31 Questions
In which zone of the lung does no blood flow occur?
Zone 1
What is the defining characteristic of Zone 1 in terms of blood flow?
Alveolar dead space
Which pressure is always greater in the pulmonary circulation in relation to pulmonary venous pressure?
Pulmonary arterial pressure (Pa)
Under what conditions can Zone 1 occur?
+Pressure ventilation
What effect does high alveolar pressures have on pulmonary blood flow?
Increase fluid in alveoli
In which lung zone is there continuous blood flow?
Zone 3
What percentage of Cardiac Output does the Bronchial Circulation account for?
2%
Where is the alveolar pressure highest compared to arterial pressure, resulting in no forward blood flow?
Zone 1
Why might new vessels branch from the bronchial veins?
To create collateral circulation for gas exchange airways
During exercise and when recumbent, which lung zone exhibits recruitment due to gravity?
Zone 3
What is the average diameter of pulmonary capillaries?
6 um
Where is pulmonary capillary wedge pressure (PCWP) typically measured within the lung?
Zone 3
How long does a red blood cell (RBC) take to travel through the pulmonary capillaries at resting Cardiac Output?
4-5 seconds
Which lung zone maintains a matching balance between pulmonary blood flow and ventilation under normal conditions?
Zone 3
What is the primary function of Pulmonary Circulation?
Gas exchange
How many functional pulmonary capillaries are there that supply 300 million alveoli in the lungs?
280 billion
What causes compression or collapse of vessels due to negative transmural pressure differences?
Intrapleural pressure
Why is pulmonary vascular resistance (PVR) usually 1/10 systemic vascular resistance (SVR)?
Passive factors determining PVR
At high lung volumes, what happens to the resistance of alveolar vessels?
Resistance increases due to vessel compression
What is the relationship between lung volume and extra-alveolar vessel resistance?
Increases at high lung volumes
How does the location of alveolar vessels affect their resistance?
Location affects resistance, with resistances being additive
What happens to pulmonary vascular resistance (PVR) during exercise with increased cardiac output?
PVR decreases due to distention and recruitment
What causes the decrease in pulmonary vascular resistance (PVR) with increased pulmonary blood flow?
Distention and recruitment of vessels
In the lungs, where does pulmonary edema typically first occur according to Starling's forces?
Base of the lung
Why does hypoxic pulmonary vasoconstriction (HPV) occur?
In response to alveolar hypoxia or hypercapnia
How does gravity affect blood flow in the lungs?
"Leads to more blood flow in lower regions"
How does HPV help mitigate shunt in the lungs?
By diverting blood away from poorly ventilated alveoli
What happens to arterioles supplying hypoxic alveoli during HPV?
They constrict
How do anesthetic gases affect the HPV response?
Completely stop the HPV response
What is the role of O2-sensitive voltage-gated K+ channels in HPV?
Depolarize smooth muscle cells causing contraction
What is the main purpose of hypoxic pulmonary vasoconstriction (HPV)?
To redistribute blood away from poorly ventilated alveoli
Test your knowledge about bronchopulmonary anastomoses, including their occurrence between bronchial and pulmonary circulation, the entry of bronchial venous blood into pulmonary veins, and more.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
