Functional histology of the lungs Flashcards
what are the three principle compartments of the respiratory system
- Conduction zone
- Respiratory zone
- Musco-elastic ventilation apparatus
What does the conduction zone do
Conditions inhaled air
What does the respiratory zone do
Site of gas exchange
What does the music-elastic ventilation apparatus do
Drives ventilation
What does air come in through and what happens here
Nasal cavity
-air gets swirled around
Where does air go after the nasal cavity
Nasopharynx and then the trachea through the voice box
What is the gas exchange region in the lungs called
Distal respiratory tree
What are airways kept open by and why
Bony/cartilaginous scaffolds
-To cope with changing pressure
What do turbinate bone do an where are they
In the nasal cavity and they form narrow passageways that create turbulence so drive air in and out of the sinuses because opening of sinuses is very small
How is temperature adjustment and moisturizing enhanced
Due to large venous plexus in the submucosa
How are large particles prevented entry
By vibrissae (small hairs at entry to nasal cavity)
What is the epithelium of the respiratory tract to the bronchioles
Respiratory epithelium
What is below the epithelium
Mucosa has a sponge like epithelium due to the extensive venous plexus
What does the venous plexus do
Mediate exchange of moisture with the air; their filling status also relates the flow of air through the nasal cavities
What is on top of the nasal cavity
Olfactory elithelium
What does the olfactory epithelium do
Conveys the sense of smell
What do the cilia on the olfactory epithelium carry
Odorant receptors
what do the central processes of the olfactory processes of the olfactory receptor neurons in the olfactory epithelium unite to form
Nerve bundles that pass through the crifriborm plate (which collectively constitute the olfactory nerve) and enter the olfactory bulb
What is the trachea kept open by
Horse shoes shaped cartilage
What glands does the trachea have and where
Seromucous glands in the submucosa
What completes the rings which are partially formed by the cartilage
Smooth muscle
What does respiratory epithelium consist of
Pseudostratified, ciliated epithelium of varying thickness (depending on region) with mucous producing goblet cells
What areas ave additional seromucuous glands in their submucosa
Trachea
What is mucociliary clearance
Mucus getting transported towards the pharynx by constantly beating cilia
What does bronchus haven its wall
cartilage
what is the lumen of bronchus bordered by
Respiratory epithelium
When there is an incomplete ring of smooth muscle located between the epithelium and cartilage, what may be present
Submucosal glands
what does the presence of cartilage mean
It is a bronchus
How are the bronchioles different from bronchi
- No cartilage in its wall
- Epithelium is smaller and the cells are not columnar anymore
- Fewer goblet cells
What is the epithelium of the smaller bronchioli like
Cells become cuboidal and the cells consist of ciliated and non-ciliated club cells
What is the role of club cels
Protective role as they generate serous secretions
What surround the epithelium in smaller bronchioli
complete ring of smooth muscle
What is the ration of muscle ring thickness to luminar diameter like in bronchioli than bronchi
Higher
What does the bronchiolar constriction induce
High airway resistance
What do terminal bronchioles give rise to
Respiratory bronchioles that have cuboidal epithelium and alveoli built in their walls
What does the connective tissue of the alveoli and the lower airways contain
Numerous elastin fibres
What is the blood air barrier in the alveoli built of
Ultra thin walls of capillary endothelium and type 1 cells
Where is the blood supply to the alveolar capillary networks from
Pulmonary circulation (which are elastic to distal part)
What are pulmonary arteries like
Elastic arteries with comparatively thin walls
What are do the larger pulmonary arteries accompany
bronchi and bronchioli
What do the bronchi have their own blood supply from
aorta which are muscular
What are the bronchial arteries like
Small strong muscular wall like elastin
Why are surfactants used
Because in a space of such a small diameter as an alveolus, any water on the alveolar surface would exert strong capillary forces which would inhibit the expansion of the lung
What do surfactants do
Reduce surface tension
Where are the lymph vessels of the lung’s lymphatic drainage system found
In the septa next to the vessels of the pulmonary circulation
What do the lymph vessels in the lung drain into
A series of major lymph nodes along the trachea
Where are there also a network of lymph vessels
Interstitial layer adjacent to the pleura
Where are tonsils found
In oral and nasal cavity
What are tonsils
Antigen presentation sites which have access to the airways
How many tonsils are there in nasal cavity
5
What is Waldeyer’s ring
Ring of tonsils at the anterior pharynx which are basically aggregates of lymph follicles
What do the mucus of the airways contain
immunoglobins
What are the primary line of defense in alveoli
alveolar macrophages
