Anatomy of Chest Wall and Mechanics of Breathing Flashcards

1
Q

Which gas law is breathing based on?

A

Boyle’s Law

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2
Q

What does Boyle’s Law state?

A

The pressure exerted by a gas is inversely proportional to its volume

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3
Q

What is the top of the lung called?

A

Apex

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4
Q

What is the first lobe below the apex called in both lungs

A

Superior lobe

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5
Q

What is different in the superior lobe of the left lung compared to the right

A
  • Much bigger - Curved lower border
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6
Q

What are the lungs and interior of the thorax covered in?

A

Pleural sac

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7
Q

What is the pleural membrane made of?

A

An extremely thin layer of intrapleural fluid

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8
Q

What does the visceral pleural membrane coat?

A

Outer surface of the lungs

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9
Q

What does the parietal pleural membrane coat?

A

Inner surface of the ribs

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10
Q

What does the interaction between the pleural membranes mean for the lungs and the ribs?

A

The lungs are effectively stuck to the ribs

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11
Q

What is pleurisy?

A

Inflammation of the pleura

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12
Q

Why does breathing occur?

A

Thoracic cavity changes volume

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13
Q

Why do the lungs need to be “stuck” to the ribs?

A
  • The lungs are trying to move in the way and would collapse
  • The ribs are moving against this force to maintain the shape of the cavity
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14
Q

Where do the two pleural membranes overlap?

A

The hilux of the lung

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15
Q

What is the overlapping membrane known as?

A

Visceralparietal membrane

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16
Q

What volume of fluid is there in the pleural cavity?

A

3ml

17
Q

What does the pleural fluid allow the membranes to do?

A
  • Slide over eachother
  • Stick to eachother strongly (imagine 2 microscope slides with water between them
18
Q

What symptoms, to do with the pleural membranes, can you get when you have pleurisy?

A

Pain and discomfort as they can’t slide over each other

19
Q

What is the average negative pressure of the lungs due to the interaction with the ribs?

A

-3mm Hg

20
Q

What is the name given to the force that the lungs and the ribs exert on each other due to the pleural membranes?

A

Elastic recoil

21
Q

What is pneumothorax?

A

A collapse of the lung due to loss of pleural membrane interaction

22
Q

What happens to the ribcage as the diaphragm is relaxed?

A

It rises

23
Q

What effect does the rising of the ribcage have on the thoracic cavity and what does this cause?

A
  • Lowers the pressure
  • Air from the atmosphere moves into the lungs
24
Q

What happens to the thoracic pressure when the air moves in?

A
  • Increases above atmospheric pressure (PATM)
25
Q

What happens to the alveoli when air moves into them?

A
  • They expand
  • Elastic fibres stretch
26
Q

How does air move back out of the alveoli?

A

Under elastic recoil from the elastic fibres surrounding the alveolar sacs

27
Q

What two groups of muscles can be recruited to aid in expiration during exercise?

A
  • Intercostal muscles
  • Abdominal muscles
28
Q

How do the intercostal muscles aid in expiration?

A
  • Innervating alpha motor neurone is switched off and they relax
29
Q

How do the abdominal muscles increase expiration?

A
  • Contraction of them increases thoracic pressure by decreasing thoracic volume
30
Q

What shape is the diaphragm when it contracts?

A
  • Flat
31
Q

What does the shape change to a flat shape of the diaphragm do to thoracic pressure?

A
  • Increases volume so decreases pressure
32
Q

How does intercostal muscle contraction increase anterior posterior thoracic volume?

A

Similar to a pump handle

33
Q

How does intercostal muscle contracting increase lateral thoracic volume?

A

Similar to a bucket handle shape

34
Q

How does inspiration follow Boyle’s Law?

A

Air moves in from the atmosphere from high pressure to low pressure because the volume of the container (lungs) is increased.

35
Q

How does expiration follow Boyle’s Law?

A

Pressure of the thoracic cavity excedes atmospheric pressure as the volume is reduced by elastic recoil, rib cage decending and diaphragm rising

36
Q

List reasons why intrapleural pressure is always lower than alveolar pressure

A
  • Alveoli have residual volume in them ALL THE TIME
  • Intrapleural space contains fluid
  • Intrapleural pressure is always negative compared to atmospheric pressure, whereas alveolar pressure is sometimes above
  • If intrapleural pressure equals alveolar pressure then a pneumothorax will form