L28. Physiology - Gas Exchange I

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Questions and Answers

How does recruitment and distention of pulmonary vessels affect calculated pulmonary vascular resistance?

It leads to an immediate blockage of blood flow to the lungs.

It has no effect on resistance as resistance remains constant.

It decreases resistance due to the parallel arrangement of capillaries. (correct)

It increases resistance significantly due to greater vessel length.

What role does lung volume have on pulmonary vascular resistance?

Pulmonary resistance is unaltered by changes in lung volume.

Narrowing of capillaries occurs at increased alveolar pressure, affecting resistance. (correct)

Decreases resistance at low lung volumes only.

Increases resistance regardless of lung volume.

What occurs to extra alveolar vessels during inspiration?

They remain unchanged regardless of lung volume changes.

They constrict due to increased intrapleural pressure.

They initiate blood flow redistribution towards the alveoli.

They expand as intrapleural pressure becomes more negative. (correct)

How does gravity influence blood flow through the pulmonary circulation?

It can enhance blood flow to the lower regions of the lungs. Signup and view all the answers

What is the effect of high pulmonary vasculature pressures on capillaries?

They can cause damage leading to pulmonary edema. Signup and view all the answers

What characteristic distinguishes the blood carried by the pulmonary artery from that carried by systemic arteries?

Higher levels of carbon dioxide and lower levels of oxygen Signup and view all the answers

Which factor most directly influences pulmonary vascular resistance when cardiac output increases?

Distention of pulmonary vessels Signup and view all the answers

How does hypoxia influence pulmonary blood flow distribution?

By inducing hypoxic pulmonary vasoconstriction Signup and view all the answers

Which statement correctly describes the compliance of pulmonary blood vessels?

Pulmonary vessels have high compliance similar to systemic veins Signup and view all the answers

What role does the diaphragm play in pulmonary blood flow?

It generates negative pressure to facilitate air inspiration Signup and view all the answers

Which component primarily regulates pulmonary blood flow through vasoactive substances?

Presence of metabolic by-products and hormones Signup and view all the answers

Which mechanism is responsible for the decreasing resistance in pulmonary blood vessels during inhalation?

Recruitment of additional vessels Signup and view all the answers

How does lung volume affect pulmonary vascular resistance?

Increased lung volume generally lowers vascular resistance Signup and view all the answers

What distinguishes pulmonary veins from systemic veins in terms of blood composition?

Pulmonary veins transport blood with elevated oxygen levels and reduced carbon dioxide. Signup and view all the answers

Which characteristic is NOT true of pulmonary circulation compared to systemic circulation?

Pulmonary circulation has higher resistance. Signup and view all the answers

What percentage of cardiac output is received by bronchial circulation from the left heart?

2% Signup and view all the answers

From which arteries do bronchial arteries typically arise?

Branches of the aorta, intercostal, subclavian, or internal mammary arteries. Signup and view all the answers

How does bronchial circulation drain its venous blood?

Through the azygos, hemiazygos, and intercostal veins. Signup and view all the answers

Which function is NOT associated with the pulmonary blood flow?

Nutrient storage Signup and view all the answers

What is the role of the bronchopulmonary circulation?

To connect bronchial and pulmonary circulations. Signup and view all the answers

Which statement does NOT accurately describe pulmonary blood flow?

It exclusively performs respiratory functions. Signup and view all the answers

What happens to a portion of bronchial capillary blood?

It drains into anastomoses that empty into the pulmonary veins. Signup and view all the answers

What best describes the compliance of the pulmonary system compared to systemic circulation?

Higher compliance than systemic circulation. Signup and view all the answers

What effect does the first breath have on the alveoli and pulmonary blood flow?

Decreases resistance and increases blood flow Signup and view all the answers

Which type of nerve fibers innervate the pulmonary arteries and veins?

Cholinergic and adrenergic nerve fibers Signup and view all the answers

What is the relationship between pulmonary vascular resistance and blood flow or left atrial pressure?

Pulmonary vascular resistance decreases with increases in blood flow or left atrial pressure Signup and view all the answers

What underlying mechanism contributes to the decrease in pulmonary vascular resistance with increased blood flow?

Capillary recruitment and distension Signup and view all the answers

Which of the following statements is true regarding the innervation of pulmonary vessels across different species?

Innervation extent varies, particularly in pulmonary arteries Signup and view all the answers

How do humoral substances affect pulmonary vascular smooth muscle?

They can cause either contraction or relaxation, altering resistance Signup and view all the answers

What is one consequence of increased pulmonary blood flow?

Recruitment of collapsed capillaries for perfusion Signup and view all the answers

In the context of pulmonary vasculature, what role do vasoactive substances play?

They alter vascular resistance and consequently blood flow Signup and view all the answers

Which factor does NOT influence pulmonary blood flow?

Ambient temperature changes Signup and view all the answers

How does pulmonary arterial pressure respond to increases in blood flow?

Slightly increases in proportion to increased blood flow Signup and view all the answers

What role do pulmonary microvessels play in the filtration of blood?

They trap foreign materials to prevent systemic flow interruption. Signup and view all the answers

What potential consequences can result from emboli entering systemic circulation?

Occlusion of vascular beds leading to stroke or heart attack. Signup and view all the answers

How do trap foreign particles in pulmonary vessels affect gas exchange?

There is no effect on gas exchange due to the reserve capacity. Signup and view all the answers

What mechanism is involved in the removal of trapped emboli from pulmonary vessels?

Enzymatic processes and macrophage ingestion. Signup and view all the answers

What function does the pulmonary circulation serve during periods of increased left ventricular output?

Serving as a stable reservoir for the left ventricle. Signup and view all the answers

What is the relationship between pulmonary circulation and cardiac output?

Cardiac output can be rapidly increased by utilizing pulmonary blood volume. Signup and view all the answers

Which type of cells in the lung vasculature are primarily responsible for the metabolic conversion of circulating substances?

Endothelial cells lining the vessel lumen. Signup and view all the answers

What is a significant feature of pulmonary vessels that contributes to their function?

Greatest number of capillaries compared to other systems. Signup and view all the answers

Which of these describes the role of biologically active compounds released by lung vascular cells?

They act locally or can influence other organs. Signup and view all the answers

Which statement best reflects the relationship between systemic circulation and pulmonary emboli?

Pulmonary emboli can obstruct systemic vessels leading to serious complications. Signup and view all the answers

Study Notes

Pulmonary and Bronchial Circulation

Pulmonary circulation perfuses the alveoli for gas exchange, while bronchial circulation provides nutrients and gas exchange for conducting airways
Bronchial circulation is part of the systemic circulation, receives 2% of cardiac output from left heart
Bronchial arteries originate from branches of aorta, intercostal, subclavian, or internal mammary arteries
Bronchial arteries supply tracheobronchial tree with nutrients and oxygen
Blood pressure in bronchial circulation is similar to other systemic vascular beds
About a third of bronchial venous drainage is via azygos, hemiazygos, and intercostal veins
About 2/3 of bronchial capillary blood drains into anastomoses that empty into pulmonary veins
This connection between bronchial and pulmonary circulation is called the bronchopulmonary circulation
The bronchopulmonary circulation adds a small volume of poorly oxygenated bronchial venous blood to the freshly oxygenated blood in the pulmonary vein

Functions of Pulmonary Blood Flow

Pulmonary circulation facilitates gas exchange in the alveoli
Pulmonary circulation serves as a blood filter, capturing foreign material that could harm systemic vessels
Pulmonary circulation acts as a blood reservoir for the left ventricle, accommodating around 500 ml of blood
Pulmonary circulation metabolizes circulating substances, particularly through endothelial cells lining the vessels' lumen

Factors that Regulate Pulmonary Blood Flow

Hypoxia: Low oxygen levels lead to vasoconstriction, redirecting blood flow to better ventilated areas
Motor Innervation: Pulmonary veins and arteries have cholinergic and adrenergic innervation, influencing vascular tone
Vasoactive Substances: Humoral substances in the circulation or produced by lung endothelial cells can cause vasoconstriction or dilation, affecting pulmonary vascular resistance
Recruitment and Distention: Increased blood flow or left atrial pressure leads to capillary recruitment and distention, decreasing pulmonary vascular resistance
Hematocrit: High hematocrit can increase pulmonary vascular resistance
Lung Volume: Pulmonary vascular resistance is lowest at Functional Residual Capacity (FRC) and increases at both high and low lung volumes
Gravity: Gravity impacts blood flow distribution, with blood flow being higher at the base of the lungs due to gravitational force

Pulmonary Blood Flow Changes with Lung Volume

Alveolar Vessels: Compressed during inspiration, increasing resistance to blood flow
Extra-Alveolar Vessels: Dilate during inspiration due to decreasing intrathoracic pressure, reducing resistance to blood flow

Hypoxic Pulmonary Vasoconstriction

Hypoxia causes vasoconstriction in poorly ventilated areas, diverting blood flow to better ventilated areas
This mechanism optimizes gas exchange by ensuring that blood flows to areas where oxygen uptake is most efficient

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Description

This quiz covers the essential aspects of pulmonary and bronchial circulation, focusing on their roles in gas exchange and nutrient supply. It explains how the bronchial circulation connects to systemic circulation and its significance in the respiratory system. Test your knowledge on the vascular structures and functions involved in these processes.