9-23a Pulmonary Physiology I

Question 1

What are the pulmonary processes?

Answer 1

Ventilation, gas exchange, gas transport, ventilation-perfusion matching, defense systems

Question 2

How does air get into the lungs?

Answer 2

Contraction of the inspiratory m. ^ thoracic volume and the pressure inside the alveoli is less than the pressure outside; air flows into alveoli until Pin = Pout

Question 3

How does air get out of the lungs?

Answer 3

Lung is stretched during inspiration

When the diaphragm relaxes, it decreases thoracic volume and lungs recoil and compress alveoli

Question 4

What is ventilation?

Answer 4

The bulk flow of air into and out of the lungs

Question 5

What is tidal volume?

Answer 5

1/2 a L (normal inspiration volume)

Question 6

What is IRV?

Answer 6

Inspiratory Reserve Volume
Volume of air that can be inspired beyond tidal volume (not including)
IC - TV = IRV

Question 7

What is IC?

Answer 7

Inspiratory Capacity

sum of TV and IRV

Question 8

What is ERV?

Answer 8

The volume from the bottom of normal expiration to the bottom of maximal expiration

Question 9

What is RV?

Answer 9

The air left in the lungs after maximal expiration

Question 10

What is FRC?

Answer 10

Functional Residual Capacity
Volume of air in the lungs at the bottom of normal exhalation
resting point
no m. activation

Question 11

What is VC?

Answer 11

Total volume of air breathed out after breathing in as much as the person can
(IRV + TV + ERV)
good diagnostic test

Question 12

What is TLC?

Answer 12

Total Lung Capacity

VC + RV

Question 13

What does spirometry do?

Answer 13

allows measuring of lung volumes and capacities

Question 14

What is compliance?

Answer 14

change in volume/change in pressure

Question 15

What does the pleura line?

Answer 15

the outside of the pleural cavity and the outside of the lung

Question 16

What does the pleural fluid act as?

Answer 16

cohesive force b/w the lung and the chest wall pulls the parietal and visceral pleura together

Question 17

At what point are the chest wall and the lungs at equilibrium with each other?

Answer 17

Functional Residual Capacity; relaxation point

Question 18

What is the residual volume in terms of lung and thorax equilibrium?

Answer 18

The smallest volume we can get at the end of exhalation
moves the equilibrium system to the left during collapse
here, the chest wall AND the lungs want to expand to get back to equilibrium

Question 19

What is total lung capacity in terms of lung and thorax equilibrium?

Answer 19

the largest volume we can get
moves the equilibrium graph to the right during expansion
here, the chest wall AND the lungs want to collapse to get back to equilibrium

Question 20

What is the pressure inside and outside of the lungs at FRC?

Answer 20

0

Question 21

What is intrapleural pressure at FRC? What is the difference between the pressure of the alveoli and the intrapleural space at FRC?

Answer 21

-5 cm H2O

5

Question 22

What happens to alveolar pressure and intrapleural pressure?

Answer 22

the increase in volume of the thoracic cage has caused Intrapleural pressure becomes more negative and alveolar pressure to become more negative (-1) that atm pressure (0) so air flows in

Question 23

How does intrapleural pressure change throughout ventilation?

Answer 23

Pressure begins at -5 and becomes more negative during inspiration due to the cavity wall pulling on the lungs (up to -8 at total lung capacity) and then returns to -5 after expiration

Question 24

How does alveolar pressure change throughout ventilation?

Answer 24

Pressure begins at 0, and once the alveoli are pulled open, their pressure drops to -1 (less than an atmospheric pressure of 0), pressure returns to O at TLC and then +1 when the lungs are collapsing for expiration, and then 0 again at FRC

Question 25

How is minute ventilation (total ventilation) calculated? What is it analogous to?

Answer 25

``` Respiratory Rate (12 breaths/min) * Tidal Volume (450 mL or 1/2 L) = 5400 mL/min or roughly 5.5 L/min CO ```

Question 26

How many mL are left in the conducting zone and do not participate in gas exchange? What is this called?

Answer 26

150 mL | Dead space

Question 27

What is alveolar ventilation equal to?

Answer 27

(tidal volume - dead space volume) * RR

Question 28

How do the alveoli at the top of the lung compare to the alveoli at the bottom?

Answer 28

They are more stretched out and less compliant due to the weight of the lung They get less ventilation Change in position can change the degree of ventilation of different regions of the lung and use it therapeutically

Question 29

What is measured in an air flow measurement?

Answer 29

Forced Vital Capacity Maximum inhalation to maximum exhalation; is forced because the pt is breathing as hard and as fast as possible FEV1: volume of air exhaled in the first second (sensitive indicator of pulmonary disease) FEV1/FVC: Ratio of total volume exhaled in first second

Question 30

For a given volume, can we get a higher flow rate for expiration?

Answer 30

no

Question 31

What causes a pneumothorax? What happens?

Answer 31

(decoupling of the lung and chest wall) air getting into the intrapleural space (it has negative pressure (-4 mmHg) so air rushes into the cavity to equillibrate pressure) the lung collapses and the chest wall expands (return to individual equilibrium points)

Question 32

What is treatment for a pneumothorax?

Answer 32

Chest tube is inserted into the inrapleural space and re-establishes pressure gradient that allows the lung to expand

Question 33

What happens to ventilation when someone has a high lesion to their spinal cord?

Answer 33

A high lesion (C3 or above) paralyzes the diaphragm and requires machine ventilation Air is pumped in because the pressure is increased outside the lung to create gradient (positive pressure ventilation)

Question 34

What happens to ventilation when someone has a low lesion to their spinal cord?

Answer 34

An upper chest paradoxical pattern The diaphragm is strong, but the chest wall (intercostals) and abdominal muscles are weak contraction of the diaphragm causes the thoracic cage to collapse because it cannot expand The diaphragm flattens and the abdomen expands during inhalation Can be helped with an abdominal binder/different positioning

Question 35

What problems arise with an abnormal airway diameter?

Answer 35

Asthma causes vasospasm Resistance to airflow increases as the diameter of the trachea decreases requires a greater pressure gradient to maintain flow and therefore greater muscle effort requires greater work to breathe

Question 36

What is dynamic airway compression?

Answer 36

collapsing of the lung during expiration causes the collapsing of small airways harder we exhale, smaller they get, resistance is increased in the alveoli pressure tending to pull the airways open goes from positive to negative, and the harder we exhale, the more the airway collapses

Question 37

What does increased compliance cause (disease-wise)?

Answer 37

Emphysema: for the same change in pressure, there is a much lower volume due to destroyed elastic fibers in the lung compliance is increased The lung expands easily (greater FRC) and can flatten the diaphragm and lowers its mechanical advantage and change in volume lungs don't have much elastic recoil, therefore it can require active contraction of abdominal m. destruction of airway support causes collapse O2 cost of breathing can go up to 25% of resting O2 consumption (normally 5%)

Question 38

What does decreased compliance cause (disease-wise)?

Answer 38

pulmonary fibrosis; chest wall disorders causes a smaller equilibrium volume (FRC) of the chest wall, which causes a smaller airway diameter requires more muscle effort to expand the lungs/more resistance to airflow/harder to breathe

Question 39

What does surface tension tend to do to spheres (alveoli)? What prevents this?

Answer 39

Tends to collapse the alveoli | Surfactant (produced by epithelium) reduces surface tension

Question 40

What disease is caused by reduced surfactant? What does it result in?

Answer 40

Respiratory distress syndrome | The alveoli tend to collapse, which lowers lung SA for gas exchange and lung compliance