Histology of the Lower Respiratory Tract Flashcards
What are the section of upper respiratory tract?
Nasal cavity
Paranasal cavity
Sinuses
Nasopharynx and oropharynx
What are the parts of the lower respiratory tract?
Larynx
Trachea
Brochi
Bronchioles
Alveoli
What are the anatomical divisions of the respiratory tract?
Upper and lower respiratory tract
What are the functional divisions of the respiratory tract?
The conducting zone (movement of air from outside to the end of the bronchial tree
Respiratory zone (gas diffusion areas in respiratory bronchioles and alveoli)
Where does gas exchange occur in the respiratory tract?
In the lower bronchioles and the alveoli
What are the 3 main functions of the respiratory functions?
Air conduction
Air filtration and conditioning (fibrasae in the nasal cavity trap foreign bodies)
Gas exchange (respiration)
Where is the trachea located?
Trachea extends from larynx to the level of the sternal angle (T4/5) where it divides into 2 primary bronchi.
What is more anterior the oesophagus or the trachea?
The trachea
How many cartilage rings does the trachea have?
16 - 20 C-shaped rings
What bridges the ends of the cartilaginous rings of the trachea?
The trachealis muscle which are joined vertically by the annular ligamnets
What structure joins the trachealis muscles to each other vertically?
Annular ligament
What are the layers that surround the trachea?
Lumen -> Mucosa -> Submucosa -> Cartilage and muscularis -> Adventitia
What makes up the mucosa?
2 layers;
Respiratory epithelium containing pseudostratified ciliated columnar epithelium and numerous goblet cells which produce mucous. (they are closest to inner surface of the trachea)
Lamina propria containing loose connective tissue with lots of elastic fibers and diffuse nodular lymphatic extending from lamina propria to submucosa
Which tissues have respiratory epithelium?
nasal cavity, larynx, trachea, and bronchi
What kind of tissue is present in the submucosa?
Loose connective tissue which is similar to that of the lamina propria and different to the connective tissue in digestive tract.
What kind of tissue layer is present in respiratory tract and GI tract but absent in urinary tract?
Submucosa
What lines the lamina propria of the mucosa?
Loose connective tissue with lots of elastic fibers.
Diffuse and nodular lymphatic extending from lamina propria to the submucosa
What makes up the submucosa layer?
Relatively loose connective tissue and numerous submucosal glands
What makes up the cartilage and smooth muscle?
C-shaped hyaline cartilage rings keep tracheal lumen open
Posterior ends of the cartilage ring connected by trachealis
What kind of cartilage forms the cartilage rings?
Hyaline cartilage
What makes up the adventitia?
Dense irregular connective tissue which merges with adventitia of other organs such as the oesophagus
What part of the trachea meets the oesophagus?
The trachealis side
What are the functions of the trachealis muscle?
2 important functions:
During swallowing the trachealis relaxes to facilitate the passage of food and bulging of oesophagus into the lumen of the trachea.
Trachealis muscle is also important for coughing the trachea narrows the lumen to allow air to be expelled with more force.
What structures are contained within the submucosa of the trachea?
The ducts and the acini (mucous and serous)
Mucous glands + acini are more common than the serous glands + acini
What cells does the epithelium of the trachea contain?
Ciliated columnar cells (oval shaped nuclei and are tall cells with cilia)
Goblet cells (They produce mucous and are tall)
Basal cells (cuboidal cells sitting on basement membrane of epithelium)
What gives hyaline cartilage its glassy appearance?
Its matrix is homogenous with a special type 2 collagen fiber
Where is cartilage produced?
In the lacuna of the cartilage cells. In a rift between chrondrocytes.
What kind of cells are found in the respiratory mucosa?
Ciliated columnar cells (most abundant cells, columnar shaped with oval nucleus each has up to 300 cilia on its surface)
Goblet cells (They are numerous throughout respiratory tract but absent from the bronchioles and alveoli and secrete mucus that is expelled by cilia towards the pharynx)
Basal cells (progenitor cells)
Clara cells (exocrine bronchilar cells)
What do cilia do?
Expel debris opposite to air in a synchronous manner.
What occurs if cilia activity is ruined?
Dirt can accumulate inside lungs
What does mucus produced by goblet cells do in the respiratory tract?
It filters small dust particles that escape thick hairs in nasal cavity.
Conditioning and moistening of air in lungs