Pulmonary Circulation

Question 1

GR: Brinchial venous blood contrinutes to physiological sjunt

Answer 1

Because the bronchial venous blood is not drained into systemic veins but into pulmonary veins.

Question 2

GR: Resistance in pulmonary circulation is far less than systemic

Answer 2

It is shorter wider and its arterioles normally have little smooth muscle so offer less resistance than systemic circulation.

Question 3

In pulmonary circulation, precapillary is ….. postcapillary resistance.

Answer 3

Equal to

Question 4

GR: Pulmonary circulation is low pressure system

Answer 4

1. Increased capillary distension
2. Recruitment (open of new capillaries)
   This is imp to prevent pulmonary edema by high pressure.

Question 5

In upright position, Pulmonary pressure is …. At hilum, …..at base, …..at apex.

Answer 5

15 mmHg
25 mmHg
5 mmHg

Question 6

Mention sites of mixture of venous with arterial blood

Answer 6

Bronchial circulation where some bronchial veins drain into pulmonary veins
Coronary circulation , some coronaries drain directly into left ventricle

Question 7

V/Q ratio is …., can be measured regionally by …..

Answer 7

0.8
Radioactive Xenon (Xe)

Question 8

Define transient time

Answer 8

It the time taken by a RBC to travel through pulmoanry circulation, 0.75 at rest, 0.3 sec during exercise.

Question 9

GR: O2 lack produces VC in pulmonary circulation

Answer 9

To prevent hypoxia, and shift blood to non-hypoxic areas.

Question 10

Mention reflexes taht have pulmonary afferents

Answer 10

Bainbridge reflex, BezoldJarisch refLex, baroreceptor reflex

Question 11

Describe effects of hypoxia on pulmonary circulation

Answer 11

If part of lung suffers hypoxia it is VC to divert blood to oxygenated alveoli, later this causes Cor-pulmonale which is heart disease due to lung disease. Hypoxia of diseased lung tissue causes VC of pulmonary blood vessels, leading to pulmonary HTN causes right vent hypertrophy then rt vent failure.

Question 12

Describe effects of respiration on pulmonary circulation

Answer 12

Inspiration dec VR with more pulmoanry vein distension

Expiration inc VR with constriction of pulomary vessels

Question 13

Mention causes of pulmonary edema

Answer 13

Increased capillary pressure by rise of atrial venous pressure
Increased capillary permeability by toxicity or infections

Question 14

GR: In mitral stenosis pulmonary edema is late

Answer 14

Because precapillary resistance inc with gradual rise in left atrial pressure, so there is no increase in capillary pressure and no edema.