pulmonary circulation Flashcards
what is pulmonary circulation?
what are the 2 lung circulations?
what are they ?
circulation/circuit of blood from right side of heart to lungs and back into the left
bronchial and pulmonary
bronchial = part of systemic and meets metabolic requirements of lungs
pulmonary = blood supple to alveoli for gas exchange
what is the average CO?
whats the max CO in exercise?
5L/min
20-25L/min
what are 2 key features of pulminary circulation?
how does it achieve low resistance?
low pressure
low resistance
short wide vessels, lots of capillaries, little smoothmuscle in pulmonary arterioles
what adaptions are there in the lungs for efficient lung exchange ?
- high density of capillaries - large capillary SA
- short diffusion distance- thing endothelial and epithelium cells
what is the ventilation perfusion ratio?
what is the optimal ratio
what happens when ventilation is too low?
V/Q ratio
it measures how efficient oxygenation is
needs to match ventilation with perfusion in alveoli for good oxygenation
0.8 - V divided by Q
blood will be diverted from alveoli to bring up the ratio
what is hypoxic vasoconstriction?
what triggers it?
what happens after the trigger?
what does this mean?
it ensures perfusion will match ventilation so the VQ ratio is good for oxygenation
alveolar hypoxia
vasoconstriction of pulmonary vessels
poorly ventilated alveoli are less well perfused - ensures perfusion matches ventilation and optimise gas exchange
why is chronic hypoxic pulmonary vasoconstriction bad?
when does it commonly happen?
what does it lead to?
chronic vasocontriction = pulmonary hypertension
chronic hypoxia= altitude or lung disease
right side ventricular heart failure as the hypertension in the pulmonary circuit increases the after load the RV needs to push against
where in the lungs are the capillaries always open?
why?
at the apex (apical), when do those vessels collapse?
what is the effect of exercise on CO?
what is the effect of exercise on pulmonary arterial pressure?
what is the effect of exercise on apical capillaries?
what is the effect of exercise on O2 uptake?
what is the effect of exercise on capillary transit time?
bottom
gravity increases hydrostatic presssure making them patent all the time
diastole - open in systole
increases
increases
open even in systole
increases
lowers - faster !!
why does tissue fluid form?
what law?
what blood vessel pressure influences hydrostatic pressure the most?
what features of pulmonary circuit minimises the formation of lung oedema/lymph?
what would an increase capillary pressure in lungs cause?
how could this happen?
hydrostatic increase, capillary oncotic decrease
starlings law
venous pressure-
hypertension in ateries is not usually a cause of oedema
low pressure - so low hydrostatic - tissue fluid isnt pushed out as much
oedema
mitral valve stenosis
left ventricular failure - both cause back log of blood on pulmonary circulation = high pressure
why is pulmonary oedema bad?
what posture makes oedema formation worse?
how to treat?
it impairs gas exchnage
laying down (less effect of gravity) - capillarys are open all over rather than just at bottom when standing up
duiretics relieve symptoms
treat underlying cause
