Structure & function of airways Flashcards
What term is used to describe the branching of the trachea?
Dichotomous branching
How is the trachea held open?
By C-shaped cartilage rings
What does the trachea divide into?
Two primary bronchi
Where does the trachea extend from?
Extends from the larynx towards the lungs
What type of cartilage forms the C-shaped rings?
Hyaline cartilage connected by tracheal muscle and elastic connective tissue, forming a fibroelastic membrane, encloses the posterior surface
Which membrane enables the stretching of the trachea and expansion during inhalation & exhalation?
Fibroelastic membrane
Which tracheal muscle contracts to assist for forceful expiration? (N.B: IGNORE)
Trachealis muscle (N.B: we do not need to know this)
What type of epithelium lines the trachea and larynx ?
Pseudostratified columnar epithelium
Where does the trachea bifurcate?
At the tracheal carina (T4/5)
Which cells are integrated within pseudostratified columnar epithelium?
Goblet cells
Where does the bronchi enter the lungs?
At the hilum
What is the main function for the bronchi?
Conducting zone, passageway for inspired and expired air
What is the alveolar duct?
Tube composed of smooth, muscular and connective tissue, periphery opens into alveoli.
Alveolar sac comprises of multiple individual alveoli, responsible for gaseous exchange
What is the purpose of elastic walls in the alveoli?
Enables alveolus to stretch during inspiration, increases surface area available for gas exchange. Elastic recoil enables ventilation mechanism
What is the purpose of alveolar pores?
Connect adjacent alveoli maintaining equal air pressure
Which type of alveolar cells form the majority of the alveolar surface?
Type 1 alveolar cells
Which type of alveolar cells are permeable to gas exchange ?
Type 1 alveolar cells
Where are type 1 alveolar cells attached to?
Attached to thin, elastic membrane, borders capillaries
What forms the respiratory membrane?
Alveoli and capillary membranes
Which cells are interspersed amongst type 1 cells?
Type II alveolar cells
What is produced by type ii alveolar cells?
Pulmonary surfactant
What is contained within pulmonary surfactant?
Phospholipids and proteins that reduce surface tension of alveoli
What is the purpose of pulmonary surfactant?
Reduced surface tension of the alveoli, to enable elastic recoil
What are the 3 main functions of type II alveolar cells?
Replications to form Type I cells
Secretes pulmonary surfactant, and antiproteases
Xenobiotic metabolism
What is the purpose of alveolar macrophages?
Phagocytic cells removes pathogens and debris present in the alveoli
What are the 3 basic functions of the respiratory system?
Conduit to conduct oxygen to the alveoli
Conduct carbon dioxide out of the lung
Gas exchange
How are the basic functions of respiratory system maintained?
Mechanical stability (cartilage)
Control of calibre (smooth muscle)
Protection and cleansing
What does the lateral wall so the nasal cavity contain?
The superior middle and inferior nasal conchae
What are the three main types of conchae?
Superior
Middle
Inferior
What is the function performed by nasal conchae?
Conchae increases the surface area of the nasal cavity, and disrupt flow of inspired air, contact with the epithelium results in filtration and humidification
What enables the nasal conchae to humidify and warm air?
Highly vascular enables warming through convection currents
How is water conserved within the nasal cavity?
Conchae and meatuses conserve water & minimise dehydration of nasal epithelium during exhalation
What type of epithelium lines the conchae, meatuses and paranasal sinuses?
Columnar pseduostratified ciliated cells
What is the function of the columnar cells in the nasal cavity?
Produce mucous to trap debris
Goblet cells are present
What function is performed by cilia in the nasal cavity?
Assist in the removal of mucous and debris from nasal cavity
What cartilage is the epiglottis attached to?
Thyroid cartilage
What is the epiglottis?
Flexible piece of elastic cartilage that covers the opening of the trachea.
Act of the swallowing causes the pharynx and larynx to life upwards
Prevents aspiration of food
What is superficial to the submucosal glands?
Ring of smooth muscle
How do submucosal glands release mucous?
Contractile mechanism,
contraction of smooth muscle stimulates mucous secretion into epithelial lining and lumen of airways
What cells are found within the airway lumen?
Goblet cells
Ciliated and squamous epithelial
What is deep to cartilage of the airways?
Smooth muscle
What type of circulation supplies oxygen and respiratory substrates to the tracheal tissue?
Bronchial systemic circulation
How are the C-shaped cartilage arranged to maximise mechanical stability of the trachea?
Are offset and angulated