Respiratory System/Pulmonary Surfactant

What does the Respiratory System include?

• Trachea

• Right and left bronchi

• Bronchioles

• Lungs

• Respiratory muscles of the thorax & abdomen

Alveoli

Clusters of thin-walled, grape-like sacs at the terminal bronchioles.

Alveoli are the site for….

gas exchange in the respiratory system.

Gas exchange

The process by which respiratory gases (O2 and CO2) move via diffusion across a surface

Alveoli 🔁 Pulmonary Capillary

Type 1 alveolar cells

Thin, single layer of flattened cells that make up the alveolar wall

Type 2 alveolar cells

secrete pulmonary surfactant & surfactant facilitates lung expansion

has macrophages

Approximately how thick is the alveolar-capillary membrane?

0.5 μm

What are pulmonary surfactant composed of?

a complex mixture of lipids and proteins

What is Pulmonary Surfactant secreted by?

Type 2 alveolar cells

How does pulmonary surfactant affect water molecules?

oily & interrupts hydrogen bonds between water molecules

What does pulmonary surfactant decreases?

alveolar surface tension

Why does pulmonary surfactant decrease surface tension?

less interaction between water molecules

What is one benefit of pulmonary surfactant?

increase pulmonary compliance, reducing the work of inflating the lungs

What is the second benefit of pulmonary surfactant?

It reduces the lungs’ tendency to recoil, so they don’t collapse as readily