Human Phys 6.8 Flashcards

1
Q

What do our lungs aim at?

A

Keeping ventilated alveoli in areas that are well perfused

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2
Q

How can keeping ventilated alveoli in areas that are well perfused be accomplished?

A

Compensatory bronchoconstriction (controls V)

Compensatory hypoxic vasoconstriction (controls Q)

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3
Q

What results when small regions of alveoli are not well perfused? (Pulmonary embolus)

A

Dead space

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4
Q

What does compensatory bronchoconstriction do when regions of alveoli are not well perfused?

A

Send air to other well perfused areas of the lungs

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5
Q

What results when small regions of alveoli are not ventilated? (Airway collapse or obstruction)

A

Right to left shunt

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6
Q

What does the compensatory hypoxic vasoconstriction do when small regions of alveoli are not ventilated?

A

Sends blood to other well ventilated areas of the lungs

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7
Q

Why is blood flow higher at base?

A

Due to impact of gravity and hydrostatic pressure

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8
Q

What is ventilation higher at base?

A

Gravity and weight of lung reduce alveolar volume but alveoli at base is more compliant and capable of oxygen exchange

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9
Q

What is normal ventilation?

A

4 L/min

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10
Q

What is normal perfusion?

A

5 L/min

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11
Q

What is the normal ventilation/perfusion ratio for the lung as a whole?

A

0.8

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12
Q

What does it mean when V/Q is higher than 0.8?

A

Ventilation exceeds perfusion

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13
Q

What is the V/Q at the apex of the lung?

A

Higher (less Q)

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14
Q

What is the V/Q at the middle of the lung?

A

Even

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15
Q

What is the V/Q at the base of the lung?

A

Lower (too much Q)

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16
Q

What happens in a high V/Q?

A

PaO2 increases

PaCO2 decreases

17
Q

What happens in a low V/Q?

A

PaO2 decreases

PaCO2 increases