Respiratory Histology Flashcards
What structures comprise the conducting portion of the respiratory tract?
- nasal cavity, paranasal sinuses, nasopharynx
- trachea
- primary, secondary, tertiary bronchi
- conducting and terminal bronchioles
What is the function of the conducting portion of the respiratory tract?
- warm, filter, and humidify air
- transmit air to the respiratory portion
- no gas exchange
What structures comprise the respiratory portion of the respiratory tract?
- respiratory bronchioles
- alveolar ducts and sacs
What is the function of the respiratory portion of the respiratory tract?
-pass air to alveoli for gas exchange
What is the larynx?
-short passage for air b/w the pharynx and the trachea
What substance reinforces the walls of the larynx?
- hyaline cartilage
- smaller elastic cartilages
What type of cells are found in the true vocal cords?
- nonkeratinized stratified squamous
- -protects mucosa from abrasions
What is found deep to the true vocal cords?
- vocalis m.
- -allows movement of the vocal folds
What is the trachea?
- short, flexible tube that serves as a conduit for air
- connects larynx to main bronchi
What structure keeps the lumen of the trachea open?
-C-shaped ring of hyaline cartilage
What cell type is found in the trachea?
-pseudostratified ciliated columnar
True or False: the trachea has many submucosal glands
True
What type of cells are goblet cells?
-modified columnar epithelial cells
What is the role of goblet cells?
-synthesize and secrete mucous
What is a histological characteristic of a goblet cell?
-apical cytoplasm contains mucigen granules
Does the trachea have goblet cells?
Yes, numerous!
What cell type is found in the bronchi?
-pseudostratified ciliated columnar
What are histological characteristics of cells in the bronchi?
- shorter cells
- fewer goblet cells
- few submucosal glands
Describe the cartilaginous rings in the bronchi?
- full cartilage rings instead of C-shape in trachea
- transition to irregular cartilage plates
What is the size of the bronchi?
> 1 mm diameter
What is the size of the bronchioles?
< 1 mm diameter
What cell type is found in the conducting bronchioles?
- large: simple ciliated columnar
- small: simple cuboidal
Do bronchioles have cartilage?
No
What are histological characteristics of conducting bronchioles?
- few goblet cells (club cells instead)
- increased elastic fibers
- prominent smooth muscle
What cell type are found in the terminal bronchioles?
- simple cuboidal
- club cells
What are club cells?
- non-ciliated, dome-shaped
- secrete a lipoprotein
- prevents luminal adhesion w/airway collapse
- detoxification by antimicrobial peptides
What type of cells are found in the respiratory bronchioles?
- simple cuboidal
- club cells
What is a histological characteristic of respiratory bronchioles?
- mucosa contain openings to alveoli
- moving distally, alveoli become more numerous and group together
What are alveolar sacs?
-clusters of 2+ alveoli
What are alveolar rings?
-aggregates of smooth muscle, collagen, and elastic fibers that form rings around alveolar ducts
What type of cells are found at the alveolar level?
-simple squamous
–most efficient for oxygen absorption
What are histological characteristics at the alveolar level?
- lots of capillaries
- Type I and Type II pneumocytes
What are alveoli?
-blind-ended sacs lined with pneumocytes
What are alveolar pores?
-small openings that permit movement of air b/w alveoli
What type of cells are Type I pneumocytes?
-squamous
Where are Type I pneumocytes found?
- lining almost the entire alveolar surface
- closely associated w/ capillaries
What is the role of Type I pneumocytes?
-create a surface for gas exchange
What type of cells are Type II pneumocytes?
-cuboidal/rounded
What is the role of Type II pneumocytes?
- secrete surfactant via exocytosis
- precursor for Type I and Type II pneumocytes
What are the components of the Blood-Air Barrier?
- Type 1 pneumocytes
- fused basal lamina
- capillary endothelial cells
Pathology: Asthma
- chronic inflammatory disease
- bronchospasms
-infiltration of bronchiolar wall by eosinophils, lymphocytes, and mast cells
What are histological changes as a result of chronic asthma?
- thick bronchiolar epithelium
- increased goblet cells
- thick basement membrane
- hyperplastic smooth muscle
What are symptoms of asthma?
- wheezing
- dyspnea
- productive cough
Pathology: Emphysema
-permanent enlargement of air spaces distal to terminal bronchiole
- destruction of alveolar walls
- significant loss of gas exchange
What are histological characteristics of emphysema?
- loss of elastic fibers in bronchioles
- - narrower bronchioles
What are the causes of emphysema?
- smoking
- chronic inhalation of particulates
- autoimmune
What are the symptoms of emphysema?
-dyspnea, cough, weight loss
Pathology: Pneumonia
- inflammation of lung tissue
- air spaces filled with fluid exudate containing WBC, RBC, and fibrin
What are histological characteristics of pneumonia?
- red hepatization stage, looks like liver
- enlarged capillaries congested with RBC
What does a lung with pneumonia look like on gross examination?
- red
- firm
- heavy
What are symptoms of pneumonia?
- fever and chills
- productive cough
- decreased breath sounds
- crackles
