muscle of inspiration (use when)
2. External and accessory muscles (exercise and respiratory distress)
muscle of expiration
expiration is passive. Muscles uses during exercise or airway resistance (eg. asthma)
internal vs external intercostal muscles according to function
external intercostal –> inspiration
internal intercostal –> expiration
Compliance (C) equation
C=V/P
Lung - hysteresis?
lung inflation (inspiration) curve follows a different curve than the lung deflation (expiration) curve due to need to overcome surface tension forces in inflation
surfactant reduces surface tension by … (mechanism)
disrupting the intermolecular forces between liquid molecules
the site in respiratory system with the highest resistance
medium sized bronchi
changes in airway resistance - mechanism (explain)
by alterining the radius (SMCs contraction or relaxation)
resistance of lung during deep-see dive
both air density and resistance to airflow are increased (increased viscosity)
resistance of lung - decreased viscosity during
breathing a low-density gas (such as helium)
lung - physiologic shunt (definition, results)
appriximately 2% of the systemic cardiac cardiac output bypasses the pulmonary circulation – PO2 of arterial blood slightly lower than the alveolar air
nomal values of PO2 and PCO2 in venous blood
PO2 –> 40
PCO2 –> 46
LUNG - for perfusion-limited process, diffusion of the gas can be increased only if
blood flow increases
P02 40 (venous blood) - Hb saturation
75%
PO2 25 - Hb saturation
50%
Hb saturation - the curve is almost half when PO2 is …. (purpose)
60 - 100 mmHg
humans can tolerate changes in atmospheric pressure
hemoglobin curve - P50?
partial pressure of PO2 in which Hb saturation is 50%
deohyhemoglobin
Hb + H+
Carboxyhemoglobin
Hb + CO
distribution of pulmonary blood flow - supine vs standing
supine –> uniform throughout lung
standing –> effect of gravity –> highest at the base
distribution of pulmonary blood flow - in Apex the alveolar pressure may compress the cappillaries and reduce blood flow - situation
if arterial blood pressure is decreased as a result of hemorrhage or if alveolar pressure is incresaed because of positive ventilation
The magnitude of a right-to-left shunt can be estimated by
having the patient breath 100% 02 and measuring the degree of dilution of oxygenated arterial blood by nonoxygenated shunted (venous) blood
LUNGS - normal V/Q is approximately
0.8
pO2 and pCO2 - apex vs base
pO2 is highest and pCO2 is lower at the apex because gas exchange is more efficient