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CSF3 Exam 2 > Pulmonary Mechanics/Respiratory Physiology I- Johnson > Flashcards

Pulmonary Mechanics/Respiratory Physiology I- Johnson Flashcards

1
Q

What are the 4 main functions of the pulmonary system?

A
  • gas exchange
  • allows for regulation of bodies’ pH 7.4
  • protection from inhaled pathogens
  • vocalization, singing, and production of speech
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2
Q

Pulmonary physiology is primarily concerned with what type of respiration? What are the components of this type of respiration?

A

external respiration: what it takes to get O2 to the cells so that it can be utilized

we’re not talking about cellular respiration where were utilizing O2

  1. exchange of air between atmosphere and lungs
  2. exchange of O2/CO2 between lung space and the blood circulating through the lungs
  3. uses cardiovascular system to transport gases to and from their destinations
  4. exchange of gases between blood and tissues where O2 will be utilized and CO2 will be eliminated
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3
Q

What are the two components of pulmonary mechanics and what role do they play?

A
  • lung
  • chest wall

The two determine lung volume and play a major role in gas exchange and the work of breathing.

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4
Q

What is the lung comprised of?

A
  • airways
  • lung parenchyma
  • interstitial matrix (composed of fibrin, collagen, and a few cells), alveolar gas exchange surface and pulmonary circulation
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5
Q

What is the chest wall comprised of?

A
  • rib cage
  • diaphragm
  • abdominal cavity and anterior abdominal muscles: involved in removing excess air in forced expiration
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6
Q

What is the most important muscle of inspiration? What type of muscle is it? What is it innervated by?

A

diaphragm- it is the pressure generator for the inspiratory activity

skeletal muscle

innervated by phrenic nerve (C3, C4, C5); will contract rhythmically increasing thoracic volume allowing air to travel from external compartment to the lungs

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7
Q

Is expiration active or passive? Inspiration?

A
  • expiration is passive: results from passive recoil of lungs
  • inspiration is ACTIVE
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8
Q

When you need extra air forced out of your thoracic cavity during expiration which muscles are used?

A

abdominal muscles

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9
Q

What are the function of inspiratory muscles? What are these muscles?

A

-elevate the chest cage (increase thoracic volume but decrease thoracic pressure)

external intercostals
sternocleidomastoid
anterior serrati
scaleni

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10
Q

What are the function of expiratory muscles? What are these muscles?

A

-pull the rib cage down (decreasing thoracic volume but increasing thoracic pressure)

abdominal recti
rectus abdominus
internal intercostalis

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11
Q

What happens when you create increase in thoracic volume?

A

decrease in thoracic pressure

Boyle’s law

this is how we establish a pressure gradient (atm vs thoracic pressure) for air to enter lungs

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12
Q

Describe the atmospheric pressure relative to thoracic pressure in inspiration.

A

low thoracic pressure compared to high atmospheric pressure

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13
Q

Describe the atmospheric pressure relative to thoracic pressure in expiration.

A

high thoracic pressure compared to low atmospheric pressure

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14
Q

What is compliance?

A

the ability of lung to receive air (how well does it distend) when the pressure gradient is established

is a measure of the elastic properties of the lung and is an indication of distensibility

-compliance is a measure of distensibility and is the change in lung volume resulting from a change in the distending pressure of the lung equal to 1 cm H2O

high: easily distended
low: stiff; not easily compliant

200 mL/cm H2O is normal lung compliance

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15
Q

Nonuniformity in the phases of expiration and inspiration is called?

A

hysteresis: lung in ation curve follows a different curve than the lung de ation curve due to need to overcome surface tension forces in in ation

expiration and inspiration are not superimposable due to differences in surface tension

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16
Q

What is the maximum amount of air that can be held in the lung at any moment called?

A

total lung capacity (TLC)

steep portion in volume pressure curve means you approach TLC

pressure gradient will be absorbed as air fills the lungs

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17
Q

The compliance of what two components will give you the compliance of the entire respiratory system?

A
  • lung
  • chest wall

They both move together. If you were to separate them by severing the pleural membrane then the two units are free to move toward their own compliance. Lung will deflate like a balloon. Normally it is being held open by a force that allows it to be stretched against thoracic wall. The chest wall would be be free to spring out.

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18
Q

Lung compliance flattens out in the pressure volume curve at what two points?

A

RV (low lung volume) and TLC (high lung volume)

At both high and low lung volumes, large changes in the pressure across chest wall result in small changes in the volume enclosed by the chest wall—reduced compliance

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19
Q

What is the difference between emphysema and pulmonary fibrosis?

A

emphysema: easily compliant; due to destruction of alveolar type I cells; large changes in lung volume

pulmonary fibrosis: increased CT preventing expansion of lung so very small change in lung volume; reduce lung compliance

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20
Q

What are examples of things that can give lungs a harder time to expand?

A
  • obesity/pregnancy
  • increased fluid in interstitial spaces
  • pleural effusion
  • musculoskeletal disease
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21
Q

When individuals have decreased compliance what must occur for them to move the same amount of air as a normal individual?

A

must generate a GREATER pressure gradient (transpulmonary pressure)

22
Q

Specific compliance deals with what?

A

lung resection: takes into consideration the amount of lung parenchyma tissue available

23
Q

What is static lung mechanics?

A

when lung volume is not changing

24
Q

What is the primary determinant of lung volume?

A

the BALANCE interaction or relationship between the lung and chest wall

high recoil property of lung parenchyma (shrink to 10% of TLC in absence of chest wall) is opposed by the external force (outward spring) of chest wall (increase to 60% of TLC in absence of lung parenchyma)

25
Q

What is residual volume?

A

the smallest volume that remains in lung after forced expiration (abdominal muscles)

26
Q

What is functional residual capacity?

A

the amount of air that is in the lungs AT THE TIME when you start inspiration (at the onset of inspiration)

the suitcase of air that is always in your lungs prior to inspiration that allows for gas exchange to continue in the pause between expiration and inspiration

-it is the lung volume at which the outward recoil of the chest wall is EQUAL to the inward elastic recoil of the lung

27
Q

What will cause an elevated RV/TLC ratio?

A
  • increased RV (due to air trapping secondary to airway obstruction)
  • decreased TLC (common in pts with restrictive pulmonary disease)
28
Q

What is transpulmonary (translung) pressure?

A

the pressure difference between the alveolar air spaces (Pa) and the pressure surrounding the lung (pleural pressure)

29
Q

What is the transmural pressure of the chest wall?

A

the pressure difference between the pleural pressure and the pressure surrounding the chest wall AKA barometric pressure

30
Q

What determines airflow AKA the pressure across the respiratory system?

A
  • combine the transpulmonary pressure and chest wall pressure to get the pressure across the respiratory system
  • the pressure difference between alveolar air spaces and barometric pressure
31
Q

If the alveolar air pressure is greater than the barometric pressure, what occurs?

A

expiration

32
Q

If the barometric pressure exceeds alveolar air pressure, what occurs?

A

inspiration

33
Q

What is a pneumothorax?

A

an alternative way for air to come in is introduced (stabbing to chest wall)

lung tissue will collapse as the recoil of lung is no longer opposed by outward pull of chest wall

need to put in chest tube

34
Q

What are 3 necessary events that have to occur for respiration?

A
  • At rest, diaphragm is relaxed and the FRC is in the lung.
  • Diaphragm contracts (flattens) increasing thoracic volume thus decreasing thoracic pressure; FRC plus tidal volume
  • Diaphragm relaxes back to dome shaped position. Pressure increase in lung space as volume decreased.
35
Q

Pleural pressure is always positive or negative?

A

negative (-5)

seal between thorax and lung parenchyma

As the thoracic wall moves outward during
inspiration, the volume of the pleural cavity
increases slightly, decreasing intrapleural
pressure.
• As the thoracic wall recoils during expiration, the
volume of the pleural cavity decreases,
returning the pressure to minus 5 millimeters of mercury

36
Q

What is surface tension?

A

-surface tension is the tension that occurs in an air liquid interface; is is the attractive force that causes the molecules on the surface of a liquid to come together and form a layer

37
Q

What is the role of surfactant?

A

-surfactant lines the alveoli where the air and liquid interface is; reduces surface tension to nearly 0 facilitating lung expansion

38
Q

What is Laplace’s law?

A

air will move from a high pressure zone to a low pressure zone

there is heterogeneity in the sizes of alveoli causing airflow through the alveoli

surfactant is much more available in a smaller alveoli preventing large shifts in pressure

The law of Laplace states that a higher pressure in a small alveoli will lead to collapse of that alveoli and expansion of a larger alveoli with less pressure.

ining of surfactant becomes thicker in smaller alveoli; the reduction in surface tension is greater in smaller alveoli

39
Q

What are the most abundant components in surfactant?

A

dipalmitoyl phosphatidylcholine (DPPC) and phosphatidylglycerol (PG)

these are phospholipids

40
Q

What are the clinical significance of surfactant deficiency?

A
  • increased work of breathing
  • progressive atelectasis (lung unit collapse)
  • respiratory failure in premature infants -major cause of morbidity in neonatal period
  • standard treatment is with surfactant replacement therapy
41
Q

What is the important of alveolar interdependence?

A

there are group of alveoli that do not have adequate airflow however there are alternative pathways that will allow air to flow in maintaining alveolar inflation and allowing gas exchange

42
Q

The pressure across the respiratory system is zero at points of no airflow which are?

A

end expiration and end inspiration

43
Q

Surfactant in the alveolus changes the surface tension of the air-liquid interface as lung volume changes.

The transmural pressure required to keep an alveolus inflated_______ as lung volume (and transpulmonary pressure) increases and_________ as lung volume decreases.

A

increases

decreases

44
Q

Lung compliance is a measure of the elastic properties of the lung (distensibility). A loss of elastic recoil is seen in patients with emphysema and is associate with an_______ in lung compliance.

A

increase

45
Q

In contrast, the diseases associated with pulmonary fibrosis, lung compliance is__________.

A

decreased

46
Q

The FRC is the resting volume of the lung and represents the point where the lung recoil and the chest wall are at ?

A

equilibrium; no pressure difference across the respiratory system

47
Q

Limits of the muscle lengthening or shortening are the primary determinants for what?

A

TLC and RV

48
Q

The pressure across the chest wall (Pw) is the difference between what?

A

pleural and barometric pressure (Pw = Ppl – Pb)

49
Q

The pressure across the lung (transpulmonary pressure, PL) is the difference between what?

A

alveolar pressure and pleural pressure PL =PA – Ppl

50
Q

The pressure across the respiratory system is the sum of what?

A

the recoil pressures of the lung and the chest wall

CSF3 Exam 2 (14 decks)

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