L4 - pulmonary circ Flashcards
functions of pulmonary circ (PULMC)
gas exchange
-reservoirs for blood
filter
synthesis and metabolism
structure of pulm vessels
thin walled and highly branched than systematic vessels
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why is the pressure lower in PULMC than SYSTMC
the pulm vessels are wider and shorter so the blood move slower
- it has a lower resistance
does pulmc receives all of right ventricular output
yes
what features are low in pulmc
pressure due to thin wall and resistance due to short vessles and larger raduis
other features of pulmc
vessels can change shape easily
- have large SA capillary
- returns blood to left ventricle
whats the value of pulm ABP at the pulm artery value
28/8 mmHg
whats the pulm capillary pressure at pulmon artery level
8~10mmHg
difference in distance and its pressure between heart level to apex and base seperately
15cm and 12 mmHg for both distances
whats the pressure near base of the lungs when standing upright
28/8+12/12= 40/20 mmHg.
- the pressure becomes greater so the vessels becomes distended
whats the pressure near apex of the lungs when standing upright
28/8-12/12= 16/-4
- pressure not high enough so the vessels collapse
- no perfusion
when standing upright, what happends to pulm perfusion
increases from apex to base
when lying, what happens to pulm
perfusion is evely distributed from apex to base
what is capacitance of the pulm blood vol
when lying, there’s greater blood vol so higher capacitance
capacitiance functions
- standing upright increases return to left chambers
- CO and pulm ABP increases, perfusion increases
- increases blood vol
- if left ventr failure happens, filling towards the apex occurs
vasocont influences on pulmc
increased SNS activity increases pressure in pulmc and perfusion
- inflamm mediators like histamine
- hypoxia - pulm vasocon
what is hypoxia
when O2 supply not enough and not being supplied
what happens when theres hypoxia in one of the capillary
-vasocon of that capillary occurs
-this diverts the blood flow to other capillaries
=improves O2 exchanged
what happens if the hypoxia occurs throughout the lungs
- generalised pulm vasocon
- increases intravascular pressure
- limits O2 supply
effects of generalised pulm vasocon (chronic hypoxia)
- increases resistance in pulmc
- widens vascular SM so increases vasc R
- increases capillary hydrostatic pressure so more filteration out of capillaries > pulm odema
- impaired gas exchange
what happends during filteration across the pulm capillaries
- net outward filteration due to capillary HP higher than tissue HP
- tissue OP is higher in pulmc than sysmc so smaller OP pulls filteration into capillaries
- excess fluid taken away from lymph
what happends during filteration in the capillaries in lungs when the pulm CAP increases
what occurence it can lead to in the capillaries in lungs when the pulm CAP increases too much
alveolar odema which is not good as the alveoli need to be kept dry
what occurences does pulm odema occur in
hypoxia, inflammation, extreme exercises, anaphyliatic responses, left ventricular failure
what is microthrombi
- small particles of blood cells and fibrin together aggregrate
- get stuck in pulm ciric
what is pulm embolism
blood clot, air or fat that block pulm vessels
what do pulm cells syntheisise
NO to cause Pulm vasodil in response to stress
-PGI2- cause dilation
ACE
what do pulm endothelial cells remove
serotonin (5-HT) and NAdr
