80 - Physiological Consequences of Increased Fluid Movement across Pulmonary Membranes Flashcards
Features of pulmonary circulation
Low pressure, low resistance
Why can the pulmonary circulation be low pressure?
Mostly at the level of the heart, so don’t need pressure to push fluid against gravity
Pulmonary artery pressure
25/8 (systolic/diastolic)
Mean is 15mmHg
Capillary pressure
12/8 mmHg
What would happen if pulmonary circulation were high pressure?
Fluid would leak from vessels into the alveoli.
This would impair gas exchange
Components of pulmonary circulation
Thin-walled vessels, thin right atrium, ventricle
Capillary volume in pulmonary circulation at rest
60-80mL
Effect of exercise on pulmonary circulation pressure
No effect.
Vasodilation prevents pressure rise with increased CO
Effect of inspiration on pulmonary circulation
Pooling of blood
Amount of deoxyhaemoglobin for cyanosis to be visible
4g/L
Signs of a metabolic acidosis
Acidosis without elevated blood CO2. Low bicarbonate (EG: loss from diarrhoea, or acting as a buffer for elevated lactic acid)
Signs of a respiratory acidosis
Elevated CO2 with decreased pH
Anion gap
Difference in concentrations of commonly-measured anions and cations in the blood (Anions and cations won’t be different, just measuring the common ones, EG: K+, Na+, Cl-, HCO3-).
Used to measure electrolyte imbalance.
Sum of the commonly measured anions and cations
Difference in charge is normally under 15.
How does the anion gap appear with metabolic acidosis, from introduced acid
Bicarbonate decreases (neutralising acid). Anion gap goes above 15.