Histology Flashcards
What type of epithelium is present in the roof of the nasal cavity?
Olfactory epithelium
What is the initial part of the nasal cavity, the vestibule lined by?
Keratinised stratified squamous epithelium
Deeper into the lining of the nasal cavity, what is lost?
Keratin
What lines nearly all the rest of the conducting part of the respiratory system?
Pseudostratified ciliated columnar epithelium with goblet cells
or Respiratory epithelium
What is another description for respiratory epithelium?
Pseudostratified ciliated columnar epithelium with goblet cells
What two cells are present in respiratory epithelium?
Goblet cells Basal cells (stem cells)
What lies underneath the respiratory epithelium?
Lamina propria which is a band of connective tissue containing seromucous glands. It also has a rich venous plexus - can quickly engorge with blood and ‘block’ the nose
What two things does the oropharynx transmit?
Air and swallowed food
What is the oropharynx lined by?
Non-keratinised stratified squamous epithelium
What is the anterior (lingual) surface and upper part of the posterior surface of the epiglottis lined by?
Non-keratinised stratified squamous epithelium
What are the walls of the larynx made up of?
Cartilage and muscles
What lines the larynx, with the exception of the vocal folds and adjacent structures?
Respiratory epithelium
In the larynx, what lines the vocal folds and adjacent structures?
Stratified squamous epithelium
How many C shaped cartilages does the trachea contain?
15 - 20
In the trachea, what is the open side of the ‘C’ of the cartilage spanned by?
Fibroelastic tissue and smooth muscle (trachealis muscle)
What does the open end of the “C” cartilage of the trachea point to?
Oesophagus
What wall includes a lining or respiratory epithelium backed by a basal lamina, a lamina propria of connective tissue with abundant elastic fibres and a submucosa of loose connective tissue that includes numerous seromucous glands?
The wall of the trachea
In the bronchi, what are the rings of hyaline cartilage replaced by?
Irregularly shaped cartilage plates
Describe the epithelium of the bronchi?
Respiratory in type, with the lamoina propria containing a discontinuous layer of smooth muscle and seromucous glands
Are cartilage plates present in the bronchioles?
No
What two things make up the acini?
Respiratory bronchiole
Alveolar sacs and alveoli
What are less than 1mm in diamater and lack cartilage and glands, but may contain a few goblet cells in their initial portion?
Bronchioles
What changes with the epithelium as you progress down the respiratory tree to the smallest bronchioles?
The epithelium decreases in height from columnar to cuboidal
In the smallest of bronchioles, what is the lamina propria composed of?
Smooth muscle and elastic and collagenous fibres
What do the smooth muscles of the bronchioles respond to?
Parasympathetic innervation, histamine and other factors by contracting and constricting the diameter of the bronchiole.
What are terminal bronchioles lined with?
Cuboidal ciliated epithelium and contain non-ciliated club/clara cells that project above the level of adjacent ciliated cells.
What interrupts the continuity of the respiratory bronchioles?
Alveoli
What is the low cuboidal epithelium replaced by in alveoli?
Discontinuous squamous type I alveolar cells
What are the 4 roles of Clara cells (club cells)?
- Stem cells
- Detoxification
- Immune modulation
- Surfactant production
What two portions can the respiratory system be divided into?
- The conducting portion
2. The respiratory portion
What is the conducting portion of the respiratory system between?
Trachea to end of terminal bronchiole
What is the respiratory portion of the respiratory system made up of?
Respiratory bronchiole, alveolar duct and alveolar sac
What are terminal portions of the bronchial tree and responsible for the spongy nature of the lungs?
Alveoli
What resembles pockets similar to a honey comb?
Alveoli
What two types of cells are the alveoli lined by?
Type I alveolar cells
Type II alveolar cells (alveolar cells are also called pneumocytes)
What type of alveolar cell is simple squamous epithelium that lines the alveolar surfaces covering 90% of the alveolar surface?
Type I cells
What do type I alveolar cells provide?
A barrier of minimal thickness that is permeable to gases
What type of alveolar cells are polygonal in shape, the free surface is covered by microvilli and the cytoplasm displays dense membrane bound lamellar bodies which contain surfactant?
Type II cells
What do lamellar bodies in type II cells contain?
Surfactant
How is surfactant released from lamellar bodies of type II alveolar cells?
Exocytosis and spreads over the pulmonary surface
What reduces surface tension at the air-fluid interface?
Surfactant
What does surfactant reduce the tendency for?
The alveoli to collapse at the end of expiration
In addition to the alveolar type I and II cells, what other cells are present in alveoli?
Alveolar macrophages (dust cells)
Where are alveolar macrophages located?
In the septa or migrating over the luminal surfaces of the alveoli
What do alveolar macrophages phagocytose?
Inhaled particles that may have escaped entrapment by the mucous lining of the airway
What three things does the air-blood barrier consist of?
Type I cell, endothelial cell and the basal lamina
What three things does the nasal cavity provide an extensive area for, in relation to inspired air?
- Warming
- Moistening
- Filtering
