Airway structure+function Flashcards
What are bronchi split into following the trachea?
Secondary(Lobar) bronchus
Tertiary(Segmental) bronchus
What is a respiratory bronchiole?
A region of bronchioles containing alveoli
How do you describe the branching of the airways?
Dichotomous
What leads to an alveolar sac?
Alveolar duct
What are T1 and T2 alveolar cells and what are their functions?
T1: Thin, delicate barrier to facilitate gas exchange
T2: Replicate to replace T1 cells
-Secretes surfactant(reduces surface tension) and antiproteases
-Xenobiotic metabolism
What is the percentage cover of T1 and T2 alveolar cells?
T1~95%
T2~5%(But has greater number of cells)
By what 3 means are the functions of the airways facilitated
mechanical stability (cartilage)
control of calibre (smooth muscle)
protection and ‘cleansing’
What is the pharynx and what regions is it split into?
Def-A common passageway for food, liquids and air
Nasopharynx
Oropharynx
Laryngopharynx
Describe the general innervation of the nasal passage and the purpose of the nasal conchae
highly vascular – contribute to warming and ‘humidification’ of intra-nasally-inhaled air
Olfactory bulb branches down into nasal passage and detects smell
Ciliated cell
Blood vessel
Goblet cell, mucus
Smooth muscle
What are the 7 main types of cells in the airway and give an example of each?
Lining cells - Ciliated
Contractile cells - Smooth muscle
Neuroendocrine cells - Nerve cells
Secretory cells - Goblet cells
Connective tissue cells - Fibroblast
Vascular cells - Endothelial cells
Immune cells - Mast cells
SCLIVCN
What is the purpose of mucous and serous acini in a bronchial gland?
Mucous cells: Secrete mucus
Serous cells: Secrete anti-bacterial enzymes e.g lysozymes
Axoneme of the cilia
(Microtubules within it)
Roughly how many cilia are there per ciliated cell?
~200
What is the structure of the axonemes inside the cilia like?
‘9+2’ configuration
Intracellular anchoring proteins
Ciliary hooks-Engage with mucus
What are the 4 main functions of the airway epithelium?
-Secretions of mucus
-Movement of mucus by cilia
-Physical barrier
-Production of inflammatory/regulatory mediators
Give some examples of inflammatory/regulatory mediators produced in the airway epithelium
NO, CO, Arachidonic acid metabolites, Chemokines, Cytokines, Proteases
What is thought to be the mechanism of NO?
Increase the rate of ciliary beating, can be stained to show presence
What 3 major effects do airway smooth muscle cells have on the airway and what physiological process stimulates these pathways?
Structure
-Controls hypertrophy+proliferation
Tone
-Controls contraction, relaxation
Secretion
-Secretes cytokines, chemokines
Inflammation promotes these pathways, especially secretion
What is the mechanism of inflammation on airway smooth muscle cells?
Inflammation acts through:
-Cytokines
-Bacterial products
1)Activates nitric oxide synthase to produce NO
2)Activates COX to produce prostaglandins
3)Produces cytokines, chemokines and adhesion molecules
What is the blood flow to the airway mucosa(ml/min/100g tissue)?
100-150mL/min/100g of tissue
How does blood return from the tracheal circulation?
Systemic veins
How does blood return from bronchial circulation?
Bronchial and pulmonary veins
Give 7 functions of the tracheo-bronchial circulation
Good gas exchange (directly between airway tissues and blood)
Contributes to warming of inspired air
Contributes to humidification of inspired air
Clears inflammatory mediators
Clears inhaled drugs (good/bad, depending on drug)
Supplies airway tissue and lumen with inflammatory cells
Supplies airway tissue and lumen with proteinaceous plasma (termed ‘plasma exudation’)
What type of innervation supplies the airways and what molecules act as neurotransmitters in those pathways?
Parasympathetic - cholinergic
Sympathetic - adrenergic
Sensory
What 4 factors control airway function?
Nerves
Inflammatory mediators
Proteases
Reactive gas species
What is unique about the innervation of the airways in humans compared to most other mammals?
Human airways aren’t sympathetically innervated
Through what 2 mechanisms are the human airways able to relax?
Adrenaline produced by the adrenal glands
NO produced by nitric oxide synthase in epithelium
What nerve innervates the airways?
Vagus
How are goblet cells stimulated to produce mucus?
Through vagus nerve innervation
What are the regulatory-inflammatory cells in the airways?
Structural cells+
Neutrophils
Macrophages
Eosinophils
Mast cells
T-lymphocytes
What are the ganglions present in the system innervating the airway?
Nodose ganglion
Dorsal root ganglion
What are some diseases that lead to a loss of airway control?
Cystic fibrosis
COPD
Asthma
-All are common conditions
