Questions and Answers
What is the main function of the conducting portion of the respiratory system?
What develops from the foregut in the embryology of the respiratory system?
What is the function of the respiratory portion of the respiratory system?
What is the role of the mesoderm in the development of the respiratory system?
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What is the name of the structure that develops from the foregut and gives rise to the respiratory system?
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What is the function of the pleura in the respiratory system?
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What is the role of the respiratory system in acid-base balance?
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What is the name of the process by which the lung bud divides and forms secondary and tertiary bronchi?
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What type of epithelium lines the majority of the nasal cavity?
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Which of the following is NOT a component of the respiratory epithelium?
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What is the primary function of the cilia in the respiratory epithelium?
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What type of cartilage forms the core of the epiglottis?
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Which of the following structures is covered by respiratory epithelium?
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What is the function of the trachealis muscle?
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What type of epithelium lines the nasal vestibule?
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Which of the following structures is NOT found in the trachea?
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What is the correct order of structures in the wall of the bronchus?
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What happens to cartilage as bronchi branch into smaller bronchioles?
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What type of epithelium is found in smaller bronchioles?
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What is the function of Clara cells in terminal bronchioles?
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At what week of gestation are respiratory bronchioles present and lungs vascularized?
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Which layer is NOT present in bronchioles?
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What happens to smooth muscle in bronchioles during asthma?
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How does the connective tissue change as bronchi branch into smaller bronchi?
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Study Notes
Respiratory System Functional Components
- The respiratory system consists of three functional components: conducting portion, respiratory portion, and pleura.
- Conducting portion: nasal cavity, larynx, trachea, bronchi, and bronchioles, which conduct air to and from alveoli and condition the air (warm, humidify, filter).
- Respiratory portion: respiratory bronchioles and alveoli, where gas exchange occurs.
- Pleura: a double-layered membrane that surrounds the lungs and lines the thoracic cavity.
Respiratory System Functions
- Gas exchange and acid-base balance
- Olfaction (smell)
- Phonation (voice production)
- Haematopoiesis: platelet biogenesis and reservoir for haematopoietic progenitors
- Pulmonary defense
- Compression of abdominal cavity
- Pulmonary metabolism and handling of bioactive materials
Anatomy of the Respiratory System
- Embryology: respiratory system develops from the foregut, with the respiratory diverticulum (bud) forming from endoderm and mesoderm.
- Endoderm gives rise to epithelium and glands, while mesoderm gives rise to connective tissue, cartilage, and smooth muscle.
Respiratory Epithelium Cell Types
- Ciliated columnar cells: most abundant, with cilia that beat in unison to move mucus and trapped particles.
- Goblet cells: produce mucus.
- Basal cells: stem cells that replenish epithelium.
- Brush cells: columnar cells with apical microvilli.
- Neuroendocrine cells: epithelial cells containing hormones.
Nasal Cavity
- Respiratory epithelium everywhere except at the top, which has specialized olfactory epithelium.
- Serous and mucous glands and numerous blood vessels in lamina propria.
- Nasal septum: midline structure consisting of bone and hyaline cartilage.
- Nasal fossa: chambers on each side of septum.
- Three types of epithelium: nasal vestibule (stratified squamous epithelium), nasal cavity proper (respiratory epithelium), and olfactory area (olfactory epithelium).
Larynx and Epiglottis
- Epiglottis covers laryngeal opening during swallowing, with a core of elastic cartilage.
- Superior surface: nonkeratinized stratified squamous epithelium.
- Inferior surface: respiratory epithelium.
- Vocal folds are covered by nonkeratinized stratified squamous epithelium.
- Laryngeal cartilages support the wall of the larynx and serve as attachments for vocalis muscles.
- False vocal folds are covered by respiratory epithelium.
Trachea
- Extends from larynx and divides into two primary bronchi.
- Contains 16-20 C-shaped hyaline cartilage rings with the dorsal opening bridged by smooth muscle (trachealis muscle).
- Lined by respiratory epithelium.
- Seromucous glands in lamina propria and submucosa.
- Composed of four layers: mucosa, submucosa, cartilage framework, and adventitia.
Bronchi
- Trachea divides into two primary bronchi, which divide into secondary bronchi, and so on.
- Tertiary bronchi divide into smaller bronchi, which divide into bronchioles.
- Bronchi undergo 9-12 branchings.
- As branching progresses, connective tissue decreases in thickness, and the relative amount of smooth muscle and elastic tissue increases, with cartilage disappearing by bronchioles.
Bronchioles
- NO glands or cartilage.
- Larger bronchioles have respiratory epithelium, while smaller bronchioles have low columnar epithelium.
- In asthma, the smooth muscle in bronchioles constricts, causing difficulty breathing.
- Terminal bronchioles have simple cuboidal epithelium with cilia and Clara cells (non-ciliated epithelial cells with secretory granules).
Development of Lungs
- By week 24, respiratory bronchioles are present, and lungs are vascularized, making respiration possible, but chances of survival outside the placenta are slim.
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Description
Learn about the three functional components of the respiratory system, including the conducting portion, respiratory portion, and pleura, and their roles in facilitating gas exchange.
