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Anatomy & Physiology 208 > Respiratory Physiology > Flashcards

Respiratory Physiology Flashcards

1
Q

pulmonary ventilation

A

breathing

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2
Q

2 phases of pulmonary ventilation

A
  • inspiration: air flowing into the lungs
  • expiration: air flowing out of the lungs
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3
Q

respiratory pressures

A

Respiratory pressures are always described relative to atmospheric pressure (Patm)
- Patm: the pressure exerted by the gases/air surrounding the body
- At sea level, atmospheric pressure is 760mmHg or 1atm

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4
Q

negative respiratory pressure

A

pressure that is lower than atmospheric pressure
- ex: -4mmHg means 760mmHg-4mmHg or 756mmHg

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5
Q

positive respiratory pressure

A

pressure that is higher than atmospheric pressure

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6
Q

zero respiratory pressure

A

pressure that is equal to atmospheric pressure

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7
Q

intrapulmonary pressyre (Ppul)

A

pressure within the alveoli
- rises/falls with the phase of breathing - always equalizes with atmospheric pressure

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8
Q

intrapleural pressure (Pip)

A

the pressure in the pleural cavity
- rises/falls with the phases of breathing - always about 4 mmHg less than Ppul
- Pip is always negative relative to Ppul

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9
Q

Negative Intrapleural Pressure

A

Forces causing the lungs to collapse:
- Lungs’ natural elasticity/tendency to recoil
- Surface tension of the fluid lining the alveoli
Force causing the lungs to expand:
- Natural elasticity of the chest wall
Typically, neither force wins!
- Secondary to the presence of pleural fluid, there is a strong adhesive force between the parietal and visceral pleurae
- amount of pleural fluid is closely regulated and drained by the lymphatics
Net Result: a negative Pip!

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10
Q

Transpulmonary pressure

A

the difference between Ppul and Pip
- The pressure that keeps the air spaces of the lungs open and prevents lung collapse!
- A greater transpulmonary pressure means the lungs are larger in size
- Any condition that equalizes Pip with Ppul or atmospheric pressure will cause lung collapse

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11
Q

Atelectasis

A
  • “Lung Collapse”
  • Occurs when a bronchiole becomes plugged
  • The associated alveoli will collapse
  • Often an extension of pneumonia
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12
Q

Pneumothorax

A
  • “Air Thorax”
  • Presence of air in the pleural cavity
  • Reversed by drawing the air out via a chest tube
  • Lung will reinflate
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13
Q

pulmonary ventilation

A
  • Pulmonary ventilation is the mechanical process of breathing – inspiration and expiration
  • It is entirely dependent on volume changes in the thoracic cavity
  • Volume changes -> pressure changes -> flow of gases to equalize pressure
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14
Q

Boyle’s Law

A
  • Gives the relationship between pressure and volume of a gas
  • At a constant temperature, pressure varies inversely with volume
  • P1V1 = P2V2
  • “gases always fill their container”
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15
Q

Pulmonary Ventilation: Inspiration

A
  • Diaphragm + external intercostal muscles contract
  • Height AND diameter of the thorax increase
  • Volume of the thoracic cavity increases by ~500mL
  • Lungs are stretched, intrapulmonary volume increases
  • Ppul decreases
  • Air rushes into the lungs
  • Ppul equalizes to Patm
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16
Q

Pulmonary Ventilation: Expiration

A
  • In healthy individuals, quiet expiration is a passive process
  • It is dependent on lung elasticity
  • Inspiratory muscles relax – rib cage descends, lungs recoil
  • Thoracic + intrapulmonary volumes decrease
  • Ppul rises
  • When Ppul > Patm, air flows out
17
Q

Forced Expiration

A
  • active process
  • produced through contraction of the abdominal muscles
  • intra-abdominal pressure rises, and the abdominal organs press against the diaphragm
  • internal intercostal muscles depress the rib cage and decrease thoracic volume
18
Q

deep/forced inspiration

A
  • utilizes accessory muscles - the scalenes, SCM, and pectoralis minor further increase thoracic volume
  • spinal extension flattens the thoracic curve
  • “barrel chest”
19
Q

precise expiration

A

requires fine control and coordination of the accessory muscles

20
Q

non-respiratory air movements

A
  • coughing, sneezing, crying, laughing, hiccupping, and yawning - all alter normal respiratory rhythm
21
Q

3 physical factors that influence the ease of air passage and the amount of energy required for ventilation

A
  • airway resistance
  • alveolar surface tension
  • lung compliance
22
Q

airway resistance (R)

A

friction or drag encountered in the respiratory passageways
- F = ΔP/R
- Gas flow varies inversely with resistance (R)
- R is predominantly determined by the diameters of the conducting tubes
- The highest resistance is in the medium-sized bronchi
- Resistance disappears at the terminal bronchioles, and diffusion takes over

23
Q

ΔP

A

the difference in pressure between the external environment and the alveoli
- typically, a small ΔP can create large changes in gas flow
- the average pressure gradient during normal, quiet breathing is 2mmHg or less

24
Q

bronchodilators

A

smooth muscle in the bronchiolar walls is extremely sensitive to neural controls and chemicals
- inhaled irritants can activate a reflex of the parasympathetic ANS - a vigorous constriction of the bronchioles

25
Q

asthma attacks

A

histamine can cause such strong bronchoconstriction that pulmonary ventilation stops
- epinephrine is the antidote

26
Q

alveolar surface tension

A

attracts liquid molecules to each other, resists any force that attempts to increase the liquid’s surface area
- because it is composed of highly polar molecules, water has a high surface tension
- water is always working to keep alveoli at their smallest possible size

27
Q

surfactant

A

detergent-like complex of lipids and proteins produced by type II alveolar cells
- reduces surface tension and discourages alveolar collapse - less energy is required to expand the lungs

28
Q

Infant Respiratory Distress Syndrome

A

Condition when surfactant levels are not adequate
- Alveoli will collapse, and it takes significant energy to reinflate them
- Treated with artificial surfactant, devices that maintain positive airway pressure, ventilators

29
Q

Bronchopulmonary Dysplasia

A
  • Potential complication of IRDS
  • Often caused by prolonged ventilation and O2 therapy
30
Q

Lung Compliance

A

measure of the change in lung volume that occurs with a given change in transpulmonary pressure
- higher compliance = lungs that are easier to expand

31
Q

2 determining factors of lung compliance

A
  1. Distensibility of lung tissue
  2. Alveolar surface tension
32
Q

reducing lung compliance

A

Lung compliance is reduced by: fibrosis, reduced amounts of surfactant, and decreased flexibility of the thoracic cage

33
Q

Total Respiratory Compliance

A

Total compliance of the respiratory system is influenced by lung compliance and compliance of the thoracic wall

34
Q

Compliance of the thoracic wall is reduced by:

A
  • Thoracic deformity
  • Ossification of the costal cartilage
  • Paralysis of the intercostal muscles

Anatomy & Physiology 208 (39 decks)

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