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ANAT390 Respiratory System
ANAT390 Lecture 24 Respiratory System
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?
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
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