The respiratory system:
- Fundamental for gas exchange via negative pressure breathing.
- Consists of a conduction portion (respiratory tract) and a respiratory portion (lungs)
- Involved in voice formation (larynx) and olfactory (nasal cavity)
The air passages
Upper respiratory tract
- 1 Nasal cavity (cavitas nasi)
- 1.1 Paranasal sinuses (sinus paranasales)
- 2 Pharynx
- 2.1 Nasopharynx (pars nasalis pharyngis)
- 2.2 Oropharynx (pars oralis pharyngis)
- 2.3 Laryngopharynx or hypopharynx (pars laryngea pharyngis)
Lower respiratory tract
- 3 Larynx
- 4 Trachea
- 5 Bronchi
- 6 Lungs (pulmones)
has:
- Respiratory bronchioles
- Alveolar ducts
- Alveolar ducts
- Multiple alveoli
Development of the Respiratory System:
- Begins at about the middle of the 4th week
- Develops from both endoderm & mesoderm.
- Steps :
- 4th week: a respiratory diverticulum outgrowth from the ventral wall of the foregut.
- The diverticulum expand ventrally & caudally. & eventually separates from the foregut, forming the esophagus.
- The diverticulum forms distaly lung bud & the rest forms the trachea.
- The lung bud bifurcates into right & left primary bronchial buds
- 5th week: the 1° bronchial buds gives rise to 2° then to 3° bronchial buds
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