Respiratory Physiology Study Guide Flashcards
ventilation
breathing (inspiration and expiration), the mechanical process of breathing
- dependent on volume changes in thoracic cavity
- volume changes -> pressure changes -> flow of gasses to equalize pressure
atmospheric pressure
The pressure exerted by the gasses / air surrounding the body (at sea level atm is 760mmHg or 1 atm)
(-) respiratory pressure - lower than atm
(+) respiratory pressure - higher than atm
(0) respiratory pressure = atm
intrapulmonary pressure
(Ppul): the pressure within the alveoli
- Rises/falls with the phases of breathing – always equalizes with atmospheric pressure
- gets lower with inhale
Intrapleural Pressure
the pressure in the pleural cavity
- Rises/falls with the phases of breathing –always about 4mmHg less than Ppul
relationship between intrapulmonary and intrapleural pressure
Pip is always negative relative to Ppul
- Any condition that equalizes Pip with Ppul or atmospheric pressure will cause lung collapse
Transpulmonary Pressure
the difference between Ppul and Pip
The pressure that keeps the air spaces of the lungs open and prevents lung collapse!
how parietal and visceral pleurae are attached to each other
presence of pleural fluid causes strong adhesive force between pleurae
transpulmonary pressure is greatest when ….
the lungs are larger in size
atelectasis
“lung collapse”
- when a bronchiole becomes plugged
- associated alveoli collapse
- often extension of pneumonia
pnuemothorax
“air thorax”
- presence of air in the pleural cavity
- reversed by drawing air out via a chest tube
- lung will reinflate
boyles law
relationship between pressure and volume of gas - at constant temp, pressure is inversely related to volume (gasses always fill their container)
- p1v1=p2v2
inspiratory muscles
diaphragm and external intercostals
nerve that delivers impulses for contraction from brain’s respiratory centers
phrenic nerve
volume and pressure during inspiration
- diaphragm + external intercostals contract
- height and diameter of thoracic cavity increase
- lungs stretch, intrapulmonary volume increases, Ppul decreases
- air rushes into lungs
- Ppul equalizes to Patm
volume and pressure during expiration
- inspiratory muscles relax - rib cage descends, lungs recoil
- thoracic + intrapulmonary volumes decrease
- Ppul rises
- when Ppul > Patm, air flows out
2 muscles used for forced expiration
transerve abdominis and obliques contract (internal intercostals are also involved)
3 accessory inspiratory muscles involved in forced inspiration
scalenes, SCM (sternocleidomastoid), pectoralis minor
equation + relationship between air flow, airway resistance, and change in pressure
F = ΔP/R
- airway resistance (R): friction or drag encountered in the respiratory passageways
- small change in P can create large changes in air flow (2mmHg or less during quiet breathing)
- flow (f) varies inversely with resistance (r)
- R is determined by diameters of conducting tubes (highest resistance is in medium bronchioles, because the really small ones have diffusion)
- increased resistance = decreased flow
- increased change in pressure = increased flow
bronchodilator
relax muscles in lungs and widen airways/bronchioles
branch of ANS responsible for bronchoconstriction
parasympathetic nervous system