WEEK 4: Basic Histology; Respiratory System Flashcards
2 main functions of histological features of respiratory system include?
air conduction and air modification
external respiration - exchange of gases between air and the blood
What are the conduction pathways of the body?
nostrils, pharynx larynx, trachea, bronchi, terminal bronchioles
what is external respiration carried out by?
respiratory bronchioles, alveolar ducts, alveoli
What is the general layered wall plan to tubes in the airway?
- Mucosa
- Submucosa
-Adventitia
What is the mucosa made up of?
- epithelium
-basement membrane
-lamina propria (glands & smooth muscle)
What is the submucosa made up of?
Dense connective tissue
Hyaline cartilage & large veins
What is the adventitia made up of?
Connective tissue
Respiratory mucosa is lined by ?
Respiratory epithelium
What is a respiratory epithelium?
It is a pseudostratified columnar with ciliated cells and goblet cells
What is the connective tissue under the epithelium called?
Lamina propria
What does the connective tissue in the trachea wall contain?
- a lot of seromucous glands
- trachealis smooth muscle
- C shaped hyaline cartilage
What is the role of the C shaped hyaline cartilage
To keep the airway patent and enable inflow/outflow of air
What are the most easily picked out cell types in the respiratory epithelium
- ciliated cells
- goblet cells
- basal cells (stem cells)
What are the less common cells that can be found in the respiratory epithelium?
Brush cells with microvilli
small granule cells
What does the lamina propria contain?
Defense cells
Elastic fibres
Seromucous glands
mucosal venules
What kind of defense cells are present in the lamina propria?
- macrophages
- lymphocytes
- plasma cells
What kind of transition is it from loose to dense connective tissue (lamina propria -> submucosa)
A gradual transition with the presence of smooth muscle/cartilage with no identifiable boundary
The loose CT of the lamina propria will be closer to the __
lumen
The denser CT of submucosa has deeper location relative to the __
Lumen
What is the overarching function of respiratory mucosa
- secretions from cells within that coat the epithelial surface with sticky viscous film that traps inhaled particles & microorganisms
- debris that is trapped is moved towards the pharynx via ciliary action
Overall acting as filtration of air !
What other functions can the respiratory mucosa have?
- serous secretions keep viscous coating layer hydrated and humidify air
- heat transfer from mucosal blood vessels warm air
- removal of pathogens
What does the removal of pathogens involve?
- immunoglobulins, antiproteases and lysozyme in viscous film disable bacterial functions
- defense cells in lamina propria target and destroy pathogens that cross epithelium
cartilage holds larger airways open to maintain ___
Airflow
What is the adventitia?
The outermost CT layer of wall that merges into surrounding CT to hold tube in place
What are alevoili
Air sacs located deep in lungs at ends of alveolar ducts
Adjacent alveoli share walls called?
Interalveolar septae
Alveolar walls are lined by simple __ ___
squamous epithelium
Centre of the septae contains?
- little smooth musce
- a lot of elastic fibres
- extensive capillary network
what does the alveolar epithelium consist of?
- type 1 alveolar cell/septal cell/pneumocyte
- type 2 alveolar cell
- other cells including the alveolar macrophage (may sit on top of the epithelium)
type 1 alveolar cell is squamous for
exchange
function of type 2 alveolar cell is to
secrete sufactant onto surface of alveoli
type 2 cells are located at
septal junctions
what functions do secretions in type 2 cells have?
- decreased alveolar surface tension
- assistance in clearing foreign materials
- modulate alveolar immune response
what other function do type 2 cells have?
- producing surfactant which are secretory granules that contain phospholipids, neutral lipids and proteins
what are alveolar macrophages
cells that start as monocytes that differentiate to become macrophages
Alveolar macrophages can migrate into the __ and back to ___
alveoli and septae
what do alveolar macrophages do?
scavenge alveolar surfaces to remove particulate matter & remove escaped rbcs from septal CT
The connective tissue core of the interalveolar septum contains an extensive ____
pulmonary capillary network that is supplied by pulmonary arteries
With increasing proximity to the respiratory exchange surface, the airway walls reduce in __ and __
thickness, complexity
