Last update:

Bronchioles of the Lungs

From the tertiary bronchi, air is conducted to and from the alveoli (or air sacs) by a series of small, branching tubules called image descriptionbronchioles

Zoom in image of lobular bronchiole
Branching bronchioles of the lungs
1
2
  • The bronchioles branch many times on their way to the alveoli, and each division produces tubules that are progressively smaller in diameter (magnified here for display).
  • A image descriptionlobular bronchiole (or preterminal bronchiole), conducts air in and out of a pulmonary lobule (or secondary pulmonary lobule).

Want to ace respiratory system anatomy? Look no further than these interactive, exam-style anatomy quizzes and worksheets.

Zoom in image of lobular bronchiole
Lobular bronchioles of the lungs
1
2
  • After entering a pulmonary lobule, a lobular bronchiole divides into three or more image descriptionterminal bronchioles.
Zoom-in of the pulmonary lobule
The terminal bronchioles are labeled and highlighted
Swipe to show/ hide labels
1
2
  • Terminal bronchioles measure 0.5 – 1 mm (or less) in diameter and have walls made of simple ciliated cuboidal cells, a few smooth muscle cells, and connective tissue. They are too thick for air exchange, so these tubes are considered to be the last of the conducting zone structures.
  • Two or three image descriptionrespiratory bronchioles typically branch from each terminal bronchiole. These thin-walled tubules are the first respiratory zone structures, and they, in turn, give rise to alveolar ducts, alveoli, and alveolar sacs.
Zoom-in of the pulmonary lobule
The respiratory bronchioles are labeled and highlighted
Swipe to show/ hide labels
1
2

An Overview of the Bronchioles of the Lungs:

Expanded view: image descriptionShow/image descriptionHide answers

Zoomed view: image descriptionShow/image descriptionHide answers

Zoom in of pulmonary lobule with answers shown
Zoom in of pulmonary lobule with answers hidden
Zoom in of pulmonary lobule with answers shown
Swipe to show/ hide answers and navigate between views
1
2
3
4
Related Articles
Zoom-in and highlighted in green of the seconcary pulmonary lobules
Secondary Pulmonary Lobules of the Lungs

Walls of connective tissue (or septa) partitioned the bronchopulmonary segments into many polygonal-shaped secondary pulmonary lobules. A secondary pulmonary lobule typically contains 3-5 terminal bronchioles.
A figure demonstrating the respiratory system including alveoli, lungs, trachea and sagittal view of the mouth.
Respiratory System Anatomy – Major Zones & Divisions

The respiratory is separated into the conducting zone and the respiratory zone.
The conducting zone include structures that facilitate air to move in and out of the lungs.
The respiratory zone allow inhaled oxygen to diffuse into the lung capillaries in exchange for carbon dioxide.
Zoom-in image of respiratory membrane
Respiratory Membrane and Gas Exchange

An interactive demonstration of the structure of the respiratory membrane and the mechanism of gas exchange occurring in the lungs.