L11 Lung Volumes Flashcards
Lung primary function
• External respiration- Gas exchange
what is the trachealis
smooth muscle enables adjust air flow
what are the plueru
visceral= lungs parietal= chest
function of plural fluid
- Reduction of friction- during recoil
- Creation of pressure gradient- negative
- Compartmentalization- prevents infection spreading quickly
2 lung zone + functions
- Conducting Zone:
1. To warm and humidify air
2. To distribute the gas
3. To serve as part of the body’s defense system
• Respiratory Zone:
1. Site of Gas Exchange
what nerve innervates lungs
phrenic
describe inflation of lung mechanism
infaltion= contraction of diaphragm (skeletal muscle) – thoracic cavity expands and lungs are inflated
• Contraction of diphragm pushed abdominal organs down (increases space vertically) and pushes ribcage out (increases space horizontally)
why is normal expiration passive
elastic properties of lungs and thoracic cavity
atmospheric pressure number
760MMHG
daltons law
Pb= Pn + O2 + H20 + Pco2
boyls law
p + volume
charles
t + volume
henrys law
the solubility of a gas in a solvent is directly proportional to the partial pressure of the gas in contact with the solution S/P=k.
explain intraplural pressure
- press= neg (due to elasticity)
- stretched lungs= potential to recoil inwards, + chest wall = potential to recoil outwards. opposing forces = pleural P to decrease below atm P.
average changes in Ppl
more neg during inspiration
only pos during forced ex
explain pneumothorax
presence of air in pleural space - lungs collapse due to elastic recoil, and chest wall simultaneously recoils outwards. Ppl = atm P, and PL is zero
alveolar, airway, plural pressure abbreviations
PA (alveolar)
Pta (airway)
Ppl (plural)
what is transmural (trans airway pressure)
Ptm
pressure difference across the airways
- prevents collapsing during forced ex
what is transpulmon (trans airway pressure
PL = PA – Ppl = pressure difference across the lung wall
explain pressures at end of expiration
muscles are relaxed and there is no airflow. Pa = 0, Ppl=-5, so PL = +5
why is PL always pos during normal breathing
keeps the lungs inflated).
explain pressures during inspiration
thoracic cavity expands – Ppl becomes more –ve (-8) – PL increases and the lungs inflate Alveolar diameter increases – Pa becomes –ve – air moves into lungs
why does airflow stop (pressure)
Pa = atm P.
explain pressures during expiration
, rib cage drops Ppl becomes less –ve, PL decreases and the stretched lungs recoil and deflate. As alveolar diameter decreases, Pa becomes +ve ie greater than atmospheric P and air is pushed out of the lungs until Pa = atm P.
typical respir volumes
- TV
- IRV
- ERV
TV- 500ml
IRV- 3L
ERV- 1.3L
Typical respir capacities - TLC VC IC FRC
= TLC= 6L
VC = 4.7L
IC = 3.5L
FRC = 2.5L
Determinatns of lung volume
height wight altitude disease gender
what is pulmonary ventilation
Ve= total volume ventilated/min
= VT x F
average pulmonary vent
500ml x 12
= 6L
what is anatomical dead space
not all air does not participate in gas exchange.
• Anatomical DS = air in conducting airways = usually 150ml
what is alveolar ventilation
VA= total volume of air in gas exchange
= (VT-150ml) x Bf
typical VA
4.2l
