Lung Compliance and Elastic Recoil Quiz

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Questions and Answers

What is the primary factor influencing the elastic recoil of the lungs?

Breathing rate

Airway pressure

Lung compliance

Alveolar surface tension (correct)

Which condition is likely to decrease lung compliance?

Asthma

Chronic bronchitis

Pulmonary fibrosis (correct)

Pneumonia

What does compliance refer to in the context of lung behavior?

The volume of air exchanged in a normal breath

The ability of the lungs to recoil after being stretched

The change in lung volume per unit change in airway pressure (correct)

The speed of airflow during expiration

What role do elastin fibers play in lung function?

Facilitate lung expansion and recoil Signup and view all the answers

How does the elastic behavior of the lungs occur during expiration?

The lungs recoil to their original position Signup and view all the answers

What is the primary function of the pulmonary alveoli?

Gas exchange Signup and view all the answers

Which type of cells in the alveoli are responsible for secreting surfactant?

Type II cells Signup and view all the answers

What is the primary role of surfactant in the alveoli?

Reducing surface tension Signup and view all the answers

How much of the inspired air volume typically remains in the respiratory tract during exhalation?

85% Signup and view all the answers

What kind of epithelium is primarily found in the pulmonary alveoli?

Simple squamous epithelium Signup and view all the answers

What is the composition of the 'air-blood' barrier found in the alveoli?

1 cell thick layer, basement membrane, and capillary endothelium Signup and view all the answers

What effect does surface tension have on the alveoli during breathing?

Increases the effort needed to breathe Signup and view all the answers

Which of the following best describes the condition of the alveoli without surfactant?

Difficult to expand and prone to collapse Signup and view all the answers

What is the primary role of pulmonary surfactant in the alveoli?

It reduces surface tension in the alveoli. Signup and view all the answers

Which of the following is a major component of pulmonary surfactant?

Dipalmitoyl phosphatidylcholine (DPPC) Signup and view all the answers

What benefit does pulmonary surfactant provide regarding lung mechanics?

Reduces the work of inflating the lungs. Signup and view all the answers

How does pulmonary surfactant help in stabilizing the alveoli?

By lowering the tendency of the lungs to collapse. Signup and view all the answers

Which proteins are included in the composition of pulmonary surfactant?

Surfactant proteins SP-A, SP-B, SP-C, and SP-D Signup and view all the answers

What effect do unsaturated phospholipids and cholesterol have on pulmonary surfactant?

They enhance the surfactant's fluidity. Signup and view all the answers

What percentage of pulmonary surfactant is composed of surfactant proteins?

10% Signup and view all the answers

What is one of the defense mechanisms provided by pulmonary surfactant?

Defense against infection and inflammation Signup and view all the answers

What is the primary structure responsible for the storage and secretion of pulmonary surfactant?

Lamellar bodies Signup and view all the answers

At what gestational age do lamellar bodies first appear in the cytoplasm?

20 weeks Signup and view all the answers

What is tubular myelin thought to function as in the alveolar space?

A reservoir of surfactant Signup and view all the answers

What is the estimated alveolar storage pool of surfactant in full-term infants?

100 mg/kg Signup and view all the answers

Which surfactant protein is particularly associated with the assembly of tubular myelin?

SP-A Signup and view all the answers

How is surfactant secreted into the alveolar lining fluid?

Exocytosis Signup and view all the answers

During which process do surfactant phospholipids form lattice-like arrays?

Tubular myelin formation Signup and view all the answers

What is the estimated amount of surfactant in preterm infants at birth?

4–5 mg/kg Signup and view all the answers

What role do collectins like SP-A and SP-D play in the body?

They confer innate immunity and promote phagocytosis. Signup and view all the answers

What is a key structural feature of SP-A?

It has a collagen domain fused to a lectin domain. Signup and view all the answers

What happens to infants born with a congenital absence of SP-B?

They experience intractable respiratory failure. Signup and view all the answers

Where does surfactant production primarily occur in the lungs?

In type II alveolar cells. Signup and view all the answers

Which surfactant proteins are known to be hydrophobic membrane proteins?

SP-B and SP-C. Signup and view all the answers

What is the main function of SP-B and SP-C in surfactant dynamics?

They enhance the spread of surfactant and its biophysical properties. Signup and view all the answers

What do lamellar bodies store in type II cells?

Lipid and protein components of surfactant. Signup and view all the answers

How do SP-B and SP-C traffic to the lamellar body during production?

They traffic through the Golgi and multivesicular body. Signup and view all the answers

What is the primary cause of respiratory distress syndrome (RDS) in newborn preterm babies?

Deficiency of surfactant Signup and view all the answers

How is most of the surfactant DPPC recycled back into the lungs?

By type II pneumocytes Signup and view all the answers

What is a key therapeutic strategy for managing the risk of preterm delivery?

Cortisol administration to the mother Signup and view all the answers

What happens to surface tension in the lungs in the absence of sufficient surfactant?

It increases, leading to lung collapse Signup and view all the answers

Which surfactant preparation is derived from cow lung?

Beractant Signup and view all the answers

What is the function of nitric oxide (NO) within the human body?

It serves as a signaling molecule Signup and view all the answers

What is unique about the pulmonary surfactant preparations?

They are composed of phospholipids and spreading agents Signup and view all the answers

Which delivery method is associated with a higher risk of respiratory distress syndrome in newborns?

Caesarian section Signup and view all the answers

Study Notes

Lung Surfactant

Surfactant is a mixture of lipids and proteins.
Surfactant is secreted by Type II pneumocytes.
Surfactant reduces surface tension in alveoli.
Prevention of alveolar collapse.
Improved respiratory function.
Important for maintaining open alveoli.

Elastic Behavior of the Lungs

The lungs' elastic behavior is due to elastic connective tissue and alveolar surface tension.
During inspiration, the lungs expand.
During expiration, the lungs recoil.
Compliance is the lung's stretchability, or the change in lung volume per unit change in airway pressure.
Low compliance indicates a stiff lung, unable to stretch easily.
Pulmonary fibrosis can reduce lung compliance.

Alveolar Cells

Type I pneumocytes cover most of the alveolar surface, involved in gas exchange.
Type II pneumocytes secrete surfactant.
Important for the efficient functioning of the lungs.
Alveolar cells comprise two main types.

Elastic Recoil

Elastic recoil is the speed of lung rebound to its typical shape after stretch.
Pulmonary elastic behavior is dependent on two components: connective tissues in the lungs, alveolar surface tension.

Pulmonary Elastic Connective Tissues

Connective tissue in the lungs contains a lot of elastin, fibers surrounding the alveoli.
This tissue is responsible for the expansion and elastic recoil of the lungs.
Elastic recoil is necessary for effective breathing.

Pulmonary Alveoli

Alveoli are the endpoint of the respiratory system.
Alveoli exchange oxygen and carbon dioxide.
Alveolar sac is made of alveoli structures.
Alveoli are responsible for the gas exchange.
Alveoli are characterized by the presence of a great deal of alveoli/lungs.

Surfactant

Surfactant is a substance that decreases surface tension.
Surfactant is a mixture of lipids and proteins.
Surfactant is produced, stored, and secreted by Type II alveolar cells.
Surfactant lowers surface tension inside alveoli to prevent collapse.
Surfactant helps keep alveoli open for effective gas exchange.
Surfactant is essential for normal lung function.

Surfactant and Alveolar Surface Tension

Alveoli are lined with fluid causing opposing forces.
The attractive forces between water molecules cause tension.
Surfactant lowers alveolar surface tension by working with water molecules that line the alveoli
It increases pulmonary compliance, lowering the effort needed for lung inflation.
It prevents lung collapse, maintaining the open structure of alveoli.

Functions of Surfactant

Surfactant reduces surface tension in alveoli, thus reducing the tendency of lungs to collapse after exhalation.
Surfactant stabilizes alveoli.
Provides defense against infection and inflammation via specific proteins.
Keeps lungs patent (open) and inflated after delivery after the first breath.
Surfactant increases pulmonary compliance, reducing the work of inflating the lungs.

Composition of Surfactant

Surfactant is a complex of phospholipids and proteins.
The major phospholipid is dipalmitoyl phosphatidylcholine (DPPC).
Other phospholipids and proteins form part of the structure.
Surfactant proteins (SP-A, SP-B, SP-C, SP-D) play crucial roles.
Neutral lipids, such as cholesterol, are also present.

Nitric Oxide

NO is a gas with no cellular storage mechanism.
NO is the lowest molecular weight human cell product.
NO is synthesized from arginine by the enzyme NO synthases.

NO in Lungs

All three isoforms of NO synthases (nNOS, eNOS, iNOS) are expressed in various lung cells.
NO regulates several functions in the lung, including antiviral, antibacterial, bronchodilatory, vasodialator, and anti-inflammatory effects.

NO Gas Inhalation

NO inhalation can be therapeutic.
Results in decreased pulmonary artery pressure and improved perfusion of ventilated lung parts.

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Description

Test your knowledge on lung compliance and the factors influencing elastic recoil in the lungs. This quiz covers key concepts such as conditions affecting lung function, the role of elastin fibers, and the behavior of the lungs during expiration.