Anatomy of the Respiratory Tract Flashcards
what are the functions of the respiratory tract
- warm and humidify air
- olfaction
- phonation
- storage of blood
- metabolism of air and blood borne compounds
- immune role
what are the three regions of the respiratory tract
- nasopharyngeal
- tracheobronchial
- pulmonary
what regions constitute the upper airway tract
nasopharyngeal (nasal cavity + pharynx)
what regions constitute the lower airway tract
tracheobronchial and pulmonary
what makes up the nasopharyngeal region
nasal cavity and pharynx
function of the hard palate
separates the oral and nasal cavities
concha (turbinates)
folded epithelium that run the length of the nasal cavity
dorsal, ventral, and middle concha
functions of the concha/turbinates
- increase SA of the epithelium
- create turbulent air flow
- humidify air
- filter air
what type of concha are located rostrally
dorsal and ventral
what type of concha are located caudally
middle
meatus
the openings created by the concha that the air passes through (named by the region of the concha)
nasal septum
cartilage that separates the right and left nasal cavities
common meatus
opening around the nasal septum for air flow
vomeronasal organ
located in the nasal cavity (dogs) or hard palate (horses) to detect pheromones
choana
the connection between the nasal cavity and pharynx (nasopharynx)
what type of epithelium is found in the nasal cavity
- squamous epithelium (on the skin of the face as it enters into the nares)
- respiratory epithelium (surrounds dorsal/ventral concha)
respiratory epithelium
pseudostratified, ciliated columnar epithelium
what types of cells (and their function) are in respiratory epithelium
- ciliated cells: move mucus lining along the nose
- mucous cells: produce mucous
- basal cells: stem cell progenitors
olfactory epithelium
specialized epithelium located around the middle concha
olfactory cells
bipolar nerve cells with nuclei located in the middle of the epithelium
extend cilia into the lumen of the airway to detect odor molecules
supporting cells (of olfactory epithelium)
located in the apical segment of epithelium; surrounds the olfactory cell nuclei to provide support
basal cells (of olfactory epithelium)
located in the basal segment of epithelium; progenitor cells for olfactory cells
epiglottis during breathing
epiglottis rests on the soft palate to block the oral cavity from the esophagus
air flows from nasopharynx –> larynx –> trachea
epiglottis during swallowing
epiglottis moves back to block off the trachea
food/water flows from oral cavity –> esophagus
hyoid apparatus
moves the epiglottis to allow for breathing and swallowing
components of the tracheobronchial region
trachea and bronchi
trachea
largest air conducting region; conducts from pharynx –> mainstem bronchi
structural components of the trachea
- C shaped cartilage
- trachealis muscle (covers the opening in the C shaped cartilage)
trachealis muscle species differences
dogs: muscle is exterior to the cartilage
LA: muscle is interior to the cartilage
bronchi
air conducting region that the trachea bifurcates into
structural components of the bronchi
- cartilage islands/plates
- submucosal glands (mucous, serous, both)
mainstem bronchi
R and L branches off of the trachea that enter each lung
present in all species
tracheal bronchus
additional branch off of the trachea that provides air to the right cranial lung lobe
only in pigs and ruminants
cell types in tracheobronchial epithelium
- goblet cells
- ciliated cells
- basal cells
others: serous, brush, neuroendocrine
goblet cell function
secrete the mucous lining (gel) that protects the airways by capturing particles in the air
ciliated cell function
move the mucous lining up and out of the lungs
cilia will beat in coordination with each other to propel the mucous lining
serous cells
produce watery secretions (“sol”) that surround the cilia to allow for free movement
if mucous layer is too thick - cilia would not be able to move
mucous layer floats on top of the serous layer
brush cells
have small micro cilia that detect materials in the airway to regulate airflow
neuroendocrine cells
produce secretions to dilate/contract the airways
components of the pulmonary region
lungs, pulmonary vessels, respiratory bronchioles, alveolar ducts
right lung lobes
cranial, middle, caudal
left lung lobes
cranial and caudal
mesothelial cells
serosal lining of the visceral pleura
produces a watery solution for lung movement
pulmonary arteries and veins
arteries: bring deoxygenated blood from R heart to lungs
veins: bring oxygenated blood from lungs to L heart
immune components of the lung
tight junctions, dendritic cells, LNs in interstitial walls
airway generations
trachea –> bronchi –> bronchioles –> respiratory bronchioles –> alveolar ducts –> alveoli
how does diameter and cross sectional area change across airway generations
diameter decreases
cross sectional area of airway increases
conducting zone
trachea + bronchi + bronchioles
only function is to conduct air (NO gas exchange)
how to differentiate components of conducting zone
trachea: C shaped cartilage and trachealis muscle
bronchi: cartilage plates and submucosal glands (mucous and serous)
bronchioles: no cartilage or submucosal glands (NO mucous - overproduction would cause mucus plugs)
what cell types (and their functions) are present in bronchioles
club cells: produce watery secretions
ciliated cells: moves water secretions
transition zone
respiratory bronchioles only
air conduction AND gas exchange
NOT present in horses (terminal bronchioles open directly into alveolar ducts)
respiratory bronchioles
similar to bronchioles (no cartilage or submucosal glands) but have outpocketings of alveoli
respiratory zone
alveolar ducts + terminal alveoli
gas exchange ONLY
pulmonary acinus
site of all gas exchange
does NOT connect with other pulmonary acini
includes structures below the terminal bronchioles (respiratory bronchioles and alveolar ducts)
alveolar ducts
channels completely lined by alveolar outpocketings
(every alveoli opens into either a respiratory bronchiole or alveolar duct)
why is a high surface area of alveoli required
allows for rapid gas exchange
alveolar septa
walls surrounding the alveoli that allow for gas exchange
contains a capillary bed that brings deoxygenated blood into the lung for oxygenation
thin vs thick septal wall
thin: site of air to blood interface; type I alveolar cells
thick: contains collagen and elastin to maintain structure; type II alveolar cells
septal tip
forms the mouth opening around the alveolus; forms scaffolding
type I alveolar cells
thin, single nucleated cells that make up the gas exchange surface
fried egg appearance
type II alveolar cells
cuboidal cells that secrete the fluid that lines the alveoli (lamellar body)
lamellar body
gets secreted onto the alveolar surface and unravels to form a thin layer of pulmonary surfactant
function of pulmonary surfactant
reduce surface tension in the lungs to keep small alveoli open
alveolar macrophages
phagocytic cells that maintain sterility of the lungs
what does successful embryonic lung development require
- proper structural maturation
- surfactant development
basic embryonic lung development
- laryngotracheal groove
- forms respiratory diverticulum
- forms lung buds
- forms lung lobes
what two embryonic dermal layers are involved in lung development
- splanchnic mesoderm
- endoderm
splanchnic mesoderm
forms the outer layer of the laryngotracheal tube and lung buds
becomes smooth muscle and cartilage layers
endoderm
forms the inner layer of the laryngotracheal tube and lung buds
becomes the epithelium and submucosal glands
periods of lung maturation
- pseudoglandular period
- canicular period
- terminal sac period
- alveolar period
pseudoglandular period
formation of terminal bronchioles via branching
(NO respiratory bronchioles or alveoli yet)
goblet cells and smooth tissue around large airways forms
simple columnar epithelium
canicular period
terminal bronchioles branch into 2+ resp. bronchioles, which divide into alveolar ducts
capillary network begins developing
type I and II alveolar cells form
cuboidal epithelium
terminal sac period
terminal sacs (primitive alveoli) form and capillaries establish contact
proliferation of alveoli
alveolar period
occurs AFTER BIRTH
mature alveoli develop capillary contact
at what point can an animal be born premature and still survive
terminal sac period
what period is required for maturation of the lungs
alveolar period - need blood flow through lung for maturation to occur
