Pulmonary circulation

Question 1

1. How does the pressure in the pulmonary circulation differ from the systemic circulation?

Answer 1

The pressure in the pulmonary circulation is MUCH LOWER than in the systemic circulation

Question 2

2. State a key difference in the structure of the pulmonary arteries compared to the systemic arteries.

Answer 2

Systemic artieries are much thicker-large wall and smaller lumen, while POLMONARY arteries has less muscle-more lumen
Because has less place to go so need less pressure-why right ventricule is smaller

Question 3

3. How does the mean arterial blood pressure vary between the systemic and pulmonary circulation?

Answer 3

Overall is a much lower pressure-left ventricule produce the large pressure, but as it goes through tissue goes down-by the right ventricule its low, but it beats it a bit
Operates around 15% of the pressure as arteries
Contains about 10% of volume

Question 4

4. How does the pressure gradient differ between the systemic and pulmonary circulation?

Answer 4

The gradient from start to finish is about 9mmHg-10% of what systemic gradient is (so have time to take in

Question 5

5. How does the resistance differ between the systemic and pulmonary circulation?

Answer 5

Much smaller resistance to have time to take the O2 in time

Question 6

6. Where is ACE expressed?

Answer 6

ACE is angiotensin converting enzyme-endothelial cells in lung (also will breakdown bradokinin which vasodilates

Question 7

7. What does ACE do?

Answer 7

Converts angiotensin 1 to angiotensin 2

Question 8

8. Describe the protective role of the pulmonary circulation.

Answer 8

Very good filter-can protect against clots (stop from going to heart or brain)-breaks down thrombosis, ruptured fatty plaque, or if gas can get them out)-BUT only if they are small
If they are big, they get trapped-pulmonary embolism and loss of local perfusion-but better there than in systemic

Question 9

9. State and describe three pulmonary shunts.

Answer 9

Loosely-allow blood to bypass the respiratory exchange units

1) By definition, bronchial circulation. Blood will go through left side of heart and to bronchiole, then to venous
2) Foetal circulation-blood isn’t sent to lungs in foetal, as no air is taken. 2 main wholes-foramen ovale linking both atriums, and ductus ateriosus-pulmonary valve to aorta
3) Congenital defects-like foetal but in adult. If keep foramen ovale, then atrial spetal defect. Or in ventricule-ventricular septal defect. And as pressure from left is higher, then high BP blood pushed in right. So much so that right becomes actually stronger, and the pushes back the other way. Not the end of the world-is in 25% of people, but lose filtration capacity

Question 10

10. Give two examples of congenital heart defects.

Answer 10

Atrial septal defect and ventricular septal defect. As bp is higher in the left, blood flows into right ventricule, so much so it becomes stronger. Before that its fine as still goes through lungs. Once right is stronger, mixed venous blood is pushed into left and arteries-drop in saturation

Question 11

11. How does the pulmonary circulation respond to an increase in cardiac output?

Answer 11

Pulmonary is low resistance, but high capacity
As CO increases, Q (cardiac output) increases, but as the venous arteries are more compliant, they dilate and change shape easily. Also increases perfusion of hypoperfused beds-so more blood comes up to the apex-actually allows minimal map change, therefore no leakage of fluid to pressure and np oedema

Question 12

12. Describe the perfusion across the lungs at rest when standing up.

Answer 12

Top of lung/apex has much lower perfusion due to gravity. As cardiac output increases, the more the apex of the lung receives blood

Question 13

13. Describe and explain the effects of increasing ventilation on pulmonary resistance.

Answer 13

Aleveolar and non aleveolar capillaries are different. As alveolar breathes air, squish the capillary. As the Thorax gets smaller, pinches down on the non alveolar. So both when breathing in real deep (FLC) and being empty (RV), the resistance is maximal. In between its low

Question 14

14. How do the systemic and pulmonary circulation differ in their response to hypoxia?

Answer 14

Systemic vascular is vasodilation-why hands flush pink after constrict
Pulmonary vasoconstrict-why? To maintain perfusion/ventilation-if oxygen isn’t coming there, then don’t send blood.
This is done with K+, not Ca2+ as usually
But when breathing hypoxic air, reaction is all overlung and that’s bad

Question 15

15. What channel is response for this response to hypoxia?

Answer 15

O2 sensitive K+ channels

Question 16

16. Give an example of a situation in which the response of the pulmonary circulation to hypoxia is USEFUL.

Answer 16

If one part of lung isn’t ventilating well-very efficient

Question 17

17. Give an example of a situation in which the response of the pulmonary circulation to hypoxia is DETRIMENTAL.

Answer 17

Hypoxic air (altitude), COPD

Question 18

18. Describe the factors that impact fluid movement in lungs

Answer 18

Jv-determined a lot by difference between hydrostatic pressure in intertisium and in capillary. Other part is difference between oncotic pressure in and out (protein determined)
Hydrostatic pressure varies as you go down. Highest as it becomes capillary (as it loses SMC). Interstitial hydrostatic is nearly 0. Plasma oncotic is very high-proteins in blood are common but not in interstitial-sucks into blood. Interstitial oncotic nearly balances with the other molecules in by taking fluid in-but net oncotic is going to vessel
So overall well balance between hydrostatic and oncotic-only about 1mmHg comes out, and that’s taken in by lymph vessels easy. When it fails –and it overflows-odema

Question 19

19. State three causes of pulmonary oedema.

Answer 19

Mitrial stenosis-pressure backup from left atrium-plasma hydrostatic increases a lot and overwhelms rest-if surpass lymph capacity-oedema
Liver failure-plasma proteins would drop, causing the oncotic pressure to drop-less fluid back into plasma-again oedema
Metastatic breast cancer-as the cells block up the lymph nodes-no drainage for the very little ultrafiltration and will accumulate overtime causing oedema