Pulmonary Histology Flashcards
Where is air filtered?
Nasal Cavities
What 4 things comprise the air conduction system?
Pharynx
Larynx
Trachea
Bronchial Tree
What is responsible for your sense of smell?
Olfactory mucosa
What does each nasal cavity open external to? Internal with?
External - with a nostril
Internal - with a choana
What is the most anterior portion of the nasal cavity? What type of epithelium is it lined with?
Vestibule
Stratified squamous
What is found on the epithelium of the vestibule? What is their purpose? What is associated with these structures?
Vibrissae - stiff hairs
Trap larger dust particles
Sebaceous glands
What segment occupies most of the volume of the nasal cavity? What 4 things constitute its function?
Respiratory segment
Warm, moisten, filter, and inspire air
What two layers compose the lining of the respiratory segment?
Ciliated pseudostratified columnar epithelium
Lamina propria
What 5 cells types compose the ciliated pseudo-stratified columnar epithelium? Are they found throughout the conducting part of the respiratory system?
Ciliated Cells Goblet Cells Basal Cells Brush Cells Small granule Cells Yes
What is the purpose of ciliated cells?
Move mucous towards to larynx
What type of secretion do goblet cells utilize?
Merocrine
What is formed by ciliated cells and goblet cells? What is its function?
Mucociliary apparatus
Trapping and removing small particles from the respiratory system
Where are basal cells found in the epithelium? What is their purpose?
Near base/lamina propria
Replacement cells
What cover brush cells? What is their purpose? Absorption?
Short blunt non-motile microvilli
Receptor cells, NOT for absorption
What cells are small granule cells homologous to from the GI tract?
Enteroendocrine cells
What two things can the lamina propria of the respiratory tract be attached to?
Perichondrium or periostium
What does the lamina propria contain to help warm the inspired air? Between what two conchae is this most prominent? What happens during an allergic reaction?
Extensive venous plexus
Middle and inferior conchae
This may become engorged and obstruct airflow
What are the two main functions of turbinates?
Increase surface area for warming/moistening air
Cause air turbulence
How does the lamina propria of the olfactory segment differ from that of the respiratory segment?
Thick lamina propria in olfactory segment
What type of cell does the olfactory epithelium contain that the respiratory system does not? What cell type does it lack?
Contains neurons
Lacks goblet cells
Where does the nulcei of supporting cells, olfactory cells, and basal cells lie in the epithelium of the olfactory segment?
Supporting cells - nuclei are apical
Olfactory cells - nuclei are in middle
Basal cells - nuclei are near base (lamina propria)
What type of cell is an olfactory cell? Where is it found in the epithelium?
Neuron
Spans entire thickness of epithelium
What do the dendrites of olfactory cells form as they profect toward the apical pole of the cell? What is this covered with?
Olfactory vesicle - a knob like structure
Covered with immotile cilia
What type of receptor is contained within the plasma membrane of the cilia of the olfactory vesicle? What family does it belong to?
Olfactory receptor
Belongs to G protein-coupled receptors
What do axons of olfactory cells form?
Olfactory nerve
What is the most numerous cell type in the olfactory epithelium?
Sustentacular (supporting) cell
What two roles do sustentacular cells provide to olfactory cells?
Mechanical - support
Metabolic - produces odorant-binding proteins
What is one major unique characteristics of olfactory neurons?
Can be replaced in postnatal development
What three things compose the lamina propria of the olfactory epithelium?
Bowman’s glands
Unmyelinated axons
Venous sinuses
What type of glands are Bowman’s glands of the olfacory mucosa?
Branched tubuloalveolar serous-secreting glands
What lines the nasopharynx?
Respiratory epithelium
What is most of the larynx lined with? What does it change to in areas of high abrasion?
Ciliated pseudostratified columnar
High abrasion areas - stratified squamous
What is the flexible tube that connects the larynx to the bronchi?
Trachea
What are the 4 layers of the trachea?
Mucosa
Submucosa
Cartilage
Adventitia
What two things compose the mucosa of the trachea?
Ciliated pseudostratified columnar epithelium
Lamina propria
What is the main component of the well developed reticular lamina of respiratory epithelium in the trachea?
Collagen
What is the boundary between the mucosa and submucosa of the trachea?
Elastic membrane
What separated the submucosa of the trachea from the adentitia?
Tracheal cartilage
What is connected to the free ends of the tracheal rings?
Trachealis muscle
Where do the submucosal glands in the trachea extend to? What do they secrete?
Extend through lamina propria and open on surface of epithelium
Secrete mostly glycoproteins
Is the tracealis muscle continuous? What type of muscle is it?
No
Smooth muscle
What are two distinct characteristics of bronchi?
Cartilaginous plates
Continuous layer of smooth muscle
What are the 5 layers of the wall of a bronchi?
Mucosa Muscularis Submucosa Discontinuous cartilaginous plates Adventitia
Besides ciliated pseudostratified columnar epithelium with goblet cells over the lamina propria, what is found within the lamina propria of bronchi that is not typically found in the trachea?
BALT - bronchi-associated lymphatic tissue
What type of muscle is the muscularis?
Smooth
What two things compose the submucosa loose CT of the bronchi?
Glands and adipose tissue
What disappears as bronchi’s descend that makes them turn into bronchioles?
Discontinuous cartilaginous plates disappear
How big are bronchioles?
1mm or less
What two things to bronchioles not contain?
Cartilage and glands
What separated bronchioles?
Pulmonary septa - thin layer of connective tissue
What line terminal bronchioles? What two types of cells are found here? Purpose of each?
Simple cuboidal epithelium (ciliated)
Cuboidal with cilia - transport of secretions upward
Club cells - specialized secretory cells - secreting lipoproteins (surface-active agents) and club cell proteins - abundant component of airway secretions
Is there a significant amount of smooth muscle in walls of terminal bronchioles?
Yes
What is the first segment to perform gas exchange?
Respiratory bronchioles
What type of cell composes a majority of the lining of respiratory bronchioles?
Club cells
Is there a significant amount of smooth muscle in the walls of respirtory bronchioles?
No
What does the respiratory bronchiole become when more and more alveoli open up into it?
Alveolar duct
What are spaces surrounded by clusters of alveoli called?
Alveolar sacs
How larg is the inner surface of human lungs?
75 m^2
What separateds alveoli from eachother?
Alveolar septa
What do the capillaries and the connective tissue of the septum form?
Interstitium
Where is the richest capillary network in the body found?
Interstitium of alveoli
Are the walls of capillaries surround alveoli continuous or fenestrated?
Continuous
What are the two main types of cell that line the air spaces of the alveolus?
Type I pneumocyte
Type II pneumocyte
Which pneumocyte is regenerated from the other? Discuss similarities and differences
Type I pneumocyte - flattened squamous cell, 95% surface, only 1/2 of the cells on the surface, joined by occluding junctions, basal lamina fused with tight capillaries. Regenerated from Type II
Type II pneumoctye - large secretory cell, contains mulilamellar bodies contianing surfactant, constitute 1/2 of cells on alveolar surface
What three things compose the barrier that most gas exchange occurs across?
Type I pneumocyte
Endothelial cells
Fused basal laminae
How are granules of surfactant released?
Exocytosis
Where are Type II pneumocytes more concentrated?
Around septal junctions
What is RDS (respiratory distress syndrome)?
Insufficient synthesis of surfactant by Type II pneumocytes
What are found within the interalveolar septum that connects neighboring alveoli? What is their function?
Alveolar pores - equalize air pressure and provide collateral air circulation if bronchi are obstructed
What are alveolar macrophages derived from? What two areas are they found? What is their purpose?
Blood monocytes
Septal walls and alveolar spaces
Collect particles such as dust and pollen
What is the most common lung cancer and can be found in both smokers and non-smokers?
Non-small-cell carcinoma
Two types - squamous cell carcinoma and adenocarcinoma
What are the most aggressive and rapidly growing lung cancer?
Small cell carcinomas (Oat cell carcinomas)