Lung: Week 1a Flashcards
What is the percent oxygen in dry air at sea level?
20.93%
What is the partial pressure of O2 at sea level? What is the equation?
0.2093 x 760mmHg = 159mmHg
What is the partial pressure of O2 inside the lung? Why is it different than in the air?
In the lung, water vapor pressure = 47mmHg
760mmHg - 47mmHg = 713mmHg
0.2093 x 713mmHg = 149mmHg
What does Fick’s law state?
The amount of gas that moves across a sheet of tissue is proportional to the area of the sheet and inversely proportional to the thickness.
How does inspired air move to the terminal bronchioles? How does it move in the respiratory zone?
It moves to terminal bronchioles by bulk flow. It then moves by diffusion in the respiratory zone.
Why does the velocity of gas flow diminish greatly in the respiratory zone?
The total cross-sectional area increases tremendously.
What are the two major zones of the respirator system?
The conducting zone and the respiratory zone.
What is the volume of the anatomic dead space?
~150ml
What is the volume of the alveolar region?
~2.5-3L
How thick are the alveoli? How many alveoli are there, and what is the total surface area?
Alveoli are about 0.2-0.3 microns thick. There are about 500 million of them, and they have a total surface area of 50-100m^2
What is the role of surfactant?
it lowers surface tension and prevents the alveoli from collapsing.
Alveoli have no cilia, so how do they clear debris?
Particles that are deposited in the alveoli are engulfed by macrophages and removed by blood or lymphatic system.
What is the tidal volume?
normal breathing
what is vital capacity?
max inhale to max exhale
What is residual volume?
What’s left after max exhale, the bit you can never get rid of.
What is functional residual capacity?
amount left in lung after normal exhale.
How can we measure functional residual capacity (FRC)?
use a known concentration of Helium, breath it in, and find new concentration.
How can we measure TLC in older people?
plethysmograph
What can a spirometer measure?
TV and VC
What is the equation to measure total ventilation? What are the approximate values?
RR x TV
15 breaths/minute x 500ml = 7500ml/min
What is the physiologic dead space? What is Anatomic Dead Space?
Physiologic: volume of gas that does not eliminate CO2.
Anatomic: volume of conducting airways, ~150ml
How are the physiologic and anatomic dead spaces related in healthy people? How can they change with lung disease?
In healthy people, PDS = ADS
In lung disease, PDS > ADS
How many tertiary bronchial divisions and lobes are there in the R lung? The L lung?
R lung: 3 lobes, 10 tertiary divisions
L lung: 2 lobes, 8 tertiary divisions
When is the pseudoglandular period? What happens then?
5-16 weeks. branching has continued to form terminal bronchioles. no respiratory bronchioles or alveoli are present.
When is the canalicular period? What happens then?
16-26 weeks. each terminal bronchiole divides into two or more respiratory bronchioles, which in turn divide into 3-6 alveolar ducts.
When is the terminal sac period? What happens then?
26 weeks to birth. terminal sac with primitive alveoli form, and capillaries establish close contact.
When is the alveolar period? What happens then?
8months to childhood. terminal sacs form, and capillaries establish close contact.
How many of the adult number of alveoli are present at birth?
1/6
What is the respiratory tract an outgrowth of?
ventral wall of foregut
What does the endoderm give rise to? Mesoderm?
Endoderm: epithelium or larynx, trachea, bronchi and alveoli
Mesoderm: cartilaginous, muscular and connective tissue components.
What gene is affected by cystic fibrosus?
CFTR (cystic fibrosis transmembrane regulator)
What are the types of CFTR mutations that can lead to CF?
a. no synthesis
b. block in processing (deltaF508 is the most commone, >70%)
c. block in regulation
d. altered conductance
e. reduced synthesis
How do infections spread in CF?
mucus layer gets very thick and bacteria hide in there. Cytokines are released, IL-8 goes up and attracts neutrophils. When neutrophils die, they release lots of bad stuff.
What is Kartagener syndrome?
An immotile cilia syndrome. It’s a genetic disease, and a form of primary ciliary dyskinesia.
How is malnutrition associated with lung disease?
low birth weight is associated with impaired lung function in adults, COPD and asthma
What is alpha-1 antitrypsin deficiency?
a disease that carries a genetic predisposition (mutation in SERPINA 1 with M, Z, S alleles), but smoking is what makes it happen. Smoking increases presence of neutrophils, neutrophils create the elastase (this is the really bad stuff), and the alpha-1 antitrypsin inhibits elastase. So an lapha-1 antitrypsin deficiency is bad.
