Respiratory Physiology Flashcards
Functions of the lungs
gas exchange
pH maintenance via retention or elimination of CO2
Conversion of ANG1 to ANG2 for blood pressure control
Pressure and volume relationship
inversely related
air will flow from areas —
high pressure to low pressure
Is inspiration an active or passive process?
active
primary inspiratory muscles
diaphragm (phrenic nerve fires –> diaphragm contracts)
external intercostals (elevate ribs –> increase transverse diameter)
external intercostals (evert ribs –> increase AP diameter)
Accessory inspiratory muscles
Sternocleidomastoid
Serratous anterior
Scalenes
Pectoralis
Is expiration a passive or active process?
passive
Muscles for forced expiration
internal intercostals
abdominal muscles
Pressure and volume for inspiration
Volume increases –> pressure in lungs decreases –> air flow from atmosphere into lungs
Pressure and volume for expiration
Volume decreases –> pressure increases –> air flows out
Conducting zone
nasal cavity
pharynx
trachea
bronchus
bronchioles
What is considered the anatomic dead space?
conducting zone; no gas exchange occurs here
volume in conducting zone/dead space
150 mL
1/3 of tidal volume
What is surfactant created by?
Type 2 pneumocytes
What is the alveolar epithelium created by?
type 1 pneumocytes
Volume in the respiratory zone
3L
Does diffusion occur actively or passively?
passively
Diffusion is directly proportional to
pressure difference (P1-P2; AA gradient)
Surface area
temperature
solubility (easier to offload CO2 than to transfer O2 over)
Diffusion is inversely proportional to
molecular size
thickness of membrane
alveolar dead space (pathologic)
Alveoli not receiving blood supply –> no gas exchange
shallow rapid breathing –> decreased alveolar ventilation –> decreased O2/CO2 exchange
deep slow breathing –> increased alveolar ventilation –> increased O2/CO2 exchange
High V/Q
Pulmonary HTN, PE
blood is not getting perfused
Low V/Q
emphysema due to decreased ventilation
positive pressure causes
tension pneumothorax
valsalva
Causes of less negative pressure
emphysema –> less recoil
leads to air trapping
Cause of zero pressure
birth
stab wound without valve
spontaneous pneumothorax
what decreases our lung’s ability to collapse
surfactant decreases surface tension which decreases our lung’s ability to collapse
How is compliance related to surface tension and elasticity
inversely related
Who do we worry about not having enough surfactant?
premies
Alveolar ventilation
amount of volume involved in gas exchange
Normal V/Q ratio
0.8, 80%
When is pressure lowest
mid inspiration
when is pressure highest
mid expiration
Is transmural pressure always positive or always negative
always positive
Least resistance
alveoli due to higher surface area
Premature babies are at high risk of lung collapse so we put them on
positive pressure breathing
stimulate surfactant production via steroids or thyroxine or prolactin
Compliance
expansibility of lungs
change in volume divided by change in pressure
(if increased compliance then you are able to get air in)
Emphysema and compliance
increased compliance –> decreased recoil
think of an old sock and a useless rubber band
Pulmonary fibrosis and compliance
decreased compliance –> increased recoil
think about compression stockings that are very strong and difficult to stretch
Alpha 1 antitrypsin deficiency and compliance
decreased elastin –> decreased lung recoil –> increased compliance
Eupnea
normal breathing
Hypopnea
decreased breathing
Hyperpnea
increased breathing
Apnea
no breathing
Orthopnea
erect breathing
CHF
platypnea
flat breathing
trepopnea
side breathing
CHF or fibrosis of one lung
