Pulmonary Blood Flow Flashcards
What are the two systems for blood flow to the lungs?
Pulmonary Circulation
Bronchial Circulation
Pulmonary circulation
Total output of the right ventricle
Goes to alveoli low-pressure, high flow circulation
What is the flow of pulmonary circulation?
Deoxygenated blood:
R. atrium –> R. ventricle –> alveolar capillaries (oxygenation) –> oxygenated blood flows to the l. heart
Bronchial circulation
Systemic circulation
L. atrium to l. ventricle to all tissues and organs
High pressure, low-flow circulation
~ 2% of left ventricular output
What does bronchial circulation supply?
Airways and other structures within lungs like branches of pulmonary arteries and veins
What are the two groups within pulmonary circulation?
Alveolar vessels
Extra-alveolar vessels
Alveolar vessels
Thin-walled capillaries in alveolar septa
Extra-alveolar vessels
Arteries, veins, arterioles, venules in bronchovascular bundle
Portal veins
Transport blood from capillaries to the left ventricle and also serve as a reservoir
How does muscle affect reactivity of pulmonary arteries?
Thick- pig, cattle
Intermediate- horse, llama
Thin -dogs and sheep
Thick muscles causing more contraction/ obstruction
Pulmonary Vascular resistance
PVR= (Ppa -Pla)/ Q
PPa- pulomnary arterial
Pla- left arterial pressure
Q- cardiac output
What are the factors influencing distribution of pulmonary blood with lung?
Gravity
Selective Vascularization
Selective vascularization
Dorsocaudal region is more vascularized in quadrupeds (blood flow not uniform)
Changes in vascular transmural pressure passively affect ___________
Vascular resistance
At residual volume, arteries are _______ but capillaries are _______
- Narrowed
- Distended
At TLC, capillaries are __________ but arteries are _______
- flattened
- distended
What is a potent constrictor of pulmonary arteries?
Alveolar hypoxia
blood flow shunted and less O2 coming in
The ____________ the tunica media the greater the _________ response to hypoxia
- thicker
- vasoconstrictive
increased pressure
Brisket disease (High Mountain Disease)
High-altitude pulmonary hypertension (HAPH)
Altitude over 6,500 ft
Generalized hypoxia leading to right side heart failure (edema)
Cor pulomale
When animals have generalized hypoxic vasoconstriction due to lung disease
Right side heart failure
Localized hypoxic vasoconstriction
Beneficial
In poorly ventilated alveoli it limits blood flow (good adaption to redistribute blood to well ventilated alveoli)
Normoxia
Dilator factors keep voltage-gated K channels open and pulmonary arterial smooth muscles don’t contract
Hypoxia
Voltage-gated K channels close favoring depolarization and Ca influx
Smooth muscle contraction
How does hypoxia keep muscle contracted?
K+ is trapped inside the cell
Cell remains positive and depolarized
