Introduction to Respiration Flashcards
What doesn’t change regardless of the concentration of O2?
Partial pressure in different environments - Air, Water, Blood
How does gas move? According to partial pressure or according to concentration?
Partial pressure from high to low
What is the partial pressure in the alveolus?
100mmHg
What is the concentration of O2 in the alveolus?
0.3mlO2/100ml blood
What is the partial pressure in the mixed venous blood?
40mmHg
What is the concentration of O2 in the blood?
15.8mlO2/100ml blood
Why does O2 move according to partial pressure and not concentration?
if it moved according to concentration then O2 would flow out of the body and we would die
What is the partial pressure in dry room air?
159 mmHg
What is the partial pressure in tracheal gas?
149mmHg
What is the partial pressure in alveolar gas?
100mmHg
What is the partial pressure of pulmonary veinous blood?
98mmHg
What type of epithelial cell is the Type 1 alveolar?
squamous epithelial for thin blood gas barrier
What type of epithelial cell is the type 2 alveolar?
cuboidal - stem cell for type 1, produces mucus and surfactant
What is the significance of alveolar branching?
it reduces resistance throughout the branch network as the diameter narrows
increases the area for gas exchange
What is the law associated with resistance in the airway?
Poiseuille’s Law
R= 8nl/(pi)r4
What does a doubling of total airway diameter do?
reduces resistance 16-fold
When does gas move into the alveoli?
alveolar pressure is less than atmospheric
airways are open
When does gas move out of the alveoli?
alveolar pressure is greater than atmospheric
airways are open
What is alveolar pressure the sum of?
elastic recoil pressure
pleural pressure
What are the main inspiratory muscles?
Diaphragm
External intercostals
Accessory muscles
How is the diaphragm innervated?
phrenic nerves C3-5
How are the external intercostals innervated?
intercostal nerves at the rib level
What are the accessory muscles?
sternocleidomastoid, scalenes
As the chest expands, what happens to intrapleural pressure?
it falls
What are the muscles involved in forced expiration?
internal intercostals
abdominal wall
What are some of the vital volumes and capacities?
Vt - tidal volume FEV - forced expired volume FRC ERV IRV Residual volume
What is the typical pulmonary volume in males and females?
6L in males
4.2L in females
How do you calculate vital capacity?
IRV+Vt+ERV
How do you calculate the FRC?
ERV and residual volum
How do you calculate the inspiratory capacity?
IRV and Vt
How do you measure the FRC?
helium inhalation method
V2 = V1(C1-C2)/C2
Take known concentration of helium in tank of known volume, take concentration after breathing
What is anatomical dead space?
component of the lung that does not participate in gas exchange
airway, nasal cavity and mouth
How may anatomical dead space vary?
Disease
mechanical ventilation
alveolar collapse
species
How can you measure anatomical dead space?
O2 inhalation method
Carbon dioxide dilution method
How does the oxygen inhalation method work?
single inspiration of O2
o2 flushes out the gas in the lung which is composed of 75% N2
As subject exhales the breath is initially O2 rich but eventually equilibriates with O2, when a=b that is the dead space
How does the CO2 dilution method work?
Dead space dilutes the CO2
Vd/Vt = PaCO2 - PexpCO2/PaCO2
What is considered a normal FEV1?
80% of FVC
What is FVC?
maximum exhalation under forced conditions
What is FEV1?
amount of air exhaled in 1s
What would be the expected FEV in asthmatics and emphysema?
42% ish
What would be the expected FEV in restrictive diseases like pulmonary fibrosis?
90%
