Ventilation

Question 1

What is ventilation

Answer 1

Amount of air-flow in the lungs

Question 2

Describe the difference between minute ventilation and alveolar ventilation

Answer 2

Minute ventilation is the volume of air that flows into or out of the lung in one minute, and alveolar ventilation is
the volume of air that flows into or out of the alveolar space in one minute. Minute is always larger than alveoli ventilation b/c it includes air flowing in the conducting paths plus alveoli Minute ventilation is the volume of air that flows into or out of the lung in one minute, and alveolar ventilation is
the volume of air that flows into or out of the alveolar space in one minute. Minute is always larger than alveoli ventilation b/c it includes air flowing in the conducting paths plus alveoli

Question 3

List factors that influence lung ventilation

Answer 3

Bronchodilators/constrictors, exercise, altitude, obstructive diseases, restrictive disease, gravity

Question 4

How do bronchodilators/constrictors affect ventilation

Answer 4

Bronchodilators increase alveolar ventilation, whereas bronchoconstrictors reduce ventilation.

Question 5

How does exercise affect ventilation

Answer 5

During moderate exercise, ventilation can increase ~10-fold in order to meet the
demands of increased CO2 productionDuring moderate exercise, ventilation can increase ~10-fold in order to meet the
demands of increased CO2 production

Question 6

How does altitude affect ventilation

Answer 6

Ventilation increases to meet the increased demands of O2

Question 7

How do obstructive and restrictive diseases affect ventilation

Answer 7

These can reduce ventilation by increasing airway
resistance or altering lung compliance. For many obstructive diseases, overall ventilation does not go down, but there are
reductions in ventilation regionally that are balanced by increases elsewhereThese can reduce ventilation by increasing airway
resistance or altering lung compliance. For many obstructive diseases, overall ventilation does not go down, but there are
reductions in ventilation regionally that are balanced by increases elsewhere

Question 8

How does gravity affect ventilation

Answer 8

Causes regional differences in ventilation. Intrapulmonary pressure is smaller at the base than the apex of the lung due to the weight of the lung which causes a stronger pull from the chest wall at the apex (more negative IP). Bronchioles/alveoli at apex are larger in volume, thus they are less compliant and are less well ventilated

Question 9

Components of work of breathing

Answer 9

(a) work done against the elastic recoil of the lungs and (b) work done against airway resistance

Question 10

Two general causes of increased work of breathing

Answer 10

Increase in elastic recoil (decreased compliance) of the respiratory system, increase in airway resistance, or a combination of the two.

Question 11

Describe the work of breathing and its influence on breathing rate and tidal volume

Answer 11

At small tidal volumes (and faster rate), the work required to overcome elastic recoil is small, but the work required to overcome airway resistance is large. For large tidal volumes (and slower rates), the opposite is true.

Question 12

Define anatomical dead-space and what conditions result in increased anatomical dead space

Answer 12

Of the 500 ml of air in each breath, about 150 ml (or 30%) remains in the conducting path. This air is termed anatomic dead-space. Increased anatomical dead space can occur if we breath rapidly and at small tidal volumes (when much of the tidal volume fails to reach alveoli) or during snorkeling (which increases the total conducting path for air).

Question 13

Define alveolar dead-space

Answer 13

These are alveoli that are well-ventilated but do not participate in gas exchange (do not eliminate CO2). Are present in unperfused regions of the lung

Question 14

Define physiologic dead-space

Answer 14

The sum of the anatomic dead-space and the alveolar dead-space is called the physiologic dead-space. In a healthy person, physiologic and anatomic dead space have the same volumes.

Question 15

List different lung volumes

Answer 15

Residual volume, Functional residual capacity, total lung capacity, Tidal volume, vital capacity, minute ventilation

Question 16

What is residual volume

Answer 16

Volume of air remaining in the lungs after a maximal expiration. ~1.5L

Question 17

Functional residual capacity

Answer 17

The volume of gas present in the lung and upper airways at the end of a normal expiration. ~2.5L

Question 18

total lung capacity

Answer 18

The volume of air inside the lungs at the end of a maximal inspiration. ~7.5L

Question 19

tidal volume

Answer 19

difference in lung volume between a normal inspiration and normal expiration. ~500mL

Question 20

vital capacity

Answer 20

The volume of air exhaled after a maximal inspiration followed by a maximal expiration. VC= TLC- RV

Question 21

Minute ventilation

Answer 21

The tidal volume (ml) × frequency of breathing (breaths/min) product

Question 22

Changes in lung volume are measured with what?

Answer 22

spirometer

Question 23

What is body plethysmograph

Answer 23

Measures functional residual capacity: the subject sits in an airtight chamber, breathing through a mouthpiece. FRC is
estimated essentially from the change in pressure that occurs when the lung expands.

Question 24

Dynamic measurement of lung volume

Answer 24

forced expirogram

Question 25

What is forced expirogram

Answer 25

Can separate normal from obstructive and restrictive anomalies. Subject inspires maximally then exhales as hard and completely as possible. The volume exhaled in the first second is called the forced expiratory volume, FEV1.0. The
total volume exhaled is the forced vital capacity, FVC (or just vital capacity VC). Normal FEV/FVC = 80%.

Question 26

What is a flow volume curve

Answer 26

plots lung volumes during forced expirations

Question 27

How does restrictive disease (pulmonary fibrosis) affect vital capacity, FEV/FVC, airway resistance, lung compliance, total lung capacity, functional residual capcity?

Answer 27

Vital capacity is decreased b/c they have difficulty inflating the lung maximally. FEV/FVC is not changed b/c airway resistance is not impacted, and the decreased lung compliance can actually cause a small increase in FEV/FVC. TLC decreases and FRC decreases

Question 28

How does obstructive disease (asthma and chronic bronchitis) affect FEV/FVC, functional residual capacity and residual volume, and vital capacity?

Answer 28

FEV/FVC decreases b/c airway resistance increases. Functional residual capacity and residual volume increase b/c air gets trapped in the lungs due to limited airflow during expiration plus patients breathe at higher lung volumes. Vital capacity decreases also because of increased airway resistance and air trapping

Question 29

How does emphysema affect FEV/FVC, functional residual capacity, vital capacity?

Answer 29

FEV/FVC is reduced (reduced rate of expiration), and functional residual capacity is increased. Vital capacity is unchanged or slightly increased (b/c increased lung compliance allows for higher total lung capacity)