Respiratory system Flashcards
Respiratory system
Lungs and airways that link the sites of gaseous exchange with the external environment
2 divisions: Conducting (transport of air) and respiratory (gaseous exchange)
What structures are within the conducting portion of the respiratory system?
Nasal cavity
Internal nares/ paranasal sinuses
Nasopharynx
Larynx
Trachea
Bronchus
Bronchioles through terminal bronchiole
What are the structures within the respiratory portion?
Respiratory bronchiole
Alveolar duct
Alveolar sac
Alveoli
What are the functions of the conducting portion?
Cleaning of air
Humidification of air
Warming/ cooling of air
Olfaction
Phonation (larynx)
What are the functions of the respiratory portion?
Gaseous exchange
Surfactant production- lowers surface tension (clara cells, great alveolar cells)
_______ also excretes volatile gases, alcohol and water
Lungs
Structures keeping airways patent (for inhalation and exhalation)
- nasal cavity (bone)
- trachea (cartilage rings)
- Bronchi (cartilage plaques/ musculoelastic tissue)
- Bronchiole (musculoelastic tissue)
- Alveolar duct (musculoelastic tissue)
- Alveoli (fibroelastic tissue)
Sagittal section of dog’s nasal cavity
Vestibular (cutaneous)
Respiratory
Olfactory
Vestibular (cutaneous part of the nasal cavity)
Alar cartilage support (hyaline)
Stratified squamous keratinized
Hair follicles, sebaceous glands
Respiratory part of the nasal cavity
Pseudostratified columnar with cilia and goblet cells for cleaning air
Sebaceous glands for humidification of air
Venous sinuses for warming/ cooling of air
Turbinate bone labyrinth
Where heavy dust particles are retained
What are the three cells of the olfactory portion of the nasal cavity
Supporting cells
Bipolar olfactory neurons
Basal cells
What are the components of the olfactory part of the nasal cavity
Cilia: non-motile, dendrite of bipolar olfactory neurons
Axons of bipolar neurons: form olfactory nerve
Lamina propria: serous glands (Bowman’s), odor particles dissolved
What does the olfactory cells give rise to?
Olfactory hairs: long non-motile cilia where the distal two thirds of the cilia contain 9 peripheral single microtubules
What do the Bowman’s glands produce?
Watery secretion where odorous substances are dissolved then detected by olfactory cilia
Epithelium of the Oropharynx
Stratified squamous non–keratinized in dogs and cats
Keratinized in ruminants
Nasopharynx
Pseudostratified columnar with cilia and goblet cells
Larynx
Organ of phonation (vocal cords): Pseudostratified columnar to stratified squamous non-keratinized
Cartilage: hyaline, few elastic
Epiglottis
Lingual side: strat. squamous
Pharyngeal side: pseudostrat. columnar in dogs and cats, strat. squamous in ruminants
Elastic cartilage: replaced by fat with age
Trachea and extrapulmonary bronchi
Pseudostratified columnar
Lamina propria and submucosa inseparable
Adventitia has C-shaped hyaline cartilage rings whose dorsal ends are covered by trachialis m.
Components of the Mucociliary apparatus
Pseudostrat. columnar with:
1. goblet cells: secrete mucous which trap dust particles
2. cilia: sweep trapped particles to pharynx where they’re swallowed
Immotile cilia syndrome (Kartagener’s syndrome)
Caused by dynein deficiency
Prone to respiratory infections and are infertile
Cilia runs ________ in the nasal cavity and _________ in the trachea
- clockwise
- anticlockwise
allows trapped particles and mucus to be pushed toward pharynx and swallowed
Intrapulmonary bronchial tree
- Primary bronchus: each lung
- Secondary bronchus: each lobe of lung
- Tertiary bronchus: each segment of lobe
- Primary bronchiole: each lobule of segment
- Terminal bronchiole: gives rise to 3 respiratory bronchioles
- Respiratory bronchiole gives rise to 2-11 alveolar ducts
- Alveolar sacs with alveoli
What happens to bronchus as it goes deeper?
Will decrease in size and have:
Smaller lumen and cartilage
Shorter epithelium
Thicker muscle cells
Fewer glands
How does the bronchiole differ from the bronchus?
No cartilage or glands
Thicker smooth muscles
How is the bronchi different than the trachea?
Cartilage ring replaced by cartilage plates
Smooth muscles cells under epithelium
Muscularis mucosa present
What are the 3 layers of the bronchus?
Tunica mucosa
T. submucosa
T. adventitia
T. mucosa
Pseudostrat. columnar with goblet and cilia
Lamina propria (loose irreg. CT)
Muscularis mucosa (smooth muscle cells)
T. submucosa
Serous glands embedded in loose irreg. CT
T. adventitia
Contains hyaline cartilage plates
Bronchioles
1 mm or less diameter
Respiratory epith. in larger ones, simple cuboidal epith. with clara cells in smaller
Terminal bronchioles
Most distal part of the conducting portion
Less than 0.5 mm diameter
Clara cells, some ciliated cells, no goblet cells
Smooth muscle contraction
In response to allergy/ anaphylactic shock/ asthma leads to dyspnea
Smooth muscle dilation
In response to sympathetic stimulation leads to widening of the air ways
Respiratory bronchioles
Transition from conducting to respiratory portion
Sites of gaseous exchange
Alveolar ducts
Adjacent alveoli separated from one another by intralveolar septum
Smooth muscle cells in walls
Simple squamous with type I and type II cells
Alveoli
Thin walls across which oxygen and CO2 can diffuse between the air and blood
Separated by intralveolar septa
Simple squamous
Alveoli structure
Type 1 cells: gaseous exchange (95%)
Type 2 cells: surfactant production
Alveolar macrophages: phagocytosis (heart failure cells)
When does alveolar macrophages increase?
In patients with congestive heart failure
Cytoplasm filled with hemosiderin
Interalveolar septa
Capillaries
CT cells
Type 1 collagen and elastic fibers (fibroelastic skeleton)
Surfactant
Reduces surface tension of the alveolar surface so alveoli can expand easily during inspiration and are prevented from collapsing during expiration
Respiratory distress syndrome
Life-threatening disorder of immaturely born babies
Surfactant deficiency inversely increases with the gestation age
lack of Type II cells
Air-blood barrier
- Surfactant
- Type 1 alveolar cells
- Fused BM of alveolar epith. and endothelium of capillaries
- endothelial cytoplasm
- Blood plasma
Total thickness: 300 nm
Blood supply
Functional: pulmonary a.
Nutritional: Bronchial a.
