pulmonary circulation Flashcards

1
Q

Describe the pulmonary circulation

A

pul artery = low oxygen blood
pul vein = high ox blood
function: perfusion of resp airways for GE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Comparison of the systemic circulation with the pulmonary circulation

A

different wall thickness: lumen ratio
pul circ - thinner walls because going to a smaller distance
in heart LV main compartment
RV ‘additional’ - less mechanically strong force and structure - shorter distance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

circuit pressures in systemic and pul circulation `

A

LV give on/off pressure, systole/diastole
aorta - vascular compliance so make flow more pulsatile
blood goes from low to high pressure
pulmonary circuit similar process - under much lower pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

cardiac parameters in systemic and pulmonary systems

A

pul has 10% of blood vol
blood is mainly in systemic/pul veins
pul has 15% pressure
pul has 10% of the pressure gradient - impacts the velocity
pul is a low resistance circuit - more resistance = faster, needs time to load

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

3 functions of the pulmonary circulation

A

GE
metabolism of vasoactive substances
filtration of blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

GE

A
deliver O2, take CO2 
CO2 move quick - v diffusible 
anaesthetic moves from lungs to neurological system 
NO inert so travels in and out of lungs 
pulmonary transit time .75s
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

metabolism of vasoactive substances

A

endothelium that expresses ACE - convert ANG1 - ANG2 - vasoconstrictor
break down bradykinin (vasodilator)
only expressed at end of lungs or in the kidney

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Filtration of the blood

A

filters things that get ‘caught’ before they reach the systemic arteries
eg venous thrombosis from stasis, ruptured fatty plaques, air bubbles
small embolus - eliminated in pul microcirc
large embolus - trapped in pul microcirc - local perfusion obstructed - can stop flow to entire lung - affects pressure and GE - better than in systemic `

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

embolus

A

mass in circulation capable of causing an obstruction `

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

embolism

A

event characterised by the obstruction of a major artery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

in theory what should happen if CO (Q) is increased

A

increase MAP
therefore increase leakage
= pul oedema
reduced lung function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what actually happens when Q is increased in pul circ

A

pul artery distension - prevent increases in MAP
also the increase in pressure increases perfusion of the apex of the lung - increased throughput of the lung
both mean Q is increased with little increase in MAP
minimal fluid leakage
no onset of pul oedema
no detriment to pul func

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

pulmonary response to hypoxaemia

A
closure of O2 sensitive K+ channel 
reduced KJ efflux 
increased mem potential 
membrane depol = open V gated Ca channel 
vascular sm constriction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

effect of breathing hypoxic air

A
global vasoconstriction 
RV work hard against resistance 
get stronger 
concentric hypertrophy 
septum change 
change in EDV on L 
affect in SV
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

beneficial effect of pul vasoconstriction with hypoxia

A

in foetus
perfusion matches inadequate ventilation
blood follows path of least resistance
increased flow through shunt (pul circuit is higher pressure)
first breath increases alveola PO2 - dilate the vessels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

when is vasoconstriction as a result of hypoxia detrimental

A
COPD 
reduced ventilation 
increased resistance in pul circuit 
= pul hypertension 
RV hypertrophy
congestive heart failure
17
Q

Why is there a fluid balance in the lungs

A

vessels aren’t water tight

factors effect movement and move the water into the extracellular space

18
Q

important components in the Starling eqn

A

hydrostatic pressure in the interstitium Pi
hydrostatic pressure in the capillary Pc
oncotic pressure in the interstitium (pi)i
oncotic pressure in the capillary (pi)c

19
Q

describe the fluid balance in the lungs

A

plasma hydrostatic - highest when first get to capillary, forces fluid out
interstitial hydrostatic - tiny sucking force (ie negligible move out)
plasma oncotic - big sucking force into the vessel
interstitial oncotic - force out of the vessel
net movement out
small leakage
increase in interstitial hydrostatic pressure
pulmonary circulation can manage - uses -ve pressure to mop up the fluid
easier for the excess fluid to drain into the lymph and then drain into the capillaries

20
Q

what happens if there is excess fluid

A

fluid exceeds ability of lymph to drain it

pulmonary oedema

21
Q

effect of mitral valve stenosis on fluid balance

A
pressure build up from L of heart through pul circulation 
increased plasma hydrostatic pressure 
more fluid forced into the interstitium 
max lymph clearance rate exceeded 
pul oedema
22
Q

effect of liver failure on fluid balance

A
plasma oncotic reduced - less plasma proteins made
less fluid drawn into the capillary 
fluid accumulates in the interstitium 
lymph clearance exceeded 
oedema
23
Q

effect of metastatic breast cancer on fluid balance

A

cancer spresd to lympoh nodes
tumours obstruct lymphatic drainage
lymph clearance compromised
oedema

24
Q

effect of increase in systemic pressure on fluid balance

A

no effect
systemic circulation doesn’t affect pul circ
unless shared cause like hypovolaemia

25
the concept of shunting
circumstances associated with the bypassing of the resp exchange surface
26
adult example of shunting
bronchial circulation blood goes through the L side of the heart and the aorta to keep the tissue alive - some drains into the pul vein and reenters the left heart
27
foetal shunting
lungs not ventilated - so the bv are vasoconstricted don't want to pump blood into lungs = damage heart because of the high resistance so shunt between atria - foreman ovale - close with 1st breath ductus arteriosus - blood from pul artery straight to aortic arch
28
complications if foetal shunts don't close
congenital defect atrial septal defect - deox and ox blood mix open a little - stop the filtration function of the pul circulation can have elective surgical repair initial L side higher pressure = blood pushed through foreman ovale to R side = increased pressure on the R side R side becomes stronger - blood pushed into L - less O2 in the systemic circ as mixed with deox blood
29
shuntings affect on blood returm
more blood returns to the L of the heart because of bronchial shunt blood misses the pul circ ie the R side of the heart