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Unit 1 > 9-23a Pulmonary Physiology I > Flashcards

9-23a Pulmonary Physiology I Flashcards

1
Q

What are the pulmonary processes?

A

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

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2
Q

How does air get into the lungs?

A

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

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3
Q

How does air get out of the lungs?

A

Lung is stretched during inspiration

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

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4
Q

What is ventilation?

A

The bulk flow of air into and out of the lungs

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5
Q

What is tidal volume?

A

1/2 a L (normal inspiration volume)

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6
Q

What is IRV?

A

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

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7
Q

What is IC?

A

Inspiratory Capacity

sum of TV and IRV

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8
Q

What is ERV?

A

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

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9
Q

What is RV?

A

The air left in the lungs after maximal expiration

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10
Q

What is FRC?

A

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

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11
Q

What is VC?

A

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

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12
Q

What is TLC?

A

Total Lung Capacity

VC + RV

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13
Q

What does spirometry do?

A

allows measuring of lung volumes and capacities

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14
Q

What is compliance?

A

change in volume/change in pressure

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15
Q

What does the pleura line?

A

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

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16
Q

What does the pleural fluid act as?

A

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

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17
Q

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

A

Functional Residual Capacity; relaxation point

18
Q

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

A

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

19
Q

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

A

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

20
Q

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

A

0

21
Q

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

A

-5 cm H2O

5

22
Q

What happens to alveolar pressure and intrapleural pressure?

A

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

23
Q

How does intrapleural pressure change throughout ventilation?

A

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

24
Q

How does alveolar pressure change throughout ventilation?

A

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

25
Q

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

A 
Respiratory Rate (12 breaths/min) * Tidal Volume (450 mL or 1/2 L) = 5400 mL/min or roughly 5.5 L/min
CO
26
Q

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

A

150 mL

Dead space

27
Q

What is alveolar ventilation equal to?

A

(tidal volume - dead space volume) * RR

28
Q

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

A

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

29
Q

What is measured in an air flow measurement?

A

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

30
Q

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

A

no

31
Q

What causes a pneumothorax? What happens?

A

(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)

32
Q

What is treatment for a pneumothorax?

A

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

33
Q

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

A

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)

34
Q

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

A

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

35
Q

What problems arise with an abnormal airway diameter?

A

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

36
Q

What is dynamic airway compression?

A

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

37
Q

What does increased compliance cause (disease-wise)?

A

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%)

38
Q

What does decreased compliance cause (disease-wise)?

A

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

39
Q

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

A

Tends to collapse the alveoli

Surfactant (produced by epithelium) reduces surface tension

40
Q

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

A

Respiratory distress syndrome

The alveoli tend to collapse, which lowers lung SA for gas exchange and lung compliance

Unit 1 (25 decks)

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