5.2 - Gas Laws and Ventilation Flashcards

1
Q

What is the total pressure of a mixture of gases?

A

sum of partial pressure of individual gases

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2
Q

What factors determine the amount of gas dissolved in a liquid?

A
  • partial pressure of the gas

- solubility of the gas in the liquid

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3
Q

How is partial pressure of an atmospheric gas calculated?

A

P X % of gas in atmosphere

atm

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4
Q

What does Boyle’s law explain?

A

The rs b/w volume and pressure

p1v1 = p2v2

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5
Q

What are the driving forces of air flow during ventilation?

A

alveolar pressure changes which are caused by changes of the thoracic cavity during inspiration and expiration

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6
Q

TRUE OR FALSE:

The lungs have their own muscles by which they can change volume

A

FALSE:

Lungs depend on muscles located in the chest wall

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7
Q

What is the structure of lungs?

A

passive elastic structures like balloons

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8
Q

What factors contribute to the volume of the lungs?

A

transpulmonary pressure
- difference between alveolar pressure intrapleural pressure

degree of elasticity of the lungs

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9
Q

What is the pressure inside and outside of the lungs?

A

inside: alveolar pressure
outside: pressure in the intrapleural fluid

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10
Q

What is the function of the airways?

A
  • warm up air to 37 degrees celcius to maintain core body temp and protect alveoli
  • add water vapour to air to prevent drying of epithelia
  • filter out foreign material
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11
Q

What is the cellular process of filtering out foreign material?

A
  • airways are lined with ciliated epithelia that secrete watery saline solution
  • cells move Cl- from ECF into cell via NKCC
  • Cl- transported to lumen of airway via apical anion channel
  • Na+ moves between cells from ECF to lumen
  • [] gradient of NaCl draws water towards the lumen creating the watery saline solution
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12
Q

What are cilia covered with?

A

covered with mucus

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13
Q

What secretes mucus and how is it secreted to the digestive tract?

A

goblet cells secrete muscus
mucus contains immune cells that kill invaders
mucus moved up to pharynx (mucus escalator)
transfered to disgestive tract where additional bacteria are destroyed

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14
Q

What are medical conditions that complicate ventilation?

A

cigarette smoking

  • paralyzes cilia
  • infections lead to smoker’s cough

cystic fibrosis

  • inherited condition
  • mutations in Cl- channel, not transported in lumen
  • prevents appropriate secretion of water into the mucus
  • thick and sticky in airways
  • blocks airways
  • prevents removal of bacteries = repeated infections
  • over active immune cells start destroying lung
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15
Q

What are the steps of inspiration?

A
  • somatic motor neuron trigger contraction of diaphragm and inspiratory muscles
  • thorax expands, thoracic volume increases
  • alveolar and intrapleural pressure decreases
  • lungs expand resulting in air flowing into lungs
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16
Q

What are the steps of expiration?

A
  • somatic motor neurons stop firing
  • diaphragm and thoracic muscles relax, returning thorax to original position = decreased volume
  • alveolar and intrapleural pressure increases
  • lung volume decreases due to air flowing out of lungs due to elastic recoil of the lung
17
Q

During quiet breathing, expiration is a ____ process. What does it depend on?

A

passive

depends on elastic recoil of lungs and thoracic muscles

18
Q

During heavy breathing, expiration is a ____ process? What does it depend on?

A

active process, depends on contraction of internal intercostals and abdominal muscles

19
Q

TRUE OR FALSE:

intrapleural pressure is sub-atmospheric and decreases during foetal development

A

FALSE:

sub-atmospheric and INCREASES during foetal development

20
Q

How does the lungs stay expanded and open?

A

when outside pressure in the pleural fluid is low, pressure inside the lungs stay high, thus expanded and open

21
Q

What is pneumothorax?

A

When the lungs collapse due to absence of pressure difference
- air gets into the pleural cavity and intrapleural pressure increases

22
Q

What is the treatment for pneumothorax?

A

Apply suction and remove the air and seal the hole

23
Q

List and define the factors of breathing

A

compliance of the lungs: stretchability

resistance to airflow in airways