Peculiarities of Pulmonary vascular bed

 Human without lungs is impossible.They have two lungs with two source of blood supply. such as Pulmonary blood vessels & Bronchial blood vessels.Pulmonary and Bronchial arteries anastomose around the intrapulomnary bronchi and bronchioles. Pulmonary vascular bed is the main source of gaseous exchange.But the pulmonary vascular bed have some peculiar characteristic that quite different.

• Pulmonary Vessels have thinner and more compliant wall i.e  they are highly destensible.
• Shorter transient time ( 1 sec ) through the capillaries where the systemic is 2 sec.
• Shorter in length & larger in diameter
• Low resistance circuit ( 1/10th of systemic circuit)
• Low pressure circuit system (in the pulmonary artery the systolic,diastolic & mean pressure is about 25 ,8 ,15 mm of Hg respectively; The pulmonary capillary pressure is about 10 mm of Hg )
• Response in some conditions

                            

Traits	Pulmonary arteriole	Systemic
Hypoxia	vasoconstriction	Vasodilation
low PH	vasoconstriction	Vasodilation
Hypercapnia	vasoconstriction	Vasodilation