Week 3/4 - C - Histology (epithelium in resp tree) - Nasal cavity, larynx/pharnyx, trachea, bronchioles, alveoli (alveolar cells) Flashcards
What is the function of the nasal cavity with regards to respiration?
The nasal cavity provides an extensive area for warming, moistening and filtering the inspired air
What epithelium lines the nasal cavity? What epithelium does the roof of the cavity contain?
The most anterior part of the nasal cavity is the nasal vestibule. The vestibule is enclosed by the cartilages of the nose and lined by the same epithelium of the skin (stratified squamous, keratinized). Within the vestibule this changes into the typical respiratory epithelium that lines the rest of the nasal cavity and respiratory tract - pseudostratified ciliated columnar epithelium with goblet cells * The roof contains an area of specialised olfactory epithelium for smell
What do goblet cells produce? What effect does adrenaline and ACh have on goblet cells?
Goblet cells produce mucus - Adrenaline decreases mucus secretion via B2-adrenorecepters on goblet cells Acetylcholine increases mucus secretion via M3 muscarinc receptors on goblet cells
What is the larynx lined with? (what part of the larynx is the exception) What part of the pharynx is lined by the same epithelium as the majority of the larynx?
The larynx is lined with respiratory epithelium except the vocal cords which are lined by stratified squamous epithelium The nasophraynx is also lined by respiratory epithelium
What are the oropharynx and laryngopharynx lined by?
The orophaynx and layngopharynx however must transmit both air and swallowed food - therefore it must resist abrasian and is lined by non-keratinizing stratified squamous epithelium
The trachea is continous with the larynx and terminates by divided into the main bronchii What are the C-shaped rings that exist throughout the trachea? Are the complete? What spans the open side of the C-shaped rings?
The trachea contains incomplete C-shaped hyaline cartilaginous rings The trachealis muscle is a smooth muscle that bridges the gap between the free ends of C-shaped cartilages at the posterior border of the trachea, adjacent to the esophagus
What allows for expansion of the oesophagus into the trachea during swallowing? Name the other function for this muscle?
The trachealis allows for expansion of the oesophagus into the trachea during swallowing and also contracts during coughing to expel air with more force from the trachea
The trachea divides into 2 main (primary) bronchi (singular, ‘bronchus’) which divide further within the lung. The ‘rings’ of hyaline cartilage are replaced by irregularly shaped cartilage plates As bronchi branch and become smaller the cartilage becomes more discontinuous and is finally lost when the airway is about 1mm in diameter What are these smaller airways lacking any cartilage known as?
It is the bronchioles onwards which lack any cartilage
The smallest bronchioles that lack respiratory (gas exchange) function are referred to as terminal bronchioles - what do these branch to give rise to? (explain the branching from trachea to terminal bronchioles)
Trachea - main bronchii - lobar braonchii - segmental bronchii - bronchioles - terminal bronchioles The terminal bronchioles branch to give rise to the first part of the respiratory tree that has a respiratory function - the respiratory bronchioles
The conducting portion of the airways extends from trachea to the terminal bronchioles. What lines the terminal bronchioles? What are the cells in the terminal bronchioles that produce surfactant?
Terminal bronchioles are lined with simple cuboidal epithelium - these contain non-ciliated cells known as - * Clara cells (aka club cells) exist in the terminal bronchioles - amongst other functions they also produce surfactant - now known as club cells * Functions * Produce surfactant * Stem cell * Immunomodulator * Detoxification
The respiratory bronchioles are the beginning of the respiratory portion of the airways The respiratory bronchioles and alveoli are lined by simple squamous epithelium What are the two cells types that are contained within the lining of the alveoli?
Type 1 alveolar cells (aka type 1 pneumocytes) - these are simple squamous epithelium lining the alveolar surface Type 2 alveolar cells (aka type 2 pneumocytes) - contain secretory granular organelles known as lamellar bodies that fuse with the cell membranes and secrete pulmonary surfactant.
What are the cells located on the internal lumen of the alveoli that engulf foreign particles in the lungs? Also known as dust cells How are these cells removed?
Dust cells - alveolar macrophages - phagocytose enhaled particles and migrate up bronchial tree via ciliary action where they are swallowed
Describe the changes in the respiratory tree epithelium as one progresses from nasal cavity to alveoli?
Pseudostratitfied ciliated columnar epithelium Changes to simple columnar epithelium at bronchioles Changes to simple cuboidal epithelium at terminal bronchioles Finally becomes simple squamous epithelium at respiratory bronchioles and the alveoli
What is the layer of simple squamous epithelium that lines the bodies serous cavities and the organs within known as?
This is the mesothelium - mesothelial cells also produce lubricating fluid to facilitate non friction movement within the cavity
