Flipped Class Respiratory System Flashcards
What are the functions of the respiratory system?
- Olfaction
- Olfactory mucosa in nasal cavity
- Phonation
- Vocal folds
- Conduction and conditioning of air
- transport of air to respiratory portion
- Warmth
- Air clearance
- Gaseous exchange :
- Respiratiry portion—> blood-gas barrier
- Endocrine—> hormones
- Neuroendicrine cells
- Immune functions
- Bronchial associated lymphoid tissue
- Alveolar macrophages
Describe the vestibule of the nasal cavity
Cartilage framework
Stratified squamous epithelium (skin)
-short firm hairs(“vibrissae”)
-sweat and sebaceous glands
-Glands and vibrissae trap large particlesDescribe the respiratory region of the nasal cavity
-Respiratory epithelium (pseudostratified, columnar, ciliated, with Goblet cells)
-Lamina propria
-Vessels (capillaries) lined up perpendicular to the airflow—>warms the air.
Clinical correlate: nasal congestion
-Turbinates—> increase the surface area covered by respiratory mucosa
Summarize the olfactory region
Found at the roof of nasal cavity and the superior nasal conchae
Lined by psuedostratified columnar epithelium with four cell types
What are the effects of rhinitis?
Allergic reactions or viral infections (e.g. common cold)—> Rhinitis/coryza( inflammation of the nasal mucous membrane)
Capillaries that reside near the surface of the Lamina propria become engorged —> Lamina propria becomes distended with fluid—> marked swelling of the mucous membrane —> restriction of the air passage—> breathing difficult
What are the features of olfactory receptor cells?
Histolog8cql features:
-longboard thin nonmotile cilia with odor receptors
Axons from the olfactory nerve
Function: bipolar neurons
What are the features of Brush cells?
Histological features:
-Columnar and extend to the Apical surface (basal surface synapses with nerve fibers)) Short microvilli
Function- Sensory receptors
What are the features of supporting cells?
Histological features:
- Apical microvilli
- Mitochondria ++++, sER and rER
- Secretory vesicles—> contain odorant binding protein OBP
Function: mechanical and metabolic support
Helps in odor perception
What are the histologicak features of the basal cell?
Histological features:
-nuclei form a row in close proximity to the basal lamina
Function: regenerate supporting and olfactory receptor cells
What are the structures of the olfactory regions?
Serous olfactory glands/ Bowman’s glands have their secretory units in the Lamina propria
- Acinar cells have lipofuscin granules
- Serous secretion—> lysozyme and IgA
What is the larynx ?
Skeleton of hyaline and elastic cartilages
Function: air condition and phonation
What are the layers of the trachea?
- Mucosa:
- RE- respiratory epithelium
- Lamina propria- loose connective tissue
- Longitudinal elastic fibers in deep LP - Submucosa:
- loose connective tissue
- seromucous glands - Cartillaginous layer
- C-shaped hyaline - open posteriorly “Gap” between free cartilage ends is completed by a fibroelastic membrane and Trachealis muscle (smooth) - Adventitia
- Connective tissue-binds trachea to adjacent structures
Describe respiratory epithelium
Pseudostratified
Lines most of the conducting part of the respiratory system and has five cell types: ciliated columnar, mucus, brush, small granule and basal
What are the features of ciliated columnar Cells?
Histological features:
Columnar and extend to surface about 250 cilia each
Function: sweeping motion helps expel particles trapped in mucus
Clin8cal notes: primary ciliary dyskenesis in Kartegener’s syndrome
What are the features of mucus?
Histological features: short blunt microvilli
Function: secretes mucin granules which forms a protective barrier
Clinical notes: increased in smokers and chronic inflammation
What are the features of small granule or Kulchitsky?
Most numerous at bifurcation of primary bronchi
Basal granules
Function: enteroendocrine cells
Secrete Catecholamines, ADH, ACTH, serotonin and bombesin
Clinical notes: primary cells affected in small cell carcinoma of the lung
What are the features of Basal cells?
Histological features: near basement membrane
Function: stem cells that regenerate all other cell types
What are the features of brush cells in respiratory epithelium?
Histological features:
Columnar and extend to the Apical surface short microvilli
Function: synapse with afferent nerves—> Sensiry function
What is the mucociliary escalator?
Ciliary beating moves particles trapped in mucus towards the pharynx
Clinical correlate: kartegeners syndrome
Give an overview of the bronchi
Primary or main bronchi are structurally like trachea
Primary bronchi—> 2-3 secondary/lobar bronchi—> total 8- 10 tertiary/segmental bronchi per lung
Segmental bronchi supply a bronchopulmonary segment
Bronchi can also be classified as:
A. Extrapulmonary
B. Intrapulmonary: surrounded by lung tissue
Summarize the structure of bronchi
Mucosa: respiratory epithelium
Muscular layer: Spirally oriented smooth muscles in—> regulates the airway diameter
Submucosa: loose connective tissue with sero-mucus glands (GI) in larger bronchi
Cartilage layer:
- Extrapulmonary bronchi: cartilage rings
- Intrapulmonary bronchi-cartilage plates
Adventitia: connective tissue in the extrapulmonary part then surrounded by lung tissue in intrapulmonary broncho
What is chronic bronchitis?
-Associated with smoking, inhalation of toxic fumes and exposure to heavy air pollution
Clinical: chronic productive cough and positive history
On examination wheezing, cyanosis—> blue bloater
Chronic irritation—> inflammatory changes—> metaplasia
Shows thickened basement membrane
Hypertrophy of smooth muscle
Increased glands >50% of the wall
Explain the squamous metaplasia of respiratory epithelium
Columnar to squamous metaplasia of the respiratory epithelium
-Basal cells generate squamous cell
- Smoking: loss of ciliated cell activity—> cough —> metaplasia
- Bronchitis, bronchiectasis—> chronic cough—> metaplasia
- Metaplasia—> squamous cell carcinoma
Give an overview of bronchioles
Diameter is 1 mm or less
Larger (regular) bronchioles—> terminal bronchioles —> respiratory bronchioles
Epithelium
-Large bronchioles: Ciliated, psuedostratified columnar that transition into simple ciliated columnar (Goblet cells present)
-Smaller bronchioles (terminal and respiratory ): simple cuboidal with secretory club cells interspersed among ciliated cells (No goblet cells)
No subepithelial cells
-Smooth muscle replaces cartilage plates (branching points may contain small elements of cartilage)
Widespread construction in the bronchioles, decrease diameter and increases resistance to airflow
Explain the structure-function 9f club cells in bronchiol3s
Club cells (Cc) are bronchioles exocrine cells
- Secretes:
- surfactant active agent
- club cell protein - CC16–> marker for the disgn9sjs of chronic lung diseases- leaks across blood gas barrier in lung injury—> elevated in serum
- decreases in bronchi-alveolar lavage
- Detoxification
- Stem cells
Explain the pathophysiology of bronchial asthma
Inflammatory airway disease
-Main symptoms are short breath, wheezing and coughing
Pathophysiology- Airway obstruction -increased mucus -increased smooth muscle contraction -Bronchiolar wall inflammation
How is bronchial asthma?
Albuterol (B2 agonist), anti cholinergic medications which relax the smooth muscles
Corticosteroids—> anti-inflamnatory
Explain cystic fibrosis (Mucoviscidosis)
Autosomal dominant disorder recessive disorder
Mutation in CFTR gene- encodes for epithelial Cl- ion channel protein (causing defective/absent Cl ion transport and abnormal exocrine gland secretion - typically increased viscosity of secretions with obstruction of excretory ducts)
In lungs leads to ‘mucociliary escalator’ dysfunction
-accumulation of unusually thick, viscous mucus
- bronchiolar obstruction (with subsequent bronchiolar wall thickening and alveolar degeneration)
- frequent respiratory tract infections
What is the significance of respiratory bronchioles ?
Forest sites where gaseous exchange take place
Transitional zone (involved in BOTH ‘air comfuction’ and ‘gas exchange’)**
- Supported by a small amount of smooth muscle and elastic fibers
- Walls are interrupted by alveoli
- Simple cuboidal epithelium with ciliated and Club cells proximal to TB but predominantly Club cells distally
Simple cuboidal epithelium with ciliated and club cells
Smooth muscle plates
What is the significance of alveolar ducts?
Respiratiry bronchioles transition into alveolar ducts as the number of alveolar out-pouching’s increase.
Alveolar ducts are lined by numerous alveoli
Bundles of smooth muscle cells found between alveolar out-pocketing (interalveolar septum)
What is the significance of alveolar sacs ?
Alveolar ducts terminate into alveolar sacs
Several alveoli will open into a single alveolar sac
Alveoli are thin-walled polyhedral terminal sacs where gaseous exchange takes place
-Alveoli are separated from each other by an interalveolar septum
-Cell types: Macrophages, type 1, and Type 2 pneumocytes
What is the function of dust cells?
Alveolar macrophages or dust cells move freely between the interstitial tissue and alveolar surface
- Phagocytosis of inhaled particles as well as degrade surfactant
- In septum dust cells are frequently observed loaded phagocytizes material:
- RBCs in heart failure-heart failure cells
- asbestos particles in asbestos
What is the function of type 1 pneumocytes?
- Squamous cells which line 95% of alveolar surface
- Terminal cells not capable of mitosis
- Surface is covered by surfactant
- Form tight junctions with adjacent type II and type 1 cells- firm part of the blood-air barrier
What is the function of type 2 pneumocytes ?
- Cuboidal cells which secrete surfactant
- Found at the septal junctions—> AKA septal cells.
- Most numerous but cover only 5% of alveolar surface
- Apical lamellar bodies—> foamy appearance
- Stem cells for both type 1 and type 2 cells
What is the function of alveolar surfactant?
Reduces the alveolar surface tension at the air-epithelium interface (pr3vents alveolar collapse during exhalation)
What is the composition of alveolar surfactant?
- Phospholipid- Dipalmitoyl phosphatidylcholine (DPPC)—> principal agent responsible for reducing surface tension
- Surfactant proteins (SP)
SP-A: most abundant, regulates synthesis and secretion of surfactant and modulates immune response to microorganisms
SP-A and SP-D: regulates the allergic response to airborne antigens
SP-B and SP-C: regulates spreading of surfactant
Adequate amount of surfactant is produced after 35th week of gestation
Regulated by cortisol, insulin, thyroxin, and prolactin
What is the clinical correlate of alveolar surfactant ?
Premature infants especially <28 weeks old
Management: exogenous surfactant at birth
Glucocorticoids to the mother with possible preterm delivery a few days prior
Describe the interventricular septum
Contains
Collagen fibers
Elastic fibers—> pulmonary recoil
Continuous capillaries
Permanent and transient cells
Site of the air-blood barrier
Adjacent alveoli communicate through alveolar pores (of Kohn) which allows collateral airflow
What is pneumonia?
Air spaces filled with exudate containing white blood cells (mainly neutrophils), red blood cells, fibrin
Capillaries in the interalveolar septum are enlarged and congested with red blood cells
What are the parts of the thin portion of blood gas barrier?
Most. Effective blood-air barrier
- Surfactant
- Type 1 pneumocytes
- Fused basal lamina of P1 and capillary endothelium
- Endothelial cells
What are the composition of the thick blood gas barrier?
- Surfactant
- Type 1 pneumocytes
- Basal lamina of P1
- Connective tissue elements
- Basal lamina capillary endothelium
- Endothelial cells
Explain emphysema
Characterized by a permanent enlargement of respiratory spaces affecting airways distal to the term8nal bronchioles
-Neutrophils release proteases including elastance—> breaks down elastic fibers
Serum. Alpha 1 antitrypsin (AAT) counteracts elastase activity
Smoking elevates neutrophils activity—> elevated elastase—> destruction of elastic fibers—> permanent dilation of airways
Give the pathophysiology of different lung cancer types?
Small cell lung cancer- associated with smoking
Non small cell lung cancer -small cell carcinoma- associated with smoking
Adenocarcinoma-most common in non smoking women
Give the origins of lung cancer types
Small cell lung cancer (oat cell carcinoma)-Neuroendocrine cells. Cushing syndrome due to ACTH secretion
Non small cell lung cancer (SCC)- squamous metaplasia of respiratory epithelia. Eosinophilic keratin pearl lesions—> see SCC of larynx
Adenocarcinoma- bronchial, bronchiolar and alveolar epithelium—> bronchoalveolar carcinoma or bronchigenic. Glandular tumor
What are the characteristic features of different types of lung cancers?
Small cell lung cancer (oat cell carcinoma)-central mass, aggressive often metastasized when diagnosed
Non small cell lung cancer- SCC-central mass
Adenicarcinoma-peripheral mass
As conduction system becom3s respiratory zone…
Decrease in goblet cells
Support carried out by cartilage—> smooth muscle—> elastic and reticular fibers
Where is respiratory epithelium found?
Nasal cavity, trachea, bronchi,
Where are simple squamous epithelia (pneumocytes) found?
Anyth8ng that has alveolar in it, including capillaries
What is the respiratory zone ?
Respiratory bronchioles
Alveolar ducts
Alveolar sacs
Alveoli
What is the conducting zone?
Nasal cavity
Larynx
Trachea
Bronchi
Bronchioles
Term8nal bronchioles
