1: Respiratory Histology Flashcards
Conducting vs respiratory portions of the respiratory system (specific organs)
Conducting: nasal cavity, paranasal sinuses, nasopharynx, larynx, trachea, bronchi, bronchioles, terminal bronchioles
Respiratory: respiratory bronchioles, alveolar ducts, alveolar sacs, alveoli
Respiratory epithelium ***
Pseudostratified columnar ciliated epithelium
Five cell types in the respiratory epithelium
- Ciliated columnar cells (70%)
- Goblet cells (15%)
- Brush cells
- Small granule cells
- Basal cells
Brush cells
Chemosensory cells with short microvilli -> connect to sensory nerve fibers
Small granule cells
Have secretory granules for endocrine functions (part of the DNES)
Basal cells
Non-ciliated stem cells on basement membrane of respiratory ep
Larynx is between which two structures?
Pharynx and trachea
Three parts of the larynx made of hyaline cartilage
Thyroid, cricoid, inferior aretenoid cartilages
Four parts of the larynx made of elastic cartilage
Epiglottis, cuneiform, corniculate, superior arytenoid cartilages
Core of epiglottis
Elastic cartilage
Vestibular vs vocal folds
Vestibular: immovable pair of folds, superior
Vocal: movable for phonation and sound; inferior
Vocal ligament
Dense CT bundle that supports free edge of each vocal fold
Trachealis M
SM bundle that spans the open ends of cartilage rings posteriorly in the trachea
Where primary bronchi enter
Lungs at the hilum, along with vessels and lymphatics
Bronchi pathway
Primary bronchi -> secondary (lobar) -> tertiary (segmental) bronchi -> bronchioles
Cartilage rings in bronchi as it moves downward
Primary bronchi have complete cartilage rings -> gradually replaced by plates of hyaline cartilage as lumen size decreases
How many terminal bronchioles are formed from one tertiary bronchi
5-7
Where are club cells found?
Terminal bronchioles
Club cells
Non-ciliated, dome shaped apical ends contain secretory granules
Three exocrine functions of the terminal bronchioles
- Secrete surfactant and mucins onto epithelium
- Detox inhaled xenobiotics by enzymes of SER
- Secrete antimicrobial peptides and cytokines for local immune response
First part of respiratory region of airways
Respiratory bronchioles
Where are alveoli found?
Off respiratory bronchioles and respiratory ducts
Path from respiratory bronchioles -> alveoli
Respiratory bronchioles -> alveolar ducts -> alveolar sacs -> alveoli
What completely lines the alveolar ducts?
Openings of alveoli
Alveolar sacs
Large clusters of 2+ alveoli forming the distal ends of alveolar ducts
Alveolar pores
Small openings that permit movement of air between alveoli
Interalveolar septa composition
Reticular fibers, elastic fibers, scattered fibroblasts, sparce ECM, richest capillary networks in the body
Elastic fibers in interalveolar septa
Expand with inspiration, contract with expiration
Reticular fibers in interalveolar septum
Prevent collapse and excess distention of alveoli
Laryngitis
Inflammation of the larynx due to viral infection or allergies
Mechanism of laryngitis
Edema of lamina propria -> changes shape of vocal folds -> hoarseness/loss of voice
Croup
Viral laryngitis in young children with seal-like cough
Asthma mechanisms
- Bronchiole inflammation + SM contstriction -> bronchospasms
- Infiltration of bronchiole walls by eosinophils, lymphocytes, and mast cells
How are asthmatic bronchioles different than regular bronchioles
Thickened epithelium, increased goblet cells, thick basement membrane, hyperplastic smooth muscle cells
Emphysema mechanism
Narrowing of bronchioles + destruction of alveolar walls -> chronic obstruction of airflow + significant loss of area for gas exchange + permanent enlargement of air spaces distal to terminal bronchiole
Causes of emphysema
Cigs, chronic inhalation of particulate matter (coal dust, construction dust)
Pneumonia mechanism
- Air spaces fill with exudate: WBCs, RBCs, fibrin
2. Capillaries enlarge and fill with RBCs
Red hepatization stage in PNA
On gross exam, lungs appear red, firm, and heavy; due to lack of air spaces and exudate
