Pulmonary Blood Flow Flashcards
(24 cards)
What physiological factors induce pulmonary vessel pressure drop?
Recruitment of more capillaries
Distention of capillaries to allow more flow
Expansion of the lung
What are some disease states that change the pressures of pulmonary capillaries?
CHF, mitral stenosis
What drugs induce pulmonary vessel pressure decrease?
Acetylcholine, isoproterenol, prostacyclin
What physiological influences cause increase in pulmonary vessel pressure?
Alveolar pressure increase
Hypoxia induced vasoconstriction
What chemicals promote vasoconstriction in pulmonary vessels?
Histamine, Norepinephrine, serotonin
Which COX product inhibits platelet aggregation?
Prostacyclin
What is the extremly undesirable side effect of selective COX2 inhibitors?
Hypercoagulability from decreased prostacyclin synthesis, resulting in higher risk for MI
How can you calculate pulmonary blood flow with only knowing the oxygen concentrations in veins and arteries as well as consumption rate?
Fick principle
Q=VO2/([O2]a-[O2]v)
What does zone one represent in terms of pulmonary blood flow distribution?
PA>Pa>Pv, means that alveolar pressure is collapsing both veins and arteries in the area
What does zone 2 represent in the pulmonary blood flow distribution?
Pa>PA>Pv
Means that the flow is determined by pressure difference between alveoli and arteries.
What does zone 3 represent in the pulmonary blood flow distribution?
Pa>Pv>PA
Normal situation in circulatory system, means that flow is determined by arterial and venous pressure differential
What would cause zone 1 to be present?
Not naturally present, only in disease states like hemorrhage or positive pressure breathing
Becomes physiological dead space
Where is zone 2 most representative?
Apical regions of the lung
Where is zone 3 representative of in the lung?
Midregions or base
What mechanism is thought to take place in hypoxia-induced vasoconstriction?
Closure of voltage gated K channels
leading to intracellular [Ca] increase
What would closure of VG K channels do to the membrane potential?
Hyperpolarize
What controls fluid movement in and out of the pulmonary vasculature?
Starling forces (Osmotic pressure and oncotic pressure)
Why must there be some flow out of the capillaries?
Lymph drainage is needed
What is the function of the lungs when we lie down?
They become a reservoir of blood as the blood goes from legs to lungs
How do lungs prevent stroke?
Venous emboli from legs cannot go to brain because they must first go through pulmonary bed
What are some metabolic responsibilities of the lung relating to ACE?
Converting ATI to ATII through ACE
Inactivating Bradykinin through ACE
What are the lungs’ responsibilities when it comes to serotonin?
Remove from system through accumulating it
What is the role of the lungs when it comes to PG and LT?
Metabolizes PGE1, PGE2, PGF2alpha
Synthesizes prostaglandins as well as some leukotrienes (bronchoconstrictors)
Removes some leukotrienes from systemic circ
What makes the lungs less likely to experience edema than any other circulation?
Low hydrostatic pressure
