Respiration: Pulmonary Circulation

Front 1

Functional circulation

Back 1

- gas exchange
- blood coming from RV: gets loaded with O2 and relieved of CO2 in the lung

Front 2

Nutritional circulation

Back 2

- supply of nutrients and relief of wastes
- originates in the LV perfuses the lung and returns to the LA
- LV output 1-2% higher than RV output because of the nutritional pulmonary blood
-due to low P in pulmonary circulation not sufficient to perfuse upper parts of lung at all times

Front 3

blood P in pulmonary circulation

Back 3

- blood returns from lung to LA at 2-5
- pulmonary a: 8-25
- pulmonary capillaries: 7-8

Front 4

zone 1: no blood flow

Back 4

systolic P < hydrostatic P

Front 5

zone 2: perfusion only during systole

Back 5

systolic P > hydrostatic P> diastolic P

Front 6

zone 3: continuous perfusion

Back 6

systolic and diastolic P> hydrostatic P

Front 7

BP and CO

Back 7

increased systemic circulation (eg exercise): R heart also has to increase P in order to increase BV through pulmonary circulation:
1. To raise CO(5 to 24), you must raise P ( 15 to 28)
2. P and therefore BF in all zones is increased

Front 8

exchange in capillary bed

Back 8

- qualitatively same as systemic
- quantitative differences:
1. mean capillary BP lower: 12 vs 18
2. interstitial oncotic P higher (leaky capillaries): 18 vs 1
3. alveolar walls thin and fragile: positive interstitial P can cause injuries, edema

Front 9

net pressure

Back 9

- Starling: net P= hydrostatic - oncotic
1. lung= (12 --5) - (25 - 18)= +10
2. systemic= (18--7) - (25- 1)= 1

Front 10

actual interstitial P in healthy lung

Back 10

- theoretical net P = 10
- actual interstitial hydrostatic P= -5
- lymphatic drains all filtered fluid
- (-)P reabsorbs fluid filtered by alveolar cells into the alveolar lumen: prevents accumulation, keeps alveoli open

Front 11

interstitial edema

Back 11

- filtration/ reabsorption imbalance
- decreased (-) interstitial P
- not in alveoli, diffusion distances longer, but still some as exchange

Front 12

alveolar edema

Back 12

- (+) interstitial P: alveoli rupture and fluid enters other alveoli
- filled alveoli cannot exchange gas
- can be fatal

Front 13

fluid exchange in intrapleural spaces

Back 13

exchange between visceral pleura and:
1. parietal pleura
2. mediastinum
3. diaphragm