Mechanics of Breathing Flashcards
Conducting zone
transports gases
Respiratory zone
takes part in gas exchange
Airway resistance is greater in the conducting airways because:
they are arranged in series
Lungs synthesize
surfactant, prostaglandins, histamine
Lungs activate
Angiotensin I to Angiotensin II
“air-blood” barrier includes:
Surfactant
Alveolar epithelium
Interstitial fluid
Capillary endothelium
Alveolar 3 cell types of epithelium
- Type I alveolar cells:
•form a part of the thin gas diffusion barrier - Type II alveolar cells:
•produce surfactant
• differentiate into type 1 epithelial cells (when the pulmonary membrane is damaged ) - Club (Clara) cells:
• Secrete component of surfactant, degrade toxins, act as reserve cells.
Primary muscles of respiration
diaphragm
external intercostal
(also produce a quiet inspiration)
Accessory muscles of inspiration
sternocleomastoid
scalene
pectoralis minor
serratus anterior
(also produce forced inspiration)
Accessory muscles of exhalation
internal intercostal transversus thoracis external oblique rectus abdominis internal oblique
also produce forced exhalation)
Inspiration
thoracic volume to increase
lung volume to increase
lung pressure to decrease
*** A premature newborn infant is noted to have a deficiency of pulmonary surfactant. Which of the following muscles will the infant likely require to use to accomplish adequate inspiration?
Diaphragm, external intercostals, scalene, sternomastoids
Pressures:
- at rest
- during inspiration
- end of inspiration
- during exhalation
at rest
- Patm = 0
- Alv. press. = 0
- Intrapleural = -5
during inspiration
- Patm = 0
- Alv. press. = -1
- Intrapleural = -6.5
end of inspiration
- Patm = 0
- Alv. press. = 0
- Intrapleural = -8
during exhalation
- Patm = 0
- Alv. press. = +1
- Intrapleural = -6.5
transmural pressure
alveolar pressure - intrapleural pressure
*** The intrapleural pressure of a 37-year-old man is -4.5 cm H2O, immediately before the inspiration. What is the transpulmonary pressure at rest?
+4.5 cm H2O
*** The airway tree is divided into two zones, the conducting zone and respiratory zone. Which of the following is not part of the conducting zone?
both respiratory bronchioles and alveoli
*** A 58-year-old factory worker, who has worked in the insulation industry for over 30 years, develops progressive shortness of breath. His wife has tried to get him to go to the doctor, and he finally relents with the appearance of hemoptysis. A chest x-ray is consistent with an alveolitis from asbestos inhalation. Which of the following is the major route for removal of small particles from the alveoli?
Phagocytosis
*** Which of the following is true during inspiration?
Intrapleural pressure is more negative than it is during expiration
Compliance
ΔV / ΔP
- inversely related to Elastance
- inversely related to stiffness
pulmonary fibrosis
elastic tissue is replaced by fibrous tissue
↓ Compliance
↓ resting lung volume
↑ resistance
↑ work of breathing
pneumonia
↓ Compliance
pulmonary edema
↓ Compliance
emphysema
↑ Compliance (due to loss of elastic recoil)
↓lung elastance
asthma
↓ Compliance
