Pressure/
Ventilation
Ventilation
what is intrapulmonary pressure (Ppul)
equal to the pressure in the alveoli, also called intra-alveolar pressure
what is expiratory reserve volume (ERV)
amount of air that can be forcibly expelled from lungs (1000–1200 milliliters)
what it henry's law
for gas mixtures in liquids - each gas will dissolve in the liquid in proportion to its partial pressure
what are the two ways molecular O2 is carried in the blood
1.5% is dissolved in plasma and 98.5% is loosely bound to each Fe of hemoglobin
what muscles are responsible for inspiration
1. diaphragm
2. intercostal muscles
what is transpulmonary pressure
4 mmHg, equal to the difference between the Intrapulmonary pressure (Ppul) and Intrapleural pressure (Pip)
is also the pressure that keeps lung spaces open, preventing collapse
T/F - men and women have different tidal volumes
false - men and women have a TV of ~500 ml
what is Dalton's law of partial pressures
total pressure exerted by mixture of gases is equal to sum of pressures exerted by each gas
what causes the hemoglobin saturation curve to shift right
increased PCO2, H+ (pH 7.2), and BPG
- decreases His affinity for O2
- enhances O2 unloading
what is Boyle's law
P1V1 = P2V2 | shows that there is an inverse relationship between pressure and volume
what are the two inward forces promoting lung collapse
1. the lungs’ natural tendency to recoil
2. surface tension of alveolar fluid
what is the equation for functional residual capacity?
why does CO2 diffuse in equal amounts of oxygen in the alveoli
reason is that CO2 is 20× more soluble in plasma and alveolar fluid than oxygen
PO2, temperature, blood pH, PCO2, concentration of BPG
what is the name of the graph that shows the relationship between PO2 and hemoglobin saturation
S-shaped curve - oxygen-hemoglobin dissociation curve
during inspiration, air flows into the lungs; why?
Intrapulmonary pressure drops by 1mm Hg as the thoracic cavity increases, air will flow down it's pressure gradient from the atmosphere (0mm Hg --> -1 mm Hg)
what is the equation for vital capacity
sum of TV + IRV + ERV
what factors influence external respiration
1. partial pressure gradients and gas solubilities
2. thickness and surface areas of respiratory membrane
3. ventilation-perfusion coupling - matching of alveolar ventilation with pulmonary blood perfusion
how is CO2 transported in the blood
1. dissolved in plasma (7-10%)
2. chemically bound to hemoglobin (~20%)
3. as bicarbonate ions (HCO3-) in plasma (~70%)
what is the Bohr effect
declining blood pH (acidosis) and increasing PCO2 cause the hemoglobin-O2 bond to weaken
- O2 unloading will occur where it is needed most
describe the mechanical process of pulmonary ventilation
1. volume changes lead to pressure changes
2. pressure changes lead to flow of gases to equalize pressure
what is the alveolar ventilation rate (AVR)
flow of gases into and out of alveoli during a particular time
what is an example of henry's law
hyperbaric chambers, force greater-than-normal amounts of O2 into blood for people with carbon monoxide poisoning.
what is the Haldane effect
amount of CO2 transported is affected by PO2
the lower the PO2 and hemoglobin O2 saturation, the more CO2 can be carried in blood
what are the 5 steps of expiration
1. inspiratory muscles relax
2. thoracic cavity volume decreases
3. elastic lungs recoil passively; intrapulmonary volume decreases
4. intrapulmonary pressures rises (+1 mmHg)
5. air flows out of the lungs down its pressure gradient until intrapulmonary pressure is 0 mmHg