Alveolar ventilation Flashcards

1
Q

What is meant by minute ventilation?

A

Total volume of air moved into the respiratory tract per minute

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2
Q

What is the calculation for minute ventilation?

A

Respiratory rate x tidal volume

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3
Q

What is the average respiratory rate?

A

15 breaths/min

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4
Q

What is the average minute ventilation?

A

0.5L x 15 = 7.5L/min

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5
Q

What is meant by alveolar ventilation?

A

Volume of air moved into the respiratory part of the respiratory tract per minute

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6
Q

What is the calculaton for alveolar ventilation?

A

Respiratory rate x (tidal volume - anatomical dead space)

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7
Q

How can a person change their minute/alveolar ventilation?

A

Changing their respiratory rate

Changing their depth of breathing to change the tidal volume

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8
Q

What is dead space?

A

Volume of air in the respiratory tract that is not used in gas exchange

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9
Q

What are the types of dead space?

A

Anatomical dead space

Alveolar dead space

Physiological dead space

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10
Q

What is anatomical dead space?

A

Volume of air in the conducting part of the respiratory tract

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11
Q

What is the average anatomical dead space?

A

0.15L out of 0.5L tidal volume

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12
Q

What is the disadvantage of anatomical dead space?

A

The air in the upper respiratory tract, conducting part is expired before the air in the alveoli

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13
Q

What is alveolar dead space?

A

Volume of air in alveoli that are only partially functional or non-functional because of poor or absent blood flow through adjacent pulmonary capillaries

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14
Q

What is physiological dead space?

A

Anatomical dead space + alveolar dead space

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15
Q

What is the average physiological dead space? Why?

A

Approximately 0.15L

Because alveolar dead space is very small since most alveoli are fully functional

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16
Q

What is the average alveolar ventilation?

A

15 x (0.5L-0.15L) = 15 x 0.35L = 5.25L/min

17
Q

What is the most important factor of resistance in a tube?

A

Radius of tube

18
Q

How does resistance in a tube relate to the radius of the tube?

A

It is inversely proportional to the radius of the tube

so if the radius increases, the resistance decreases significantly

19
Q

Is there more resistance in the trachea or in a bronchi/bronchiole? Why?

A

Bronchi/bronchiole has higher resistance
because it has a smaller radius
which increases the resistance significantly

20
Q

Is there more resistance in the trachea or all of the bronchioles?

A

Trachea has higher resistance
because there is only one trachea but there are many bronchioles
connected to each other in parallel
reduces the overall resistance of the bronchioles

20
Q

Is there more resistance in the airways during inspiration or expiration? Why?

A

Expiration has higher resistance
because during inspiration, the airways are pulled open, increasing their radius, decreasing resistance significantly
whereas during expiration, the airways narrow by elastic recoil, decreasing their radius, increasing resistance significantly

22
Q

How does air flow change during expiration? Why?

A

Decreases from the beginning to the end of expiration
because the airways narrow by elastic recoil, reducing their radius, increasing resistance against air flow significantly

23
Q

Where in the tracheobronchial tree do pathological increases in resistance to air flow mostly occur? Why?

A

The smaller bronchioles

because they have a smaller lumen so they are more easily occluded

24
Q

What are some examples of pathological causes of increased resistance to air flow in the smaller bronchioles?

A

Increased mucus

Hypertrophy of smooth muscle in the walls of the airways

Oedema

Loss of radial traction

24
Q

What is radial traction?

A

Connective tissue surrounding respiratory bronchioles, alveolar ducts, alveolar sacs and alveoli
that hold those airways open

26
Q

How do all of the pathological causes increase resistance to air flow in the smaller bronchioles?

A

Reduce radius of bronchioles, which increases resistance significantly