• Dissolved as bicarbonate ions

• Bound to proteins other than haemoglobin

​In your groups

• Discuss the difference between minute ventilation and alveolar ventilation

• What is anatomical dead space? What is physiological dead space?

• What are the implications of this difference​?

Multiple Choice

Imagine you are having a breath-holding competition with your friend at the pool. It's been 8 minutes now (lung diff) and you have well and truly won, but for some strange reason you feel the urge to breathe. Which of these does NOT cause this sensation?

• Low PO₂

• High PCO₂

• High H⁺ concentration

• High H₂O concentration