pulmonary ventilation Flashcards
define respiration
provide oxygen to tissues and removes co2 from tissues
four functions of lung
pulmonary ventilation (air from atmosphere to alveoli), regulation of ventilation, diffusion of o2/co2, transport of o2/co2in blood to and from tissues
upper respiratory system
esophagus, vocal cords, larynx pharynx tongue, nasal cavity
lower resipratory system
trachea, bronchi, lungs
normal respiration
diaphragm contracts (decreases pleural pressure) and relaxes (increases pleural pressure) allows elastic recoil of lungs chest all and abdominal structures to compress lungs
heavy breathing
add contraction of abs because elastic forces dont expel air fast enough
why does lung naturally collapse
lungs are very elastic and surface tension of water
Explain why the normal pressure of the pleural cavity (pleural pressure) is negative.
The lymphatic system drainage as well as the surface tension of water creates suction
Explain how a negative pleural pressure tends to expand the lungs.
Negative pressure holds visceral layer close to chest wall and allows for expansion of lungs
pleural pressure start of inspiration, during inspiration during expiration
-5,-7.5,-5
alveolar presssure start of inspiration, during inspiration during expiration
0,-1,+1
transpulmonary pressure start of inspiration, during inspiration, during expiration
-5,-6.5,-5
duration of inspiration normal breathing
2 sec
duration of expiration
2-3 seconds
define compliance
how much lungs will expand for each unit increase
normal compliance
200 ml air/1cm h20
what are elastic force of lung tissue
stretch of elastin and collagen fibers 1/3 of total elastic forces
elastic forces caused by surface tension
2/3 of total elastic forces caused by air fluid interface
transmembrane/transpulmonary pressure
recoil pressure that wants to collapse the lungs
Normal dead space/anatomical
Part of respiratory system that does include alveoli 150 ml
Normal breath per minute
12
Max breath per minute
40-50
Define alveolar ventilation
Total air that comes in contact with alveoli/blood each minute 500-150 x12=4200
Two types of elastic forces
Surface tension 2/3 and elastic forces tissue 1/3
Define air water interface
Water molecules at surface form very strong attraction and actually cause surface to want to contract
What is surfactant and what does it do
Reduces surface tension of water by 8 -50% has several phospholipids
Collapsing pressure equation
2x surface tension/ radius of alveolus
Amount of collapsing pressure alveolus create
4 cm H2O
Amount of collapsing pressure created by alveolus without surfactant .
18 cm h20
Effect of halving alveolar radius on collapsing pressure
Double. Smaller radius equals higher tendency to collapse
Source of surfactant
Type 2 alveolar epithelial cells 10% surface area
Tendency of alveoli to collapse in a premature baby vs adult
6-8 times respiratory distress syndrome
Why are premature babies at risk for respiratory distress syndrome
Surfactant is produced at 7 months of gestation. No surfactant coupled with a radius 1/4 the size of an adult equals bad news.
Compliance of lungs vs lungs and thorax
110ml/cmh20 everything vs 200ml of air/1cmh20 just lungs
Three things that effect energy required for breathing
- Force required to overcome elastic work Compliance or elastic work(takes surface tension into account). 2. Force required to expand lungs against viscosity of tissue. ( tissue resistance work)
- airway resistance work
Percentage of total energy used for pulmonary ventilation. How much will it increase during heavy exercise?
3-5%, 50 times
Vt
Tidal volume
VC
= IRV+Vt+ERV or IC + ERV
TLC
VC+RV or IC FRC
FRC
= ERV + RV
Vd Va
Vol of dead space gas
Vol. of alveolar gas
. . . . . . .
Vi Ve Vs Va Vo2 Vco2 VCO
Inspired volume of ventilation per minute, expired volume of ventilation per minute, shunt flow alveolar ventilation per minute, o2 uptake per minute, co2 eliminated per minute, carbon monoxide uptake per minute.
