Respiratory Tract Histology Flashcards
The ______ portion of the respiratory system begins as a system of cavities that collect and warm air and transmit that air to the respiratory portion
Conducting
What structures are associated with the conducting portion of the respiratory system?
Nasal cavity Paranasal sinuses Nasopharynx Trachea Primary, secondary, and tertiary bronchi Bronchioles, terminal bronchioles
The ______ portion of the respiratory system passes air to the alveoli with the purpose of gas exchange to blood in capillaries
Respiratory
What structures are associated with the respiratory portion of the respiratory system?
Respiratory bronchioles
Alveolar ducts
Alveolar sacs
What is the role of the conducting portion of the respiratory system?
Collects and warms air, transmits it to respiratory portion
What is the purpose of the respiratory portion of the respiratory system?
Passes air to alveoli with purpose of gas exchange
What type of epithelium is the respiratory epithelium
Pseudostratified columnar ciliated
What is unique about the pseudostratified columnar ciliated epithelium lining the respiratory tract?
It has the appearance of 2+ cell layers, but it is a simple epithelium
All the cells rest on the basement membrane with the nuclei located at varying levels
[note that cilia are NEVER present on true stratified epithelia]
T/F: the pseudostratified columnar ciliated respiratory epithelium is confined to the airways
True
Whate are the major cell types associated with respiratory epithelium?
Ciliated columnar epithelial cells
Nonciliated colmnar epithelial cells
Goblet cells
What is the purpose of the nonciliated columnar cells that are found among the ciliated columnar cells in the respiratory epithelium?
They are typically stem cells responsible for regenerating epithelia throughout life
_______ cells are modified columnar epithelial cells that synthesize and secrete mucous
Goblet
Describe the cytoplasm and “stem” of goblet cells
Apical cytoplasm that contains a dense aggregation of mucigen granules
“Stem” is occupied by basal nucleus and crammed with organelles
Goblet cells have apical cytoplasm that contains a dense aggregation of mucigen granules. How are these released?
Released by exocytosis, then combine with water to form mucus
Visceral pleura is covered in a flattened ________, which is a simple squamous epithelium found as part of the serous membrane
There are underlying fibrous tissues of _______ and ______ fibers
Mesothelium
Collagen; elastin
The visceral pleura extends into the lung as fibrous septa and is continuous with lung _________, serving the purpose of dividing it into lobes and structures; it contains extensive _______ vessels
Parenchyma; lymphatic
How does the height of epithelium change from the trachea (highest part of conducting portion) to alveolar sacs (lowest part of respiratory portion) of the respiratory tract?
Fairly constant in conducting portion
Decreases significantly in respiratory portion
How does the distribution of goblet cells change from the trachea (highest part of conducting portion) to alveolar sacs (lowest part of respiratory portion) of the respiratory tract?
Goblet cell distribution begins to decrease in secondary bronchioles and completely disappears after tertiary bronchi
[none in terminal bronchioles or respiratory portion]
How does the distribution of ciliated cells and glands change from the trachea (highest part of conducting portion) to alveolar sacs (lowest part of respiratory portion) of the respiratory tract?
Ciliated cells stick around until just after respiratory portion begins
Glands begin to dcrease in secondary bronchi and disappear at the tertiary bronchi level
How does the distribution of hyaline cartilage change from the trachea (highest part of conducting portion) to alveolar sacs (lowest part of respiratory portion) of the respiratory tract?
Gradually decreases beginning in the trachea, disappears after tertiary bronchi (none in terminal bronchioles or respiratory portion)
How does the distribution of smooth muscle change from the trachea (highest part of conducting portion) to alveolar sacs (lowest part of respiratory portion) of the respiratory tract?
Steady distribution from trachea to tertiary bronchi, starts to decrease in terminal bronchioles, and stops just after respiratory portion begins
How does the distribution of elastic fibers change from the trachea (highest part of conducting portion) to alveolar sacs (lowest part of respiratory portion) of the respiratory tract?
Elastic fibers are abundant from the trachea down to the terminal bronchioles, start to decrease in respiratory bronchioles, and end in the alveolar sacs
The trachea is made up of C-shaped _____ cartilage and is under the control of the ______ muscle.
Its submucosa is rich in ________ glands. It is lined with respiratory epithelium and its distal end forms a ring of fibroelastic tissue. It is also associated with a ______ ______ rich in blood vessels.
Hyaline; trachealis
Seromucinous; lamina propria
Describe the epithelia associate with the primary bronchus
Pseudostratified columnar ciliated
Cells shorter in height
Fewer goblet cells
Describe the lamina propria of the primary bronchus
Increased elastic fibers; separated from submucosa by smooth muscle
Describe the submucosa of the primary bronchus
Fewer seromucinous glands; incomplete cartilage plates
Describe the epithelia associated with the bronchioles
Simple columnar ciliated
Fewer goblet cells
Describe the lamina propria associated with the bronchioles
Increased elastic fibers
Prominent smooth muscle
T/F: bronchioles do not have submucosa, airways are <1 mm diameter, and they are associated with hyaline cartilage
False: they do not have submucosa, airways are <1 mm diameter, and they are NOT associated with cartilage!!
Smooth muscle controls what functions of the bronchioles?
Bronchoconstriction
Bronchodilation
Describe the epithelia associated with terminal bronchioles
Simple columnar ciliated
Clara cells (secrete surfactant)
_______ cells are nonciliated dome-shaped cells with granular cytoplasm and they secrete surfactant to reduce surface tension and prevent bronchiole collapse
Clara
Describe the lamina propria associated with the terminal bronchioles
Increased elastic fibers; 1-2 layers of smooth muscle
What are the levels of branching of the respiratory bronchioles?
Respiratory bronchioles branch into:
Alveolar ducts –> alveolar rings –> alveolar sacs –> alveoli
Alveolar _____ end in alveolar sacs
Ducts
Alveolar _____= 2+ clusters of alveoli
Sacs
Alveolar ____ = aggregates of smooth muscle, collagen, and elastic fibers that form rings around alveolar ducts
Rings
_____ = blind-ended sacs lined with pneumocytes
Alveoli
Describe the epithelium associated with alveoli
Simple squamous, associated with supporting tissue and blood vessels
How many types of pneumocytes are there?
2 - Type I and Type II
______ ______ = wall of alveolar capillaries surrounded by elastin and collagen fibers
Alveolar septum
______ ______ = small opening that permit movement of air between alveoli
Alveolar pores
_______ ______ aka dust cells are also present in the alveoli
Alveolar macrophages
What 3 components make up the “respiratory membrane”
Alveolar epithelium
Fused basement membranes of the alveolar epithelium and capillary endothelium
Capillary endothelium
Which type of pneuomocytes lines almost the entire alveolar surface, creating surface for gas exchange, and is closely associated with capillaries?
Type I pneumocytes
Which type of pneumocyte consists of rounded cells that comprise about 60% of the epithelium and secrete surfactant that prevents collapse during respiration?
Type II pneumocytes
Type II pneumocytes are associated with ____ _____ that hold pulmonary surfactant after processing its components in the rough ER and golgi
Lamellar bodies
What region of the respiratory tract would you find no cartilage, no submucosa, few goblet cells, prominent smooth muscle, and less than 1 mm diameter?
Bronchioles
How would you distinguish between bronchioles and terminal bronchioles?
Bronchioles are first branches from primary bronchi, they still have prominent smooth muscle while the terminal bronchioles will have less smooth muscle
Bronchioles have no cartilage, no submucosa, few goblet cells, prominent smooth muscle, and are les than 1 mm in diameter. What type of epithelium is associated with the bronchioles?
Simple columnar ciliated epithelium
[note that the bronchioles are the first area of transition from pseudostratified columnar ciliated]
What type of epithelium is associated with the alveoli?
Simple squamous
While viewing a section of an alveolus, you see that about 60% of the alveolar epithelial cells have a large rounded nucleus. What type of cells are these?
A. Goblet cells
B. Type I pneumocytes
C. Type II pneumocytes
D. Alveolar macrophages
C. Type II pneumocytes
[goblet cells are not found in alveoli, type I cells are thin, flat cells associated with gas exchange]
Which of the following is covered by a flattened mesothelium and has extensive lymphatic channels?
A. Visceral pleura
B. Alveoli
C. Parietal pleura
D. Trachea
A. Visceral pleura
