Respiratory Physiology II Flashcards
Anatomical Shunt is defined as blood that goes from the ___ side to the ___ side of the heart without traversing ____ capillaries. Anatomic Shunts exists because of the ___ and ____ circulations, which account for a Shunt of 2-3%.
Anatomical Shunt is defined as blood that goes from the right side to the left side of the heart without traversing pulmonary capillaries. Anatomic Shunts exists because of the bronchial and thebesian circulations, which account for a Shunt of 2-3%.
Blood pressures within the pulmonary circulation are lower than those in the systemic circulation because of a much lower vascular resistance to blood flow
Blood pressures within the pulmonary circulation are lower than those in the systemic circulation because of a much lower vascular resistance to blood flow
why is there a lower resistance in the pulmonary circulation vs the LS systemic circ?
The low vascular resistance of the pulmonary circulation arises in part from the absence of muscular arterioles which are responsible for the high resistance found in the systemic circulation
pulmonary vascular resistance ___ during exercise. Why?
decreases on exercise (high cardiac output- because of recruitment and distention of capillaries.
hypoxia, serotonin,
histamine, thromboxane A 2
, endothelins are ____ of the pulmonary vascular resistance
vasoconstrictors
nitric oxide, prostacyline I2, Ca++ channel blockers are all ___ of the pulmonary vascular system
vasodilators
why does resistnace decrease during exercise/when pulmonary blood flow increases?
When pulmonary blood flow and pressure rises, these pulmonary capillaries open or further increase in diameter, thus reducing vascular resistance and preventing large increases in pulmonary arterial pressures
in response to low O2,
systemic arteries ____ in response to perfusion with blood low in O2. Pulmonary arteries ___ in response to alveolar hypoxia but not to perfusion with blood low in oxygen.
systemic arteries dilate in response to perfusion with blood low in O2. Pulmonary arteries constrict in response to alveolar hypoxia but not to perfusion with blood low in oxygen.
how does lung volume affect the pulmonary vascular resistance
if there is more lung volume, there is more pressure and thus alveolar vessels get compressed if it increases.
extra-alveolar vessels are exposed to a pressure less than alveolar and are pulled open by the radial traction of the surrounding parenchyma
overall, the total PVR increases as the lung volume increases
normal VQ match is ____ across the alveolar capillary membrane in a health lung
0.84.
Pa CO2 < 35 mmHg,= __
PaCO2 35-45 mmHg, =__
PaCO2> 45 mmHg= __
Pa CO2 < 35 mmHg,= Hyperventilation
PaCO2 35-45 mmHg, =Normal
PaCO2> 45 mmHg= Hypoventilation
5 major causes of hypoxemia (paO2<80)
- hypoventilation
- diffusion impairment
- ventilation-perfusion inequality
- reduction of inspired O2
- shunt: his means that some blood reaches the arterial system without passing through ventilated regions
of the lung
outline the ratio of PaO2 to PaCO2 during hyper and hypoventilation
outline a circumstance of diffusion impairment cuasing hypoventilation
ex if the person has interstitial lung fibrosis.
- DIs means that equilibration does not occur between the PO2 in the pulmonary capillary blood and alveolar gas.
normal value for the alveolar-arterial oxygen difference
normal should be 10-15.
What happens to alveolar-arerial gas equation when there’s hypoxemia due to:
- reduction of inspired O2
- hypoventilation
- diffusion imparment
- ventilation-perfusion inequality
- shunt
what two components make up the arterial oxygen content
- oxygen dissolved in plasma
- oxygen bound to hemoglobin in RBC
- recall that systemic oxygen transport = cardiac output x arterial oxygen conten
2,3-DPG – inorganic phosphate produced in RBC ___ Hb’s affinity for oxygen, shifting the curve ____
2,3-DPG – inorganic phosphate produced in RBC lowers Hb’s affinity for oxygen, shifting the curve right.
what is P50
the PO2 at whcih Hb is 50% saturated with O2
3 ways that CO2 is transported by the blood
- dissolved in plasma
- carbaminohemoglobin
- bicarbonate ion
what 3 chemical factors control ventilation
PaO2, pH and PaCO2
main peripheral chemoreceptor sensor location
heart and caortid
most important central chemoreceptor of Ph and PCO2
ventral surface of the medulla
- exit of the 9 th and 10th cranial nerves
what receptors in the lungs help control ventilation
the heart and the brain have chemoreceptors, but the lung has
- pulmonary strethc receptors
- irritant receptors
- J receptors
External intercostals – ___ function
Internal intercostals – ___ function
External intercostals – Inspiratory
Internal intercostals – Expiratory
( very simplified)
