Term
| what is the difference in pressures between the systemic and pulmonary systems and what contributes to this difference? |
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Definition
the pulmonary system is a low pressure (25/10)
whereas the systemic system is high pressure (120/80)
the pulmonary has short and large diameter vessels as opposed to the systemic system which has long and narrow vessels |
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Term
| true or false, the lungs can serve as a reservoir for blood holding about 0.5L of blood? how is this determined? |
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Definition
| true, the pulmonary artery can be occluded and the aortic pressure is not affected for several beats |
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Term
| what pattern does the pulmonary artery pressure resemble? |
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Definition
| the aortic pressure (but much lower pressure) |
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Term
| define alveolar and extra-alveolar vessels. |
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Definition
alveolar vessels surround the alveoli
and extra-alveolar vessels run through the stroma of the lung |
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Term
| what forces affect pulmonary circulation? |
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Definition
| gravity, alveolar pressure, perfusion pressure, and lung volume |
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Term
| what affect does alveolar pressure have on pulmonary circulation? |
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Definition
| as the alveolar pressure increases the alveolar vessel can become impinged reducing flow through that alveoli |
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Term
| what affect does lung volume have on pulmonary circulation? |
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Definition
| lung volume controls how many extra-alveolar vessels are open and therefore affects flow |
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Term
| what are the functions of the lung? |
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Definition
| gas exchange, blood reservoir, blood filtration, metabolism, and defense |
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Term
| what are the three parts of gas exchange? |
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Definition
| ventilation, diffusion, perfusion |
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Term
| how does the lung serve as a blood filter? |
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Definition
| it can trap tiny particles from entering the coronary and cerebral circulations, and due to the large degree of collateralization it is hardly affected |
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Term
| what is the metabolic function of the lung? |
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Definition
| the pulmonary endothelial cells produce ACE which is important in the breakdown of bradykinin |
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Term
| what immune functions do the lungs perform? |
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Definition
| the lungs produce Ig's, store WBC's, and sequester platelets |
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Term
| what affect does pulmonary artery pressure have on pulmonary circulation, how does it occur, and how is it different from the systemic circulation? |
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Definition
as pressure increases the vascular resistance decreases in order to increase flow, this is achieved through the recruitment and distention of vessels.
in the systemic circulation increased pressure results in vasoconstriction and a decrease in flow |
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Term
| what are the critical opening / closing pressures? |
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Definition
| the pressure required to open new vessels in the pulmonary circulation, and below that pressure would cause closing of the vessels |
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Term
| compare the vascular resistance of a deflated vs inflated lung? |
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Definition
| resistance in a deflated lung is higher than in the inflated lung because you must inflate alveolar and extra-alveolar vessels in order to perfuse the lung, past a certain amount of inflation however the alveolar pressure impinges on the vessels and increases resistance |
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Term
| describe the role of gravity on pulmonary circulation. |
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Definition
| the pulmonary arteries enter the lungs at the sternal angle, below this flow is increased because of hydrostatic forces caused by gravity, but above this flow is reduced due to negative hydrostatic forces as well as potential collapse of the lung tissue |
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Term
| describe the regional differences in pulmonary blood flow. |
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Definition
| at the bottom of the lung you have high vascular pressure and distended vessels so alveolar pressure is not an issue, whereas at the top of the lung you have low vascular pressure and less distention in which alveolar pressure can be an issue. The middle is somewhere in between. |
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Term
| describe the chemical control of pulmonary circulation. |
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Definition
| alveolar O2 pressure controls blood flow, a decrease in O2 levels causes vasoconstriction to limit flow to areas that have higher O2 content |
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Term
| what affect does high altitude have on pulmonary circulation? |
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Definition
| due to low O2 content you get global vasoconstriction throughout the lung, this raises pulmonary arterial pressure in order to utilize more of the lung tissue |
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Term
| what are the six structures found in fetal circulation that are not found in the adult and where are they located? |
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Definition
2 umbilical arteries - branching off descending aorta to placenta
umbilical vein - branches off IVC to placenta
ductus venosus - runs from umbilical vein to IVC
foramen ovale - hole between atria
ductus arteriosus - runs from aorta to pulmonary trunk |
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Term
| what causes the closure of the foramen ovale, ductus arteriosus, and ductus venosus? |
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Definition
| a change in blood pressure from the venous to arterial circulation, the RA to LA, and from the pulmonary artery to the aorta |
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