Cpwk3 Physiology 11-16 Compliance Pressure- Also Work Of Breathing

Front 1

Describe how the thoracic cage and lung the functions of the inspiratory and expiratory
Quiet breathing?
Expiration?

Back 1

Inspiratory muscles increase the volume of the thoracic cavity and pumlonary volume

-Quiet breathing is done by the diaphragm and only this unless vigorous breathing

- Expiration- internal intercostals and abdominal recti

Front 2

Explain the recoil tendency of the lungs recoil?
What is recoil pressure?

Back 2

collapsing force attempting to pull the lungs away from the thoracic cage is referred to as lung
recoil and is caused by:
– Elastic nature of parynchma
– Surface tension
- the negative pressure in the intrapleural space (-5 cm H20 at rest) sucks lungs to chest wall, during expiration lungs will pull diaphragm back up and will pull away from thoracic wall
- intraplural pressure is also recoil pressure

Front 3

At their normal resting positions (which inspiration, what holds the lungs open and/

Back 3

- pleural pressure from parietal to visceral forces lungs to stay open. In pleural space there is liquid that acts a lubrianct allowing lungs to slide along chest wall

Front 4

Define the following terms and include values...
a. pleural pressure
b. alveolar pressure (at rest)
c. Transpulmonary pressure

Back 4

a. pleural pressure = pressure between thoracic cage and lungs or within the
pleural space. It is given in cm. H20 relative to atmospheric pressure (1cm H20 = 0.74 mm Hg)
b. Alveolar (also pulmonary or intrapulmonary) pressure is the pressure inside the lungs
(tubes or alveoli). It equals 0 at rest.
c. Transpulmonary pressure = difference between pulmonary and pleural pressure. It equals the absolute value of the pleural
pressure at rest but not during breathing.

Front 5

Define lung compliance. How is it measured?
How does surface tension play into compliance?

Back 5

how much volume change will occur with a given change in transpulmonary pressure (measured separately for inspiration/expiration).
- inversely related to elastic recoil
- If a great amount of effort is required to inflate the lungs to the same volume, the compliance is low
- Surface tension decreases compliance

Front 6

What is a pneumothorax and what does it to to lung?

Back 6

A pneumothorax will allow air to enter
the pleural cavity and the lungs will
become smaller (collapse).
- alveolar pressure will be atmospheric pressure

Front 7

Descibe lung flow and the pressure gradient between atmospheric and alveolar

Back 7

Flow occurs down a pressure gradient atmospheric pressure must me more than alveolar to keeps the lungs expanding and "sucking" air in
– Q = ΔP/R
– = (P1 - P2)/R
P1 = atmosphere
P2 = pulmonary pressure at rest,
Q =

Front 8

Graph the typical pressures that would be lungs (alveolar and pleural):
a with the lungs at their resting position
b held breath at end of normal inspiration
c during a forced expiration starting
d. Held breath at end of normal inspiration
e. held breath at end of deep inspiration

Back 8

a. Intrapleural (pleural) = (-5) Pulmonary (alveolar)= (0)
b. Intrapleural (pleural) = (-9) Pulmonary (alveolar) = (0)
c. Intrapleural (pleural) = (+20) Pulmonary (alveolar) = (+18)
d. Intrapleural (pleural)= -9 Pulmonary (alveolar) = 0
e. Intrapleural (pleural) = -18 Pulmonary (alveolar) = 0

Front 9

Define lung surface tension and size or alveolus

Back 9

- Results from the attractive forces between liquid molecules lining the alveoli the surface tension naturally makes lung collapse in a ratio that is directly proportional to its tension and inversely proportional to alveolar radius
P= 2T/r
So if alveolus is small it is more likely to collapse due to increase surface tension

Front 10

What allows smaller alveoli to remain uncollapsed?

What would changes in compliance show for changes associated with emphysema and fibrosis

Back 10

surfactant lines the alveoli and reduces surface tension by disrupting intermolecular forces between liquids and increases compliance

- Compliance increases with emphysema, and decreases with fibrosis

Front 11

What types of work are performed during normal respiration? Which one would increase most during a bad asthma attack and why?

Back 11

Both inspiratory and expiratory do work to overcome resistance of air and tissue

Inspiratory
Includes- work to stretch elastic components of lung
Expiratory-work to return to original volume

- during asthma attack radius of airways decreases, increasing resistance to flow. Due to obstructiveness of disease Expiratory has to do more work and FEV is lower

Front 12

Which type of breathing can occur passively?

Back 12

quiet expiration uses stored energy (from inspiratory work) in elastic elements of the lung

Front 13

Describe how obstructive and restrictive diseases, neonatal respiratory distress syndrome and congestive heart failure
alter pulmonary compliance, pleural and alveolar pressures during breathing and the work of breathing.

Back 13

With obstructive disease expiration becomes harder (Asthma, COPD)

With inspiratory- inspiratory becomes harder (fibrosis)