Tracheobronchial Tree: Difference between revisions
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== Introduction == | == Introduction == | ||
[[File:Tracheobronchial tree.jpeg|thumb|<small>1: Trachea</small><small>2: Mainstem bronchus</small> | [[File:Tracheobronchial tree.jpeg|thumb|The lower respiratory tract <small>1: Trachea</small> | ||
<small>2: Mainstem bronchus</small> | |||
<small>3: Lobar bronchus</small> | <small>3: Lobar bronchus</small> | ||
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<small>4: Segmental bronchus</small> | <small>4: Segmental bronchus</small> | ||
<small>5: Bronchiole, | <small>5: Bronchiole,</small> | ||
<small>Alveolar duct , 7:Alveolus</small> <ref>https://en.wikipedia.org/wiki/Respiratory_tract </ref>|alt=|300x300px]] | <small>6:</small> <small>Alveolar duct ,</small> | ||
<small>7:Alveolus</small> <ref>https://en.wikipedia.org/wiki/Respiratory_tract </ref>|alt=|300x300px]] | |||
The tracheobronchial tree is a branching tree of airways composed of: | The tracheobronchial tree is a branching tree of airways composed of: | ||
* the trachea | * the trachea | ||
* the bronchi | * the bronchi | ||
* the bronchioles | * the bronchioles.<ref name=":0">[https://www.ncbi.nlm.nih.gov/books/NBK556044/ Downey] RP, Samra NS. [https://www.ncbi.nlm.nih.gov/books/NBK556044/ Anatomy, Thorax, Tracheobronchial Tree]. InStatPearls [Internet] 2020 Jul 31. StatPearls Publishing.</ref> | ||
Its main function is the transfer of air from the environment to the lungs for gas exchange. | |||
The tracheobronchial tree has a branching structure of approximately 23 branches or generations extending from the trachea (generation 0) to the last order of terminal bronchioles (generation 23).<ref>Gauthier SP, Wolfson MR, Deoras KS, Shaffer TH. [https://www.nature.com/articles/pr199230.pdf?origin=ppub Structure-function of airway generations 0 to 4 in the preterm lamb.] Pediatric research. 1992 Feb;31(2):157-62.</ref><ref>Patwa A, Shah A. [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4613399/#:~:text=The%20terminal%20bronchioles%20(generation%2016,are%20completely%20lined%20with%20alveoli. Anatomy and physiology of respiratory system relevant to anaesthesia. Indian journal of anaesthesia]. 2015 Sep;59(9):533.</ref> | |||
<u>Conducting zones</u> : | <u>Conducting zones</u> : | ||
{| class="wikitable" | {| class="wikitable" | ||
!'''Generations''' | !'''Generations''' | ||
! | ! | ||
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|<small>Lobar bronchus</small> | |<small>Lobar bronchus</small> | ||
|- | |- | ||
|3 | |3<sup>rd</sup> | ||
|<small>Segmental bronchus</small> | |<small>Segmental bronchus</small> | ||
|- | |- | ||
Line 60: | Line 61: | ||
|20-23 | |20-23 | ||
|<small>Alveolar ducts , alveoli</small> | |<small>Alveolar ducts , alveoli</small> | ||
|} | |} | ||
== Trachea == | == Trachea == | ||
The main functions of the trachea comprise air flow into the lungs, mucociliary clearance. | [[File:Anatomy of trachea.png|thumb|321x321px|alt=|border]]The main functions of the trachea comprise air flow into the lungs, mucociliary clearance. The trachea is a C-shaped structure, flexible tube that is composed of '''hyaline cartilage on the anterior and lateral walls.''' Also contains of the trachealis smooth muscle forming the posterior wall of the trachea .Also the trachea is composed of several primary structural annular ligament.<ref name=":1">Mieczkowski B, Seavey BF. [https://www.ncbi.nlm.nih.gov/books/NBK448070/ Anatomy, Head and Neck, Trachea.]</ref> Posterior surface of the trachea is flat where its cartilaginous rings are incomplete (anatomy book ) | ||
# The trachea descends from the larynx into the lung.<ref name=":0" /> | |||
# | |||
# The trachea is tube 10-12 cm. | # The trachea is tube 10-12 cm. | ||
# Is situated anterior to the oesophagus. (biblio) | # Is situated anterior to the oesophagus. (biblio) | ||
# .Extends from cricoid cartilage (c6 level) by cricothyroid membrane to carina (level of sternal angle ). At the level of carina the trachea bifurcates into the right and left m<nowiki/>ain bronchi. | # .Extends from cricoid cartilage (c6 level) by cricothyroid membrane to carina (level of sternal angle ). At the level of carina the trachea bifurcates into the right and left m<nowiki/>ain bronchi.<ref name=":0" /><ref name=":1" /> | ||
Inner mucosal layer made of ciliated pseudostratified columnar epithelium with goblet cells. Goblet cells produce mucus that traps airborne particles and microorganisms, and the cilia propel the mucus upward, where it is either swallowed or expelled. | <code>Inner mucosal layer made of ciliated pseudostratified columnar epithelium with goblet cells. Goblet cells produce mucus that traps airborne particles and microorganisms, and the cilia propel the mucus upward, where it is either swallowed or expelled.</code> | ||
===== '''Hyaline cartilage''' ===== | ===== '''Hyaline cartilage''' ===== | ||
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* Type of muscle = Smooth muscle | * Type of muscle = Smooth muscle | ||
* Connects the ends of the C-shaped tracheal cartilages. | * Connects the ends of the C-shaped tracheal cartilages. | ||
* Is in contact with the anterior esophagus[[File:Cross section trachea.png|thumb| | * Is in contact with the anterior esophagus[[File:Cross section trachea.png|thumb|400x400px|alt=]]The trachealis muscle functions to constrict the airway by pulling the cartilages together, decrease the diameter , allowing for increased expiratory force during coughing with the smaller aperture allowing greater velocity to be achieved and the particle to be expelled. http://education.med.nyu.edu/Histology/courseware/modules/respiratory-sy/respiratory.07.html. This action is helpful, especially when eating food, which requires the expansion of the esophagus. | ||
==== Bronchi ==== | ==== Bronchi ==== | ||
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=== Bronchioles === | === Bronchioles === | ||
[[File:Healthy alveoli Primal.png|thumb]] | [[File:Healthy alveoli Primal.png|thumb]] | ||
Bronchioles arise from segmental bronchi and represent the smaller branches of the bronchial tree. | Bronchioles arise from segmental bronchi and represent the smaller branches of the bronchial tree. They differ histologically from bronchi as they lack C shaped cartilages in their walls. | ||
Bronchioles | Bronchioles initially divide into many generations of '''conducting bronchioles''' which eventually divide further into '''terminal bronchioles''' which further divide into r'''espiratory bronchioles'''. | ||
* '''Conducting bronchioles ( part of conducting zone)''' | |||
** segmental bronchi give rise to 20 to 25 generations of conducting bronchioles that further divide to terminal bronchioles. | |||
** function - as part of the conducting system they allow air to travel from the trachea to alveoli where gas exchange occurs. | |||
* '''Terminal bronchioles (part of conducting zone)''' | |||
** represent the last part of the conducting part of the bronchial tree and give rise to several generations of respiratory bronchiole | |||
** function - as part of the conducting system they allow air to travel from the trachea to alveoli where gas exchange occurs. | |||
* '''Respiratory bronchioles ( part of respiratory zone)''' | |||
** distinguishable to other types of bronchioles by the presence of alveoli) extending from their lumens | |||
** function - represent the first part of the respiratory airways where they facilitate gas exchange | |||
This exchange occurs in the respiratory bronchioles, alveolar ducts and alveoli, which collectively form the respiratory zones deep in the lungs. | |||
{| class="wikitable" | |||
|+ | |||
!'''Generations''' | |||
! | |||
|- | |||
|''Conducting zones'' | |||
| | |||
|- | |||
|0 | |||
|<small>Trachea</small> | |||
|- | |||
|1 | |||
|<small>Primary bronchus</small> | |||
|- | |||
|2 | |||
|<small>Lobar bronchus</small> | |||
|- | |||
|3<sup>rd</sup> | |||
|<small>Segmental bronchus</small> | |||
|- | |||
|4, 5, 6 | |||
|<small>Subsegmental bronchus</small> | |||
|- | |||
|16 | |||
|<small>Terminal bronchioles</small> | |||
|- | |||
|''Respiratory zones'' | |||
| | |||
|- | |||
|17- 19 | |||
|<small>Respiratory bronchioles</small> | |||
|- | |||
|20-23 | |||
|<small>Alveolar ducts , alveoli</small> | |||
|} | |||
Revision as of 17:13, 22 April 2022
Original Editor - User Name
Top Contributors - Stella Constantinides and Kim Jackson
Introduction[edit | edit source]
The tracheobronchial tree is a branching tree of airways composed of:
- the trachea
- the bronchi
- the bronchioles.[2]
Its main function is the transfer of air from the environment to the lungs for gas exchange.
The tracheobronchial tree has a branching structure of approximately 23 branches or generations extending from the trachea (generation 0) to the last order of terminal bronchioles (generation 23).[3][4]
Conducting zones :
Generations | |
---|---|
Conducting zones | |
0 | Trachea |
1 | Primary bronchus |
2 | Lobar bronchus |
3rd | Segmental bronchus |
4, 5, 6 | Subsegmental bronchus |
16 | Terminal bronchioles |
Respiratory zones | |
17- 19 | Respiratory bronchioles |
20-23 | Alveolar ducts , alveoli |
Trachea[edit | edit source]
The main functions of the trachea comprise air flow into the lungs, mucociliary clearance. The trachea is a C-shaped structure, flexible tube that is composed of hyaline cartilage on the anterior and lateral walls. Also contains of the trachealis smooth muscle forming the posterior wall of the trachea .Also the trachea is composed of several primary structural annular ligament.[5] Posterior surface of the trachea is flat where its cartilaginous rings are incomplete (anatomy book )
- The trachea descends from the larynx into the lung.[2]
- The trachea is tube 10-12 cm.
- Is situated anterior to the oesophagus. (biblio)
- .Extends from cricoid cartilage (c6 level) by cricothyroid membrane to carina (level of sternal angle ). At the level of carina the trachea bifurcates into the right and left main bronchi.[2][5]
Inner mucosal layer made of ciliated pseudostratified columnar epithelium with goblet cells. Goblet cells produce mucus that traps airborne particles and microorganisms, and the cilia propel the mucus upward, where it is either swallowed or expelled.
Hyaline cartilage[edit | edit source]
- Series of 16 to 20 hyaline cartilage rings one top the other each is individually connected by an annular ligament.
- The tracheal cartilaginous rings, are responsible for keeping the trachea lumen open in spite of the changes in intrathoracic pressure that occur during respiration, and hence prevent air flow limitation.
Trachealis muscle[edit | edit source]
- Type of muscle = Smooth muscle
- Connects the ends of the C-shaped tracheal cartilages.
- Is in contact with the anterior esophagusThe trachealis muscle functions to constrict the airway by pulling the cartilages together, decrease the diameter , allowing for increased expiratory force during coughing with the smaller aperture allowing greater velocity to be achieved and the particle to be expelled. http://education.med.nyu.edu/Histology/courseware/modules/respiratory-sy/respiratory.07.html. This action is helpful, especially when eating food, which requires the expansion of the esophagus.
Bronchi[edit | edit source]
At the level of the fifth thoracic vertebra, the trachea divides into the left and right main bronchi. The right main bronchus has a length of 2.5 cm, and the left main bronchus is 5 cm long. https://www.sciencedirect.com/topics/medicine-and-dentistry/trachealis-
The trachea divides at the carina (at the level of the sternal angle) to give rise to the two primary bronchi – the right and left bronchus (figure X). Differences between right and left bronchus are illustrated below in table X .The right and left bronchus conduct air from the trachea into the right and left lung respectively.
The primary bronchi then branch into secondary bronchi (lobar bronchi) – three on the right and two on the left. Each secondary bronchus supplies a lobe of the lung.
Each secondary bronchi (lobar bronchi) subsequently divide into narrower tertiary bronchi (segmental bronchi) that supply bronchopulmonary segments (largest subdivisions of a lobe).
Segmental bronchi undergo further branching to form numerous smaller airways, called the bronchioles, .
Right Bronchus | Left Bronchus |
- Wider
- More vertical - Shorter (2-3cm) - Supported by C shaped cartilages - 20 to 30 degree angle |
- Narrower
- More angular - Longer (5cm) - Supported by C shaped cartilages - 40 to 60 degree angle |
Bronchioles[edit | edit source]
Bronchioles arise from segmental bronchi and represent the smaller branches of the bronchial tree. They differ histologically from bronchi as they lack C shaped cartilages in their walls.
Bronchioles initially divide into many generations of conducting bronchioles which eventually divide further into terminal bronchioles which further divide into respiratory bronchioles.
- Conducting bronchioles ( part of conducting zone)
- segmental bronchi give rise to 20 to 25 generations of conducting bronchioles that further divide to terminal bronchioles.
- function - as part of the conducting system they allow air to travel from the trachea to alveoli where gas exchange occurs.
- Terminal bronchioles (part of conducting zone)
- represent the last part of the conducting part of the bronchial tree and give rise to several generations of respiratory bronchiole
- function - as part of the conducting system they allow air to travel from the trachea to alveoli where gas exchange occurs.
- Respiratory bronchioles ( part of respiratory zone)
- distinguishable to other types of bronchioles by the presence of alveoli) extending from their lumens
- function - represent the first part of the respiratory airways where they facilitate gas exchange
This exchange occurs in the respiratory bronchioles, alveolar ducts and alveoli, which collectively form the respiratory zones deep in the lungs.
Generations | |
---|---|
Conducting zones | |
0 | Trachea |
1 | Primary bronchus |
2 | Lobar bronchus |
3rd | Segmental bronchus |
4, 5, 6 | Subsegmental bronchus |
16 | Terminal bronchioles |
Respiratory zones | |
17- 19 | Respiratory bronchioles |
20-23 | Alveolar ducts , alveoli |
Resources
- bulleted list
- x
or
- numbered list
- x
References[edit | edit source]
- ↑ https://en.wikipedia.org/wiki/Respiratory_tract
- ↑ 2.0 2.1 2.2 Downey RP, Samra NS. Anatomy, Thorax, Tracheobronchial Tree. InStatPearls [Internet] 2020 Jul 31. StatPearls Publishing.
- ↑ Gauthier SP, Wolfson MR, Deoras KS, Shaffer TH. Structure-function of airway generations 0 to 4 in the preterm lamb. Pediatric research. 1992 Feb;31(2):157-62.
- ↑ Patwa A, Shah A. Anatomy and physiology of respiratory system relevant to anaesthesia. Indian journal of anaesthesia. 2015 Sep;59(9):533.
- ↑ 5.0 5.1 Mieczkowski B, Seavey BF. Anatomy, Head and Neck, Trachea.