Anatomy of Chest Wall and Mechanics of Breathing Flashcards

1
Q

What is meant by Boyle’s law?

A

Boyle’s Law states that the pressure exerted by a gas is inversely proportional to to its volume (P a 1/V). Note that gases (singly or in mixtures) move from areas of high pressure to areas of low pressure.

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2
Q

What is Dalton’s law?

A

Dalton’s Law states that the total pressure of a gas mixture is the sum of the pressures of the individual gases.

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3
Q

What is Charle’s Law?

A

Charles Law states that the volume occupied by a gas is directly related to the absolute temperature (v a T)

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4
Q

What is Henry’s law?

A

Henry’s Law states that the amount of gas dissolved in a liquid is determined by the pressure of the gas and it’s solubility in the liquid.

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5
Q

Where does the esophagus and the aorta pass through the thorax?

A

Between the pleural sacs

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6
Q

Where does the parietal membrane fold back on itself?

A

At the lung hilux?

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7
Q

What type of fluid exists in the pleural cavity?

A

Intrapleural fluid

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8
Q

What is the function of pleural fluid?

A

Lubrication, two membranes can glide across each other. Fluid holds the two membranes together

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9
Q

What is pleurisy?

A

Inflammation of the pleura.

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10
Q

How does pressure of intrapleural cavity compare to the atmospheric pressure?

A

Subatmospheric

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11
Q

What creates the outward pull of the chest?

A

Elastic recoil of the chest wall

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12
Q

What pulls the lungs inward?

A

Elastic recoil of lung?

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13
Q

When are inward and outward forces of the lungs equal?

A

At the end of an expiration

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14
Q

How is boyle’s law applied in breathing?

A

Thoracic cavity changes in volume. increase volume = decrease pressure decrease volume = increase pressure Gases always move from high pressure to low pressure

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15
Q

What brings about expiration?

A

Expiration is passive at rest, but uses internal intercostal and abdominal muscles during severe respiratory load

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16
Q

What muscles are used in inspiration?

A

Sternocleidomastoids, Scalenes, External intercostals, diaphragm

17
Q

What activates the skeletal muscles?

A

Alpha motor neurones

18
Q

What direction do the internal intercostal muscles travel?

A

Opposite direction to external intercostal muscles

19
Q

What is the movement of the sternum during inspiration?

A

Moves outwards and forwards - pump handle movement

20
Q

What is the movement of the ribs during inspiration?

A

Moves outwards - bucket handle movement

21
Q

What is asthma?

A

Over-reactive constriction of bronchial smooth muscle. Increases resistance, expiration difficult.

22
Q

Why are airways open during inspiration?

A

Physical forces of inspiration holds them open

23
Q

What happens to airways during expiration?

A

Compressed by physical forces of expiration

24
Q

What happens when the pleural cavity is opened?

A

Air flows in since pleural cavity is subatmospheric Lung collapses to unstretched size

25
Q

What is Intra-thoracic (Alveolar) Pressure (PA)?

A

Pressure inside the thoracic cavity, (essentially pressure inside the lungs). May be negative or positive compared to atmospheric pressure. During rest it’s zero - since equals atmospheric pressure

26
Q

What is Intra-pleural Pressure (Pip)?

A

Pressure inside the pleural cavity, ALWAYS negative (in healthy lungs at least!)

27
Q

What is Transpulmonary pressure (PT):

A

Difference between alveolar pressure and intra-pleural pressure. ALWAYS positive (in health) because Pip is always negative. PT = Palv – Pip.

28
Q

How do these three pressures change during breathing?

A
29
Q

What factors influence bulk flow of air between the atmosphere and the alveoli?

A

The difference between atmospheric pressure and alveolar pressure Airway resistance

30
Q

What are the features or the lungs during the end of an unforced expiration?

A

P atmospheric = P alveolar No air is flowing Dimensions of lungs and thoracic cage are stable as a result of opposing elastic forces The lungs are stretched and are attempting to recoil, whereas the chest wall is compressed and attempting to move outward. This creates a subatmospheric intrapleural pressure and hence a transpulmonary pressure that opposes the forces of elastic recoil.

31
Q

What does airway resistance determine?

A

How much air flows into the lungs at any given pressure difference between atmosphere and alveoli

32
Q

What is the major determinant of airway resistance?

A

The radii of the airways