Working from the lumen outwards, name the layers involved in the general organization of internal organ tubes.
Epithelium, Lamina Propria, Submucosa, Adventitia
What are the two functions of the respiratory system?
- Conduct- conducts air in and out of the lungs
- Respire- exchanges O2 and OC2 in the lungs
What are the components of the conducting portion of respiratory system?
nasal cavity, pharynx, larynx, trachea, primary bronchi, secondary bronchi, tertiary/segmental bronchi, primary bronchioles, terminal bronchioles
Describe the functional role of the trachea.
- Major conducting airway
- Seromucociliary clearance of debris from lumen (cilia beats debris back to the pharynx)
- Lumen is always open (kept open by hyaline cartilage)
- Smooth muscle in wall decreases diameter of lumen when contracted- elastic connective tissue in wall facilitates reopening of lumen when smooth muscle relaxes
Describe the three layers of the trachea wall.
- Mucosa- respiratory epithelium, lamina propria, MALT, elastic lamina
- Submucosa- dense fibroelastic CT, seromucous glands
- Adventitia- Hyaline cartilage, smooth muscle
What is the structure of respiratory epithelium?
- Pseudostratified columnar epithelium- endodermally derived
- Made up of columnar cells with motile cilia, goblet cells with microvilli (secrete mucous apically), basal cells (stem cells), and small mucous granule cells (have some neural and endocrine functions)
Describe the structure of the tracheal seromucous glands.
- Exocrine, complex acinar glands.
- Mucous acini- lighter staining, carbohydrate/viscous secretion
- Serous demilune- denser staining, protein/watery secretion
- Consistency of secretions require proper ion transport (important in cystic fibrosis CFTR)
Describe the structure of the pharynx.
- Common air/food passageway
- Lamina propria has prominent MALT aggregates
- Submucosa has seromucous glands
- Adventitia has skeletal muscle for swallowing
Describe the structure of the larynx.
- Box between the pharynx and trachea
- Roof contains the epiglottis which prevents food entry into dedicated airway- has elastic cartilage in adventitia for flexibility
- Floor has the vocal folds
In the epiglottis, what epithelial transition occurs?
Respiratory epithelium to stratified columnar to stratified squamous
What is the function of the vocal folds?
- Responsible for vocalization via vibration of folds of mucosa and submucosa
- Taughtness and movement of folds mediated by skeletal muscle in adventitia
Describe the structure of the vocal folds.
- The true vocal folds are made of dense regular connecctive tissue. In the submucosa, it becomes the vocal ligament.
- The skeletal muscle fibers of the vocalis muscle are attached to the vocal ligament.
- The false vocal folds don't move and contain lots of seromucous glands.
What is the function of the nasal cavity?
- Warms air
- Trap particles (mucous)
- Cilia beat back to pharynx
- Lymphoid nodules (MALT)
- Mucociliary clearance due to mucosal goblet cells in respiratory epithelium
- Has specialiazed olfactory mucosa in roof for smell/olfaction
What is the structure of the nasal cavity?
- Highly vascular lamina propria
- Posterior aspect has respiratory epithelium and simple mucosa glands in lamina propria
- Anterior aspect has stratified squamous epithelium which merges with the skin
- Little submucosa
- Prominent adventitia-hyaline cartilage anteriorly, bone posteriorly
- Continuous with the paranasal sinuses
- Respiratory epithelium has embedded olfactory sensory neurons and supportive sustentacular cells
- Lamina propria contains Bowman's (serous) glands- liquid trap for odorants