RESPIRATORY: 594 - 596 Flashcards
What are the two parts of the respiratory tree?
Conducting zone and respiratory zone
What makes up the conducting zone?
- Large airways: nose, pharynx, larynx, trachea, and bronchi
- Small airways: bronchioles and terminal bronchioles
How are the terminal bronchioles arranged and why?
Large numbers in parallel giving minimal airway resistance
What is the function of the conducting zone?
Warms, humidifies, and filters air
What does it mean that the conducting zone is “anatomic dead space”?
Does NOT participate in gas exchange
How far do the cartilage and goblet cells extend in the conducting zone?
To the end of the bronchi
Describe the epithelia in the conducting zone.
Pseudostratified ciliated columnar cells extend to the beginning of the terminal bronchioles, then transition to cuboidal cells
In general, how far do the airway smooth muscles extend?
To the end of the terminal bronchioles
What makes up the respiratory zone?
Lung parenchyma: respiratory bronchioles, alveolar ducts, alveoli
Why is most of the epithelia in the conducting zone ciliated?
To beat mucus up and out of the lungs
What is the function of the respiratory zone?
Gas exchange
Describe the epithelia in the respiratory zone.
Mostly cuboidal cells in the respiratory bronchioles then simple squamous cells up to alveoli
Is the epithelia in the respiratory zone ciliated?
No
What do alveolar macrophages do?
Clear debris and participate in immune response
What are the three types of pneumocytes?
- Type I
- Type II
- Club (Clara) cells
What is the main function of Type I vs. Type II pneumocytes?
Type I - Line the alveolar surfaces and allow for gas diffusion
Type II - Secrete pulmonary surfactant, also serve as precursors to Type I and Type II cells
How are type I pneumocytes optimized for gas diffusion?
Squamous cells that are thin
What is pulmonary surfactant made of?
Complex mix of lecithins - most important of which is dipalmitoylphosphatidylcholine
What is the term for alveolar collapse?
Atelectasis
Explain the Law of Laplace.
Alveoli have an increased tendency to collapse on expiration as the radius decreases
Why do we need pulmonary surfactant?
Decreases alveolar surface tension and prevents alveolar collapse
Which cells proliferate during lung damage?
Type II
When does surfactant synthesis begin?
Around week 26 of gestation, but mature levels are not achieved until around week 35
What is an indicator of fetal lung maturity?
Lecithin-to-sphingomyelin ratio > 2.0 in amniotic fluid
Describe club/clara cells.
Nonciliated, low-columnar/cuboidal with secretory granules
What are 3 functions of club cells?
- Secrete component of surfactant
- Degrade toxins
- Act as reserve cells
How many lobes does each lung have?
Right - 3
Left - 2
What is the homologue of the right middle lobe?
Lingula - it is a projection of the upper lobe of the left lung
Why is the right lung a more common site for inhaled foreign body?
Right main stem bronchus is wider and more vertical than the left
Describe the difference in location of where an aspirated item will likely end up while a person is upright vs. supine.
Will tend to end up regardless in the right inferior lobe
Upright - lower portion
Supine - superior portion
Describe the relationship between the location of the pulmonary artery to the bronchus on each side.
RALS -
Right anterior
Left superior
At what levels do the IVC, esophagus, and aorta pass through the diaphragm?
Mnemonic: I (IVC) ate (8) ten (10) eggs (esophagus) at twelve (12).
IVC - T8
Esophagus - T10
Aorta - T12
What nerve innervates the diaphragm and what are its roots?
Phrenic nerve - C3, 4, 5
Mnemonic: C3, 4, 5 keep the diaphragm alive
Where can pain from diaphragm irritation be referred to?
Shoulder (C5) and the trapezius ridge (C3, 4)
What is inspiratory reserve volume (IRV)?
Air that can still be breathed in after normal inspiration
What is tidal volume (TV)?
Air that moves into lung with each quiet inspiration
What is the normal value for tidal volume?
Around 500 mL
What is expiratory reserve volume (ERV)?
Air that can still be breathed out after normal expiration
What is residual volume?
Air in lung after maximal expiration
Which lung volume cannot be measured on spirometry?
Residual volume
What is the difference between volume and capacity?
Capacity - made up of 2 or more volumes
What are the components of inspiratory capacity (IC)?
IRV + TV
What is functional residual capacity (FRC)?
Volume in lungs after normal expiration
What are the components of FRC?
RV + ERV
What is vital capacity (VC)?
Maximum volume of gas that can be expired after a maximal inspiration
What are the components of VC?
TV + IRV + ERV
What is total lung capacity (TLC)?
Volume of gas present in lungs after a maximal inspiration
What are the components of TLC?
IRV + TV + ERV + RV
What makes up physiologic dead space (VD) in the respiratory system?
Anatomic dead space of conducting airways plus functional dead space in alveoli (volume of inspired air that does not take part in gas exchange
What is the largest contributor of functional dead space?
Apex of healthy lung
How do we calculate VD?
VD = VT x (PaCO2 - PECO2) / (PaCO2)
PaCO2 = arterial PCO2 PECO2 = expired air PCO2
Mnemonic: Taco, Paco, Peco, Paco
What are two measures of ventilation?
- Minute ventilation
2. Alveolar ventilation
What is minute ventilation?
Total volume of gas entering the lungs per minute
How do we calculate minute ventilation?
VE = VT x respiratory rate (RR)
What is alveolar ventilation?
Volume of gas per unit time that reaches the alveoli
How do we calculate alveolar ventilation?
VA = (VT - VD) x RR
