Flashcards in Respiratory Study Questions Deck (109)
Describe the cell types found in the alveolus and name their function
- type 1 epithelial: majority of alveolar surface area
- type 2 epithelial: produces surfactant and repair epithelial damage
- brush cells: not known
- macrophages: immune defense
- PMNs (polymorphonuclear neutrophils): immune defense
- mast cells: immune defense
- clara cells: secretory functions
- endothelial cells: inner lining of alveolus
What is the symbol for partial pressure of oxygen in the mixed venous blood?
- line above the v indicates mixed venous (mean venous)
What is the symbol for carbon dioxide production?
What is the symbol for expired minute ventilation?
What is the symbol for tidal volume?
Name 3 functions of the nasal cavity
Warms, filters, humidifies inspired air
What is the contribution to resistance during normal breathing for the nasal cavity? Trachea?
- nasal cavity: 50%
- trachea: 20%
- bronchi: 20%
- bronchioles: 10%
Describe the histologic structure of the trachea
Mucosa is classified as pseudostratified ciliated columnar epithelium
- apocrine, or goblet cells are also present to secrete mucous
- basal cells on innermost lumen
- ciliated cells to participate in mucociliary elevator to move out foreign debris
Compare and contrast the structure of the trachea to the bronchioles
- carilage in trachea, but not in the bronchioles
- no gas exchange in either
- clara cells in bronchioles, not in trachea
- epithelium flattens down toward the alveolus, cuboidal in bronchioles and psuedo columnar in trachea
- smooth muscle in bronchioles
What is the major muscle responsible for quiet inspiration? Accessory muscles?
Diaphragm - triggered by action potential delivered by phrenic nerve
- accessory muscles - sternomastoids, scalene
What are the 2 muscles of inspiration?
Cricoarytenoideus dorsalis and dilator nasoapicalis
Be able to calculate dead space and alveolar gas tension, and know the different factors that are important to each
Dead space: alveoli that are ventilating, but not perfused so carbon dioxide is not exchanged
- VD/VT = (PaCO2-PECO2)/PaCO2
- PaCO2 = partial pressure of alveoli carbon dioxide
- PECO2 = partial pressure of expired carbon dioxide
- VD = volume of dead space
- VT = tidal volume
Name 2 tests that can be used to assess pulmonary function
- blood gas analysis
- pulse oximetry
- volume of air that gets in and out of lungs in 1 normal ventilation
- body mass times 10/15 for average
Functional reserve (residual) capacity
- 2 volumes responsible for gas exchange
- ventilation mechanics need to match flow
- normal decreases occur during pregnancy
FRC = ERV + RV
- one normal conscious inspiration (requires effort)
IC = IRV + VT
Inspiratory reserve volume
- inspiratory volume if you take out tidal volume
Total lung capacity
- max volume of air that lungs are able to take
TLC = IRV + VT + ERV + RV
- can change with pathological conditions or medically
VC = IRV + VT + ERV + RV
To have at least 1 capacity, you need at least ________
2 different volumes
What is expired minute ventilation? How can it be calculated?
Represents a volume (liter or ml) of lung gas per minute
VE = VT x f (frequency of breaths per min)
Change in volume per unit pressure (how easily the lungs will expand)
C = V/P
What is the most important determinant of compliance behavior of the lung?
Surface tension (2/3)
- each alveolus is an air-water interface
- surface tension promotes deflation (responsible for 2/3 of the compliance behavior)
Elastic recoil (1/3)
Alveolar gas tension
-PIO2 = (PB-PH2O) x FIO2
- PaCO2 = 1:1 ratio with PACO2 at the alveoli level (can be used interchangeably)
What is the expected partial pressure of O2 in systemic arterial blood? In blood from the pulmonary artery? The alveolus?
- PO2 in systemic arterial blood = 85-100 mmHg
- PO2 in pulmonary artery blood = 40 mmHg
- PO2 in alveolus = 104 mmHg
What is the PO2 of moist inspired gas of a dog standing on the summit of Mount Everest (PB = 247 mmHg)?
PO2 = FIO2 x (PB-PH2O)
- PO2 = 0.21 x (247-47) = 42
What is hysteresis?
Term used to describe that there is a difference between the inflation and deflation curves of the lung
- takes slightly more pressure to inflate the lungs then to deflate (which is passive in most species)
What are the major components of surfactant?
- DPPC: dipalmitoyl phosphatidylcholine (major component with a hydrophobic and hydrophilic component)
- apoproteins SP-A, B, C, and D
What are the functions of surfactant?
- decreases work of breathing
- increases compliance
- stabilizes alveolar size
- has a drying effect on the alveoli