The collective term “bronchial tree” refers to the bronchi and all of their subsequent branches. The bronchi are the airways of the lower respiratory tract. At the level of the 3rd or 4th thoracic vertebra, the trachea Trachea The trachea is a tubular structure that forms part of the lower respiratory tract. The trachea is continuous superiorly with the larynx and inferiorly becomes the bronchial tree within the lungs. The trachea consists of a support frame of semicircular, or C-shaped, rings made out of hyaline cartilage and reinforced by collagenous connective tissue. Trachea: Anatomy bifurcates into the left and right main bronchi. The right main bronchus is shorter and more vertical in direction than the left. Both of these bronchi continue to divide into secondary or lobar bronchi that bifurcate further and further in order to sufficiently spread the respiratory air completely into the left and right pulmonary lobes. The terminal segment of each bronchus contains millions of alveoli Alveoli Small polyhedral outpouchings along the walls of the alveolar sacs, alveolar ducts and terminal bronchioles through the walls of which gas exchange between alveolar air and pulmonary capillary blood takes place. Acute Respiratory Distress Syndrome (ARDS), the site of gas exchange Gas exchange Human cells are primarily reliant on aerobic metabolism. The respiratory system is involved in pulmonary ventilation and external respiration, while the circulatory system is responsible for transport and internal respiration. Pulmonary ventilation (breathing) represents movement of air into and out of the lungs. External respiration, or gas exchange, is represented by the O2 and CO2 exchange between the lungs and the blood. Gas Exchange.
Last updated: 9 Mar, 2022
The development of the tracheobronchial tree and lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy occurs in 5 stages. The tracheobronchial tree and lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy originate from the foregut Foregut Development of the Abdominal Organs of the embryonic gut tube, beginning at week 4 of gestation and ending in childhood.
Stage | Description | Clinical relevance |
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Embryonic period |
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Defects:
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Pseudoglandular period |
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Canalicular period |
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Saccular period |
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Infants born ≥ 32 weeks have a higher survival rate. |
Alveolar period |
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Embryonic development of the gut tube
Image by Lecturio. License: CC BY-NC-SA 4.0Development of the
lungs
Lungs
Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2.
Lungs: Anatomy:
The respiratory system begins development by week 4 of gestation. The olfactory pit forms from the
ectoderm
Ectoderm
The outer of the three germ layers of an embryo.
Gastrulation and Neurulation, one of the structures to become the
nasal cavity
Nasal cavity
The proximal portion of the respiratory passages on either side of the nasal septum. Nasal cavities, extending from the nares to the nasopharynx, are lined with ciliated nasal mucosa.
Nose and Nasal Cavity: Anatomy. The laryngotracheal bud forms from the primitive
pharynx
Pharynx
The pharynx is a component of the digestive system that lies posterior to the nasal cavity, oral cavity, and larynx. The pharynx can be divided into the oropharynx, nasopharynx, and laryngopharynx. Pharyngeal muscles play an integral role in vital processes such as breathing, swallowing, and speaking.
Pharynx: Anatomy. From this bud, the longitudinal
extension
Extension
Examination of the Upper Limbs becomes the tracheal and bronchial buds.
The process of
elongation
Elongation
Polymerase Chain Reaction (PCR) and branching of buds continues as conducting airways up to 16 weeks of gestation. Major maturation occurs by 24 weeks, with significant alveolar precursors developing and an increased amount of
surfactant
Surfactant
Substances and drugs that lower the surface tension of the mucoid layer lining the pulmonary alveoli.
Acute Respiratory Distress Syndrome (ARDS) produced. By 28 weeks of gestation, there usually will be enough mature
alveoli
Alveoli
Small polyhedral outpouchings along the walls of the alveolar sacs, alveolar ducts and terminal bronchioles through the walls of which gas exchange between alveolar air and pulmonary capillary blood takes place.
Acute Respiratory Distress Syndrome (ARDS).
The bronchial tree begins at the bifurcation of the trachea Trachea The trachea is a tubular structure that forms part of the lower respiratory tract. The trachea is continuous superiorly with the larynx and inferiorly becomes the bronchial tree within the lungs. The trachea consists of a support frame of semicircular, or C-shaped, rings made out of hyaline cartilage and reinforced by collagenous connective tissue. Trachea: Anatomy at the carina, approximately at the level of T5. The trachea Trachea The trachea is a tubular structure that forms part of the lower respiratory tract. The trachea is continuous superiorly with the larynx and inferiorly becomes the bronchial tree within the lungs. The trachea consists of a support frame of semicircular, or C-shaped, rings made out of hyaline cartilage and reinforced by collagenous connective tissue. Trachea: Anatomy bifurcates into the main left and right bronchi, These bronchi continue to branch until they form alveoli Alveoli Small polyhedral outpouchings along the walls of the alveolar sacs, alveolar ducts and terminal bronchioles through the walls of which gas exchange between alveolar air and pulmonary capillary blood takes place. Acute Respiratory Distress Syndrome (ARDS), the site of gas exchange Gas exchange Human cells are primarily reliant on aerobic metabolism. The respiratory system is involved in pulmonary ventilation and external respiration, while the circulatory system is responsible for transport and internal respiration. Pulmonary ventilation (breathing) represents movement of air into and out of the lungs. External respiration, or gas exchange, is represented by the O2 and CO2 exchange between the lungs and the blood. Gas Exchange. Each bronchial segment progressively becomes smaller in diameter and has a thinner wall.
Anterior view of the
larynx
Larynx
The larynx, also commonly called the voice box, is a cylindrical space located in the neck at the level of the C3-C6 vertebrae. The major structures forming the framework of the larynx are the thyroid cartilage, cricoid cartilage, and epiglottis. The larynx serves to produce sound (phonation), conducts air to the trachea, and prevents large molecules from reaching the lungs.
Larynx: Anatomy,
trachea
Trachea
The trachea is a tubular structure that forms part of the lower respiratory tract. The trachea is continuous superiorly with the larynx and inferiorly becomes the bronchial tree within the lungs. The trachea consists of a support frame of semicircular, or C-shaped, rings made out of hyaline cartilage and reinforced by collagenous connective tissue.
Trachea: Anatomy, and bronchial tree:
Note the main divisions of the bronchi.
Blood supply:
The bronchial tree is supplied by branches of the left and right bronchial arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology.
Venous drainage:
Innervation:
Innervation is supplied by the pulmonary plexus of the vagus nerve Vagus nerve The 10th cranial nerve. The vagus is a mixed nerve which contains somatic afferents (from skin in back of the ear and the external auditory meatus), visceral afferents (from the pharynx, larynx, thorax, and abdomen), parasympathetic efferents (to the thorax and abdomen), and efferents to striated muscle (of the larynx and pharynx). Pharynx: Anatomy.
Microscopic anatomy of the lower respiratory tract
Image by Lecturio. License: CC BY-NC-SA 4.0Cross-section of a secondary bronchus
Image: “Cross-section of secondary bronchus” by Jpogi. License: Public DomainCross-section of a tertiary bronchus
Image: “Tertiary bronchus” by Jpogi. License: Public DomainCross-section of terminal bronchiole
Image: “Terminal bronchiole” by Jpogi. License: Public DomainThe following are conditions that can affect Affect The feeling-tone accompaniment of an idea or mental representation. It is the most direct psychic derivative of instinct and the psychic representative of the various bodily changes by means of which instincts manifest themselves. Psychiatric Assessment the bronchial tree: